Control System Design And Torque Control Of The Quadruped Robot’s Single Leg Driven By Magneto-rheological Fluid

As the most popular research point among these bionic robots,quadruped robots have many advantages such as easy-to-accept machine appearance,strong mobility,convenient obstacle crossing,etc.The structure of a common robot actuator(CRA)is consists of a rigid connection formed by a motor and a reducer.Such the structure will cause great damage to one or the both of motor and reducer when encountering external force blocking or wrong movement instructions.To cooperate better with people,it is necessary to improve the torque control performance and the flexible control ability of the robot to better adaptive the working environment,without reducing the performance of the robot.In this dissertation,using the magneto-rheological clutch(MRC)is lodged to solve that.In CRA,the output torque of the reducer is directly connected to an external mechanism.The magneto-rheological actuator(MRA)mechanism is consists of a CRA and an MRC,by a rigid connection between the output torque of the reducer and the input of the MRC.The output torque of MRC is generated by the changing current,for it can control the viscosity of the special material in MRC through the magnetic field.Because of this,the MRA can avoid that problem.This dissertation aimed to have a study of the single-leg design and torque control of quadruped robot driven by magneto-rheological fluid.In the field of hardware,it is necessary to design a current control circuit for MRC.An algorithm of MRC would be studied in the dissertation to better control the current of MRC.Both fuzzy control and Kalman observer are applied to track the current with more accuracy.Because of the nonlinear hysteresis relationship between the input current and the output torque of MRC,it is neccessary to describe the relationship of both.This dissertation uses a large enough amount of experimental data to build a neural network model.Based on that,experiments are carried out to compare the torque control performance of MRA and CRA.The result of the experiments shows that the torque control accuracy of MRA is higher than that of CRA.The next,applying MRC or CRA to the parallel single-leg mechanism can form a single-leg structure of a quadruped robot.After experimental comparison,the force control accuracy of a single leg composed of MRA is also higher than that of CRA.Finally,the position compliance control experiment can get the following results.When adjusted to appropriate parameters,the single-leg mechanism controlled by MRA can effectively avoid the influence of obstacles and external force interference on single-leg movement.In this way,the quadruped robot can be more suitable for moving on the ground with obstacles on the premise of completing the desired motion,and will not cause loss of balance.