Design And Study On Control System Of The Lower Limb Assisted Exoskeleton Robot

The lower limb-assisted exoskeleton robot is a device that combines bionic technology and robotics.It combines human initiative with the mechanics of machines.It enables humans to obtain the power and speed of the machine,and effectively improves the physical function of the wearer.Today,such robots are widely used in industrial production and medical rehabilitation.The traditional control method of exoskeleton robot is PID control,which has the following problems in practice: First,the acceleration is the second-order differential of the displacement.When the mass of the exoskeleton robot system is constant,the relationship between force and displacement has a hysteresis.Secondly,there is the problem of Human-in-the-Loop in the system,and the different walking styles of users will affect the performance of the system.To sum up the above two points,the exoskeleton robot system has hysteresis and is greatly affected by interference.In order to adjust the contradiction between overshoot and rapidity,and reduce the influence caused by the range of disturbance,the main innovations of this paper are as follows: Design and improve the fuzzy PID control method,and propose the parameter adjustment method of linear compensation.The controller is mainly controlled by variable parameters,which improves the gain coefficient and enhances the rapidity in the case of large error.When the error is small,reduce the gain coefficient to prevent overshoot.Variable parameter control has strong adaptability to large-scale disturbance.According to the structural characteristics of human body,this paper designs the joint motion range of exoskeleton robot by applying kinematics theory to ensure the safety of users.From the point of view of energy,the mathematical simulation model of exoskeleton robot is established by applying Lagrange dynamics and kinematics.PID controller,fuzzy PID controller and synovial controller are designed for exoskeleton robot,and simulation and experiment are carried out.The results show that fuzzy PID control algorithm has certain advantages in speediness and overshoot adjustment: the absolute mean value of human-computer interaction force in fuzzy PID control algorithm decreases by 9.91% and the standard deviation decreases by 16.52%compared with PID algorithm.The linear compensation fuzzy PID control method proposed in this paper reduces the design difficulty of fuzzy PID controller.The application of linear compensation fuzzy PID control improves the control effect of exoskeleton robot and provides a convenient scheme for exoskeleton robot control.