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As it is known, the modern agricultural tractor is no longer just a machine capable to pull agricultural trailers and to operate implements but has evolved into a multi-purpose and mobile energy source with standardized interfaces (mechanical, hydraulic and electronic) to connect to a several typologies of agricultural operating machines. It follows that the selection of the most appropriate tractors for the specific production realities is a crucial aspect for farmers, advisors, contractors and farm machinery experts. The tractors choice thus must consider different parameters, concerning not only the cost of the machines but also their dimensions, power, weight, technological level, etc. The availability of simplified models for estimating the purchase investment and sizing the machine in relation to its mechanical characteristics could be a useful tool in the choice of the tractor more suitable for the specific agricultural context. The aim of this study was to collect and to analyse the technical parameters of tractors present on the Italian market (more than 1300 models), divided into: i) four wheel-drive (4WD) standard tractors, ii) two wheel-drive (2WD) standard tractors, iii) narrow track 4WD tractors, iv) Isodiametric specialized 4WD tractors, v) crawler tractors and vi) rubber-tracked tractors), in order to define the most relevant parameter-to-parameter and parameter-to-price relations for updating reference models to calculate the machine price and the weight to engine power ratio. Other relations, including the three-point hitch efficiency with respect to tractor's weight and the relationship between the rated engine power and its displacement, are proposed in order to provide synthetic tools to characterise and to compare - from the mechanical point of view - the different categories of agricultural tractors. [ABSTRACT FROM AUTHOR]

The application of autonomous navigation technology of electric crawler tractors is an important link in the development of intelligent greenhouses. Aiming at the characteristics of enclosed and narrow space and uneven ground potholes in greenhouse planting, to improve the intelligence level of greenhouse electric crawler tractors, this paper develops a navigation system of electric crawler tractors for the greenhouse planting environment based on LiDAR technology. The navigation hardware system consists of five modules: the information perception module, the control module, the communication module, the motion module, and the power module. The software system is composed of three layers: the application layer, the data processing layer, and the execution layer. The developed navigation system uses LiDAR, Inertial Measurement Unit (IMU) and wheel speed sensor to sense the greenhouse environment and the crawler tractor's information, employs the Gmapping algorithm to build the greenhouse environment map, and utilizes the adaptive Monte Carlo positioning algorithm for positioning. The simulation test of different global path planning algorithms in Matlab shows that the A* algorithm obtains the optimal overall global path. In the scene of map 5, the path planned by the A* algorithm is the most significant, and the number of inflection points is reduced by 40.00% and 87.50%, respectively; meanwhile, the path length is the same as that of the Dijkstra algorithm, but the runtime is reduced by 68.87% and 81.49%, respectively; compared with the RRT algorithm, the path length is reduced by 7.27%. Therefore, the A* algorithm and the Dynamic Window Approach (DWA) method are used for tractor navigation and obstacle avoidance, which ensures global path optimality while also achieving effective local path planning for obstacle avoidance. The test results suggest that the maximum lateral deviation of the built map is 6 cm, and the maximum longitudinal deviation is 16 cm, which meets the requirement of map accuracy. Additionally, the results of the navigation accuracy test indicate that the maximum lateral deviation of navigation is less than 13 cm, the average lateral deviation is less than 7 cm, and the standard lateral deviation is less than 8 cm. The maximum heading deviation is less than 14°, the average heading deviation is less than 7°, and the standard deviation is less than 8°. These results show that the developed navigation system meets the navigation accuracy requirements of electric crawler tractors in the greenhouse environment. [ABSTRACT FROM AUTHOR]

In the Brazilian Amazon, logging is primarily restricted to the driest months of the year by law. Even so, the dry season in the humid tropics is susceptible to considerable rain events, with rain occurring monthly. Therefore, an experiment was established in unentered Central Amazonian old-growth forest to compare skid trail use in the wet season, when logging operations are not permitted, as well as in the dry season. This was done to investigate the differences in soil compaction for the season closed to logging versus the season open to logging. A randomized complete block design (RCBD) was utilized with three blocks composed of seven sub-blocks each, which contained a control, 1, 3 and 12 tractor cycles in both the wet and dry seasons. A Caterpillar track-type tractor model D6D was used for experimental skid trail establishment. Regardless of season the initial machine cycle caused the greatest increase in soil bulk density (BD) and penetration resistance (PR), as well as the greatest decrease in macroporosity. In fact, the initial dry season cycle caused more severe compaction than the wet season. Nevertheless, after 3 cycles, increases to BD and PR were similar for both seasons, with the end result after 12 cycles nearly identical. To the contrary, macroporosity was substantially reduced in the dry season versus the wet season. Overall, the site impacts were similar in both seasons. Thus, skidding operations could be permissible during the wet season with similar impacts caused in the dry season. [ABSTRACT FROM AUTHOR]

Logging is essential to provide society with fuel, building materials, furniture and myriad other needs. At the same time, the ecosystem must be conserved so that the resources are sustainable. This paper considers the impact of forestry activities on forest vegetation and soil indicators: mean height, mean diameter, mean age, tree stock, plant density, soil density, thickness and porosity. The authors analyse the effect of five types of forest machinery operating three extraction (skidding) procedures: butt-first, top-end first, and untrimmed trees. Butt-first skidding using the Amkodor 2242B wheeled tractor was found to have a minimal effect on plant valuation indices; the least damage to soil attributes was inflicted by crawler tractors skidding untrimmed trees. [ABSTRACT FROM AUTHOR]

Because of its good performance, crawler-type running gear plays a very important role in the fields of modern agriculture. This article aims to study the construction of the drive system of the crawler self-propelled rotary tiller with the deep learning network and carry out the system simulation experiment. In this article, deep learning-related algorithms, auto-encoding networks, convolutional neural networks, and structural design of crawler self-propelled rotary tillers are proposed. It then used the self-developed crawler-type rotary tiller and straw paddle machine to compare the field operation performance with the combination of ordinary wheeled tractors and rotary tillers. The experimental results show that the tillage performance indicators such as the working depth, tillage depth stability, ground flatness, stubble pressing depth, and vegetation coverage qualification rate of the "crawler self-propelled tractor + straw stubble pulper" are better than those of "wheel tractor + ordinary rotary tiller" and "crawler tractor + ordinary rotary tiller," increased by 9.92% and 4.88%, 4.31% and 4.13%, 42.59% and 19.12%, 40.15% and 34.57%, and 13.04% and 7.16%, respectively. The mechanical transplanting index was significantly better than other treatments. The yield increase effect of the field test is remarkable, with the average yield increase rate of 9.63% and 4.57%, which is suitable for popularization and application in the southern double-cropping rice area. [ABSTRACT FROM AUTHOR]

The aim of research is to analyse the process of the wide span vehicle motion on the treads of the permanent process track with the use of the traction method of turn. The completed studies have proved that the plane-parallel motion of a wide span vehicle solely with the use of the traction method of turn on the treads of the permanent process track requires a significantly smaller difference between the moments applied to the wheels on the right side and on the left side of the vehicle, as compared to that of a crawler tractor. This difference is in proportion to the width of its wheel base that has a relatively smaller length. It has been established that the use of solely tractionbased turn does not provide for the adjustment of the motion trajectory through the lateral (planeparallel) displacement of the fore-and-aft axis of the agricultural wide span vehicle. The oscillations in the lateral displacement of the agricultural wide span vehicle in the process of its motion are low-frequency ones. The main variance spectrum of these oscillations is concentrated within the range of frequencies of 0-2 s-1. At the same time, the maximum transverse displacement of the agricultural wide span vehicle equal to 1.3 10-5 m N-1, occurs also at low frequencies. In view of the fact that the main variance spectrum of the oscillations of the tangential forces applied to the wheels on the left and right sides of the agricultural wide span vehicle is concentrated exactly within a low frequency range, only the high accuracy of the system using a laser beam can ensure its satisfactory steerability. [ABSTRACT FROM AUTHOR]

In order to improve the automation level of the crawler tractor leveling system, an adaptive leveling control system was designed for the developed crawler tractor leveling device. The overall hardware of the leveling control system was determined and the software system of the leveling device was designed using the proportional algorithm. The designed leveling control system is composed of the real-time detection part, control part, driving part and display part. The system can realize the real-time detection of the tractor inclination angle, and complete rapid leveling of the leveling device. The test results of the leveling control system show that the leveling accuracy and leveling time of the lateral and longitudinal slope increase with the increase of the tractor inclination angle. The leveling accuracy and stability of the longitudinal slope are better than that of lateral slope leveling, and the leveling speed is higher than that of the lateral slope. The coordination leveling accuracy is higher than the independent leveling accuracy of the lateral slope and longitudinal slope, and the collaborative leveling accuracy of the longitudinal slope is better than that of the independent leveling accuracy. The developed leveling control system can independently complete the leveling work under the actual working conditions of the crawler tractor. The leveling accuracy can be in 1° and the leveling time is in 0-6 s. The leveling accuracy and time can meet the design requirements. [ABSTRACT FROM AUTHOR]

With the excessive use of fossil fuels such as oil, the energy crisis and environmental pollution have become important problems related to people's livelihoods. In agriculture, as a new type of green agricultural machinery, the electric tractor has the advantages of high energy utilization and no exhaust emission. The motor is the core component of an electric tractor's drive system. Its characteristics and control directly affect a tractor's operating efficiency, operating quality, and energy consumption. A motor drive control scheme based on a characteristic curve at the maximum efficiency of an electric motor was adopted to address the problems of low motor power utilization and short continuous operation time on a full charge in electric tractors. By leveraging methods to obtain characteristic curves at the lowest fuel consumption for gasoline engines, we determined the characteristic curve at the maximum efficiency for a motor in a crawler-type electric tractor. Plowing is the most basic form of tractor operation, and it represents the agricultural work that accounts for most of a tractor's use. A field test was conducted on the drive control in plowing operation based on the curve, and the energy consumed to plow each m2, continuous plowing operation time on a full charge, and operating efficiency were tested. The test results showed plowing power consumption per m2 of about 8.40 × 10−3 kWh and work efficiency of 707.07 m2/h. Compared with the traditional tractor, the cost of plowing 1 m2 by the crawler-type electric tractor was reduced by 20.3%–32.5%. Because the control improves operating efficiency, battery energy consumption is reduced and continuous operation time is extended; hence, the control achieves its purpose. [ABSTRACT FROM AUTHOR]

Conventional electric crawler tractor platforms are ineffective in parameter matching. The fluctuation of tractor implements during rotary tillage operation results in unstable tillage depth, which compromises operational quality. In order to improve tillage depth control by electric crawler tractors, this study proposed a parameter matching and tillage depth control method based on a prediction model for the rotary tillage operation of the tractor. Utilizing the electric tractor platform in the laboratory, regression models for the energy consumptions per unit area of rotary tillage and whole machine operations were created against the forward velocity, the blade roller speed, and the tillage depth. Tillage depth was predicted by establishing a tillage depth prediction model based on the matching of operational parameters. Finally, the feasibility of the control program and the accuracy of the model were validated through experiments. Results demonstrate that when the proposed method is not used, the tillage depth fluctuates greatly during the rotary tillage operation, with a maximum tillage depth reaching 4 cm. The tillage depth is greatly affected by the fluctuation of tractor implements, and the operational quality is drastically reduced. By using the proposed method, the maximum extremum of tillage depth data is only 2.6 cm, which immensely improves the stability of tillage depth. This study can serve as a reference for the research of tillage depth control for electric crawler tractors. [ABSTRACT FROM AUTHOR]

Controlled traffic farming allows to minimize traffic-induced soil compaction by a permanent separation of the crop zone from the traffic lanes used by wide span tractors. The Authors developed an agricultural wide span vehicle equipped with a skid equipment for turning and an automatic driving system prototype based on a laser beam. The aim of this work was to study the kinematic conditions that control the steering of this machine. Furthermore, the accuracy and the maximum delay time of the signal transmission by the automatic driving system of the set-up was also assessed. In comparison with crawler tractors, the turning of the agricultural wide span vehicle needs a smaller difference in the moments applied to its right- and left-side wheels. For the predetermined accuracy of the beam position relative to the plant rows, ±ds = ±0.025 m, the accuracy of the direction of the laser beam at a distance S=200 m should not be more than ±0.07° and ±0.0014°, considering a run length of 1000 m. Furthermore, at a speed V=2.5 m s-1 a trajectory deviation φ≤5° requires a topmost delay time of the control signal of Δtmax=0.11 s is required. [ABSTRACT FROM AUTHOR]

A real-life case study has been presented in this paper, where a crawler crane machine is investigated for the root cause of failure, using an expert opinion-based technique which comprises of an integrated model which is based on an Intuitionistic Fuzzy TOPSIS model Exponential related function, and the intuitionistic entropy model. The main contribution and advantages of the proposed approach are in the use of a subjective and objective model for the computation of the criteria weight, which allows for complete assessment of the actual performance and value of each of the criteria. The application of the exponential-related function, which represent the aggregated effect of the positive and negative evaluations in the performance ratings of the alternatives based on the intuitionistic fuzzy set (IFS) data used. And finally, the method ranks all alternatives using the exponential-related function matrix, which accounts for the expert's attitudinal character, which a strong influencing factor in subjective assessments like the one used in some of the root cause of failure/reliability analysis. [ABSTRACT FROM AUTHOR]

Multi-body dynamics modeling and simulation has also become an important means to study the dynamic performance of the tracked vehicles, where the reliability of the analysis results depends on the accuracy of the established dynamics model. In this paper, a self-developed small mountain crawler chassis was used as the research object. To ensure the accuracy of the dynamics model, the centroid coordinates and Euler angles of the crawler chassis were selected as generalized coordinates. And the kinematics equation of the crawler chassis was established by using the limit theory and the transient motion analysis method, and the dynamic equation was established by the Lagrangian method, where the parameters that affected the precision of numerical simulation model in theory was analyzed. On this basis, combined with the topology analysis, the multi-body dynamics model of the crawler chassis was established. Firstly, using the three-dimensional software SolidWorks, combined with the physical prototype and design drawings of the crawler chassis, the three-dimensional model of the components was built and the quality characteristics, such as the coordinates of centroid, mass, moment of inertia and so on, were calculated. Secondly, the three-dimensional model of the components was imported into the multi-body dynamics software RecurDyn, and the parametric modeling of the tracks, drive wheels, tensioners and other wheel train components was built in a RecurDyn/Track (LM) environment. All of these were assembled to establish a preliminary multi-body dynamics model of the crawler chassis. Thirdly, combined with the topology analysis of the crawler chassis, the constraint relationship among the components was defined. And the quality characteristic parameters of each component were defined according to the previous calculation results. Finally, according to the actual vehicle test results under the idling condition of the crawler chassis, the stiffness coefficient and damping of the internal bushing force of the crawler belt were determined by the trial and error method. The coefficient was debugged, and the pre-tensioning force of the crawler belt was in accordance with that of the physical prototype measured at rest. In order to further verify the reliability of the established multi-body dynamics model of the crawler chassis, the real vehicle test of the crawler chassis were carried out, where two straight running conditions on hard ground and soft terrain were taken into account, and the parameters such as the average speed, side position offset, driving wheel torque and tension force were considered. By comparing the results between real vehicle test and simulation analysis under the two working conditions on hard ground and soft terrain, the validity and credibility of the model were verified. The results showed that the simulated analysis data and the actual vehicle test results of the average speed, side position offset, driving wheel torque and tension force of the crawler chassis under rigid and soft road conditions were in good agreement. The error was 5.00% and 2.27%, 3.86% and 6.83%, 3.15% and 4.66%, 0.15% and 0.62%, respectively, and the range between the simulation and the measured of driving wheel torque and tension force were 3.05% and 7.30%, 2.80% and 4.02%, respectively. Therefore, the established dynamic model of crawler chassis had high accuracy and good consistency of fluctuations, which could provide a reference model for the in-depth study of the dynamic performance of the crawler chassis. [ABSTRACT FROM AUTHOR]