Development Of Control-By-Wire System For Autonomous Driving And Its Application In Lane Keeping Control

Autonomous driving is a research hotspot,which is expected to replace manual driving and reduce traffic accidents.The control-by-wire system for chassis,that consisting of brake-by-wire,steer-by-wire,and drive-by-wire,is the basis of achieving lateral and longitudinal control for autonomous vehicles.However,there are few technical solutions for control-by-wire system in China,and the design of control-by-wire systems are in urgent need.Aiming at supporting the research of autonomous driving,this paper designed the control-by-wire system for chassis and its control algorithms,and developed a prototype for autonomous driving.Firstly,this paper designed the technical structure of the control-by-wire system,including the steer-by-wire system based on the dual-motor safety redundant mechanism,the brake-by-wire system based on the body electronic stability system(ESC),and the drive-by-wire system based on electronic throttle.Furthermore,those systems were integrated into a vehicle through vehicle modification,and the layout of vehicle sensor and electrical system were designed,then the prototytpe equppied with control-by-wire system was developed for autonomous driving.Secondly,the software of control-by-wire system was developed.A highly reliable closed-loop steering control algorithm was designed to achieve automatic control of steering wheel angle by segment feedback,the control algorithm of brake-by-wire was designed to achieve the automatic control of the vehicle deceleration on the basis of brake pressure model and feedback by controlling the motor and solenoid valve of the hydraulic control unit(HCU),and the automatic vehicle acceleration control was achieved through the control of the throttle's output voltage.Both the mechanism of control-by-wire system and the control algorithm were verified by vehicle experiments.In order to facilitate the calibration of control-by-wire system,this paper also developed a calibration tool and data real-time display system of control-by-wire based on controller area network calibration protocol(CCP),which can achieve online calibration of parameters and visualization of the vehicle status.This tool provides a convenient development environment for control-by-wire system and improves its calibration efficiency.Finally,this paper applied the control-by-wire system into the research of lane keeping control.Focusing on the uncertain time-delay of sensor's signals in lane keeping system,a hierarchical lateral robust controller of autonomous driving was designed.The bench experiment results showed that the robust control algorithm designed in this paper has obvious advantages by comparing with the traditional control algorithm,which reducing the trajectory tracking error and vehicle chatter effectively.The mechanism and the control algorithm of chassis control-by-wire system for autonomous driving were developed in this paper,and a completed control-by-wire chassis for autonomous driving vehicle was constructed by integrating on real vehicles.The developed control-by-wire system proposed in this paper has been applied to several vehicle companies,providing a solution for the motion control actuators of autonomous vehicles.