Research on Design Method of Product Functional Hybridization for Integrated Innovation

Abstract

Product hybridization design is a new model of integrated innovation. Existing methods of product hybridization design focus on technological recombination, and there is a lack of research from the perspective of function. Therefore, this paper proposes the concept of functional product hybridization. Obtaining goal products and fusing the existing product function systems are two keys to implementing product functional hybridization. However, existing functional integration methods acquire goal products too widely, and there is less research on fusing product function systems. In this paper, a scenario analysis model based on the divergence tree is established by combining scenario analysis and the divergence tree, and three paths of goal product prediction for functional hybridization are proposed. Based on the idea of biological gene recombination, a product gene model and a method of product gene recombination for functional hybridization are studied. Moreover, integrating the Theory of Inventive Problems Solving (TRIZ), a method of establishing a concept structure is proposed. On this basis, a process model for product functional hybridization design is established. An example of a new tree-planting machine illustrates the application of the proposed model. The proposed method enriches the theory of product hybridization design and achieves the fusion of product function systems to meet the multi-functional needs of users.

1. Introduction

With the globalization of the economy, competition among enterprises is intensifying. In order not to be eliminated in the fiercely competitive environment, enterprises are eager to quickly produce innovative products with high quality and low cost [1,2,3]. Integrated innovation is the process of creatively integrating product design elements based on existing resources to develop a new product that meets the needs of users [4]. Integrated innovation provides a new and effective way to meet the innovation demands of enterprises [5].

In nature, biological hybridization integrates desired dominant biological traits into offspring to improve the economic benefit of organisms and promote species diversity [6,7]. Taking advantage of biological hybridization, product hybridization design has become a new approach to integrated innovation. Product hybridization design is the process of improving the technical performance of products or forming completely new products by integrating the advantageous characteristics of existing products. The traditional process of product hybridization design focuses on technological recombination. Based on breaking the original technology portfolio, a new technology system is formed by recombining the new technology with several technologies in order to improve its technical performance. The product is the carrier of the function, and technology is the means and methods that can realize the function according to certain principles. Therefore, product hybridization design can be implemented in two dimensions: function and technology. However, there is a lack of research on product hybridization from the aspect of function. Therefore, the concept of product functional hybridization is proposed in this paper.

Current research on function-based integrated innovation focuses on functional integration. Functional integration is the process of integrating several existing functions to form a new product to meet user needs. The existing literature has mainly studied the methods of functional integration from three aspects: functional decomposition, functional combination, and functional solution. Product functional hybridization focuses on the fusion of different existing product function systems. Similar to biological hybridization, there are two critical problems that need to be addressed to realize product functional hybridization: the first is how to acquire the product to be hybridized, which is called the goal product in this paper, and the second is how to fuse multiple product function systems to form a new product concept structure. However, existing functional integration approaches cannot fully achieve product functional hybridization. Therefore, it is necessary to find a systematic approach to achieve product functional hybridization.

In summary, a concept of product functional hybridization is proposed in this paper. To solve the two critical problems of product functional hybridization, firstly, a method for obtaining goal function hybridization products is established in this paper. Scenario analysis and the divergence tree are used in this method to obtain scenario-related products from the three perspectives of the action objects, people, and objects. On this basis, goal products can be acquired. After that, learning from the idea of biological gene recombination, a method of constructing a conceptual structure is proposed to achieve the fusion of product function systems. In this approach, product genes can be recombined by constructing the product gene model and the product genome, and the problems in the process of recombination can be solved by the Theory of Inventive Problems Solving (TRIZ) [8,9]. Finally, a process model for product functional hybridization design is developed by combining the above methods.

The rest of this paper is organized as follows. Section 2 presents the development status of product hybridization design, functional integration, and product genes. Section 3 introduces the proposed concepts and the process of functional hybridization design, including the acquisition of goal products and establishing the product concept structure. Section 4 presents the design process of the new tree-planting machine to prove the proposed approach. Section 5 concludes this paper.

2. Related Research

2.1. Product Hybridization Design

The idea of integrated innovation can be traced back to the innovation theory first proposed by Joseph Schumpeter in 1912 [10]. He considered innovation as “the creation of a new production function”, i.e., the realization of a new combination of production factors and production conditions. This new combination included the following five forms: introducing a new product, introducing new technology, opening a new market, controlling new supply sources of raw materials, and achieving new organization for the industry. Integrated innovation is the process of optimizing, matching, and integrating new design elements to improve the overall system performance. Integrated innovation includes product integration, integration between the product and service, process integration, method integration, etc. Integrating the advantageous features or technologies of other existing products with the prototype product [4,5] to meet user needs belongs to product integration. Product–Service Systems (PSSs) [11] are the integration of a product and service, which can provide solutions that meet the needs of end customers and help reduce resource consumption and environmental impact. In addition, the integration of products with digital services [12,13] that use Internet of Things technologies can enable business model innovation [14]. Biological hybridization is the mating between individuals in different groups. It is the process of matching the genes of each parent together to create new and more favorable genotypes. Biological hybridization can increase genetic variation and create characteristics that the parents do not originally have to promote the adaptation and persistence of the organism [15,16,17]. Taking advantage of biological hybridization and based on product integration, many scholars have proposed methods of product hybridization to achieve integrated innovation.

Zhou [18] defined hybridization integration as the hybridization of new knowledge, advanced technical methods, and new properties to form a dominant system with new properties or improve the properties of the original system. Prushinskiy et al. [19] proposed product hybridization as the process of integrating the advantages of competitive products to form a new product. Fayemi et al. [20] proposed that product hybridization is a means of technological system evolution. Litvin [21] proposed that product hybridization design is the process of integrating products with complementary technologies. Liu et al. [22] defined technology hybridization as the process of recombining technological bases to achieve integration between product technology properties. Aiming at product family design, Luo et al. [23] hybridized the obvious factors with scenario factors to produce new products. Gunasekaran et al. [24] hybridized the solar subsystems with the Advanced Zero-Emissions Power (AZEP) cycle to achieve solar–thermal hybridization in AZEP, resulting in high incremental solar efficiency. Prushinskiy [25] applied hybridization to flexible display devices, which improved their attractiveness for potential demand. Stein et al. [26] and Wang et al. [27] hybridized certain features of subsonic and transonic airfoils to develop a new hybrid airfoil, which improved the lift of an aircraft. Yang et al. [28] proposed a design process for product hybrid configuration based on the backcross theory for the design of large-scale container cranes. Cao et al. [29] proposed an integrated hybrid design based on biological genetic engineering that effectively combined hybrid integration with gene fragment recombination to achieve the rapid design of mechanical products. He et al. [30] proposed a hybrid technology of product morphological genes to improve the comprehensive performance of the products.

The above studies for the concepts, processes, and engineering cases of product hybridization were mainly from the perspective of technology. Moreover, these studies focused on the technological recombination of products. Multiple technical elements of the product (form, material, structure, principle, etc.) are recombined to achieve technical optimization and further satisfy users’ needs. Product function is the essence of user needs, and the product is the carrier of realizing the function. The real purpose of buying a product for consumers is not the product itself, but the functional value of the product, while the product performs the function based on certain technologies. Therefore, product hybridization design can be implemented in two dimensions: function and technology. Product hybridization based on the function can be helpful for achieving the fusion of existing product function systems and meeting the multi-functional needs of users. However, the existing literature includes less research on product hybridization from the perspective of function.

2.2. Functional Integration

Functional integration is the method of integrating multiple functions to form a new multi-functional product. It can improve the overall performance of the product function system to adapt to changes in the market and environment. Based on analyzing the evolutionary process of product function systems, Liu et al. [31] proposed a function combination pattern of existing products for integrated innovation. In this pattern, potential customer needs were obtained by analyzing products that had similar, opposite, or different functions from the prototype product. However, it did not provide a specific process for searching products. Liu [32] constructed a multi-domain knowledge-acquisition method based on the function-oriented search to achieve function fusion. The scope of function acquisition mainly covers patent databases. Kalyanasundaram et al. [33] proposed a function-based product integration approach. A function-sharing matrix and a component-sharing matrix were created based on the reconfigurable principle to identify the shared functions and components of two products. After that, a new product was obtained by combining the functional structure of the integrated product. The approach focused on assessing the feasibility of integrating two existing single-state products to produce a new reconfigurable or multifunctional product, and it did not describe how to obtain the integrated product. Jiang et al. [34] presented the establishment of a functional combination matrix to innovatively form various products and enrich the product system through the combination and collocation of functions. However, in this method, functions were known, and there was no process to acquire new functions. Cao et al. [35] proposed a design process for function combination. In this process, the product function was decomposed to analyze the combination relationship between the sub-functions, and the function combination solution was selected according to the market demand. This process mainly focused on the recombination of the product’s own functional resources. Lu et al. [36] proposed a function combination method for conceptual design based on the functional structure and design matrix to combine multiple product functions into a single product. The method mainly analyzed the functional redundancy in the process of functional combination. Hou et al. [37] and Wang [38] proposed functional recombination methods for the integration of multi-biological effects and biological features, which were mainly aimed at solving and improving functions. Klaiber et al. [39] described four generic strategies of functional integration derived gradually from differential designs. This study used different strategies to generate solutions in a systematic way. Moreover, these strategies were proposed to save weight, cost, and time for assembly and gain more installation space. To reduce the complexity of the design task, Frohlic et al. [40] presented an approach for multi-functional design. The method aimed to achieve different functions in a single structure that could be applied to the process of developing multi-functional components.

Product functional hybridization is the utilization of existing resources. Obtaining the required goal products and achieving the fusion of existing product function systems are two keys to facilitating product functional hybridization. In the above literature, there are fewer studies on how to obtain the goal products. They mainly gained the goal products by means of functional search under the premise of obtaining the user’s functional requirements. However, the scope of acquisition is wide, and the number of goal products generated is high. Thus, a problem that the goal products are not highly applicable and not strongly related to the prototype products arises. Product functional hybridization requires the creative fusion of design elements to achieve complementary advantages. However, the existing functional integration methods mainly adopted the approach of functional combination to recombine the product’s own functional resources, solve the problem of functional redundancy, seek solutions to the function of the prototype product, etc. There has been less research on how to fuse existing product function systems.

2.3. Product Gene

In biology, gene recombination is used for biological hybridization to produce new varieties. Genes are the basic genetic units controlling biological traits and store the whole information of processes such as race, blood type, conception, growth, and apoptosis of life. With the cross-integration of various disciplines, product genes were inspired by the ideas of biological genes or genetic engineering. Product genes are heritable knowledge about a product’s function and means of achieving that function, and determine the basic traits of the product. Inspired by biological hybridization, product genes are used in this paper to assist in product functional hybridization design.

Many scholars have studied product genes from different perspectives. Chen et al. [41] defined product genes as the characteristic information of relevant principal solutions from the perspective of product functional representations, which are used to index principal solutions. Chen et al. [42,43] defined virtual genes as some genetic and/or evolutionary information in the virtual chromosome that affects a product’s performance. Moreover, a genetic engineering-based innovation design approach was proposed to innovate products. Tai et al. [44] considered the product gene as the basic unit of information that determines a product’s characteristics. A method of product gene representation and acquisition was proposed based on product case clusters to solve the problem of difficult acquisition of design knowledge. Li et al. [45] considered product genes as the critical form of product information that determines the nature of the product and influences the conceptual design process. An intelligent product-gene-acquisition method based on K-means clustering and the mutual information-based feature selection algorithm was proposed to obtain product genes. Gu et al. [46] considered product genes as the basic information units in the process of the transplantation, expansion, reproduction, and proliferation of products in time and space, and an information model for product genes was established. In view of the principal solution, Feng et al. [47] considered product genes as functional knowledge that can be inherited. Meanwhile, a conceptual design framework based on product genetic inheritance and recombination was established, which was helpful for achieving principal innovation in the conceptual product-design stage. Liu et al. [48] proposed an approach for product gene expression based on physical units. A variant design model based on product genes and physical expression was formed that could improve the innovation level of the product. Li et al. [49] defined product genes as an information collection of verbs and attributes in the process of functional expression. In addition, they presented a conceptual design method based on product genes that could make the key product information explicit.

The above studies focused on the representation, acquisition, and application of product genes in terms of conceptual design. In these studies, the purpose of acquiring or representing product genes was to find the principal solution that could achieve the function, while this paper focused more on using product genes to realize the fusion of existing product resources. Therefore, a new model of product genes for product functional hybridization is proposed in this paper.

2.4. Summary of the Literature Review

The above discussion shows that product hybridization design is a mode of integrated innovation that is under constant development. Based on the analysis of the research status, it can be studied from the aspect of function to achieve product hybridization. In response, the concept of product functional hybridization is proposed in this paper to enrich the existing theories. The existing research methods cannot fully realize product functional hybridization. Therefore, a method of obtaining the goal products for functional hybridization is proposed with the scenario analysis and the divergence tree in this paper. In addition, based on the idea of biological genetic recombination, a product gene model is established and a method of establishing a product concept structure is proposed. Consequently, a product functional hybridization design approach for integrated innovation is established to systematically achieve product functional hybridization.

3. Proposed Methods

3.1. Concept of Product Functional Hybridization

Products are evolving toward an ideal solution. The degree of idealization can be measured by Equation (1). The equation shows that the idealization degree of a product can be improved in two ways: adding useful functions and reducing harmful functions. Useful functions can be both the main function and secondary functions of the product. Adding secondary functions that meet the user’s needs for the existing product function system is mainly aimed at improving the product’s function system. A new product with multi-functional properties can be obtained by integrating the main functions of different products. This process is similar to the biological hybridization process, which is called product functional hybridization in this paper.

$$i=\frac{\mathsf{\Sigma }UF}{\mathsf{\Sigma }HF}$$

(1)

where i (ideality) is the idealized level, UF denotes useful functions, and HF denotes harmful functions.

According to the genetic relationship of hybrid parents, biological hybridization can be divided into intraspecific hybridization and distant hybridization. Distant hybridization can combine the biological properties of different individuals belonging to different species, genera, and other distant genetic relationships to expand genetic variation and create new strains with superior traits [50,51,52]. Intraspecific hybridization is the interbreeding of organisms of the same species, including intra-varietal hybridization between different individuals within the same varieties and inter-varietal hybridization between different varieties within the same species [53]. Similar to biological hybridization, product functional hybridization can be divided into intraspecific functional hybridization and distant functional hybridization.

Intraspecific functional hybridization involves integrating the main functions of family products to form a product with multi-functional properties, as shown in Figure 1. Product evolution is the process of the product core technology evolving from a low to a high level. The development of technology is accompanied by the evolution of products. Therefore, a series of products based on the same core technology form a product family. The evolution of the product represents the gradual enrichment of product families on the one hand and the improvement in the product family’s performance on the other. It can be seen from the process of technological development that, in the time domain, all product families followed the S-curve. The products in the product family had the same core technology, but could meet different user needs. A functional hybridization product that meets a user’s multi-functional requirements can be obtained by integrating several products that achieve different functions in a product family. With the emergence of the new core technology, a new S-curve of product families is formed. After that, a new function hybridization product can be generated.

Distant functional hybridization involves integrating the main functions of products in different fields to form a product with multi-functional properties, as shown in Figure 2. Products in different fields evolve along their own S-curves. A new function hybridization product is formed by integrating the main functions of two products in different fields. As the two products evolve further, a new function hybridization product can be formed, causing the function hybridization product to continuously evolve. Distant functional hybridization is not limited to two products. It also allows the simultaneous or sequential hybridization of multiple products.

The evolution of the product is divided into four stages: infancy, growth, maturity, and exit. The stage in which the product is located can be judged by predicting the technology maturity [54]. Products in different evolutionary stages should adopt different innovation strategies. The innovation strategy of products in the infancy and growth stages is mainly to improve their technical performance. However, there are fewer benefits to be gained by improving the product’s performance further for products in the maturity and exit stages. For this, it is necessary to seek new technology systems to obtain new products. Products with multi-functional properties can be obtained through function hybridization to meet the needs of different customers and increase the market share of the products. Therefore, product functional hybridization design is suitable for products in the maturity stage.

3.2. Method of Acquiring Goal Products Based on Scenario Analysis and the Divergence Tree

Acquiring goal products is the key to successfully implementing product functional hybridization. The prerequisites of product functional hybridization are different products that meet the multi-functional needs of users in the same scenario at a certain moment. Such products are called scenario-related products in this paper.

The term “scenario” was first proposed by Kahn. Based on the diversity and uncertainty of the future, the possible future and the paths to achieve it constituted the scenario [55]. In subsequent scenario studies, the concept of the scenario was continuously enriched [56,57,58]. The uncertainty and foresight of the scenario make it widely used for future-oriented projections and representations of state processes [59]. In product design, scenario analysis is used to analyze interactions between users, product systems, environments, and activities to simulate scenarios that the product may encounter in the future [60,61,62]. In scenario analysis, design requirements can be predicted by reasonably changing the objects, users, environment, and activities. However, the development of scenarios is random and may deviate from the design theme, which may lead to the production of unreasonable ideas.

In order to design reasonable scenarios, the divergence tree in extenics is used in this paper [63,64,65]. The divergence tree is a way to stimulate designers to generate problem solutions based on the divergence of objects. Specifically, based on establishing an extension model of objects, the extension model was extended according to the divergence rules to obtain multiple innovative ideas.

A scenario analysis model based on the divergence tree was established by combining scenario analysis with the divergence tree, as shown in Figure 3. In the scenario analysis process, the people, environment, activities, and products were separately extended by applying the divergence tree to drive scenario development.

Based on establishing a scenario analysis model of the product, three paths of goal product prediction for functional hybridization are proposed. By extending the relevant elements, designers are stimulated to acquire scenario-related products. After that, goal products can be identified through product evaluation.

3.2.1. Goal Product Prediction Based on Extending the Action Object

What consumers buy is the function of the product, rather than the product itself. The product function directly reflects the relationship between the product and action object, and produces the action result required by the user. From the viewpoint of the action object, multi-functionality directly reflects the change in the characteristics of the action object. Therefore, extending the action object is a powerful way of acquiring scenario-related products. Product functions form the basis of the activity elements in scenario analysis, and the direct change in the action object is an important factor driving scenario transformation. By extending the action object-related features and extending to other action objects, different activities can be constructed to drive the transformation of the scenario. The specific action relationship is shown in Figure 4.

In order to acquire scenario-related products, the divergence tree is used to extend the action object of the prototype product. The characteristics transformation of the input/output of the product action object is the external performance of the product’s function. Some object features are changed in the process of achieving a function. In this paper, these object features are called function-related features. The action object has multiple features, and the features other than the function-related features are called function-independent features. In addition, some action objects with the opposite functional characteristics of the action object can meet the opposite needs of people. These action objects are called inverse objects. Therefore, the action object is extended from three perspectives: function-related features, function-independent features, and inverse objects, in this paper. A model for extending the action object based on the divergence tree is proposed, as shown in Figure 5.

3.2.2. Goal Product Prediction Based on People

In the same environment, people interact with the product to accomplish different activities. People will exert different functional demands on the product in different environments. Therefore, based on putting people at the center, it is possible to acquire scenario-related products by extending the activities and environment. The scenario-related product acquisition model based on people is shown in Figure 6, with Figure 6a showing the expansion of activity and Figure 6b showing the expansion of the environment. In this model, the two elements of the user and product are fixed. According to the interaction between the user and product, the activity or environment elements can be extended with the divergence tree to predict different functional requirements of the product. Thus, scenario-related products can be acquired.

3.2.3. Goal Product Prediction Based on the Object

Product functional hybridization is the process of creatively fusing different functional systems to form a product with multi-functional properties. Therefore, it is allowed to extend from the product itself, i.e., in terms of objects, to acquire scenario-related products. The scenario-related product-acquisition model based on the object is shown in Figure 7. The product is placed in the center. Then, scenario-related products can be obtained by extending the products and users. As a result, it can be performed in terms of both behavior-related products and different user populations.

Relevance of product behavior means that there is an interactive relationship between the products; for example, the products cooperate to accomplish a task together. In order to save time, improve efficiency, etc., such products can be hybridized to form multi-functional products. By analyzing the product function, the main activity of the product can be identified and a scenario analysis model of the product can be built. After that, according to the main activity of the product, the scenario can be converted by extending toward related behaviors to acquire scenario-related products.

When using the products, different populations may have different requirements for the use of the same product. In order to meet the different functional needs of these populations, different functions can be fused through functional hybridization to form products with multi-functional properties. Different populations have differences in characteristics, such as gender, age, and preferences. Therefore, it is possible to build different scenarios and acquire scenario-related products by extending these characteristics.

3.3. A Method of Establishing a Product Concept Structure Based on Product Gene Recombination and TRIZ

The functional hybridization process is not a simple superposition of two products—it is more focused on the fusion of systems. In this paper, based on the idea of biological genetic recombination, a product gene model is constructed and the product gene is reorganized by combining the TRIZ theory to fuse the system.

3.3.1. Product Gene Model

The product gene (PG) is a unit of information that stores product information related to the function, principle, structure, and related design information. A product gene model oriented toward functional hybridization is proposed in this paper, as shown in Figure 8.

The composition of the product gene (PG) includes: serial number (N), i.e., the product gene serial number and logical address; input object (I) and input object feature elements (C_i V_i), denoting the input object of the functional action and the feature element of the input object, respectively; function element (F), denoting the action process; output object (O) and output object feature element (C_O V_O), denoting the output object of the functional action and the feature element of the output object, respectively; effect (P), denoting the effect of achieving the function; constraint factors (ES), denoting technical requirements, environmental constraints, quality requirements, and other relevant constraints; structure (S), denoting the physical carrier that realizes the function; structural feature element (C_S V_S), denoting the feature description of the structure; and the number of related genes (NL), denoting the address of the gene with which the flow-related relationship exists.

The correlation of elements within the product gene model is shown in Figure 9. It reflects the process of forming a conceptual structure through the function in the product concept design. The effect is the bridge between the function and structure, and it reduces the difficulty of mapping from the function to the structure. The appropriate effect is matched according to the function and the action object’s relevant characteristics. On this basis, the structure is generated according to the relevant constraint.

The product genome is the sequence of the product genes. It is a form of expression for describing complete product systems. The product genome (G_P) can be expressed as a collection of product genes, as shown in Equation (2).

$${\mathrm{G}}_{\mathrm{p}}=\left\{{\mathrm{PG}}_1{,\mathrm{PG}}_2,\cdots {,\mathrm{PG}}_{\mathrm{m}}\right\}$$

(2)

3.3.2. Construction Process of Product Genome

Similar to the biological gene, the product gene is the basic unit of recombination. A series of product genes are combined together in a certain order to form a product genome, which constitutes a product system. The product genome model mainly contains functional elements and their input/output flows, effects, structures, and other product information. The construction process model of the product genome is shown in Figure 10.

Step 1: The functional tree and structural tree can be built according to zigzag decomposition. Zigzag decomposition is a parallel decomposition process of the function and structure of the existing product. The decomposition of the product technology system can be achieved by repeatedly mapping between the functional and structural domains.

Step 2: The functional structure can be constructed according to the flow action relationship between functional elements. The functional model can be constructed according to the action relationship between structures.

Step 3: The flow variation between functional elements and their flow characteristics is determined, and the effects that realize functional elements are determined.

Step 4: The constraint factors, such as constraints generated by effects and technical constraints, between existing structures are determined. Finally, the product genome is determined by collating the information.

3.3.3. Product Gene Recombination

In biology, gene recombination is the process of recombining genes that control different traits to form new recombinant sequences [66,67]. The process of product gene recombination is similar to that of biological gene recombination. Based on constructing a product genome, the product genes that realize the superior characteristics of the product are transplanted into another product genome according to recombination rules to form a new product genome. Five main basic operations are involved in the process of product gene recombination, as follows.

(1)

Sharing

In biology, allelomorphic genes are genes that control the same trait. Similarly, in product design, allelomorphic genes are a pair of product genes located in different product genomes. They have the same or similar functions. In addition, they are located in the same position in different product structures. Genes other than allelomorphic genes are called personality genes. Without affecting the product function integrity, it is necessary to ensure the maximum sharing of product genes during the product gene recombination process so as to control the cost and product complexity. Three main operations are involved in allelomorphic gene sharing: selection, reconstruction, and inclusion. A model of the sharing process is shown in Figure 11. Selection is used to determine whether the effects and structures in the allelomorphic gene all meet the design requirements for sharing. If the answer is yes, the optimal one will be chosen. If not, it is necessary to reconstruct the allelomorphic gene according to the design requirements by a reconstruction operation. Two forms are included in the reconstruction operation. One is that, if the effects contained in the allelomorphic genes meet the design requirements, only structures need to be redesigned according to the constraint factors to complete the reconfiguration and form shared genes. The second is that it is necessary to re-select the effects and design new structures according to the constraint factors to form shared genes. During the reconstruction operation, the allelomorphic genes will be retained by the inclusion operation if there are no technologies available that meet the design requirements.

(2)

Separation. Based on the existing product genome, redundant or problematic genes are removed to form a new product genome. The operation process involves separating a product gene PG_i or a segment of product genes PG_iPG_i+1PG_i+2 from the existing product genome and then reconnecting the product genome to form a new product genome.

(3)

Adding. Based on the existing product genome, the required product genes are added to form the new product genome. The process involves adding an external product gene PG_i or an external segment of product genes PG_iPG_i+1PG_i+2 to the product genome and then reconnecting them to form a new product genome.

(4)

Replacement. Superior product genes replace product genes with harmful or insufficient functions. The operation process involves replacing product gene PG_i or a segment of product genes PG_iPG_i+1PG_i+2 with the product gene PG_j or a segment of product genes PG_jPG_j+1PG_j+2 to re-form the product genome.

(5)

Variation. Variation is used to improve the existing product genome based on the design requirements. The elements in the product genes are changed through variation. The operation process involves changing the internal elements of gene PG_i to produce gene PG_i′ based on problem analysis and solution, and then reforming the product genome G_P′ = { PG₁, PG₂, ⋯, PG_i′⋯, PG_n}.

TRIZ is a scientific methodology for problem-solving that was generated by Altshuller’s team by studying and generalizing a large amount of patent library knowledge [68]. It is widely used as a powerful problem-analysis tool and problem-solving tool for the innovative design of products [69,70,71]. Computer-aided innovation (CAI) software is an innovative technology based on TRIZ theory that incorporates modern design methodology, computer technology, and multi-domain subjects [72,73]. In order to implement variations in product genes correctly and effectively, a variation process for product genes based on TRIZ is proposed, as shown in Figure 12. First, the problems in the existing product genome need to be clarified. Then, resource analysis is used to determine whether there are resources in the original product genome to solve the problem. If there are available resources, the resources are used to generate solutions and establish variant product genes. If available resources do not exist, other TRIZ problem-solving tools, such as the Inventive Principle, Separation Principle, Effects, 76 Standard Solutions, etc., are used to solve the problems. After that, solutions will be generated to establish the variant product genes. The process can be implemented based on CAI software. The product genes can vary effectively with the inspiration of the CAI software knowledge base to make them meet the design requirements.

3.3.4. Transcription and Translation of Product Genome

After acquiring the new product genome, transcription and translation processes are used to generate a new product concept structure. Transcription is the process of extracting information about the functional elements and flow from the product genome and generating a new product functional structure according to this information. The transcription process of the product genome is shown in Figure 13. Transcription starts from the gene at the start position to the gene at the end to form a new product function structure. Translation is the process of generating a new product concept structure based on the product function structure and information such as the structure, structural features, and constraint factors in the product gene.

In the process of product functional hybridization, the technical characteristics of the original system will be inherited by the new product. Therefore, after transcription and translation, it will be necessary to determine whether there are problems with the new product concept structure. If there are problems, TRIZ problem-solving tools can be applied to solve them.

3.4. Process Model of Product Functional Hybridization Design

Starting from the existing product function system, its position on the S curve is judged, and the scenario analysis model based on the dispersion tree is then applied to obtain goal products for function hybridization. Finally, product functional hybridization can be achieved through product gene recombination. A process model of product functional hybridization design is shown in Figure 14.

Step 1: Preparation phase. The prototype product is selected, and the application timing of the product functional hybridization is judged. Combining the development status of the product technology, the technology maturity prediction method is applied to judge whether the prototype product is in the maturity stage. If not, the other innovation methods are chosen.

Step 2: Acquiring goal products.

(1) Establishment of the initial scenario of the prototype product. After analyzing the main daily activities of the prototype product and identifying its main application audience and the general environment, the initial scenario analysis model of the prototype product can be built.

(2) Goal product prediction for functional hybridization. An extension model of the relevant elements as action objects, people, or objects is established and then extended according to the divergence tree. After that, different scenarios can be built based on the obtained extension model to acquire scenario-related products.

(3) Evaluation of scenario-related products. After acquiring scenario-related products, the occurrence probability and the weight of the scenario-related product relative to the prototype product are obtained by the designer based on their own design experience. Finally, the probability scores and weights are multiplied to determine the scores of scenario-related products, as shown in

Table 1. Score list of scenario-related products.

Number	Function	Scenario-Related Product	Occurrence Probability	Weight	Score
···	···	···	···	···	···

.

(4) Determination of goal products. The scenario-related products with higher scores are identified according to the score list of scenario-related products. On this basis, goal products are determined according to market demand.

Step 3: Establishing a new product concept structure.

(1) The product genomes of the prototype product and the goal product are built separately.

(2) The product genes are recombined. The allelomorphic genes and personality genes in the prototype product and goal product genomes are determined. The allelomorphic genes are transformed into shared genes through a sharing operation, and then a new product genome is formed by recombining shared genes and personality genes according to the separation, addition, replacement, and variation operations.

(3) The new product concept structure is generated through transcription and translation.

Step 4: Problem-solving and evaluation of the new concept structure.

(1) By analyzing problems of the new product concept structure, whether there are problems in the new product concept structure is judged. If the answer is yes, the problems are solved according to TRIZ problem-solving tools, such as the Invention Principle, Separation Principle, 76 Standard Solutions, Trimming, etc., [74,75,76]. Then, the improved product concept structure is established.

(2) Solution evaluation is performed on the improved product concept structure to form a new product. In this paper, the analytic hierarchy process (AHP) [77] is used to evaluate the solution. Firstly, the hierarchical structure of the evaluation index is established. Secondly, the pairwise comparison judgment matrix is constructed. Then, the relative weights of the compared elements are calculated by the judgment matrix and consistency checking is carried out. Finally, the total scores of each solution are calculated. The specific steps of consistency checking are as follows:

1. Calculate the consistency index (CI), as shown in Equation (3).

$$CI=\frac{{\lambda }_{max}-n}{n-1}$$

(3)

where λ_max is the maximum eigenvalue of the judgment matrix and n is the order of the judgment matrix.

2. The mean random consistency index (RI) is obtained by looking up the table. The RI values of the 1~10 order judgment matrices are shown in

Table 2. Mean random consistency index.

n	1	2	3	4	5	6	7	8	9	10
RI	0.00	0.00	0.52	0.89	1.12	1.24	1.36	1.41	1.46	1.49

.

3. Calculate the consistency ratio (CR), as shown in Equation (4).

$$CR=\frac{CI}{RI}$$

(4)

when CR < 0.1, it is generally believed that the consistency of the judgment matrix is acceptable; otherwise, the judgment matrix should be appropriately corrected.

4. Case Study

Tree planting is important for the improvement of the ecological environment. However, the efficiency of manual tree planting is low. Therefore, there is a demand for tree-planting equipment in the market. The market already has tree-planting equipment, including drill pole tree-planting machines, tree transplanting machines, sapling-planting machines, and other products. Drill pole tree-planting machines are simple in structure and easy to operate, but their main function is to dig tree pits, and the degree of automation is low. During operation, a lot of subsequent work needs to be conducted by people. Tree-transplanting machines can meet needs such as garden construction, highway widening, and community construction for the rapid transplanting of trees. However, it is mainly used to transplant large trees, and only one tree can be transplanted at a time. Therefore, they are not applicable for transplanting large quantities of trees. Sapling-planting machines are used to cultivate saplings. They have a high degree of automation and are suitable for large-area sapling-planting work. However, it is expensive and only suitable for planting young saplings.

4.1. Preparation Phase

Drill pole tree-planting machines are widely used, but their single function means that a large number of people still need to be involved in the tree-planting process. Therefore, the drill pole tree-planting machine is selected as the prototype product in this paper, as shown in Figure 15. When it works, the soil is removed by rotating the drill pole, and a tree pit is formed. The PatSnap patent database was used to search and predict patents on drill pole tree-planting machines. The relationship between the number of patents and the year is shown in Figure 16. The comparative analysis with other tree-planting technologies is shown in Figure 17. It can be seen from Figure 16 that the number of patents for drill pole tree-planting machines is increasing over time, but the speed of the increase in patents is decreasing. It can be seen from Figure 17 that there are more patents for the drill pipe technology compared with other tree-planting technologies, indicating a larger market share for this technology. Therefore, it can be judged that the drill pole tree-planting machine is in the mature stage. Therefore, the product functional hybridization design method is used in this paper to improve its idealization.

4.2. Acquiring Goal Products

4.2.1. Establishing the Initial Scenario

After analyzing the main functions, the action object, the use environment, and the users of drill pole tree-planting machines, the initial scenario of this machine is established, as shown in Figure 18. The main function of a drill pole tree-planting machine is to dig tree pits, and its action object is forestland. They are used for forestland and are generally used by farmers.

4.2.2. Predicting Goal Product

(1)

Predicting the goal product based on extending the action object

When planting trees with the drill pole tree-planting machine, the action objects are the land and the trees. Therefore, extension models of the land and the trees are established, respectively. According to the extension rules of the action object based on the divergence tree, the extension models of the land and trees are extended. The specific extension processes are shown in Figure 19 and Figure 20, respectively.

Different scenario activities were established for the obtained extension model, causing the initial scenario of the tree-planting machine to change. The scenario-related products were determined according to the different scenarios formed. The specific analysis process is shown in

Table 3. Scenario-related product-acquisition process based on extending the action object.

Environmental Characteristics	Object (O)	Characteristics (C)	Value (V)	Activity	Scenario
Location: woodland Weather: sunny	Land	State	Tree pit	Dig tree pit	Workers operate tree planter to dig tree pit
		Humidity	Lower	Irrigate land	Workers irrigate land through motor-pumped well
		Organic ingredient	Insufficient	Apply fertilizer	Workers apply fertilizer by hand
		Harmful organism	Pest	Kill pests	Workers kill pests with spray.
		Looseness	Low	Plow land	Workers loosen the land with plow car
	Similar objects	—	—	—	—
	Tree	Position	Tree pit	Move position	Workers move trees and insert them into tree pits
			Fixed	Fix trees	Workers cover and compact soil with shovel
		Morphology	—	Prune branches	Workers prune branches with scissors or saws
		Tree age	3 years	Transplant trees	Workers transplant trees of different ages with different tree planters
	Telegraph pole	Position	Fixed	Fix telegraph pole	Workers dig pit with drill pipe machine
Scenario-related products		Motor-pumped well, spray, plow car, shovel, scissors, electric saw, and drill pipe machine

.

(2)

Predicting goal product based on the object

An extension model of the drill pole tree-planting machine was established. After that, the extension model was extended based on the divergence tree. The specific extension process is not listed again due to space limitations. The process of acquiring scenario-related products based on the object is shown in

Table 4. Process of acquiring scenario-related products based on the object.

Environment Characteristic	Product (O)	Characteristics (C)	Value (V)	Activity	Scenario
Location: woodland Weather: sunny Activity: planting trees	Tree planter	Function	Dig pit	Dig tree pit	Workers operate tree planter to dig tree pits
	—	Function	Carry trees	Move trees	Workers insert trees into tree pits
	Shovel	Function	Cover soil	Fill soil	Workers use the shovel to fill the tree pits with soil
	—	Function	Compact soil	Compact soil	Workers compact soil with their feet
	Motor-pumped well	Function	Draw water	Water trees	Workers irrigate land through motor-pumped well
Scenario-related products	Shovel and motor-pumped well

.

4.2.3. Evaluating Scenario-Related Products

According to the probability of obtaining scenario-related products relative to the drill pole tree-planting machine and the importance of the functions of the scenario-related products relative to the drill pole tree-planting machine, the occurrence probability and weights of the scenario-related products are determined. A score list of scenario-related products was constructed, as shown in

Table 5. Score list of scenario-related products.

Number	Function	Scenario-Related Product	Occurrence Probability	Weight	Score
1	Dig pit	Tree planter	1	1	1
2	Carry trees	—	1	1	1
3	Cover soil	Shovel	1	1	1
4	Compact soil	—	0.8	0.6	0.48
5	Draw water	Motor-pumped well	0.5	0.5	0.25
6	Prune branches	Scissors	0.6	0.5	0.3
7	Apply fertilizer	—	0.5	0.6	0.3
8	Kill pests	Spray	0.4	0.5	0.2
9	Plow land	Plow car	0.4	0.5	0.2
10	Fix telegraph pole	Drill pipe machine	0.1	0.1	0.1

.

4.2.4. Determining the Goal Product

As shown in Table 5, the two functions of carrying trees and covering soil had the highest scores. When planting trees, the trees are generally carried and placed in the corresponding pits by people, and there is a lack of products that can achieve the function of carrying trees. Therefore, a hydraulic wood grabber was identified as an alternative product through the search, as shown in Figure 21. The function of covering soil can be achieved using a shovel, but its automation level is low. Thus, it is not considered as the goal product. Therefore, the hydraulic wood grabber is finally selected as the goal product of functional hybridization.

4.3. Establishing a New Product Concept Structure

4.3.1. Establishing the Product Genome for the Drill Pole Tree-Planting Machine and the Hydraulic Wood Grabber

The functional tree and structural tree of the drill pole tree-planting machine were established according to zigzag decomposition, as shown in Figure 22. After connecting the bottom functional elements of the functional tree, the functional structure of the drill pole tree-planting machine was formed, as shown in Figure 23. According to the structural tree, the functional model of the drill pole tree-planting machine was established, as shown in Figure 24.

According to the functional structure of the drill pole tree-planting machine, the functional elements and their flow-to-flow features were extracted. According to the functional model, the action relationship between structures was clarified and then the structural features and their constraint factors were extracted. Finally, the effects that create functional elements were extracted according to the structure. The product genes were generated based on the information extracted above. Meanwhile, the product genome of the drill pole tree-planting machine was established, as shown in Figure 25. Similarly, the product genome of the hydraulic wood gripper was established, as shown in Figure 26.

4.3.2. Recombining the Product Genes of the Drill Pole Tree-Planting Machine and Hydraulic Wood Grabber

(1)

Sharing of product genes between the drill pole tree-planting machine and hydraulic wood grabber

According to the sequence number of the product genome, the product genes of the drill pole tree-planting machine and hydraulic wood grabber were indicated using TPG and YPG, respectively. According to the definition of an allelomorphic gene, the allelomorphic genes and personality genes in the two product genomes were determined. The allelomorphic-gene-sharing process is shown in

Table 6. Sharing process of allelomorphic genes between the drill pole tree-planting machine and hydraulic wood grabber.

	Drill Pole Tree-Planting Machine	Hydraulic Wood Grabber	Sharing Operation	Results of Gene Sharing
Allelomorphic gene	TPG1	YPG1	Selection	YPG1
	TPG2	YPG2	Reconstruction	NPG1
	TPG5	YPG3	Selection	YPG3
	TPG6	YPG4	Reconstruction	NPG2
	TPG7	YPG7	Inclusion	TPG7 and YPG7
	TPG8	YPG8	Inclusion	TPG8 and YPG8
	TPG9	YPG9	Selection	YPG9
	TPG10	YPG10	Selection	YPG10
	TPG11	YPG11	Selection	YPG11
	TPG12	YPG12	Reconstruction	NPG3

, and the results of the reconstruction operation of allelomorphic genes are shown in Figure 27.

(2)

Recombining product genes

The shared genes and personality genes of the drill pole tree-planting machine and hydraulic wood grabber were recombined, and a new product genome was initially formed. The following problems were found during the gene recombination process.

1. Multiple sets of transmission mechanisms were needed when providing energy for the wood-grabbing mechanism and digging mechanism through one engine at the same time, making the structure of the new tree-planting machine too complicated.

2. The mechanical arm of the drill pole tree-planting machine drove the spiral drill pipe downward, and the form of motion was circular. Therefore, it would be easy to cause the center degree of the tree pit to shift, which may lead to the planted tree tilting.

3. The mechanical arm of the hydraulic wood gripper moved in a curve, making the operation of placing trees complicated and making tree planting less efficient.

The variation operation was used to solve the above problems. Problem 1 was solved according to the resolution of the technology conflict. According to the invention principle 15 (Dynamic), the motor was selected to control the wood-grabbing mechanism and digging mechanism separately.

A substance–field model was constructed for problem 2, as shown in Figure 28. Problem 2 was solved by applying the standard solution process in CAI software. According to standard solution No. 2.2.1 (for the poorly controllable field, replace it with an easily controllable field), the form of motion provided to the spiral drill pipe by the drill pole tree-planting machine was changed to linear. The variation process is shown in Figure 29. Problem 3 is similar to problem 2. The tree-shifting process was simplified into a combination of linear and rotational motions, by which problem 3 was solved.

In order to improve the automation of the tree-planting process, the function of covering soil was added to the tree-planting machines. This function could be achieved by using the forward and reverse operation of the spiral drill pipe through resource analysis. The forward rotation operation could remove the soil, and the reverse rotation operation could carry the removed soil to the surface. Therefore, the variation operation was applied to product gene TPG4. A sleeve was added to the periphery of the spiral drill pipe to realize the function of covering the soil.

The above variant product genes were recombined with the rest of the product genes according to the separation, replacement, and adding operations. According to the solution of problem 1, product genes of the motor were added for the linear guide, rotary table, and hydraulic cylinder. The product gene of the engine was removed, removing the traction mechanism from the tree-planting machine. Therefore, a traction mechanism was added to the product genome. The new tree-planting machine product genome was finally formed, as shown in Figure 30.

4.3.3. Transcribing and Translating the New Product Genome

The functional elements were linked by flows according to the functional elements, flow information, and gene-related sequence numbers in the product genome. After that, the new tree-planting machine’s functional structure was formed, as shown in Figure 31. Based on the formed functional structure, the structure in the new tree-planting machine product genome, and the constraint factor information, the new tree-planting machine concept structure was initially constructed, as shown in Figure 32.

A concept structure of the soil digging and covering mechanism is shown in Figure 33. When the motor is in forward rotation, the drive shaft is driven to rotate the planetary frame and sun gear together through the stamping of the tension sleeve, and the sleeve is driven to rotate at the same speed. During this process, the soil removed by the spiral drill pipe is collected in the sleeve for storage. When the motor reverses, the tension sleeve releases the pressure so that the drive shaft only drives the sun wheel to turn. At the same time, the sleeve-clamping mechanism tightens the sleeve to fix it. The collected soil flows out of the sleeve under the reverse rotation of the spiral drill pipe.

A concept structure of the linear guiding mechanism is shown in Figure 34. The sliding table and the soil digging and covering mechanism are fixedly connected. The motor rotation drives the movement of the sliding table embedded with the threaded sleeve, which achieves the linear movement of the soil digging and covering mechanism.

4.4. Problem-Solving and Evaluation of the New Product Concept Structure

4.4.1. Solving the Problems of the New Product Concept Structure

Problems were analyzed by establishing a functional model of the new tree-planting machine concept structure. There was a blockage between the soil-covering mechanism and the tree. During the covering process, the soil digging and covering mechanism needs to be located right above the tree pit for covering after the mechanical claw places the tree upright in the pit, which causes the soil digging and covering mechanism to interfere with the tree. The problem can be solved by the resolution of physical conflict. According to the time separation principle, a tilting mechanism was designed. The concept structure of the tilting mechanism is shown in Figure 35. This mechanism keeps it right above the tree pit when the soil digging and covering mechanism digs a pit, and keeps it tilted above the tree pit when covering the soil to avoid the tree.

In order to improve the planting efficiency, several mechanical claws were evenly arranged on the turntable. An improved new tree-planting machine concept structure was formed according to the problem solutions, as shown in Figure 36.

4.4.2. Solution Evaluation

Based on the improved new tree-planting machine concept structure, solution evaluation of the drill pole tree-planting machine, tree-transplanting machine, and new tree-planting machine was carried out according to the AHP. The tree-planting efficiency, automation degree, manufacturing cost, and operability were selected as the evaluation factors for tree-planting machines. A hierarchical structure for the evaluation of the overall performance of tree-planting machines was established, as shown in Figure 37.

The judgment matrices of the criterion and scheme layers were constructed according to the hierarchical structure. Then, the relative weights of the compared elements were calculated and consistency checking was carried out. The judgment matrix and the weights of the criterion layer are shown in

Table 7. Judgment matrix and weights of the criterion layer.

	Indicator A	Indicator B	Indicator C	Indicator D	Weight
Indicator A	1	3	1	5	0.4094
Indicator B	1/3	1	1/3	1/3	0.0913
Indicator C	1	3	1	3	0.3603
Indicator D	1/5	3	1/3	1	0.1391

. The judgment matrix of the scheme layer regarding the planting efficiency, i.e., indicator A, is shown in

Table 8. Judgment matrix of the scheme layer regarding the planting efficiency.

Indicator A	Drill Pole Tree-Planting Machine	Tree Transplanting Machine	New Tree-Planting Machine	Weight
Drill pole tree-planting machine	1	2	1/2	0.2970
Tree transplanting machine	1/2	1	1/3	0.1634
New tree-planting machine	2	3	1	0.5396

. The judgment matrix of the scheme layer for other indicators was obtained in the same way. Finally, an evaluation list of tree-planting machines was established, as shown in

Table 9. Evaluation list of tree-planting machines.

Product	Planting Efficiency (0.4094)	Automation Degree (0.0913)	Manufacturing Cost (0.3603)	Operability (0.1391)	Score
Drill pole tree-planting machine	0.2970	0.1094	0.5396	0.1112	0.3414
Tree transplanting machine	0.1634	0.5816	0.1634	0.4444	0.2407
New tree-planting machine	0.5396	0.3090	0.2970	0.4444	0.4179

.

The steps for consistency checking of the judgment matrix of the criterion layer are as follows:

1. The consistency index (CI) is calculated, where, λmax = 4.2640, n = 4.

$$CI=\frac{{\lambda }_{max}-n}{n-1}=\frac{4.2640-4}{4-1}=0.0880$$

2. By looking at Table 2, the average random consistency index (RI) is obtained:

$$RI=0.89$$

3. The consistency ratio (CR) is calculated:

$$CR=\frac{CI}{RI}=\frac{0.0880}{0.89}=0.0989<0.1$$

therefore, the consistency test is satisfied.

The steps for consistency checking on the judgment matrix of the scheme layer regarding the planting efficiency are as follows:

1. The consistency index (CI) is calculated, where, λmax = 3.0092, n = 3.

$$CI=\frac{{\lambda }_{max}-n}{n-1}=\frac{3.0092-3}{3-1}=0.0046$$

2. By looking at Table 2, the average random consistency index (RI) is obtained:

$$RI=0.52$$

3. The consistency ratio (CR) is calculated:

$$CR=\frac{CI}{RI}=\frac{0.0046}{0.52}=0.0088 < 0.1$$

therefore, the consistency test is satisfied.

As shown in Table 9, the new tree-planting machine had a greater degree of improvement in terms of the planting efficiency, automation, and operability than the drill pole tree-planting machine, although the manufacturing cost increased. Moreover, the new tree-planting machine had the highest overall score between the drill pole tree-planting machine and the tree-transplanting machine. Therefore, it could be judged that the new tree-planting machine obtained according to function hybridization had preferable overall performance.

5. Discussion and Conclusions

Hybridization design is a new pattern of integrated innovation. This paper presents the concept of product functional hybridization and establishes a process model for product functional hybridization design. A method of obtaining goal products was proposed according to scenario analysis and the divergence tree. Scenario-related products were acquired from three perspectives of action objects, people, and objects, and then the goal product could be obtained. A product gene model oriented to functional hybridization was established according to the idea of biological genes. A method of establishing product concept structure based on product gene recombination was proposed in combination with the TRIZ theory to achieve the fusion of product function systems.

As far as theoretical implications are involved, this paper expands the existing theory of product hybridization design from the viewpoint of function, systematically and effectively achieves product functional hybridization, and further reflects the superiority of integrated innovation. Firstly, existing methods of product hybridization design focus on technological recombination, so this paper proposed the concept of product functional hybridization and classified it into intraspecific function hybridization and distant function hybridization to meet the multi-functional needs of users. Then, to address the problem of existing functional integration methods acquiring goal products too widely, this paper proposed three paths of goal product prediction for functional hybridization by combining scenario analysis and the divergence tree. According to the prediction paths, the extension models of the prototype product’s relevant elements were extended to obtain the goal product, which reduced the acquisition scope and increased the accuracy of acquisition. Finally, in response to the problem that there is less research on fusing existing product function systems in the existing functional integration methods, based on the idea of biological gene recombination, this paper creatively fused design information through the operation of product gene recombination, which improved the overall performance of the product.

The core idea of integrated innovation is to optimize, match, and integrate existing product resources. With the intensification of social competition, how to make full use of existing product resources for integrated innovation has become a key concern for enterprises. By applying the design method of product functional hybridization proposed in this study, enterprises can use their own products and other existing product resources to form different kinds of multifunctional products to adapt to the development and changes in the market and improve market competitiveness. This study can help enterprises to fuse their own products with other existing product resources to improve the overall performance of their products while reducing manufacturing costs and achieving maximum benefits.

Despite the advantages of the new design approach, there are some limitations in this study.

• Acquiring goal products is the key to successfully implementing product functional hybridization. The acquisition method proposed in this paper can accurately acquire the goal products of functional hybridization. However, the extended elements need to be analyzed one by one based on the divergence tree in the acquisition process, which makes the acquisition less efficient.
• A new product concept structure can be effectively formed in the product functional hybridization design process with product genes. However, the establishment and reorganization of product genes are completed with the experience of designers.
• During the case study, a concept structure of the new tree-planting machine was established according to the process model for product functional hybridization design. Although the overall performance of this new concept structure was improved compared with the prototype product, the specific extent of improvement is to be considered.

In the future, three aspects will be taken into account to overcome the above limitations.

• The product knowledge base will be established based on three paths of goal product prediction for functional hybridization. Thus, scenario-related products can be obtained by searching the knowledge base to improve the acquisition efficiency of function hybridization goal products.
• The software will be developed to establish and recombine product genes through computer assistance, which can make product functional hybridization design more efficient.
• The prototype will be produced through detailed design. Meanwhile, quantitative evaluation criteria will be set up to analyze the specific performance parameters of the prototype. The quantitative and objective evaluation of the overall performance of products can be carried out through the comparison and analysis of data.