Avoiding of Saturation and Resonance Effects via Simple Adaptive Control of an Electrically Driven Vehicle Using Omnidirectional Wheels

Abstract

The task of solving the adaptive control of a partially and imprecísely modeled electricai vehicle driven by three omnidirectional wheels tagether with the torque andlor power limits of the drives is considered. Instead of the application ofprecise analytical models and sophisticated parameter estimation techniques the vehicle is modeled as a rigid body while the considerable part of the hurden caiTied by it through elastic connection is completely neglected in the controller's model. Instead of that, a simple kinematically designed, PID-type trajectory tracking is formulated that is approximated by robust fixed point transformations. It is shown that if the nominal trajectory to be traccd does not significantly excite the unknown degree of freedom of the vehiclc-burden connection precise and stable control can be achieved by the adaptivity, while the pure PID-type control may excite this degree of freedom and can be corropted by achieving either the torque or the power limits of the actual drives applied. This statement is substantiated by numerical simulations. The main advantage of the proposed control method is that it operates with local basin of attraction developed for convergent iterative Cauchy sequences that is easy to design by setting only a few parameters. Its disadvantage is that it  cannot guarantee global stability therefore its application must be precerled by numerical tests. lts use may be especially useful in applications in industrial workshops when modeling the dynamics of the coupled hurden technically is very difficult, e.g. when it is a tank partially containing liquid.