Drawbar Tests Research Articles

Deep neural networks to predict autonomous ground vehicle behavior on sloping terrain field

AbstractConventional large agricultural machinery or implements are unsafe and unsuitable to operate on slopes or 10%. Tractor rollovers are frequent on slopes, precluding farming on arable hills, uneven or highly sloped land. Therefore, a fleet of autonomous ground vehicles (AGV) is proposed to cultivate highly sloped land (). The fleet aims to expand agricultural land to the slopes and to strengths the human‐robot collaboration in an unsafe sloped environment. However, the fleet's success largely depends on vehicle behavior models regarding traction, mobility, and energy consumption on varying slopes. The vehicle intelligent behavior models are essential and would solve multiple objectives ranging from simulations to path planning & navigation. Therefore, this study aimed to build a deep learning‐based vehicle behavior models on sloping terrain. A standard drawbar test was performed on a single AGV operating on an actual sloped field at varying speeds and load conditions. The drawbar test quantified the AGV's behavior on slopes in metrics related to traction (traction efficiency), mobility (travel reduction), and energy consumption (power number). Deep learning‐based models were developed from the experimental data to predict the AGV's behavior on slopes as a function of vehicle velocity, drawbar, and slope. A special model called the proposed model, which combined multiple deep neural networks with a mixture of Gaussians, was developed and trained with a hybrid training method. The proposed model consistently outperformed the other well‐known machine learning models. This study explored the capabilities of machine learning algorithms to simulate the behavior of small‐track vehicle or AGV on sloping terrain. The fleet aims to provide safer agriculture keeping human safety in focus, and the developed predictive vehicle behavior models would empower the fleet's operation on currently unsafe sloped terrain by assisting in vehicle path planning, route optimization, and decision making.

Relationship between the 3D Footprint of an Agricultural Tire and Drawbar Pull Using an Artificial Neural Network

HighlightsImprovement of tractor traction provides better field efficiency.Drawbar pull increased with tire footprint length.Drawbar pull decreased with increasing tire footprint volume and depth.3D footprint parameters, which the 2D footprint do not contain, affected the drawbar pull significantly.The ANN highlighted the relation adequately.Abstract.Improving the traction of an agricultural tractor on the field increases its working efficiency and capacity. Heavy work, like plowing, entails high levels of tire slip, which is directly related to power loss when the transmission of drawbar pull is required. Accordingly, it is possible to hypothesize that a tire with a higher traction capability could increase the working efficiency of the machine. The natural evolution for measuring the geometrical parameters of tires has led to the consideration of three-dimensional (3D) footprints since the distribution of the vertical stresses at the soil–tire interface may be highly non-uniform. In this study, the data acquired from 3D footprints of 10 sets of tires underwent processing along with the data from drawbar tests carried out with the same tires on soil terrain at different slip ratios. Subsequently, artificial intelligence multivariate methods based on artificial neural networks allowed traction prediction and verified the importance that the acquired geometrical parameters have on the measured drawbar pull. The study confirmed the correlation of the geometrical parameters of the 3D tire footprint with the drawbar pull and the results of the artificial intelligence modelling underlined the impact of these acquisitions. However, further work that considers various lug geometries is required to extend the generalizability of the studied methodology. Keywords: Field efficiency, Phenolic resin, Traction, Tractor.

Mechanical Devices for Mass Distribution Adjustment: Are They Really Convenient?

Since the introduction of four-wheel drive (4WD) and especially front wheel assist (FWA), many studies have been conducted on the optimal weight distribution between tractor front and rear axles because this influences traction efficiency. The aim of this paper is to evaluate the traction and efficiency advantages in the adoption of mechanical ballast position adjustment devices. The tested device is an extendable ballast holder mounted on the front three-point hitch of the tractor, able to displace the ballast up to 1 m away from its original position. An estimation of the fuel consumption during ploughing with the extendable ballast holder in different configurations was performed. Tractive performance was evaluated through drawbar tests, performed on loam soil with a 4WD tractor having a maximum engine power of 191 kW and a ballasted mass of 9590 kg. Results show that changing the tractor weight distribution over the range allowed by the extendable ballast holder produces limited effects in terms of tractive performance and fuel saving. The adoption of such devices is thus ineffective if other fundamental factors such as tyre pressure, choice of the front-to-rear wheel combination and lead of the front wheels are not considered during tractor setup.

Tractive performance of Trelleborg PneuTrac tyres

In the last decades, heavier and more powerful tractors were introduced to the market and they require bigger tyres in order to exert higher traction forces but also to limit soil compaction. Therefore, different solutions were proposed by manufacturers to increase the footprints of traction elements, so that a higher drawbar pull is allowed especially in cohesive soils. However, these solutions have provided a limited increase in the traction efficiency. Recently, Trelleborg have developed a tyre named PneuTrac. The main feature of this tyre lies in the fact that the carcass is radially flexible like a standard radial tyre, but still able to support cornering loads like tracks. This allows the tyre to run with a very low inflating pressure. The aim of this paper was to compare the tractive performance of a set PneuTrac with that of an equivalent set of standard radial tyres. Both types of tyre were mounted on the same tractor, equipped with a CAN-Bus data logger, a load cell and a GPS receiver to measure the drawbar pull and other vehicle operating parameters. Drawbar tests were carried out in three different soil conditions. Results show that PneuTrac performance was slightly less affected by soil conditions than in the case of traditional radial tyres. Overall, PneuTrac tyres permit to increase the drawbar pull up to 5.7% and to reduce slip. PneuTrac tyres also provided a 7.7% increase in the power delivery efficiency with respect to traditional radial tyres.

Conception of an electric propulsion system for a 9 kW electric tractor suitable for family farming

This study presents an updated review of the application of electric tractors. A customised drive system for the conception of a novel low-power electric tractor suitable for family farms is also introduced and discussed. The introduced system comprises several aspects regarding energy generation, transmission, conversion, storage, utilisation, conservation, and management, as well as sustainability issues. A 9 kW prototype composed of two three-phase induction motors, two independent inverters, and a lead–acid battery bank is presented. Flexible and safe operation is ensured by using an electronic control unit specifically designed for this project, as a dedicated control algorithm is also developed to provide greater versatility under common rural activities. Also, a supervisory system is proposed for data storage and performance analysis. To verify the proper performance of the electric tractor, the methodology used for conducting drawbar tests has been based on document CODE 2 by Organisation for Economic Co-operation and Development (OECD). Experimental results are presented and discussed; thus, demonstrating that the proposed electric tractor is technically feasible in terms of performance when compared with a similar internal combustion engine one.

Fuel Consumption Models for Tractor Test Reports

Abstract. Five models for estimating fuel consumption for agricultural tractors with partial drawbar loads were compared. Data were collected from eight John Deere tractors, JD 7230R (e23), 7250R (e23), 7270R (e23), 7290R (e23), 8320R (16 speed), 7290R (IVT), 8345RT (IVT), 8370R (IVT), on the drawbar test track at the Nebraska Tractor Test Lab. The tractors were tested with seven load levels per speed at three different travel speeds as close as possible to 7.5, 10, and 13 km h-1. The IVT tractors were operated in auto mode, and the geared tractors were shifted up three gears and throttled back to the same travel speeds as obtained with the original gear (before shifting up) at maximum drawbar power. The seven loads were selected at 30%, 40%, 50%, 60%, 70%, 75%, and 80% of the drawbar pull at maximum power and rated engine speed at the selected travel speed. Model 1 (fuel consumption as a linear function of drawbar power on concrete), currently used in OECD Code 2, Section 4.4.8, resulted in a separate equation for each speed tested. When regression mean square errors were used for statistical comparison of the five fuel consumption models, model 5 (fuel consumption as a linear function of drawbar power and travel speed on concrete, and engine speed) was not significantly different from the model currently used in OECD Code 2, Section 4.4.8 (model 1, fuel consumption as a linear function of drawbar power on concrete, with separate equations specific to the three speeds tested). The simplest model (model 2), which used a single equation for fuel consumption as a linear function of drawbar power on concrete over the range of speeds tested, had significantly higher regression mean square errors compared to model 1 for half of the eight tractors tested. Model 5 (fuel consumption as a linear function of drawbar power and travel speed on concrete, and engine speed) was determined to be the best of the five models for estimating fuel consumption, with a single equation applicable over the range of speeds tested. Model 3 (fuel consumption as a linear function of drawbar power and travel speed on concrete) provided a statistically equivalent fuel consumption estimate to model 5 without the drawback of requiring an input value for engine speed. Keywords: Drawbar power, Engine speed, Fuel consumption, Model, Partial drawbar loads, Tractors, Travel speed.

Determination of traction coefficient of driving wheels of the MTZ-82 tractor

There are various ways to control the value of normal responses of surface under tractor movers. One of them is to regulate the height of hitch point and the angle of drawbar power. The advantage of this method is that the necessary conditions are created for the automatic control of position of the center of pressure, which ensures the optimization of technical and economic indices of machine-tractor unit operation. To verify this method, it is necessary to carry out the tests determining the parameters of tractor operation, including the traction coefficient of driving wheels. Two variants of its determination are proposed: the towing of tractor with locked driving wheels and the drawbar tests. In both cases, the tractive effort at drawbar is applied at an angle. As a result of drawbar tests, an experimental tractive characteristic of tractor will also be obtained. In preliminary calculations, the weight distribution along the axes is determined depending on the value and the angle of drawbar power. The weight change on the rear axle is more intense than on the front one. It is necessary to use ballast weights on the tractor rear to compensate its unloading. As for tractors and agricultural implements under design, it is necessary to choose the rational component layout and design taking into account the weight redistribution during aggregation. The pre-calculated verification confirms the possibility of use of tractor towing in reverse gear with locked wheels to determine the traction coefficient of driving wheels. The applying of drawbar power at an angle allows to increase or decrease the responses of bearing surface on tractor movers during a particular operation and therefore has an advantage over conventional ballasting at the front of tractor. In combination with the ability to change the back tipping moment, this allows to optimize the traction characteristics of tractors.

Simulation of power parameters of track mover of a tractor

The expediency of use of analogy of wheel and track movers interaction with the supporting surface is established. The research aim is to implement the possibility of simulation of power parameters of a track mover with rubber-covered caterpillars using the positions designed for movers of wheeled vehicles. It is suggested to determine an axial force in plane of contact area of track mover through the sum of products of normal responses and adhesion coefficients on slipping and idling sections of elements of contact area. The normal response in each section should be determined taking into account the variable diagram of specific normal responses. Without slipping of elements, a rectangular diagram is assumed; with full slipping, a triangle one with right angle on the rear part of contact area is assumed. A diagram is a trapezoidal in case of the intermediate slipping. It is recommended to calculate the adhesion coefficient of elements of contact area in the sliding section through the descending elliptical dependence as a function of the relative normal response on slipping section of contact area. The low value is equal to the static friction coefficient of elements without slipping, the high value is equal to the coefficient of sliding friction with full slipping. It is recommended to calculate adhesion coefficient of the idling section through the ascending elliptical dependence as a function of the relative normal response on slipping section of contact area. The low value is equal to zero without slipping, the high value is equal to the static friction coefficient in the transition to full slipping of extreme rear element. The calculated values of the axial force coefficient for track mover of John Deere 8300RT tractor with 1.91 radians of central angle of contact area are well coherent with the actual data of drawbar tests of John Deere 8310RT, 8335RT and 8360RT tractors carried out in the University of Nebraska-Lincoln. The proposed simulation algorithm of power parameters of track mover could be useful when choosing the rational traction modes of tractors operation in different operating conditions.

Loading of tractor on drawbar test when pulling force is directed at the angle

Foreign methods of tractor drawbar testing do not allow to evaluate the performance capabilities of movers and drive system in general with a number of other common characteristics, because of using a tar makadam as a surfacing. Methods of tractor testing used in Russia provide the experiments on real soils and aiming to a wide variety of the country's natural environments. But even these tests do not give a full picture of performance of a machine-tractor unit. Tractor is a multipurpose machine that aggregates with a variety of implements that have a wide range of draught resistance. Therefore, during aggregation it is necessary to load tractor’s axles efficiently. Tractor ballasting increases the rolling resistance force that affects negatively on the propulsive efficiency. In most cases, the front ballast is not removed and remains on a tractor permanently, which increases the fuel consumption. There is a search problem for technical solutions that would optimize the tractor performance without using front ballast. For solving this problem, it is proposed to improve the methods of drawbar testing by directing of pulling force at the angle. If this angle is controlled, it is possible to load a front axle without ballast. In this case, the rear axle is loaded, and its trailing weight is decreased. Additional loading of the rear axle is adjusted by adding ballast weights to the rear wheels or on a cross bar of lower arms. For each case of loading by pulling force, it is necessary to provide the proper rational weight distribution to achieve the highest propulsive efficiency.

Performance evaluation of bullock cart on various roads using various loading materials

This paper covers work carried out at Department of Farm Power and Machinery, Dr. PDKV, Akola. This paper discussed about the performance of the exiting bullock cart on various roads by using the different kind of materials. Drawbar test, track test and haulage test were carried and evaluated the performance of bullock cart. It was found that the pull increased as the laden mass of cart increased on various kinds of roads with the different types of loading materials. The forward speed decreased with continuous work as the laden mass of cart increased on various kinds of roads with the different types of loading materials. The wheel slippage increased as pull increased with laden mass of cart increased for various type of roads. It was observed that the bullock could pull one tonne load at a forward speed of 2 to 3 km/hr with continuous work of 3 hrs. At turning it needs to reduce speed of travel and more attention should give by operator, when cart is fully loaded in order to avoid accident.

Development of a dynamometric vehicle to assess the drawbar performance of high-powered agricultural tractors

Agricultural tractors are machines originally designed to mechanize agricultural tasks, especially tillage and pulling. A large part of research activities have been interested in optimizing tractor efficiency, in particular in terms of emissions and energy. In this frame, the OECD Tractor Code 2 sets out a drawbar test in specific controlled conditions with the aim of evaluating the power of the tractor available at the drawbar. The principal measurement chain relies on dynamometric vehicles (DV) that are instrumented vehicles specifically engineered to develop horizontal force at the drawbar of agricultural tractors. The CREA Laboratory of Treviglio, Italy, engineered a new dynamometric vehicle to test tractors with up to 200kW at the drawbar (245kW at the engine flywheel) and a maximum of 118kN drawbar force. The chosen basis is a FIAT 6605N truck (TM 69 6×6) which has been transformed into a hydrostatic vehicle driven by a hydraulic system and an auxiliary gearbox. The maximum drawbar force was verified up to 122kN. The drawbar power verification (200kW) was successfully carried. The final verification confirmed that the project is valid for the investigation and optimization of the parameters regarding the traction efficiency of agricultural tractors.

최대 견인 출력시 트랙터 엔진의 견인 부하 분석

This study was conducted to investigate the load acting on a tractor engine when it delivers the maximum power at drawbar. The results of the drawbar tests on the 5 locally-made and 14 imported tractors conducted at NIAE in 2004, and the 15 tractors tested at OECD test stations in foreign countries were analyzed and presented by the torque load ratio, defined as a ratio of the engine torque load caused by drawbar pull to its full-load capacity, as a function of pull speed. The NIAE test results showed that the torque load ratio increased from 20 to 80% with pull speed less than 5 km/h. At speeds faster than 5 km/h, it was 80<TEX>${\sim}$</TEX>110% regardless of the pull speed. However, the OECD test results showed that the torque load ratio was evaluated mostly to be 70<TEX>${\sim}$</TEX>90% in the entire pull speed range. The same trend was also shown for the maximum drawbar load. The difference in the torque load ratio may be attributable to bias-ply tires for locally-made and some imported tractors. It is also suggested that the input torque load may be increased safely up to 120% of the full load capacity of the tractor engine for an accelerated life test of tractor transmissions.

UMEB - Unidade Móvel para Ensaio da Barra de Tração

Um equipamento denominado "Unidade Móvel de Ensaio da Barra de Tração - UMEB", foi desenvolvido na FCA/UNESP de Botucatu para realizar ensaios de tratores em solo agrícola. Construída a partir de um reboque ("trailer"), a UMEB foi adaptada para servir como carro dinamométrico instrumentado, utilizado na avaliação do desempenho de tratores submetidos a ensaios na barra de tração. Sua massa total é de 10.500 kg sustentados por um conjunto de seis rodados pneumáticos. Ensaios de campo mostraram que a UMEB proporcionou força de tração acima de 35 kN, mantendo-a constante, em diferentes condições de superfície do solo, mesmo quando a velocidade de deslocamento foi modificada.

TRACTIVE PERFORMANCE COMPARISONS BETWEEN A RUBBER BELT TRACK AND A FOUR-WHEEL-DRIVE TRACTOR

ABSTRACT Field tests were conducted to evaluate and compare the tractive performance of a rubber belt track tractor and a four-wheel drive tractor. Data were obtained by drawbar tests on each tractor operating on four ground surface conditions: untilled oats stubble, disked oats stubble, plowed oats stubble, and com stubble. Tractive performance comparisons between the two test tractors were made by comparing the relationships of dynamic traction ratio and tractive efficiency to slip. In general, the rubber belt track tractor exhibited small tractive performance advantages over the four-wheel drive tractor on firm surfaces with more significant advantages on soft surface conditions.

Prediction of drawbar test performance

Standard tests of agricultural tractors include measurement of drawbar performance on a concrete or tarmacadam surface. Because these tests are time-consuming and expensive, the possibility of replacing them with axle dynamometer tests is under consideration. To maintain comparability with conventional drawbar tests it would be desirable to estimate drawbar performance on a hard surface from results of axle dynamometer tests. This requires a method for predicting slip-pull relationships on a hard surface. Ninety-nine drawbar tests carried out in France, Germany, U.K. and U.S.A. have been analysed and equations of varying complexity derived to predict performance. It was found that, whereas drawbar pull at maximum drawbar power could be predicted fairly accurately, the corresponding slip and consequently maximum drawbar power could not be predicted with sufficient accuracy to enable valid comparisons to be made with drawbar tests. It is suggested that the reason for the kack of accuracy is the presence of unquantifiable variables such as differences in rubber compound, tread pattern or track condition. It is suggested that these throw doubt on the validity of the drawbar tests themselves as a means of comparison and suggestions are made of ways in which the test could be modified to make it more suitable for comparing different drawbar tests and for comparing drawbar tests with axle dynamometer tests.

The determination of traction-coefficient curves for synthetic farm tractor field tests

THE TECHNICAL testing of tractors may be carried out by using test rules valid only in a particular country, or rules which are worked out in collaboration with several countries and valid in only these countries, e.g. the O.E.C.D. Standard Code and Test Bulletin for Agricultural Tractors. A common factor to these tests is that they are all laboratory tests, the results of which, especially those of the drawbar tests, are obtained neither under agricultural conditions nor on arable land. Drawbar tests are generally carried out on an artificial track with a surface of concrete or tarmac because on arable land it is not possible to reproduce the measurements, and therefore the results of different tests are not strictly comparable. The gap between the technical test results as they are stated in a report and real tractor performance in the field, has become so great that it is impossible for the farmer to determine a relationship between them. Farmers are, therefore, demanding that the technical reports should be supplemented by performance data in agricultural conditions. However it has been impossible to comply with this demand, since for any comparison to be valid the soil conditions must remain constant, and this has not been possible. To overcome these shortcomings of the technical tests the Tractor Testing Station at Darmstadt has worked out a method for calculating the field performance of tractors. The basic idea of this method is to select a field and measure the soil coefficients which influence the performance of the tractor. These coefficients are the characteristics of the selected test-field and the calculation for each test is based on these coefficients. Hence a constant test-field is established and the method of calculating the performance complies with the demand for strict comparability of the performance of different tractors. The results of research work on agricultural tractors and tractor tyres coupled with the laws of mechanics make it possible to calculate the performance of any tractor, once all the necessary coefficients have been determined. The results are no longer influenced by changes in the soil conditions but only by the dimensions and weights of the corresponding tractor. If the calculated values in technical terms are converted into agricultural terms, such as drawn load or ploughed furrow-depth, this method always allows the tractor performance to be calculated and reported in terms which the farmer can understand. In order to use this method of calculating tractor performance, the following characteristic values of the selected test-site must be measured at the same time: (a) The traction-capacity of all sizes of tractor tyres; the traction-capacity is characterized by the relationship between the tyre-slip and the tractioncoefficient;

Paper 6: Experiments on the Performance of Slow-Speed Hydraulic Motors for Use in Agricultural Tractors

Two series of experiments were carried out. In the first series, drawbar performance tests were conducted with a tractor fitted with slow-speed hydraulic wheel motors of different capacities. The advantage to be gained from the use of dual-capacity motors may be assessed from the results of these tests. An experimental dual-capacity motor is described and details of its performance are given. In the second series of experiments, an attempt was made to isolate and analyse sources of output torque loss in a slow-speed motor of the radial piston type.

Studies on the relation between cultivation implements, soil structure and the crop II. The effects of the Fowler “Gyrotiller” on the soil

A general account is given of four experiments in which the action on the soil of the Fowler “Gyrotiller” has been compared with that of the traditional cultivation implements. The gyrotiller has produced well-marked changes in the soil on both heavy and light land. These changes have been demonstrated and recorded by tests of the compactness, the resistance, the degree of comminution and the permeability of the soil.On the heavy land, the initial effect has been to produce a very loose and open soil. This has gradually settled down until, after the end of the first winter, no difference in compactness was demonstrable by means of the revolver test. But the resistance of the soil, measured by a special recorder and by plough drawbar tests, has remained demonstrably lower on the gyrotilled plots than on the controls for a considerable time after this, and a method of soil fixation has shown that small cavities persisted for more than a year. In one experiment, differences in resistance have been shown to exist up to 19 months after gyrotilling.