The tracking performance of motor current is an important factor that affects the assistance torque of electric power steering （EPS） system. Bad tracking performance will cause assistant torque delay, and make road ...The tracking performance of motor current is an important factor that affects the assistance torque of electric power steering （EPS） system. Bad tracking performance will cause assistant torque delay, and make road feeling bad, and is influenced by the input steering torque and system measuring noise. However the existing methods have some shortages on system＇s robust dynamic performance and robust stability. The mixed H2/H∞ strategy for recirculating ball-type EPS system in a pure electric bus is proposed, and vehicle dynamic model of the system is established. Due to the existence of system model uncertainty, disturbance signals, sensor noises and the demand of system dynamic performance, the indexes of robust performance and road feeling for drivers are defined as the appraisal control objectives. The H∞ method is introduced to design the H∞ controller, and the H2 method is applied to optimize the H∞ controller, thus the mixed H2/H∞ controller is designed. The response of EPS system to the motor current command with amplitude of 20 A, the road disturbance with amplitude of 500 N and the sensor random noise with the amplitude of 1 A is simulated. The simulation results show that the recirculating ball-type EPS system with the mixed H2/H∞ controller can attenuate the random noises and disturbances and track the boost curve well, so the mixed H2/H∞ controller can improve the system＇s robust performance and dynamic performance. For the purpose of verifying the performance of the designed control strategy, the motor current tracking performance ground tests are conducted with step response input of the steering wheel, double-lane steering test and lemniscate steering test, respectively. The tests show that the mixed H2/H∞ controller for the recirculating ball-type EPS system of pure electric bus is feasible. The designed controller can solve the robust performance and robust stability of the system, thus improve the tracking performance of the EPS system and provide satisfied road feeling fo展开更多
受模型偏差和系统扰动等影响,复杂系统难以获得准确的状态估计,往往仅能确定状态的区间,即设计区间观测器.通常,考虑单一性能指标的区间观测器难以获得较好的观测效果.对此,研究一种H_(2)/H_(∞)混合性能指标的线性参数变化系统区间观...受模型偏差和系统扰动等影响,复杂系统难以获得准确的状态估计,往往仅能确定状态的区间,即设计区间观测器.通常,考虑单一性能指标的区间观测器难以获得较好的观测效果.对此,研究一种H_(2)/H_(∞)混合性能指标的线性参数变化系统区间观测器设计方法,基于真实值、估计值和误差三者关系,通过区间壳(interval hull)计算求取误差区间,以一般观测器和误差上下限的组合表示状态估计区间.引入混合H_(2)/H_(∞)范数约束,提高观测器的抗干扰性和鲁棒性,并提出基于H_(2)/H_(∞)混合性能指标的区间观测器设计方法.实例仿真表明,所提出的H_(2)/H_(∞)区间观测器设计方法对连续搅拌反应器(continuous stirred tank reactor,CSTR)系统能够获得更窄的状态上下界估计,有利于后续故障诊断、控制的设计与实施.展开更多
基金supported by National Natural Science Foundation of China (Grant No. 51005115, No. 51005248)Science Fund of State Key Laboratory of Automotive Safety and Energy of China (Grant No. KF11201)
文摘The tracking performance of motor current is an important factor that affects the assistance torque of electric power steering （EPS） system. Bad tracking performance will cause assistant torque delay, and make road feeling bad, and is influenced by the input steering torque and system measuring noise. However the existing methods have some shortages on system＇s robust dynamic performance and robust stability. The mixed H2/H∞ strategy for recirculating ball-type EPS system in a pure electric bus is proposed, and vehicle dynamic model of the system is established. Due to the existence of system model uncertainty, disturbance signals, sensor noises and the demand of system dynamic performance, the indexes of robust performance and road feeling for drivers are defined as the appraisal control objectives. The H∞ method is introduced to design the H∞ controller, and the H2 method is applied to optimize the H∞ controller, thus the mixed H2/H∞ controller is designed. The response of EPS system to the motor current command with amplitude of 20 A, the road disturbance with amplitude of 500 N and the sensor random noise with the amplitude of 1 A is simulated. The simulation results show that the recirculating ball-type EPS system with the mixed H2/H∞ controller can attenuate the random noises and disturbances and track the boost curve well, so the mixed H2/H∞ controller can improve the system＇s robust performance and dynamic performance. For the purpose of verifying the performance of the designed control strategy, the motor current tracking performance ground tests are conducted with step response input of the steering wheel, double-lane steering test and lemniscate steering test, respectively. The tests show that the mixed H2/H∞ controller for the recirculating ball-type EPS system of pure electric bus is feasible. The designed controller can solve the robust performance and robust stability of the system, thus improve the tracking performance of the EPS system and provide satisfied road feeling fo
文摘受模型偏差和系统扰动等影响,复杂系统难以获得准确的状态估计,往往仅能确定状态的区间,即设计区间观测器.通常,考虑单一性能指标的区间观测器难以获得较好的观测效果.对此,研究一种H_(2)/H_(∞)混合性能指标的线性参数变化系统区间观测器设计方法,基于真实值、估计值和误差三者关系,通过区间壳(interval hull)计算求取误差区间,以一般观测器和误差上下限的组合表示状态估计区间.引入混合H_(2)/H_(∞)范数约束,提高观测器的抗干扰性和鲁棒性,并提出基于H_(2)/H_(∞)混合性能指标的区间观测器设计方法.实例仿真表明,所提出的H_(2)/H_(∞)区间观测器设计方法对连续搅拌反应器(continuous stirred tank reactor,CSTR)系统能够获得更窄的状态上下界估计,有利于后续故障诊断、控制的设计与实施.
