Design And Implementation Of Three-joint Manipulator Based On BLDC Motor Direct Drive

In the intelligent manufacturing industry,robot technology has been playing an important role.Driving is the power system of robot,and the driving mode and layout have an important impact on its performance.In order to study the control performance of the robot under the direct drive mode,taking the three joint manipulator as the object,this paper studies the stable and fast trajectory tracking control of the brushless DC motor direct drive manipulator.The paper is mainly carried out from the following aspects:Firstly,the driving mode of robot and the advantages of brushless DC motor direct drive are briefly introduced.Combined with the research status at home and abroad,the main control methods of brushless DC motor and manipulator are introduced.In order to verify the control effect,T-motor R60 and MN3508 are selected as the direct drive motor,stm32f407 as the main controller,TLE5012 B magnetic encoder chip and ODrive open source motor control board to build the hardware experiment platform of the three joint manipulator.According to the homogeneous transformation matrix and D-H parameters,the forward kinematics expression of the three joint manipulator is obtained,the inverse kinematics solution is obtained by geometric method,the system dynamics equation is deduced by Lagrange formula,and the workspace range of the manipulator is obtained by Monte Carlo simulation method.The correctness of kinematics and dynamics analysis results is verified by using MATLAB Robotic toolbox and experimental platform.In order to realize trajectory tracking,combined with velocity and acceleration constraints,two velocity curve trajectory planning methods of trapezoidal wave and S-curve in joint space are analyzed.Through analysis,the calculation formula of duration of each motion stage and the specific expressions of position,velocity and acceleration are obtained.The trajectory planning method of line and arc in Cartesian space is discussed and verified by simulation.Based on the dynamic model of the manipulator system,firstly,the principle of the computed torque method is introduced.The model parameter estimation error makes the control effect of the computed torque method have steady-state error.In order to improve the anti-interference ability and robustness of the system,the principle of sliding mode variable structure control is analyzed,combined with the computed torque method,An integral sliding mode controller with global invariance for trajectory tracking of three joint manipulator is proposed.Different from sliding mode control,ADRC technology uses extended state observer to estimate the total disturbance in real time and compensate dynamically.According to its principle,an ADRC trajectory tracking controller is designed.Finally,the two methods are verified on the three joint manipulator experimental platform,and compared with the computed torque method.The experimental results show that the integral sliding mode control and active disturbance rejection control can suppress the influence of system parameter uncertainty on the control performance and eliminate the steady-state error of position tracking,so as to realize stable,fast and accurate trajectory tracking.