This paper has been focused on the design of throttle and brake controller for vehicle speed control. The control goals of the speed control are reduction of the effects of model uncertainty and external disturbance caused by the nonlinearity of the servo-level dynamics and the unpredictable driving resistance such as inclination of road and aero dynamic drag force. The tracking performance also should be guaranteed. To that end, a model free approach has been proposed in this paper. The proposed controller uses modified linear longitudinal vehicle model with reasonable assumptions to derive throttle and brake control law and a few parameters in the vehicle model has been defined to represent the system delay and variation of the vehicle parameters during driving. Since the defined parameters named vehicle characteristic variables(VCVs) vary depending on the vehicle states, an adaptation algorithm has been developed to estimate the VCVs. The error dynamics of the vehicle acceleration and VCVs have been analyzed to prove the stability of the proposed algorithm. The tracking performance of the model free cruise controller has been verified by simulation. The results not only show good tracking performance but also verify that the MFCC considerably reduces the effects of model uncertainty and external disturbance using adaptation algorithm.
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