When operating a rotary conveyor milking plant of dairy facilities for 1200 to 3000 or more cows, a milking machine operator experiences increased psychological and physical stress. The general functionality of the human operator of machine milking plants includes information and control (assessment of the physiological state, status of the animal, signal transmission from the milking point to the central computer, etc.) and physical functionality for performing manual operations (preparing the udder and teats of animals, connecting milking units). The conducted ergonomics analysis of milking machine operators at the “Carousel” plants showed that the total work of the operator per cow at the internal milking plant of the “Herringbone” type (36.62 J) is higher than at those with external milking of the “Parallel” type (26.42 J), due to the larger workload part required to move the milking machine (22.9 versus 12.7 J). The energy intensity of labor for three operators per cow is different: for internal milking (“Herringbone”), the load is 3.92, 30.74, and 1.96 J, with external milking (“Parallel”) – 3.92, 20.54, and 1.96 J. The physical load of operators per shift also varies: for a team of three people, the operator’s energy consumption during internal milking (“Herringbone”) varies from 1372 (for the third operator) to 37807 J (for the second operator); for two operators (without teat treatment after milking) the load is the same – from 24262 to 33964 J. For a team of three people working on the “Parallel”-type “Carousel”, the energy consumption ranges between 1918 and 43134 J, with two operators – between 23968 and 51366 J. The permissible upper limit for male operators (no more than 50000 J) is exceeded in the case of external milking and a maximum production of 300 head /h; for female operators (not more than 30,000 J) for all second operators at the maximum productivity of the “Carousel” with internal milking – 140 head/h, with external milking – 300 head/h. The overload of operators of rotary milking plants must be taken into account when organizing their work and upgrading the plants.

The technology of digital twins (DT) is still insufficiently widespread in agriculture. The introduction of an adequate digital twin model will reduce costs in the development, implementation and maintenance of agricultural machinery. The main problem in the development of digital twins in agriculture is the high need for resources: from the stage of designing a laboratory prototype to pilot and field testing of agricultural object prototypes. To reduce the cost of resources in the production of samples from an idea to a series and their further use throughout the entire service life, the authors proposed a technology of a virtual test site for testing digital samples of agricultural machines (equipment/parts). Digital twins used in agriculture are developed taking into account the exchange of information between the digital twin and the physical object. Thus, the adequacy of the digital twin is ensured in the real-time mode of changing its parameters. This feature helps achieve maximum correspondence of the physical object of the digital copy. Using the generated big data and artificial intelligence, it is possible to develop systems that, depending on changes in the parameters of a physical and digital object, automatically change the functioning parameters of units / parts / machines to reach their greatest efficiency. Using the example of a livestock farm and robotic milking, the authors consider possible ways of using the DT technology. The article proposes the introduction of a method of interaction between a digital twin and a physical object in laboratory and field tests. The developed technology of digital twins projects a digital shadow and ensures a two-way connection between the digital center and the physical object being tested. The presented concept of the virtual test site is promising for conducting virtual tests of agricultural machines, products, technologies, and systems.

The problem of finding the optimal ratio of mass, power, and working speed has been and remains an urgent task since laying the groundwork of agricultural mechanics. The concept of development aimed at increasing the productivity and operating speeds of machine-tractor units, has led to an increase in unit power and the mass of machines. An analysis of the development trends of tractors and self-propelled machines showed an annual increase in the average power of newly designed tractors by 2 to 4 hp. Capacity implementation of equipment with increased energy saturation is possible due to an additional increase in the mass of machines, which results in increased soil compaction. Critical stresses reaching a significant depth do not contribute to the process of complete relaxation of the soil. In the uncultivated layer, a soil horizon is formed between 25 to 30 and 100 to 120 cm (with a hardness corresponding to a clay rolled road), limiting the development zone of the plant root system and disturbing soil filtration. The intensive use of energy-saturated units and self-propelled machines has led to the accumulated overconsolidation of the uncultivated layer of more than 60% of arable land. Soil overconsolidation along the wheel track leads to a decrease in the yield of grain crops by 10% and root crops by 20%. When modernizing or designing new models of machines, we suggest taking into account the negative environmental consequences of the use of units in the feasibility study and reworking the regulatory and methodological documents for assessing the specific pressures on the soil of the running gear parts of self-propelled machines. It is necessary to reduce the machine load on the soil by using smaller machines and by implementing measures to loosen the subsoil horizon. Equally important is to determine the parameters and design a line of robotic energy systems, a set of working equipment and a control system based on the principles of multi-agent control of sets of dynamic objects in relation to agricultural production.

When organizing maintenance activities for domestic agricultural machinery, paper workflow continues to dominate, which negatively affects the performance indicators and the level of operational reliability of machines. The engineering services of domestic agricultural enterprises remain beyond automation and digitalization in matters of managing the technical service of machines. The low adaptation of existing software products to the specifics of domestic agricultural production prevents the adoption of automated CMMS and EAM systems used in other sectors to manage the reliability of equipment in operation. The authors developed software with a set of functions similar to the functionality of well-known CMMS systems. The software includes Agrokompleks ASUTO in combination with the previously developed Agrokompleks Resursy warehouse management software and Agrokompleks MTP fuel management software. The automated system data model is adapted to the needs of engineering workers responsible for the performance of agricultural machinery. A practical test of the system was carried out at an agricultural enterprise with a fleet of 25 tractors. The results obtained confirm the hypothesis that the automation of engineering activities contributes to an increase in the operational reliability of agricultural machinery and a decrease in the labor intensity of managing service processes. The use of the automated system resulted in a decrease in the time spent on maintenance management by 35 to 38%, the probability of tractors having operational failure – by 26%. At the same time, the probability of tractors being in working condition increased by 1.8%. The research could be useful for the developers of EAM systems for the maintenance and repair management of agricultural machinery.

Adjusting engines with a high compression ratio operating on traditional gasoline grades is simplified by the application of mathematical models of the operating cycle that predict the self-ignition of the fuel-air mixture. Mathematical simulation of detonation based on the analysis of a computational model of the thermodynamic cycle of a spark-ignited piston engine, which is close to the actual cycle, can be used to determine with sufficient accuracy in time the change in the current cycle pressure and the temperature of the unburned part of the charge. The model takes into account the heat exchange between the combustion zones of the charge and the walls of the combustion chamber. The onset of detonation is associated with the point of self-ignition of the unburned part of the charge and is determined depending on the thermodynamic parameters of the unburned part of the charge and the kinetic mechanism of pre-ignition chemical processes in the fuel-air mixture. It is shown that mathematical modeling of the self-ignition of the unburned part of the charge in a spark-ignition piston-type internal combustion engine can be performed in the same way as the modeling of self-ignition of the fuel-air mixture under continuing compression in units with a free-sliding piston. The accuracy of the self-ignition calculation using the cycle model has been experimentally verified by indicating it at different speeds and at different excess air and charge volume ratios, as well as different mixture temperatures in the intake manifold. The simulation results were verified experimentally on isooctane and octane blends (60% isooctane) and on commercial gasoline. It was found that at low compression ratios (up to 5 to 7), the low-temperature mechanism of self-ignition prevails, while at higher compression ratios, the high-temperature mechanism prevails. The detonation limit of an internal combustion engine can be determined by the point of self-ignition (explosion) in the unburned part of the charge at a residual cycle fraction of unburned fuel of at least 10%.

The development of digital technologies aimed at improving the diagnostic process, increasing the reliability of determining the functional characteristics of agricultural machinery in real time is important and relevant in the technical support of energy-saturated machines. To develop an intelligent system for remote diagnostics of the engines of energy-saturated agricultural machinery, the authors tested a neural network constructor with the ability to use up to ten input and output parameters. An algorithm for a digital system for remote diagnostics, a scheme for predicting failures in online monitoring, and a digital platform for diagnosing energy-saturated agricultural machinery have been developed. The developed platform makes it possible to obtain ICE diagnostic parameters (fuel consumption, engine temperature, and engine shaft speed), which are remotely transmitted in the form of encrypted data to the server using a GPS modem and digitized in the data bank. Then the received data are structured and analyzed using the developed artificial neural network models. The decrypted diagnostic parameters of the internal combustion engine are sent to the operator, who sees graphs of the parameters of the technical condition of agricultural machinery and reports on predicting possible failures of internal combustion engine parts. The article presents a method for collecting and storing diagnostic information obtained as a result of monitoring the technical condition of agricultural machinery. These data are processed using a mathematical model of a neural network. The use of digital technologies in diagnosing equipment with the help of artificial intelligence can significantly reduce the complexity of the operations performed, evaluate the efficiency of the machine as a whole and predict the onset of failures of its mechanisms, perform timely maintenance and repair of machines, and reduce unplanned downtime of energy-saturated agricultural machinery.

 Freeze-dried vegetable production is intensively developing due to its advantages – a four-time decrease in the weight of supplied freeze-dried potatoes, increased shelf life by dozens of times, and the resistance of freeze-dried products to temperature fluctuations. To study the quality indicators of potato tubers before freeze-drying and after it using standard techniques, the authors analyzed domestic and foreign varieties including those with pigmented flesh and peel. Freeze-drying of potato tubers was carried out in the vacuum-sublimation machine USS‑5 in two stages: rapid freezing of 2 to 3 cm thick sample plates to –30°C during 4 h and heating to +50°C during 2.5 h. Raw potato tubers and freeze-dried samples were tested for antioxidant, phenolic and flavonoid content using standard methods. The results of biochemical analysis showed the total content of alcoholsoluble flavonoids in fresh potato pulp in recalculation on quercetin 0.08 to 1.13 mg/g raw weight, in freeze-dried samples – 0.22 to 1.46 mg/g dry weight; total content of low-molecular antioxidants in fresh pulp from 0.12 to 1.92 mg/g raw weight, phenolic compounds in freeze-dried samples from 0.55 to 4.63 mg/g dry weight in gallic acid equivalents. The study also focused on the determination of the moisture absorption level of freeze-dried potato tuber slices. Moisture saturation of freeze-dried potato slices when immersed in room temperature water occurred within 60 min. Freeze drying had no effect on the antioxidant content of the potato tubers. Therefore, this method can be used to produce healthy foods.

The yield of corn grain depends on the tillage methods used in the cultivation technology of wide-row crops. To make comprehensive assessment of the use of various combinations of the cultivator’s working tools, the authors carried out a two-year study to improve the technology of growing corn for grain by optimizing the system of mechanized cultivation of wide-row crops. The essence of optimization is to change the combination of working tools in a combined tillage unit and change the width of their arrangement along the row spacing width and the depth of soil cultivation. Integrated deep tillage contributes to the destruction of weeds from a larger area between the rows and provides optimal conditions for the growth and development of corn. In 2021, use was made of a tillage unit with a combination of working tools – two one-side flat cutting shares (edges) with overlapping of the working tool edge and a V-shaped share in the center of the inter-row spacing. This combination resulted in a corn yield of 3.62 t/ha. Compared to other types of tillage, the increase was from 0.61 to 1.10 t/ha. This year, in comparison with 2022, in the early phases of the growth of corn and the development of its reproductive parts from April to May, excessive moisture was observed, while in June and July the moisture level was insufficient. In 2022, the use of two universal V-shaped shares with overlapping the working tool edge, inserting wheel spiders in the center of inter-row spacing ensured a yield of 9.15 t/ha. Compared to other types of tillage, the increase was from 0.33 to 1.99 t/ha. The provision of a high yield level in 2022 was facilitated by excessive moisture in the period from April to June and the accumulation of moisture in the soil. The choice of a combination of working tools should be determined by weather conditions.

The reliability of modern sealing units of agricultural machinery is insufficient. Due to surface wear of the shaft and the seal during operation, the tightness in the movable joint decreases. This condition leads to the onset of leaks and the assembly failure. Leaks of technical fluids in units account for 20 to 30% of the total number of failures; during the overhaul period, seal failures occur 1.5 times more often than in new equipment. The method of completing the parts of shaft connections with seals will be useful for assigning rational repair dimensions of the shafts and selecting suitable seals. For its development, the authors considered the main ways to ensure the operational reliability of shaft connections, including advanced methods for restoring the shaft surface. When developing the method, 100 worn input shafts of the YaMZ‑239 engine gearbox and 100 new seals 1.2‑52´72‑8 were studied. Measurements were taken of the worn surface of the shaft under the seal and the inner diameters of the seal holes. The wear of the shaft surface under the seals reached 0.5 mm, and the probability of the shafts with wear exceeding the allowable 51.7 mm was 33%. When assembling worn shafts with new seals, the spread of interference ranged from 1.7 to 3 mm. At the same time, the limit of the least tightness, equal to 2 mm, was violated in 15% of the connections. In the connections of new seals with shafts machined to a repair size of 51.4 mm, the spread of interference ranged between 1.6 mm and 3 mm, while the limit of the least interference was violated in 20% of the connections. According to the criterion of maintaining the least tightness in the connection, the method of completing the parts of the “shaft-seal” connection was tested, including the calculation of the number of groups, the assignment of shaft repair dimensions and the selection of seal diameters. As a result, the probability of appearing connections with a guaranteed tightness of at least 2 microns was 88%, therefore, the proposed method of selecting shafts and seals makes it possible to make the durability of shaft-seal connections comparable to the new ones.

Reinforced rubber seals are used in bearing assemblies. Their reliable operation is ensured by pressing the working edge of the seal to the shaft. The contact load in the connection is affected by the force generated by the band spring. The presented method is used to determine the specific contact load of the working edge of the seal on the shaft offered by the bracelet spring, depending on the parameters of the seals and springs. To check the adequacy of the methodology, the authors studied a batch of reinforced seals 1.1‑45×65‑1 GOST 8752‑79 in the amount of 25 pcs. Theoretical calculations of the contact force from the action of the spring were 2.64 to 3.804 N, specific contact loads – 0.098 to 0.153 N/mm, and according to experimental data – 2.75 to 3.50 N and 0.102 to 0.141 N/mm, respectively. High convergence confirms the correctness of the presented calculated dependencies. It has been established that the parameters of the seals have a large spread, which hampers accurate calculation of the specific load in the “shaft-seal” connection. To increase the accuracy of readings, it is necessary to reduce the tolerances on the dimensions of rubber products.

Cleaning and washing contaminated surfaces of machine parts is relevant in the repair industry. Improving the efficiency of the process of cleaning metal parts is possible using a combination of submersible, jet and ultrasonic methods. The variety of designs of washing machines and installations using different cleaning methods requires the determination of optimal technological parameters and process modes, as well as the identification of an effective washing solution. For this purpose, an experiment was carried out on the process of cleaning metal parts from the remnants of cutting fluids (coolants) in submersible washing machines using ultrasonic vibrations. Solutions of dimer, labomid, and soda ash were studied to clean metal parts from coolant residues. To intensify the process of washing metal parts, an ultrasonic unit UZDN-A with a constant oscillation frequency was used. The degree of purification of metal parts was estimated by the ratio of the mass of the pollutant removed from its surface to its initial mass, in percent. The obtained mathematical models of the degree of cleaning of metal parts (for grades of structural carbon steels and non-ferrous metals) from coolant made it possible to determine the optimal technological parameters: concentration of cleaning solutions 15 to 20%; working temperature for dimer – 20 to 30°C, for labomid – 70 to 80°C, for soda ash – 80 to 90°C. It has been established that the most energy-efficient and safe cleaning solution is a dimer, and the use of labomid for ultrasonic cleaning is not advisable due to its increased foaming. It was also found that the time of washing (the presence of metal parts in the machine) and the amount of oil on the surface of metal parts do not significantly affect the degree of cleaning.

Special operating conditions of operating electric motors in the agro-industrial sector determine their high accident rate. The rapid introduction of frequency converters leads to the need to analyze the thermal state f electric machines in non-nominal and emergency operating modes and the development of relevant software simulation model of electric drive performance in various operating modes. The thermal computer model developed by the authors and based on the calculation of all losses in an electric machine makes it possible to analyze the aerodynamics of the machine and temperature conditions. As a result of the model implementation, the speeds and directions of air flows in the individual components of the electric motor are established in the Comsol software. It is noted that the air flow velocity changes dramatically from the beginning of the air channel to the end – from 14 m/s to 3 m/s. The multiphysics interface in the software product combines aerodynamic analysis and thermal research. The results of thermal analysis showed that under nominal operating conditions the maximum body temperature was 43 degrees, and the temperature of the stator winding front part was 112 degrees. Studies of the transient process of electric motor start-up showed uneven heating of the front and back parts of the stator winding, the temperature difference was 3 degrees. The obtained computer model will make it possible to establish the influence of losses in the machine, environmental conditions, constructive elements of the electric motor on the temperature of individual components of the research object. Change of operating conditions and regulation of the rotor speed can also be estimated by means of the obtained computer model. Determining a more heated part of the machine makes it possible to properly install the temperature sensors of the emergency protection devices

 In the system of professional education, the highly relevant problem is to ensure reliable and valid assessment of graduates’ competences, as well as to develop appropriate tools to do this as explicitly as possible. One of the indicators used in the accreditation of an educational organization is the proportion of students showing certain results when working with diagnostic tools from the assessment kit. The purpose of the study is to identify and justify the diagnostic capabilities of the assessment kit tools to improve the quality of professional education. In the course of the study, the authors analyzed the practice of developing and using assessment tools for training area 35.03.06 “Agroengineering” in a number of agricultural universities in Russia: Volgograd State Agrarian University, Kuzbass State Agricultural Academy, Belgorod State Agrarian University named after V.Ya. Gorin, Irkutsk State Agrarian University named after A.A. Ezhevsky and Ulyanovsk State Agrarian University named after P.A. Stolypin. A total of 365 students took part in the study. Sets of assessment tools included 40 questions each from descriptors, reflecting the development of several general professional competences. The greatest difficulties arose for students when passing tests, which included questions reflecting the content of several competences. To ensure that the training of graduates meets the requirements of state accreditation of ducational activities, the authors emphasized the ways to modernize the content and methods of teaching students, taking into account the development trends of the competence-based approach in the theory and practice of professional education.