**1. Introduction**

The development of agricultural engineering in the Russian Federation cannot be ensured without the development of machines with digital intelligent systems [1–6].

The quality of work is determined by the optimal solution to the problem of providing the required parameters of the machines, both for sowing, harvesting, and the post-harvest processing of crops [7–9], while maintaining the full potential of seeds and grown products [10–12]. The determining indicator of the quality of crop harvesting is their preservation and the minimum amount of losses and damage to marketable products, with an effective value of cleaning from various impurities, which cannot be achieved without the introduction of modern harvesting machines. The main difference between the harvesting of root crops and onions from the harvesting of other agricultural crops is the increased volume of separated soil and plant impurities, therefore, the separating system of machines for harvesting vegetables and potatoes should have a high-throughput [13,14]. However, the separating system of harvesters, represented by bar elevators, does not allow the full cleaning of commercial products from mechanical impurities, and to eliminate this drawback, separation intensifiers of various types have been introduced into their design. R. Farhadi et. at [15] intensified the process of the separation of potato tubers, the scheme and the general view of which are shown in Figures 1 and 2.

**Citation:** Dorokhov, A.; Aksenov, A.; Sibirev, A.; Mosyakov, M.; Sazonov, N.; Godyaeva, M. Evaluation of Comparative Field Studies for Root and Onion Harvester with Variable Angle Conveyor. *Agriculture* **2023**, *13*, 572. https://doi.org/10.3390/ agriculture13030572

Academic Editor: Tao Cui

Received: 29 January 2023 Revised: 16 February 2023 Accepted: 23 February 2023 Published: 26 February 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

**Figure 1.** Gradation pipes cross-section at a semicircle of the helix ((**a**) scheme; and (**b**) general form): d—the bar diameter; е—bar thickness; s—bar spacing; r—drum radius; G—center of gravity of the drum; and Y—distance from the center of gravity to the center of the bar. ˆ

**Figure 2.** Constructive scheme of the improved machine for haulm cutting: 1—chassis frame; 2—support (reference) wheel; 3—rotor; 4—auger; 5—cutter of heads root crops; 6, 9—drum; 7—knife; 8—chute; 10—spiral; 11—casing; 12—parallelogram hinged suspension; 13—bracket; 14—copier; 15—knife; ←—forward movement.

Figure 1 shows the cross-section of the pipes at a semicircle of the helix. For the determination of the pipe diameter, the following points should be attended to: the semicircle radius and perimeter are 15 cm and πr. The initial distance between the pipes is two cm and the final distance is eight cm. The pipes' numbers of helix semicircle generators are 14 at first, for suitable grading. Anything lower than six pipes does not appear at the last pitch. The pipes' size should exist in industrial productions. This equation should be valid for avoiding semicircle defectiveness.

The various stages of piece construction were done with consideration to the presented matters before parts. Figure 2 shows the total side view of the system. Just as observed in the figure, the helix was rotated by a tractor with use of the multipurpose joint, belt and pulley, gearbox, chain, and sprocket wheel. This power transmission system was applied successfully to the reduction of the speed up to a necessary level, and diminished the rotational speed of 540 on 9 RPM. The main disadvantage of the well-known design of the separating device is the turbulent movement of the tuberous heap, which ensures the distribution of the marketable products of tubers along the diameter of the working body, without the presence of a soil layer, which increases the damage to the potato. A known separating device was developed by Ping Yuan Xiong, Xuan Lin, and Yi Wang [16]. A known machine for harvesting table roots was developed by Storozhuk I.M. and Pankiv V.R., the scheme of which is shown in Figure 2, providing an increase in the quality of the cleaning of commercial products as a result of improving the root adapter [17].

However, the disadvantage of this technical solution is the uneven height of the cut of the tops due to the changes in soil density when the machine moves across the field, which leads to a decrease in the product quality as a result of an additional mechanical impact on the root crop and the impossibility of the further utilization of plant impurities remaining on the surface of the root crop.

Thus, the improvement of the design of the digging working bodies of harvesting machines does not fully allow for the improvement of the quality of the harvesting, therefore, it is necessary to carry out the research and development of the functioning elements of the harvesting machine to clean the commercial products from plant and mechanical impurities.

The purpose of the study is to develop separating devices for harvesters that improve the quality of the separation and reduce the damage to commercial products, which is achieved through the determination of the quality indicators of harvesting with an experimental machine for harvesting potatoes and onions.

#### **2. Materials and Methods**

#### *2.1. Bar Elevator with Adjustable Web Angle*

The developed bar elevator (RF patent No. 2679734) helps to improve the quality of harvesting, in terms of indicators such as: the damage and completeness of the separation when changing the angle of inclination *α*<sup>1</sup> of the separating system web, depending on the variation in harvesting conditions [13].

In order to change the vertical position of the bar elevator (1), the weight sensors (2) installed on the harvesting machine (3) are used. (Figure 3).

**Figure 3.** Scheme for changing the angle of inclination of the bar elevator conveyor: 1—bar elevator; 2—weight sensor of the digging share; 3—digging share; 4—microcontroller; 5—electric cylinder; and 6—inertial sensor; ←—forward movement.

The mass control device (2) of the heap entering the separation transmits a control signal to the microcontroller (4), and as a result, the web inclination angle is corrected when the mass of the incoming products changes.

The drive for changing the inclination angle of the web of the bar elevator (1), consisting of electric cylinders (5), ensures the movement of the rod to the required distance when the heap mass changes and, accordingly, the inclination angle of the elevator web (1) changes.

The control of the soil that has passed through the openings of the elevator is provided by inertia sensors (6), located along the length of the elevator (1).

In spite of this, the amount of sieved soil will be characterized by peak amplitude values. Thus, the evaluation of the separation efficiency of the elevator is carried out according to the amplitude values.

If the sieving of the soil on the rod elevator is below the required value set by the microcontroller (4), the angle *α*<sup>1</sup> of the inclination of the web of the rod elevator (1) is corrected in the set range of values.

Having determined the mass of a heap of root crops and onions on the digging share, the controller with a time delay T, with the movement of the bar elevator, transmits a control signal to move the rod of the electric cylinders.

Field studies on the separating rod elevator with an adjustable tilt angle of the machine for harvesting root crops and onions (Figure 3) were carried out on the fields of the farm "Tsirulev E.P." This was in the Privolzhsky district of the Samara region in 2019 for the harvest of Meduza onion, and also in 2022 for the harvest of the Red Scarlett potato variety at Krasnaya Gorka LLC, in the Kolyshleysky district of the Penza region. The studies were carried out in accordance with STO AIST 8.7-2013 "Machines for harvesting vegetables and melons. Methods for assessing functional indicators".

The scheme of the experiment included the performance of comparative studies on the quality indicators of onion and potato harvesting by a harvester with a developed separating system on a planting area of 0.04 ha.

Before performing studies on the experimental sample of the separating systems, the physical and mechanical properties of the soil were determined, and the quality indicators of the separation of a heap of turnips and potato tubers were also determined. Other factors considered were the soil of the digging plowshare, the forward speed vK of the movement of the machine for the harvesting of the root crops and onions, as well as the forward speed vEL of the movement of the rod elevator web on the indicators of the quality of harvesting. The assessment of the quality of the technological process of cleaning was carried out according to the following indicators:


The extraction of the marketable products from the soil was carried out at a depth hL of digging from 0.02 to 0.06 m, with a value of its change equal to 0.1 m.

The step of changing the speed vK of the harvester varied within 0.2 m/s in the range from 1.0 to 1.8 m/s.

By changing the gear ratio of the separating system, the speed vEL of the rod elevator varied from 1.0 to 1.8 m/s, with a step of 0.2 m/s.

The quality indicators of the machine with an experimental separating system were determined after passing the accounting plot, and the sifted products on the tarpaulin along the entire length of the harvested area were collected.

In the selected heap, its fractional composition was determined: bulbs/tubers, free soil, and the soil associated with marketable products.

Before performing studies on the experimental sample of the separating systems, the physical and mechanical properties of the soil were determined, and the quality indicators of the separation of a heap of turnips and potato tubers were also determined. For conducting research on the site, the following were insured: that there was medium loamy chernozem, that the field relief was even, that the field contour was close to rectangular, and that the length of the rut was 350 m. Other factors considered were the soil of the digging plowshare, the forward speed vK of the movement of the machine for the harvesting of the root crops and onions, as well as the forward speed vEL of the movement of the rod elevator web on the indicators of the quality of harvesting. The assessment of the quality of the technological process of cleaning was carried out according to the following indicators:
