• International Journal of Automotive Technology
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• v.8 no.3
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• pp.375-382
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• 2007

The multi-driver off-road vehicle drive-line consists of many components, with close connections among them. In order to design and analyze the drive-line efficiently, a modular methodology should be taken. The aim of a modular approach to the modeling of complex systems is to support behavior analysis and simulation in an iterative and thus complex engineering process, by using encapsulated submodels of components and of their interfaces. Multi-driver off-road vehicles are comparatively complicated. The driving-line is an important core part to the vehicle, it has a significant contribution to the performance. Multi-driver off-road vehicles have complex driving-lines, so performance is heavily dependent on the driving-line. A typical off-road vehicle's driving-line system consists of a torque converter, transmission, transfer case and driving-axles, which transfers the power generated by the engine and distributes it effectively to the driving wheels according to the road condition. According to its main function, this paper proposes a modularized approach for design and evaluation of the vehicle's driving-line. It can be used to effectively estimate the performance of the driving-line during the concept design stage. Through an appropriate analysis and assessment method, an optimal design can be reached. This method has been applied to practical vehicle design, it can improve the design efficiency and is convenient to assess and validate the performance of a vehicle, especially of multi-driver off-road vehicles.

• Journal of Biosystems Engineering
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• v.27 no.6
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• pp.501-512
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• 2002

Traction performance of off-road vehicles is estimated using slip-traction relationships Two zero condition accepted by ASAE have been used widely to obtain the slip-traction relationships of off-road vehicles. This study was carried out using the soil bin systems to investigate the characteristic of slip-traction curves obtained using two zero conditions defined by ASAE. which are driving and driven zero condition, and to present disadvantage of slip-traction relationship based on two zero conditions of ASAE. The results of this study are summarized as follows : 1. For the driving zero condition, the curve of slip-traction relationship shows some issues. The first question is that the slip is zero when the traction is zero. The second question is that the value of slip is smaller than that of corresponding real slip, as the rolling radius decreased f3r the setting zero condition with driving wheel. 2. For the driven zero condition. slip occurs when the traction is zero, which is more realistic results than driving zero condition. But when a zero condition is set, skid occurs and this result increased the rolling radius of tire and increased slip value f3r the specific traction value of whole slip range. This kind of trend was getting bigger as the soil is softer, or the tire inflation pressure is higher. 3. From the results of this study, it was found that slip-traction relationship obtained by two zero conditions of ASAE is not realistic in estimating the traction performance of off-road vehicles. And also slip-traction relationship obtained for the same experimental condition showed different result in accordance with chosen zero condition,

• Journal of the Korean Geotechnical Society
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• v.34 no.9
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• pp.33-42
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• 2018

When an off-road tracked vehicle travels, an engine thrust that is transmitted to the continuous track induces a shearing action on the soil-track interface. Consequently, the relative displacement known as slip displacement takes place on the soil-track interface, which develops an associated soil thrust acting as a traction force. For the loose or soft ground conditions, an excessively large slip displacement can be required for the development of the desired soil thrust which will make the tracked vehicle mobile and therefore the outer surface of the continuous track is generally designed to protrude with grousers. This paper fundamentally studied the effect of grousers on the soil thrust of off-road tracked vehicles. Based on the soil-track interaction theory, a new soil thrust assessment method that properly takes into account the effect of grousers was developed. Also, the soil thrust of off-road tracked vehicles equipped with a number of grousers was evaluated using the developed assessment method. The results showed that grousers increased the soil thrust of the continuous track, enhancing the overall tractive performance of off-road tracked vehicles. These effects were more obvious as the height of grouser increased and the spacing of grouser decreased; thus, it is concluded that the grouser which has smaller shape ratio (span of the grouser to a grouser height) significantly enhances off-road tracked vehicle's performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.188-195
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• 2000

This study was conducted to develop the mathematical model and the computer simulation program(TPPMWV) for predicting the tractive performance of off-road wheeled vehicles operated on various soil conditions. The model takes into account main design parameters of a wheeled vehicle, including the radius and width of front and rear tires, the weight of vehicle, wheelbase and driving type(4WD, 2WD). Soil characteristics, such as the peressure-sinkage and shearing characteristics and the response to repetitive loading, are also taken into consideration. The effectiveness of the developed model was verified by comparing the predicted drawbar pulls using TPPMWV with measured ones obtained by field tests for two different driving types of wheeled vehicle. As a results, the drawbar pulls predicted by the TPPMWV were well matched to the measured ones within the absolute errors of 5.25%(4WD) AND 9.42%(2WD)for two different driving types, respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.3
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• pp.105-112
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• 1994

A computer program was developed for the simulation of mobility and tractive performance of tracked off-road vehicles. Input parameters for the simulation involve those characterizing track and power drive line of a vehicle and soil conditions upon which the vehicle operates. The simulation predicts tractive performance in terms of soil thrust and motion resistance of track device and mobility performance in terms of the maximum speed, time-distance and time-speed relation that a vehicle can obtain under the given soil conditions. It also determines whether or not the vehicle can move in those conditions. An example of performing simulation was presented and its results showed that the performance prediction was reasonably in a good agreement with the published data.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.248-257
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• 1999

A mathematical model was developed to investigate the mechanical interrelation between soil characteristics and main design factors of a tracked vehicles , and predict the tractive performance of the tracked vehicles. Based on the mathematical model, a computer simulation program(TPPMTV98) was developed in this study. The effectiveness of the developed model was verified by comparing the predicted drawbar pulls using TPPMTV98 with measured ones from traction tests with a tracked vehicle reconstructed for test in loam soil with moisture content of 18.92%(d.b). The drawbar pulls measured by the TPPMTV98 were well matched to the measured ones. Such results implied that the model developed in this study could estimate the drawbar pulls well at various soil conditions , and would be very useful as a simulation tool for designing a tracked vehicle and predicting its tractive performance.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.4
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• pp.372-378
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• 2009

For effective mobility control of unmanned ground vehicles in outdoor off-road environments, terrain cover classification technology using passive sensors is vital. This paper presents a novel method far terrain classification based on color and texture information of off-road images. It uses a neural network classifier and wavelet features. We exploit the wavelet mean and energy features extracted from multi-channel wavelet transformed images and also utilize the terrain class spatial coordinates of images to include additional features. By comparing the classification performance according to applied features, the experimental results show that the proposed algorithm has a promising result and potential possibilities for autonomous navigation.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.155-166
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• 1997

In this study, a simulation tool is developed in order to investigate non steady-state cornering performance of 6WD/6WS special-purpose vehicles. 6WD vehicles are believed to have good performance on off-the-road maneuvering and to have fail-safe capabilities. But the cornering performances of 6WS vehicles are not well understood in the related literature. In this paper, 6WD/6WS vehicles are modeled as a 18 DOF system which includes non-linear vehicle dynamics, tire models, and kinematic effects. Then the vehicle model is constructed into a simulation tool using the MATLAB /SIMULINK so that input/output and vehicle parameters can be changed easily with the modulated approach. Cornering performance of the 6WS vehicle is analyzed for brake steering and pivoting, respectively. Simulation results show that cornering performance depends on the middle-wheel steering as well as front/rear wheel steering. In addition, a new 6WS control law is proposed in order to minimize the sideslip angle. Lane change simulation results demonstrate the advantage of 6WS vehicles with the proposed control law.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.217-224
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• 2012

In general, transportation sources include both on-road vehicles and off-road equipment. Off-road vehicles have usually used diesel engines, which have the disadvantage of high NOx emission. Common rail direct injection (CRDI) and after-treatment systems have been applied to meet the exhaust gas emission regulations for diesel vehicles. In the present, agricultural machinery has satisfied the Tier 3 emission regulations by using waste gate turbocharger (WGT) and internal exhaust gas recirculation (EGR). In this paper, the combustion and emission characteristics of an EGR system applied to a 56kW off-road vehicle in non-road transient cycle (NRTC) mode have been investigated. The EGR map was made from foundation experiments determining the EGR duty for all engine operating conditions, and then this map was applied to the NRTC mode. Consequently, the NOx emission was reduced by the EGR system, and the Tier 4 interim emission regulations were satisfied by using both the EGR system and an after-treatment system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.3
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• pp.29-35
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• 2022

When a vehicle is driven off a road surface, the deformations of the road surface and tire are combined. Consequently, the dynamic behavior of wheel movement becomes difficult to predict and control. Herein, we propose a tire test bed to capture the dynamic behavior of tires moving on sand and soil. Based on this study, it is discovered that the slip rate can be controlled, and the vertical force can be measured using a load cell. The test results show that this test bed can be useful for capturing the dynamic behavior of the tire and validating dynamic simulations. In fact, the tire test bed developed in this study can be used to verify the results of computer simulations. In addition, it can be used for basic experiments pertaining to the speed control of unmanned autonomous vehicles.