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ABSTRACT
Construction machines represent a particular set of difficulties when modelling their system dynamics. Due to their generally low velocities and unorthodox operating conditions, the standard modelling equations used to simulate the behaviour of highway vehicles can have a poor behaviour for these systems. This paper sets forth a vehicle model which is suitable for construction machines, which travel at low velocities and encounter significant external forces in daily operation. It then shows the work done in validating the machine model with experimental data. First, the overall vehicle dynamics are developed, including a model for the machine behaviour when pushing against a resistive force. Then, a wheel force generation model suitable for low-velocity systems is discussed. Finally, pertinent experimental results are presented. Two different model validation tests were run. Both tests generated results which were matched well by the simulation model. In fact, the model matches experimental data reasonably well for both roading and pushing conditions. This indicates that the modelling methods described in this work are appropriate for the modelling of low-velocity systems such as wheel loaders and other construction machinery.
Keywords: Vehicle dynamics, dynamic system modelling, traction control, construction machinery
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INTRODUCTION
Vehicle dynamics models for on-road machines have been around for quite some time and are relatively well understood. On the other hand, vehicle systems in other areas have not enjoyed the same level of interest; therefore, a standardised dynamics modelling method has not been established. The particular behaviour of construction machines requires some further considerations which differentiate them from standard passenger vehicles. Some previous work has been done in modelling these systems, including component modelling work by Wong [1] and Andreev [2], with even more investigations recently [3, 4]. Choosing a vehicle dynamics modelling strategy is often heavily dependent on the application at hand. Many different dynamic models exist for describing aspects of the vehicle suspension system [5] or various resistances [6]. Instead, this work focuses on modelling the driveline and wheels of construction machines. Different approaches to the problem of the wheel and tire dynamics modelling have been done in the past, each incorporating different idea or physical models [7-10]. Most common modern methods stemmed from variations on the seminal work done by Pacejka [11]....