摘要
针对下肢外骨骼预定轨迹的控制问题,在构建了二自由度机械腿的运动学和动力学模型的基础上,提出了一种非对称液压缸负载力、伸缩量与外骨骼转动扭矩、运动角度的转化关系,采用反步法控制下肢外骨骼系统的运动轨迹。首先,采用D-H法建立了二自由度下肢外骨骼系统的运动学模型,研究了外骨骼末端执行器关节速度的变化关系,并利用拉格朗日动力学方程推导了外骨骼动力学的数学模型;然后,使用了液压缸负载力控制为机械腿运动提供了相应的扭矩,进而控制了下肢外骨骼的运动姿态;其次,针对下肢外骨骼运动时的高精度要求,利用反步法控制理论,建立了阀控非对称缸系统,结合下肢外骨骼动力学系统整体的状态空间方程,利用下肢外骨骼液压伺服系统控制了下肢外骨骼进行预定轨迹运动;最后,对AMESim软件与Visual Studio软件进行了联合仿真,对比分析了PID控制与反步法控制的精度问题。研究结果表明:针对下肢外骨骼预定轨迹控制,反步法控制误差最大值为2°,对比传统PID控制,误差降低了67%;设计的反步法控制器对于下肢外骨骼具有良好的控制精度。
Aiming at the study of the predetermined trajectory control problem of the lower extremity exoskeleton,the kinematics and dynamics model of the two-degree-of-freedom mechanical leg was constructed.A transformation relationship between the load force and the expansion of the asymmetric hydraulic cylinder,and the rotation torque and motion angle of the exoskeleton was proposed,and the precise trajectory control of the exoskeleton was further realized by using the backstepping method.Firstly,the kinematics model of the two-degree-of-freedom lower extremity exoskeleton system was established by using the Denavit-Hartenberg(D-H) method.The relationship between the joint velocity of the exoskeleton end-effector was studied,and the mathematical model of the exoskeleton dynamics was derived by using the Lagrange dynamic equation.Then,by controlling the load force of the hydraulic cylinder,the corresponding torque was provided for the movement of the mechanical leg,and the motion posture of the lower limb exoskeleton was controlled.Secondly,aiming at the high precision requirement of the lower extremity exoskeleton movement,the state space equation of the valve-controlled asymmetric cylinder system combined with the whole lower extremity exoskeleton dynamics system was established by using the backstepping control theory.The hydraulic servo system of the lower extremity exoskeleton was controlled,so as to control the lower extremity exoskeleton to carry out the predetermined trajectory movement.Finally,through the joint simulation of AMESim software and Visual Studio software,the accuracy of PID control and backstepping control was compared and analyzed.The research results show that the maximum error of the backstepping control was 2 ° for the predetermined trajectory control of the lower extremity exoskeleton.Comparing with the traditional PID control,the error is reduced by 67 %.The designed backstepping controller had good control accuracy for lower limb exoskeleton.
作者
苏东海
王海啸
梁全
郭新博
王忠伟
SU Donghai;WANG Haixiao;LIANG Quan;GUO Xinbo;WANG Zhongwei(School of Mechanical Engineering,Shenyang University of Technology,Shenyang 110870,China)
出处
《机电工程》
CAS
北大核心
2024年第9期1692-1703,共12页
Journal of Mechanical & Electrical Engineering
基金
国家自然科学基金资助项目(51775354)。
关键词
电液伺服系统
非对称液压缸
反步法控制
下肢外骨骼系统状态空间方程
D-H法
AMESIM
控制精度
electro-hydraulic servo system
asymmetric hydraulic cylinder
backstepping control
state space equation of lower limb exoskeleton system
Denavit-Hartenberg(D-H)method
AMESim
control accuracy
