A Computer Aided System (CAS) is developed in order to evaluate off-road wheeled vehicle mobility. The system takes into consideration both vehicle technical parameters and the main specifications of the soil on which the vehicle is expected to operate. Thirty seven vehicle technical parameters organized in nine groups are considered. These groups are: weights, engine parameters, dimensions, performance, transmission, steering, brakes, tires, and self recovery means. The main soil specifications of the soil considered are the soil type (clay, silt, or sand) and the shear and bearing resistance represented by the cone index or the gradient cone index.
The evaluation process depends on considering a datum value for each vehicle technical parameter. These datum values or norms are obtained from a statistical analysis study of the technical parameters for a sample of 155 off-road wheeled vehicles representing different schools from all over the world [1]. The effect of soil parameters is taken care of through calculation of the mobility index number of the vehicle on the soil type considered. The different relative weights given to each parameter are obtained by analyzing the response to a thoroughly prepared questionnaire for fifteen of the distinguished automobile experts from both university staff and industry consultants.
The CAS is programmed in a modular way such that addition, deletion, improving, and/or modifications are easily performed. The use of the CAS is convenient and the system integrity is realized through checking of the input data for unreasonable values. Also a separate module for checking the consistency of the producer's data is provided. The system is compared with other classical systems and it is thought to be superior for the following:
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Using the CAS system saves time and cost, and more accurate results are expected. Also, more analysis of the evaluation results can be easily carried out using the ability of the system to output different reports.
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In CAS, the obtained reference values and the relative weights depend on a statistically based study, and consequently the system design is less subjective..
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With the aid of the knowledge base stored in the CAS, any number of vehicles, even a single one, can be evaluated. It should be noted that for any method based on the principle of comparison, the evaluation of a single vehicle is impossible.
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The effect of soil can be considered with different weights according to the prospective use of the vehicle.