PID Control And Design For Two Classes Of Wheel-Direct-Drive Systems Via Time-Varying Samplings

With the popularization and application of electric vehicles,wheel-direct-drive systems in electric vehicles have attracted wide attention,many research achievements have been obtained.Compared with the traditional drive technologies,wheel-direct-drive technology reduces the complexity of the vehicle body and vehicle turning radius,makes easy wheels differential control,improves vehicle stability and performance,and increases the design flexibility,due to elimination of some special mechanisms and other mechanical equipments such as gearbox and differentials.To improve the automatization and intelligentization levels of wheel-direct-drive systems,to increase the trafficability of electric vehicles,and to propose a new vehicle body adjusting technology which is more economical and energy saving than hydraulic and pneumatic technology,in this thesis,the dual functions of vehicle body height adjusting and wheel driving are firstly realized with the aid of introducing a motor and PID control via time-varying samplings,the control and design of new single-motor wheel-direct-drive system based on PID control via time-varying samplings are studied.Furthermore,to achieve the functions of vehicle body height adjusting in parallel with wheel driving,and to improve the reliability and safety of wheel-direct-drive system,the PID control via time-varying samplings and design of new dual-motor wheel-direct-drive system are studied in this thesis.In chapter 2,the design scheme of new single-motor wheel-direct-drive system is proposed.The analyses of working mechanism and dynamic characteristics are given,the state space models of vehicle body height adjusting system and wheel speed tacking system are established,respectively.The stability criteria and the PID controller design algorithm via time-varying samplings are derived in terms of linear matrix inequalities,the platform of new single-motor wheel-direct-drive system is developed,the validity of the design and engineering significance is verified by simulations based on Matlab and practice test.In chapter 3,design scheme of a new dual-motor wheel-direct-drive system is proposed.The state space model which integrates vehicle body height adjusting function and wheel driving function are established.The stability criterion and the PID controller design algorithm via time-varying samplings of multi-controller working coordinately are obtained in terms of LMIs.The numerical simulation verifies the reasonability.The main contributions of this thesis are listed as follows:(1)Two classes of new wheel-direct-drive systems which have both vehicle body height adjusting function and wheel driving function are Designed and developed,respectively.Those design provides new technologies of adjusting vehicle body height and enrich research contents of wheel-direct-drive system.(2)Based on state space models of new wheel-direct-drive systems,the PID controller design algorithms via time-varying samplings which are used to realize the vehicle body height adjusting and wheel driving dual functions are given,these can be effectively solved by LMI toolbox of the Matlab.(3)The testing platform of the new single-motor wheel-direct-drive system which can verify the application significance and engineering significance of the designs is developed by choosing S7300PLC as the controller and DC motors as the power sources.