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19 pages, 6520 KiB

Open AccessArticle

An Intelligent Inspection Robot for Underground Cable Trenches Based on Adaptive 2D-SLAM

by Zhiwei Jia, Haohui Liu, Haoliang Zheng, Shaosheng Fan and Zheng Liu

Machines 2022, 10(11), 1011; https://doi.org/10.3390/machines10111011 - 1 Nov 2022

Cited by 4 | Viewed by 2287

With the rapid growth of underground cable trenches, the corresponding inspections become a heavy burden, and an intelligent inspection robot for automatic examinations in underground cable trenches would be a suitable solution. To achieve this, this paper establishes one new navigation methodology for [...] Read more.

With the rapid growth of underground cable trenches, the corresponding inspections become a heavy burden, and an intelligent inspection robot for automatic examinations in underground cable trenches would be a suitable solution. To achieve this, this paper establishes one new navigation methodology for intelligent inspection robots, especially when applied in complex scenarios and the corresponding hardware. Firstly, to map the underground trenches with higher precision, an improved graph optimization cartographer-SLAM algorithm is proposed, which is based on the combination of depth camera and LIDAR. The depth image is converted into pseudo laser data, and fused with LIDAR data for calibration. Secondly, to overcome the low precision of the Laser odometer due to the uneven ground, an adaptive keyframe selection method is designed. Thirdly, the forward A* model is presented, which has been adjusted in three aspects, including the convergence of node searching, the cost function, and the path smoothness, to adapt to the narrow underground environment for global path planning. Fourthly, to realize dynamic obstacle avoidance, an improved fusion scheme is built to integrate the proposed global path planning algorithm and the dynamic window approach (DWA). In the case study, the simulation experiments showed the advantage of the forward A* algorithm over the state-of-the-art algorithm in both time consumption and the number of inflection points generated, the field tests illustrated the effect of the fusion of depth camera images and LIDAR. Hence, the feasibility of this navigation methodology can be verified, and the average length of path and time consumption decreased by 6.5% and 17.8%, respectively, compared with the traditional methods. Full article

(This article belongs to the Special Issue Advanced Control Theory with Applications in Intelligent Machines)

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22 pages, 4464 KiB

Open AccessEditor’s ChoiceArticle

AI-Based Posture Control Algorithm for a 7-DOF Robot Manipulator

by Cheonghwa Lee and Dawn An

Machines 2022, 10(8), 651; https://doi.org/10.3390/machines10080651 - 4 Aug 2022

Cited by 8 | Viewed by 4153

Abstract

With the rapid development of artificial intelligence (AI) technology and an increasing demand for redundant robotic systems, robot control systems are becoming increasingly complex. Although forward kinematics (FK) and inverse kinematics (IK) equations have been used as basic and perfect solutions for robot [...] Read more.

With the rapid development of artificial intelligence (AI) technology and an increasing demand for redundant robotic systems, robot control systems are becoming increasingly complex. Although forward kinematics (FK) and inverse kinematics (IK) equations have been used as basic and perfect solutions for robot posture control, both equations have a significant drawback. When a robotic system is highly nonlinear, it is difficult or impossible to derive both the equations. In this paper, we propose a new method that can replace both the FK and IK equations of a seven-degrees-of-freedom (7-DOF) robot manipulator. This method is based on reinforcement learning (RL) and artificial neural networks (ANN) for supervised learning (SL). RL was used to acquire training datasets consisting of six posture data in Cartesian space and seven motor angle data in joint space. The ANN is used to make the discrete training data continuous, which implies that the trained ANN infers any new data. Qualitative and quantitative evaluations of the proposed method were performed through computer simulation. The results show that the proposed method is sufficient to control the robot manipulator as efficiently as the IK equation. Full article

(This article belongs to the Special Issue Advanced Control Theory with Applications in Intelligent Machines)

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15 pages, 2448 KiB

Open AccessArticle

Robot Static Path Planning Method Based on Deterministic Annealing

by Jinyu Dai, Jin Qiu, Haocheng Yu, Chunyang Zhang, Zhengtian Wu and Qing Gao

Machines 2022, 10(8), 600; https://doi.org/10.3390/machines10080600 - 22 Jul 2022

Cited by 3 | Viewed by 1659

Abstract

Heuristic calculation is an essential method to solve optimisation problems. However, its vast computing requirements limit its real-time and online applications, especially in embedded systems with limited computing resources, such as mobile robots. This paper presents a robot path planning algorithm called DA-APF [...] Read more.

Heuristic calculation is an essential method to solve optimisation problems. However, its vast computing requirements limit its real-time and online applications, especially in embedded systems with limited computing resources, such as mobile robots. This paper presents a robot path planning algorithm called DA-APF based on deterministic annealing. It is derived from the artificial potential field and can effectively solve the local minimum problem of the model established by the potential field method. The calculation performance of DA-APF is considerably improved by introducing temperature parameters to enhance the potential field function and by using annealing and tempering methods. Moreover, an optimal or near-optimal robot path planning scheme is given. A comprehensive case study is performed using heuristic methods, such as genetic algorithm and simulated annealing. Simulation results show that DA-APF performs well in various static path planning environments. Full article

(This article belongs to the Special Issue Advanced Control Theory with Applications in Intelligent Machines)

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11 pages, 2825 KiB

Open AccessCommunication

A New Parameter Identification Method for Industrial Robots with Friction

by Bin Kou, Yao Huang, Pengpeng Wang, Dongcheng Ren, Jie Zhang and Shijie Guo

Machines 2022, 10(5), 349; https://doi.org/10.3390/machines10050349 - 9 May 2022

Cited by 2 | Viewed by 1620

Abstract

Commonly used intelligent algorithms that are used to identify the parameters of friction of industrial robots have poor accuracy or involve complex coding, which is not conducive to their use in engineering. This paper uses the random wandering simulated annealing-based variable-step beetle antennae [...] Read more.

Commonly used intelligent algorithms that are used to identify the parameters of friction of industrial robots have poor accuracy or involve complex coding, which is not conducive to their use in engineering. This paper uses the random wandering simulated annealing-based variable-step beetle antennae search (RWSAVSBAS) algorithm to identify the parameters of friction of industrial robots. The moment of friction of the third joint of the robot is experimentally obtained and used to establish a Stribeck friction model. Following this, the RWSAVSBAS algorithm is used to identify the frictional parameters of the industrial robot. These parameters can be used to accurately predict the friction-induced torque of the robot. Full article

(This article belongs to the Special Issue Advanced Control Theory with Applications in Intelligent Machines)

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21 pages, 3000 KiB

Open AccessArticle

USV Application Scenario Expansion Based on Motion Control, Path Following and Velocity Planning

by Ziang Feng, Zaisheng Pan, Wei Chen, Yong Liu and Jianxing Leng

Machines 2022, 10(5), 310; https://doi.org/10.3390/machines10050310 - 26 Apr 2022

Cited by 7 | Viewed by 2265

Abstract

The ability of unmanned surface vehicles (USV) on motion control and the accurate following of preset paths is the embodiment of its autonomy and intelligence, while there is extensive room for improvement when expanding its application scenarios. In this paper, a model fusion [...] Read more.

The ability of unmanned surface vehicles (USV) on motion control and the accurate following of preset paths is the embodiment of its autonomy and intelligence, while there is extensive room for improvement when expanding its application scenarios. In this paper, a model fusion of USV and preset path was carried out through the Serret-Frenet coordinate system. Control strategies were then scrupulously designed with the help of Lyapunov stability theory, including resultant velocity control in the presence of drift angle, course control based on the nonlinear backstepping method, and reference point velocity control as a virtual control variable. Specifically, based on USV resultant velocity control, this paper proposes respective solutions for two common scenarios through velocity planning. In a derailment correction scenario, an adaptive reference velocity was designed according to the position and attitude of USV, which promoted its maneuverability remarkably. In a dynamic obstacle avoidance scenario, an appropriate velocity curve was searched by dynamic programming on ST graph and optimized by quadratic programming, which enabled USV to evade obstacles without changing the original path. Simulation results proved the convergence and reliability of the motion control strategies and path following algorithm. Furthermore, velocity planning was verified to perform effectively in both scenarios. Full article

(This article belongs to the Special Issue Advanced Control Theory with Applications in Intelligent Machines)

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24 pages, 67404 KiB

Open AccessArticle

An Artificial Neural Network Approach for Solving Inverse Kinematics Problem for an Anthropomorphic Manipulator of Robot SAR-401

by Vadim Kramar, Oleg Kramar and Aleksey Kabanov

Machines 2022, 10(4), 241; https://doi.org/10.3390/machines10040241 - 29 Mar 2022

Cited by 11 | Viewed by 2584

Abstract

The paper proposes a new design of an artificial neural network for solving the inverse kinematics problem of the anthropomorphic manipulator of robot SAR-401. To build a neural network (NN), two sets were used as input data: generalized coordinates of the manipulator and [...] Read more.

The paper proposes a new design of an artificial neural network for solving the inverse kinematics problem of the anthropomorphic manipulator of robot SAR-401. To build a neural network (NN), two sets were used as input data: generalized coordinates of the manipulator and elements of a homogeneous transformation matrix obtained by solving a direct kinematics problem based on the Denavi–Hartenberg notation. According to the simulation results, the NN based on the homogeneous transformation matrix showed the best accuracy. However, the accuracy was still insufficient. To increase the accuracy, a new NN design was proposed. It consists of adding a so-called “correctional” NN, the input of which is fed the same elements of the homogeneous transformation matrix and additionally the output of the first NN. The proposed design based on the correctional NN allowed the accuracy to increase two times. The application of the developed NN approach was carried out on a computer model of the manipulator in MATLAB, on the SAR-401 robot simulator, as well as on the robot itself. Full article

(This article belongs to the Special Issue Advanced Control Theory with Applications in Intelligent Machines)

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15 pages, 5715 KiB

Open AccessArticle

Investigation on Temperature Rise Characteristic and Load Capacity of Amorphous Alloy Vegetable Oil Distribution Transformers with 3D Coupled-Field Method

by Jing Guo, Kaiyuan Fan, Bowen Yang, Hang Yang, Qingjun Peng and Hanbo Zheng

Machines 2022, 10(1), 67; https://doi.org/10.3390/machines10010067 - 17 Jan 2022

Cited by 4 | Viewed by 3477

Abstract

The large differences in the load peak and valley of rural distribution networks always bring severe problems to system planners and operators. Given this issue, this paper deals with the hot-spot temperature (HST) of the transformer and its overload capability, and proposes a [...] Read more.

The large differences in the load peak and valley of rural distribution networks always bring severe problems to system planners and operators. Given this issue, this paper deals with the hot-spot temperature (HST) of the transformer and its overload capability, and proposes a modeling method-based online monitoring of practical parameters. In the current work, a temperature-fluid coupling field of the 315 kVA vegetable oil distribution transformer is developed in both the two-dimensional and three-dimensional geometry, by which the convection and heat dissipation process can be studied. The grid of the model is divided into regions to increase the calculation speed and ensure the accuracy of the calculation. Secondly, tests related to the temperature rise of the transformer are carried out. The accuracy of the three-dimensional model is later discussed in terms of temperature and fluid velocity distribution. Finally, the temperature distribution laws of the amorphous alloy vegetable oil distribution transformers (AVDT) are compared and analyzed under different load conditions. Findings reveal that the AVDT has low no-load loss and strong overload capacity, which is capable of reducing the internal overheating accidents of the transformer. Full article

(This article belongs to the Special Issue Advanced Control Theory with Applications in Intelligent Machines)

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19 pages, 4723 KiB

Open AccessArticle

Static Force Analysis of a 3-DOF Robot for Spinal Vertebral Lamina Milling

by Shaodong Li, Peiyuan Gao, Hongjian Yu and Mingqi Chen

Machines 2022, 10(1), 29; https://doi.org/10.3390/machines10010029 - 1 Jan 2022

Cited by 2 | Viewed by 1673

Abstract

In order to realize robot-assisted spinal laminectomy surgery and meet the clinical needs of the robot workspace, including accuracy in human–robot collaboration, an asymmetrical 3-DOF spatial translational robot is proposed, which can realize spinal laminectomy in a fixed posture. First, based on the [...] Read more.

In order to realize robot-assisted spinal laminectomy surgery and meet the clinical needs of the robot workspace, including accuracy in human–robot collaboration, an asymmetrical 3-DOF spatial translational robot is proposed, which can realize spinal laminectomy in a fixed posture. First, based on the screw theory, the constraint screw system of the robot was established, and the degree of freedom was derived to verify the spatial translational ability of the robot. Then, a kinematic model of the robot was established, and a static force model of the robot was derived based on the kinematic model. The mathematical relationship between the external force and the joint force/torque was obtained, with the quality of all links considered in the model. Finally, we modeled the robot and imported it into ADAMS to obtain the static force simulation results of the 3D model. The force error was approximately 0.001 N and the torque error was approximately 0.0001 N∙m compared with the simulation results of the mathematical model, accounting for 1% of the joint force/torque, which is acceptable. The result also showed the correctness of the mathematical models, and provides a theoretical basis for motion control and human–robot collaboration. Full article

(This article belongs to the Special Issue Advanced Control Theory with Applications in Intelligent Machines)

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