Preliminary investigations on a higher order model-free approach in antilock braking

Friction effects are complex, strongly nonlinear phenomena for the description of which various models of numerous independent parameters have been developed in the past decades. Normally they simply have to be compensated in control systems in which they appear as undesired perturbations. In other tasks as acceleration/deceleration of wheeled vehicles they are key factors determining the limits of the effective control actions. Safe braking of vehicles with prescribed deceleration or possibly minimized braking route is an interesting task for the solution of which various friction models and controllers have been elaborated. Since the friction parameters strongly depend on the environmental conditions the identification of the appropriate model for braking purposes is practically hopeless. In the present paper a simple model-free controller is suggested and outlined that needs only the observation of the deceleration of the vehicle body and the rotation of the wheels as independent physical quantities. The operation of the suggested controller is illustrated via simulations that uses a particular friction model with typical parameters taken from the literature. The method may have further development by adaptive techniques that do not concern the friction model itself but other parameters of the controlled system that are assumed to be approximately known.