Maximum Tractive Efficiency Research Articles

Data Analysis and Traction Performance Evaluation of an Electric All-Wheel Drive Tractor During Agricultural Operation

Highlights The study evaluated the feasibility of using a new type of platform, the electric AWD tractor, for agricultural operations. The data for key components of the electric AWD tractor during plowing were analyzed. The traction performance of the electric AWD tractor was evaluated via tractive efficiency and dynamic ratio. The electric AWD tractor was expected to replace conventional tractors in terms of traction performance. Abstract. Owing to the increasing need for research on electric all-wheel drive (AWD) systems, an investigation on the AWD systems applicable to tractors was conducted in this study. The experimental platform consisted of an electric power transmission system including four sets of electric motors, helical and planetary reducers, wheels, and an electrical system including chargers, batteries (LiFePO4), converters, and inverters. The drive control system of the electric AWD tractor was divided into the AWD and the motor controller. The data measurement system consisted of analog (current and traction force) and digital (battery voltage, current, motor rotational speed, state of charge (SOC) level, and travel speed) components that communicate using a controller area network (CAN) bus. Data measured during plowing were used to calculate motor power, motor torque, traction power, and driving power to analyze the power consumption of an electric AWD tractor. The traction performance of the electric AWD tractor was evaluated using tractive efficiency, calculated values (traction power and driving power), and dynamic ratio. The maximum and minimum average voltage of the electric AWD tractor during plowing were 72.2 and 64.7 V, respectively, and the average value was measured as 68.2 V. The average value of the maximum current applied to the inverter was 362.4 A, and the mean value was measured as 187.5 A. The average value of the maximum rotational speed of the four motors was 2111.5 rpm, while the mean rotational speed during the operation was 1131.9 rpm. The average value of motor torque was 79.4 Nm. The decrease rate of battery SOC level per minute was calculated as an average of 1.4%/min. The maximum values of the traction and driving power during plowing were 42.0 and 73.7 kW. The maximum tractive efficiency (TE) was 0.77, with an average TE of 0.47. The maximum dynamic ratio (DR) was 0.28, with an average DR of 0.18. The TE of a conventional tractor was found to be a maximum of 0.61, with averages of 0.41, respectively. The average TE of the electric AWD tractor was approximately 14% higher than that of the conventional tractor. Data analysis indicates that the electric AWD tractor performing speed control is vulnerable to slip, and further research is necessary to improve AWD system performance through speed and slip control. Keywords: Data analysis, Data measurement system, Electric AWD tractor, Plowing, Traction performance.

Intelligent ballast control system with active load-transfer for electric tractors

For agricultural tractors fixed ballast cannot provide high-efficiency traction under time-varying resistance in the field. Combining the characteristics of electric tractors with high-weight battery packs, this paper develops an intelligent ballast control system including a battery position adjustment (BPA) mechanism and an active ballasting control method. A tractor traction performance prediction model was developed to predict traction performance parameters and load-transfer in real time. The movement of the battery pack enables load-transfer based on the BPA. To ensure the lowest sliding rate of optimal tractive efficiency, an active ballasting control method based on a particle swarm optimisation algorithm was proposed that enabled control of the optimal battery position. The results of MATLAB/Simulink simulation indicate that the traction resistance after grading and pre-treatment not only reduced the frequency of change in the resistance signal but also retain the original trend. The results of a hardware in the loop test showed that the average tractive efficiency in the mode of active ballasting mode higher than that of the no ballasting mode (increased by 6.6%) and fixed ballasting mode (increased by 4.7%). The mean wheel slip in active ballasting mode was lower than that of the no ballasting mode (decreased by 10.3%) and the fixed ballasting mode (decreased by 4.9%). In addition, the front axle dynamic load distribution ratio in active ballasting mode was always greater than 0.2, which ensured the operational stability of the tractor. This study provides theoretical support and technical reference for optimising the traction performance of electric tractors. • An intelligent ballast control system with active load-transfer is developed. • The concept of batteries instead of ballasts. • Battery position adjustment mechanism (BPA) is designed. • Active ballasting control method based on traction performance prediction model. • The maximum average tractive efficiency is increased by 6.6%.

Traction performance evaluation of a 78-kW-class agricultural tractor using cone index map in a Korean paddy field

The cone index (CI), as an indicator of the soil strength, is closely related to the traction performance of tractors. This study evaluates the traction performance of a tractor in terms of the CI during tillage. To analyze the traction performance, a field site was selected and divided into grids, and the CI values at each grid were measured. The CI maps of the field sites were created using the measured CI. The traction performance was analyzed using the measured traction load. The traction performance was grouped at CI intervals of 400 kPa to classify it in terms of the CI. When the CI decreased, the engine speed and tractive efficiency (TE) decreased, while the engine torque, slip ratio, axle torque, traction force, and dynamic traction ratio (DTR) increased. Moreover, the DTR increased up to approximately 13%, and the TE decreased up to 9%. The maximum TE in the DTR range of 0.45–0.55 was higher than approximately 80% for CI values above 1500 kPa. The DTR and TE results obtained in terms of the CI can help efficiently design tractors considering the soil environmental conditions.

Fundamental realization of longitudinal slip efficiency of tractor wheels in a tillage practice

Longitudinal slip efficiency of driving wheels of off road vehicles is function of not only slip of all driving wheels but also their gross traction force. In this work, the slip efficiency was ascertained for a mechanical front wheel drive (MFWD) tractor in a tillage practice. Front and rear driving wheels of the MFWD tractor performed in unequal traction circumstances (size, inflation pressure, and dynamic vertical load) and soil cone indices. Obtained results indicated that the slip efficiency nonlinearly dropped from 0.94 to 0.74 as simultaneous augmentation of slip ratio of the rear wheels to that of the front wheels (0.72-0.87) along with ratio increment of gross traction force of the rear wheels to that of front wheels (1.81-4.93). These conditions occurred, when draft force requirements of implement augmented from 8.58 to 25.85 kN. Hence, it can be pointed out that the maximum slip efficiency as well as overall power efficiency of the MFWD tractor in tillage practices would be achieved at the same slip in accordance with the same gross traction force of the front and rear wheels. To do this for, specific tire type (radial or bias ply), automatic slip control of the wheels by implementing wheel slip control system would be beneficial, especially in case of lower slip than 0.2 for achievement of maximum tractive efficiency. It must be noted that adjustment of inflation pressure of the tires is also advantageous followed by ballast weight application in this realm.

Application of Soft Computing Techniques for the Analysis of Tractive Properties of a Low-Power Agricultural Tractor under Various Soil Conditions

Considering the fuel consumption and soil compaction, optimization of the performance of tractors is crucial for modern agricultural practices. The tractive performance is influenced by many factors, making it difficult to be modeled. In this work, the traction force and tractive efficiency of a low-power tractor, as affected by soil coefficient, vertical load, horizontal deformation, soil compaction, and soil moisture, were studied. The optimal work of a tractor is a compromise between the maximum traction force and the maximum tractive efficiency. Optimizing these factors is complex and requires accurate models. To this end, the performances of soft computing approaches, including neural networks, genetic algorithms, and adaptive network fuzzy inference system, were evaluated. The optimal performance was realized by neural networks trained by backpropagation as well as backpropagation combined with a genetic algorithm, with a coefficient of determination of 0.955 for the traction force and 0.954 for the tractive efficiency. Based on models with the best accuracy, a sensitivity analysis was performed. The results showed that the traction performance is mainly influenced by the soil type; nevertheless, the vertical load and soil moisture also exhibited a relatively strong influence.

Traction-energy balancing adaptive control with slip optimization for wheeled robots on rough terrain

On rough terrain, excessive wheel slippage is easily generated by changes of surface conditions such as soil types and geometries. It induces considerable loss of wheel traction and battery energy. To prevent this, wheeled robots should consistently recognize the current situation generated between wheel and surface. And also wheeled robots are required to optimally control wheel motion in limited wheel traction and battery capacity. Therefore, this paper proposes a novel wheel control algorithm based on slip optimization of traction and energy, which is adaptive to change of surface condition. Proposed wheel control algorithm is called Traction-Energy Balancing Adaptive Control (TEB) in this paper and TEB assigns optimized rotation speed to each wheel by observing wheel slip ratio which is a key parameter of TEB. As functions of TEB, TEB is largely divided into three main parts; (1) slip optimizer (2) slip controller (3) SC-compensator. In the slip optimizer, two optimal slip models were derived as a function of slip ratios regarding maximum traction and tractive efficiency using experimental data about wheel-terrain interaction in three types of soil (grass, gravel and sand). And the optimal slip models were employed in order to determine a desired slip value of wheel with observation of a change in actual robot velocity as control input in the slip controller. For optimal slip control, the proposed slip controller is based on conventional PID controller with compensating disturbance in the controller (SC-compensator) which occurs by change of surface shapes. In the SC-compensator, radial function networks (RBFN) was applied in the slip controller and RBFN was of help to readjust previously set PID gains depending on occurred slip error. Finally, TEB was experimentally verified by controlling a real robot having four wheels on various terrain types.

Improving the tractive performance of walking tractors using rubber tracks

The pneumatic wheels of a walking tractor were replaced with rubber track system to improve draught. Performance was evaluated in agricultural soils and compared with that when fitted with wheels. Tests were carried out in sandy clay loam soil with cone index (CI) varying from 250 to 1000 kPa for both the tractors. Data of motion resistance, pull and slip were acquired using different sensors and data acquisition system. For CI of 250, 500 and 1000 kPa, the observed motion resistance values for tracks were found to be 1012, 775 and 620 N, respectively, which represent 18.75%, 14.36% and 11.5% of the weight of the tested walking tractor and 935, 675 and 530 N for the wheeled walking tractor which represents 17.32%, 12.5% and 9.8% of its weight, respectively. Rubber tracked walking tractor developed greater drawbar pull than the wheeled one in all soil conditions. The drawbar pull developed with tracks is 115.2%, 75.9% and 62.4% more than that developed by comparable walking tractor fitted with standard wheels, respectively in soils with CI 250, 500 and 1000 kPa. Tractive efficiency (TE) of walking tractors fitted with rubber tracks was higher in all soil conditions. Also, tracks reached peak TE at higher net traction ratio (NTR) and maintained higher TE for a wider range of NTR. Wheels reached maximum TE at lower values of NTR, which drops off at higher NTR values. The results indicate a significant improvement in the tractive ability of walking tractor.

Traction performance of different size of cage wheel for power tiller

The selection of cage wheel is of primary importance in tillage operations for the optimization of traction performance. Selection of proper cage wheel helps in limiting slip and fuel consumption which involves energy loss and it also minimize time required for soil tillage. The present study aim to investigate the tractive and drawbar performance of different diameter of cage wheels. Three cage wheels of diameter 68 cm, 73 cm, and 78 cm with 30° lug angles were tested in four different water levels of 5 cm, 10 cm, 15 cm and 20 cm in wet land field conditions. Results shows that cage wheel of 73 cm diameter gave better performance in terms of higher tractive efficiency with less power consumption, than other cage wheels. Reducing the diameter of cage wheel increases the draft and sinkage and blocking of soil on lug surface. The maximum tractive efficiency was found in the range of 73–78% at 789 N to 1224 N draft and drawbar power was in the range of 505 W to 565 W.

Optimization of traction characteristics of agricultural tractors

The productivity of the machine-tractor unit depends on the energy saturation of the tractor. It is assumed that the optimum traction characteristic corresponds to the minimum operating weight of the tractor and its maximum energy saturation, at which the maximum productivity of the machine and tractor unit is achieved with the lowest fuel consumption and compliance with restrictions on tractive effort, slippage and theoretical speed. As a criterion for determining the maximum energy saturation, the maximum efficiency coefficient is adopted with maximum tractive power and maximum tractive efficiency. Calculation of the optimal traction characteristics is an actual task of the theory of the tractor. The purpose of the study is to develop a methodology and algorithms for calculating the indicators of the optimal traction characteristics of the tractor when the engine speed of the crankshaft is changed. The objects of research are wheeled and caterpillar tractors of general purpose. Input data: engine and tractor performance indicators; coefficients that characterize the traction and coupling properties of the tractor; the tractor power balance equation; slipping functions; the dependence of the fuel consumption of the engine and its torque on the speed of the crankshaft. The method of research is the calculation using the basic formulas of the theory of the tractor when the speed of the crankshaft is changed by one rotation. Taking into account the accepted values of the nominal engine speed and the torque adaptive factor, the gear ratio is calculated. The calculation procedure for the optimum traction characteristic is developed for tractors with a minimum operating weight, calculated taking into account the nominal tractive effort and the coefficients of using the gravity of the tractors. The maximum energy saturation for each type and traction class of the tractor is determined by calculating the tractive characteristic of the transmission, at which the maximum efficiency factor, traction power and traction efficiency are reached. The main conclusion: the optimum traction characteristic corresponds to the minimum operating weight of the tractor and its maximum energy saturation.

Draftbility of Power Tiller with Different Lug Angle of Cage Wheels in Puddle Soils for Paddy

The experiment was conducted on IGKV research farm in wet puddle condition in April month of 2015. The wet tillage practice was carried out by power tiller cage wheel attached with five tines cultivator. Paddy production increases by puddling of soil before transplanting. Cage wheel is an important traction device for any prime mower. The lug is wing provided in cage wheels which interact with the wet soil to churn the soil. The cage wheel 730 mm diameter with 30°, 45°, and 60° lug angle and three different diameter of 73 mm, 680 mm and 780 mm of 30° was tested at 0 to 50 mm, 50 to 100 mm, 100 to 150 mm and 150 to 200 mm, depth of water level in wet land field. The result was found that cage wheel C1 of 30° lug angle with 730 mm diameter give better performance than other cage wheel. The cage wheel showed the best result in 50–100 mm water level in respect to maximum tractive efficiency was found in the range of 73−78% at 996 N to 1009 N draft and drawbar power was in the range of 478.08 W to 484.32 W. While maximum drawbar power was (523.16 to 555.28 W) was observed at 0 to 50 mm water level. Therefore cage wheel of 30° lug angle with 730 mm diameter was found suitable for wet land paddy field condition.

Traction and drawbar performance characteristics of power tiller attached cage wheel

The study was carried out in the research farm of Indira Gandhi Agricultural University Raipur Chhattisgarh in June 2014. To evaluate drawbar and tractive power of 4.85kW of power tiller cultivator attached with two different types of cage wheel of half width (C1) and angle type wheels (C2) for a small power tiller operated in clay soil of wet land and flood condition. It was found that the maximum draft values of C1 and C2 were 1192N and 1039N in flood condition and 1318N and 1225N in wet condition. The results showed that maximum tractive efficiency was for cage wheel C1 and C2 values were 72.91% and 69.86% in puddle soil. The maximum field capacity was 0.084 ha/h for cage wheel C2 in puddle soil.BIBECHANA 13 (2016) 38-49

Suitability of rubber track as traction device for power tillers

Suitability of using rubber tracks as traction device in power tillers replacing pneumatic tires was studied using an experimental setup consisting of a track test rig for mounting a 0.80m×0.1m rubber track and a loading device for applying different drawbar pulls. Tests were conducted in the soil bin filled with lateritic sandy clay loam soil at an average soil water content of 9% dry basis by varying the cone index from 300 to 1000kPa. Data on torque, pull and Travel Reduction Ratio (TRR) were acquired using sensors and data acquisition system for evaluating its performance. Maximum tractive efficiency of the track was found to be in the range of 77–83% corresponding to a TRR of 0.12–0.045. The Net Traction Ratio (NTR) at maximum tractive efficiency was found to be between 0.49 and 0.36.Using non-linear regression technique, a model for Gross Traction Ratio (GTR) was developed and it could predict the actual values with a maximum variation of 6% as compared to an average variation of 50% with Grisso’s model. Based on this model, tractive efficiency design curves were plotted to achieve optimum tractive performance of track for any given soil condition.

Processes involved in the design of a segmented rubber tracked vehicle for Sepang peat terrain in Malaysia

This paper describes a framework for designing a new segmented rubber track vehicle for low bearing capacity Sepang peat terrain in Malaysia. Based on a given set of vehicle dimensions and terrain-track system constants, a simulation technique is then used to optimise the design parameters of the vehicle by establishing mathematical models for the track-peat terrain mechanism. The simulation results showed that the nominal ground pressure of the vehicle is 23.5% lower than the bearing capacity of the peat terrain. The location of the centre of gravity of the vehicle at 300mm rearward from the mid-point of the track ground contact length ensures a maximum sinkage of 90 mm, a minimum motion resistance of 12% and a maximum tractive efficiency of 74% during traversing at 10 km/hr on the peat terrain. Finally, the vehicle components have been designed by using 3D-CAD drawing software package.

EFFECT OF BELT WIDTH AND GROUSER WEAR ON THE TRACTIVE CHARACTERISTICS OF RUBBER–TRACKED VEHICLES

Extensive field tests were conducted using a Caterpillar Challenger 45 rubbertracked tractor to study the effectof belt width and grouser wear on tractive characteristics of rubbertracked tractors. The results of this study indicated thatbelt width does not significantly influence traction characteristics of a belted tractor whereas grouser wear significantlyinfluences both the maximum net traction coefficient and the maximum gross traction coefficient. However, grouser wear didnot influence the maximum tractive efficiency significantly. Moreover, the results indicated that maximum gross tractioncoefficient is linearly related to the maximum net traction coefficient with a coefficient of determination of over 98%.

Reduction of Fuel Consumption Through Improved Tractive Performance

Tractive performance and specific fuel consumption were evaluated for a tractor with front mechanical drive assistance over a range of field surfaces. Curves showing the dependence of drawbar power, tractive efficiency and specific fuel consumption on dynamic traction ratio and slip are presented. These curves are used to illustrate the increases in fuel consumption resulting from not operating the tractor at its maximum tractive performance. Depending on the soil surface, minimum specific fuel consumption was achieved at values of slip varying between 10 and 30%. A tractor should be operated at a minimum dynamic traction ratio of 0·4 and at its maximum tractive efficiency to ensure minimum specific fuel consumption. Maximum tractive efficiency was close to 0·9, 0·8 and 0·7 when operating on surfaces which consisted of stubble or which has been produced by chisel or mouldboard ploughing, respectively.

A Theoretical Ballast and Traction Model for a Wide Span Tractor

A mathematical model to simulate tractive and ballast performance of a wide span tractor, known as a field power unit (FPU), with a subsoiler on agricultural soils, was developed. A computer model based on this mathematical model was written (in C) to predict tractive efficiency, slip, and dynamic load and determine the required ballast to obtain the maximum tractive efficiency for each tire of the FPU. The modeling results showed that the improvement in tractive efficiency by proper ballasting can be up to 20%, that the static weight of the vehicle should be reduced, and that the subsoiler should be mounted in the middle position to minimize ballast changes.

The Tractive Performance of Rubber Tracks and a Tractor Driving Wheel Tyre as Influenced by Design Parameters

The tractive performance of an experimental rubber track unit was compared with that of a 16·9 R34 tractor driving wheel tyre, in 14 different field conditions, using a single wheel tester. In 1989, the track unit was fitted with a thinner, flexible, friction-driven rubber track having less aggressive lugs than that of the tyre. Tests were carried out with vertical loads of 16·68 kN and 19·62 Kn for both the track and the tyre in eight different field conditions. The rolling resistance of the track was found to be higher than that of the tyre because of the internal power losses within the track and losses between the driving sprocket and the track. The coefficient of traction produced by the track was higher than that of the tyre, but the tractive efficiency was lower, due to its higher rolling resistance. The coefficient of traction at which maximum tractive efficiency was achieved with the track was always much higher and the corresponding slip was always much lower than those achieved with the tyre. The significance of this is that a rubber-tracked vehicle could be much lighter than a wheeled tractor of the same power and still achieve the same tractive performance. In 1990, the same tests were repeated with two thicker, positively driven rubber tracks having different tread patterns, and with the same tyre in six different field conditions. The results of the comparison confirmed those of the previous investigation. The tread patterns had no statistically significant effects on their tractive performance.

TRACTIVE PERFORMANCE OF A RIGID WHEEL ON A SIMULATED MARTIAN SOIL

ABSTRACT A one-half scale model of a rigid wheel designed for an unmanned Martian rover was evaluated in a soil bin containing a simulated Martian soil. Operating characteristics of the wheel in terms of motion resistance, net traction, and tractive efficiency were established for three soil conditions and five static wheel loads. Performance was similar to results which had been reported by earlier researchers working with rigid wheels, even though the test soils were very soft, having soil cone indices ranging from 13 to 97 kPa. Maximum tractive efficiency for the wheel, operating on the soil condition anticipated to best represent the Martian surface, occurred at a travel reduction of 25%.

The performance of cage wheels for small power tillers in agricultural soil

Five sizes of lug angle and four sizes of lug pitch were tested to determine the performance of open, flat-lugged wheels for a small power tiller operated on two different types of agricultural soils (sandy and clay loam). As a result, it was found that the maximum tractive efficiency and the maximum drawbar power of the wheels are significantly influenced by the lug angle, lug pitch, wheel slip and soil type.

Real-Time Optimization of Tractive Efficiency

ABSTRACT The dynamic load and inflation pressure of a pneumatic tractor tire have been shown to greatly influence tractive efficiency. A control program was developed using a single wheel test device which would cycle a tire over it's operating range of dynamic load and inflation pressure while monitoring tractive efficiency, compute a tractive efficiency response surface for the particular soil condition and net traction level, and subsequently determine the dynamic load and inflation pressure for maximum tractive efficiency. Results showed that the difference between maximum and minimum tractive efficiency can be up to 30%.