摘要
根据电动轮汽车各轮扭矩独立可控的特点,改变左右转向轮的驱动力差提供转向助力,实现差动助力转向.考虑到差动助力转向系统对汽车稳定性的影响,利用Carsim/Simulink建立轮毂电机驱动电动汽车模型,设计了两层差动助力转向稳定性可拓协调控制系统.在上层控制器中,根据汽车行驶状态,建立可拓协调控制器,其中将二维可拓集合中的可拓距转换到一维可拓集合中计算,求解关联函数,确定各控制器输出权重.在下层控制器中,采用转向盘转矩直接控制策略,建立差动助力转向控制器;根据可拓域和非域中汽车状态的不同,实现基于横摆角速度和质心侧偏角的切换控制,进而建立横摆力矩控制器;基于二次规划方法对四轮驱动转矩优化分配,并根据所处的值域对3种不同的约束条件进行选择.最后利用Carsim和Matlab/Simulink在不同路面附着系数的双移线工况下进行仿真.仿真结果表明,与差动助力转向系统单独工作时相比,当路面附着系数为0.8时,该控制系统能够提高道路跟踪能力,横向偏差最多减少50%,纵向偏差最多减少30%,横摆角速度、质心侧偏角和侧向加速度明显减小,其均方根值分别优化了54.9%,21.4%和22.3%,改善了汽车操纵稳定性;当路面附着系数为0.4时,该系统能够避免汽车失稳,提高行车安全.
According to the feature that the torque of each wheel for the in-wheel motor drive electric vehicle is independently controllable,the left and right steering wheels＇ driving force is changed to provide steering power,and the differential drive assisted steering is implemented.Considering the effect on vehicle stability by differential drive assisted steering system,the Carsim/Simulink was utilized to establish the model of the in-wheel motor drive electric vehicle,and a two-layer extension coordinated control system was designed for the stability of automotive differential drive assisted steering system.In the upper-layer controller,according to vehicle driving conditions,the extension coordination controller was established.The extension distance was computed in one-dimensional extension set instead of two-dimensional extension set,so as to solve the correlation function to determine the controllers＇ output weights.In the lower-layer controller,the differential drive assisted steering controller was established based on steering wheel torque direct control strategy.Then the yaw moment controller was set up based on the switching of yaw rate control and sideslip angle control according to the different conditions of vehicle in the extension domain and non-domain.Next,the optimal drive torque of four wheels was distributed based on quadratic programming and three different constraint conditions were selected according to different domains.The Carsim and Matlab/Simulink were utilized to carry out the simulation under the double lane conditions with different road friction coefficient.The simulation results show that compared with differential drive assisted steering system working alone,when the road adhesion coefficient was 0.8,the control system can improve the road tracking ability that the lateral and longitudinal deviation respectively decrease by 50%and 30%,and the root mean square values of yawing angular velocity,the center of mass of side-slip angle and lateral acceleration were obviously decreased by 54.9%,21.4%and 22.3%respectively;when the road adhesion coefficient was 0.4,the system can avoid vehicle＇s instability and improve the driving safety.
出处
《中国科学：技术科学》
EI
CSCD
北大核心
2017年第3期324-335,共12页
Scientia Sinica(Technologica)
基金
国家自然科学基金(编号:51375131
51305118
51675151
U1564201)
江苏省道路载运工具新技术应用重点实验室开放基金(编号:BM20082061504)资助项目
关键词
电动汽车
横摆力矩
可拓协调
差动助力转向
关联函数
electric vehicle
yawing moment
extension coordinated
differential drive assisted steering
correlation function
作者简介
E-mail：bob．627@163．com
