Modeling and control design for a computer-controlled brake system

The brake subsystem is one of the most significant parts of a vehicle with respect to safety. A computer-controlled brake system has the capability of acting faster than the human driver during emergencies, and therefore has the potential of improving safety of the vehicles used in the future intelligent transportation systems (ITSs). In this paper we consider the problem of modeling and control of a computer-controlled brake system. The brake model is developed using a series of experiments conducted on a test bench which contains the full scale brake subsystem of a Lincoln town car and a computer-controlled actuator designed by Ford Motor Company. The developed model has the form of a first-order nonlinear system with the system nonlinearities lumped in the model coefficients. The unknown model parameters are identified by applying curve fitting techniques to the experimental data. The major characteristics of the system such as static friction, dead zones, and hysteresis have been identified in terms of model parameters. The brake controller design makes use of a standard feedback linearization technique along with intuitive modifications to meet the closed-loop performance specifications. The simulation results show that the proposed controller guarantees no overshoot and zero steady-state error for step inputs. Test of the same controller using the experimental bench setup demonstrates its effectiveness in meeting the performance requirements.