Mechanism Design And Compliant Control Of Variable Stiffness Snake-like Robot

Snake-like robot is a robot with high redundancy,multi-gaits and excellent movement flexibility.It has huge application value potentially in the fields of disaster relief and detection.In complex and variable environment,the snake-like robot is often accompanied by many unexpected situations such as collisions,joint damage,etc..Snake-like robot need to change its stiffness to reduce the adverse effects caused by the above situation.For variable stiffness of snake-like robot,the main contents in this paper are as follow:(1)According to the bionic mechanism of the snake-like robot,a modular variable stiffness snake-like robot based on magneto-rheological fluid is designed;In this study,we established the relationship between structural parameters and variable stiffness performance,and optimized the geometric structure of variable stiffness snake-like robot through intelligent optimization algorithm.(2)The magnetic distribution of the variable stiffness joint of snake-like robot is analyzed.The calculation model of the joint damping torque is established through the fluid dynamics theory.Besides,theoretical value of the joint's damping torque is compared with the experimental result.(3)The motion and force transformation of a variable stiffness snake-like robot is constructed by using the screw theory.And then,we established the stiffness model of snake-like robot to obtain the relationship of head stiffness and joints' stiffness.(4)An environment adaptive control method for snake-like robot based on stiffness control is proposed.The motion control of the snake-like robot is realized by using the velocity decomposition-based dynamic model and exponential stability control.We constructed the stiffness and torque optimization equation to optimize the robot head stiffness and joint torque,which can improve the motion stability of the variable stiffness snake-like robot.Besides,a method to configur the degree of freedom of the variable stiffness snake-like robot is proposed to deal with joint damage and improve its environmental adaptability.