Research On Key Technologies Of Delta High-speed Parallel Robot

Under the background of "Made in China 2025" and "Industrial Internet" being proposed,and the decrease of domestic population dividend,Delta parallel robot has developed rapidly with its unique advantages and is widely used in high-precision and cutting-edge fields.Therefore,higher requirements are put forward for the stability,rapidity,positioning accuracy,self adaptability and other performance of parallel robot.Kinematics solution,trajectory planning and dynamic control have become the most important research directions in parallel robot.In this paper,the key technologies of Delta high-speed parallel robot are studied in kinematics solution,trajectory planning,dynamics control and servo system control.The main research work and innovations are summarized as follows:1.Starting from the mechanical structure of Delta high-speed parallel robot,the forward kinematics and inverse kinematics of the parallel robot are solved respectively via geometric method.The accuracy of the method is verified by Matlab and using different area data to solve the forward and inverse kinematics.In view of the deficiency of geometric method in solving the forward kinematics,the BP neural network based on genetic algorithm is proposed to solve the forward kinematics of Delta high-speed parallel robot,so as to improve the operation speed and meet the demand of system rapidity.First of all,LM method is used to train BP neural network.Through training,three-layer structure BP neural network can achieve better results,but the accuracy is not high.Then,to solve this problem,genetic algorithm is used to improve the performance of BP neural network,reduce the error,achieve high-precision solution,and reduce the solution time.Compared with the geometric method,the BP neural network solution method based on genetic algorithm reduces the solution time.By using the pose data obtained from the forward kinematics,the set of all spatial positions that the end manipulator can reach is analyzed in detail,and the three-dimensional working space diagram of the parallel robot is drawn to ensure the high-speed movement of the robot without collision and singularity.2.The trajectory of the three joints of Delta high-speed parallel robot determines the positioning accuracy and moving time(speed)of the end of the moving platform,which is related to the energy consumption and life of the whole robot.Therefore,the trajectory planning of Delta high-speed parallel robot is of great significance.Firstly,this paper analyzes the existing interpolation methods 4-3-4,3-5-3 and 4-5-4 respectively for“door”type trajectory planning and the results show that the 4-3-4 degree polynomial interpolation method is the best;Then,in view of the energy consumption of 4-3-4 degree polynomial interpolation and the trajectory of the transportation section,the key points need to be added.The motion law of 4-3-3-4 degree polynomial interpolation is proposed,and the angular displacement,angular velocity and angular acceleration curve of threejoints of Delta high-speed parallel robot are designed.The simulation results show that the curve of 4-3-3-4 method is smoother and the energy consumption is lower when the system is running;Finally,In order to achieve the shortest running time of delta high-speed robot,an improved particle swarm optimization algorithm is used to optimize the 4-3-3-4polynomial interpolation of space trajectory.In order to get the optimal solution of each particle,the parameters are optimized to get the optimal time of the Delta high-speed parallel robot's trajectory.3.In order to better track the planned curve,a dynamic control strategy of Delta high-speed parallel robot based on linear active disturbance rejection control(LADRC)is proposed.The coupling and both internal and external disturbance among three joints are observed and compensated to realize decoupling control.In order to verify the effectiveness of the proposed control strategy,the representative straight-line,circular,8-shaped trajectory and a variety of disturbances are given respectively,and the PID method and the linear active disturbance rejection control(LADRC)are used for simulation respectively.The simulation and comparative analysis show that the linear active disturbance rejection control(LADRC)is applied to Delta high-speed parallel robot control,with good trajectory tracking and strong system robustness.4.The servo control system which is the joint control part of the robot is designed.The mathematical models of current loop,speed loop and position loop are analyzed.The calculation method of controller parameters is given.The realization algorithm of SVPWM is analyzed in detail.The servo system has the advantages of no overshoot,fast response speed and high positioning accuracy.5.The experimental prototype of Delta high-speed parallel robot is constructed,and the control effect of the trajectory planning waveform and the linear active disturbance rejection control(LADRC)strategy of Delta high-speed parallel robot is verified.