Research On The Key Technique Of Traiectorv Deviation Compensation For Multi-degree-of-freedom Nonorthoeonal System

As an indispensable intelligent equipment in intelligent manufacturing,industrial robots are widely used in various production and processing fields.The accuracy of robots is an important indicator to ensure production quality.Therefore,the accuracy requirements of the most representative six-degree-of-freedom tandem robots have been continuously valued.At present,the repeated positioning accuracy and absolute positioning accuracy of the most used industrial robots in the market have been greatly improved,and the trajectory accuracy of the robot's can still not satisfy the high production requirements.Therefore,how to improve the trajectory accuracy of industrial robots has become one of the important tecgniques in the robot research field.Trajectory accuracy of industrial robot is an important performance evaluation parameter.The compensation method for trajectory accuracy improvement of industrial robot is studied from the perspective of robot kinematics.Using a SR4C industrial robot with six degrees of freedom as the research object,A method of industrial robot trajectory accuracy compensation based on kinematics analysis is proposed,and the mathematical model of robot trajectory error between curve motion trajectory deviation and kinematic model parameter error is established based on national standard of robot tracking accuracy evaluation standard,based on the fast and effective coordinate system transformation method of laser tracker and robot coordinate system,an improved least squares algorithm is used to select the optimal kinematic parameters when the trajectory deviation is the smallest,The trajectory compensation experiment of the constructed robot trajectory test and compensation experimental system validated the effectiveness of the method.The results show that the average position error of the robot is improved from 3.65%to 0.79%after the compensation of the method,and the accuracy of the straight and circular trajectories are improved 38.75%and 25%respectively,including the following aspectsFirstly the current research status of the trajectory accuracy of six-degree-of-freedom tandem robots at home and abroad is introduced,and then specifically analyze the SR4C industrial robot,using DH and MDH modeling methods,respectively.Based on the theoretical joint parameters of the robot,the SR4C robot is modeled by the spatial homogeneous transformation matrix.The forward and inverse kinematics of the model robot are solved,the kinematics and workspace simulation are performed to obtain the optimal inverse solution in a specific posture.Secondly,the error sources that affect the trajectory accuracy of the robot is analyzed and summarized,and a more accurate trajectory accuracy dynamic error model based on the robot's pose and static error model are builded to solve the trajectory error of the robot's working space.The identification and compensation of trajectory error are carried by least squares and improved least squares algorithm based on the trajectory accuracy error model of SR4C robot.the robot target trajectory for numerical of the end trajectory is set to simulate based on model parameters.The influence rule of the main model parameters error to the robot trajectory in the static error source is analyzed and relevant simulation of SR4C robot in Matlab is carried.The robot trajectory deviation compensation method is introduced again,focusing on the gradation compensation based on the method of calibration,the correction of reduction ratio and the error compensation method of neural network.A method for transforming the robot base coordinate system and the measurement coordinate system on Polyworks based on robot space geometric measurement is proposed.The SR4C robot is transformed from the tool coordinate system to the base coordinate system based on the trajectory error.The algorithms are used for trajectory error identification simulation,neural network algorithms for position error prediction,and simulation analysis of the robot coordinate system in the model and the trajectory accuracy evaluation method of industrial robot is introduced.Finally,a robot trajectory measurement system is constructed to determine the position of the largest test cube of the model robot and the trajectory of the required experiment.The identification algorithm of the robot's actual motion parameter and the program design of trajectory motion are completed,and a set of measurement installation fixtures required for the experiment is designed including the target.Ball and scanning measuring fixtures are used to correct and compensate parameter errors that have a large impact on robot trajectory accuracy.The effects of different speeds on experimental trajectory accuracy are researched and analyzed.The existing robot trajectory performance detection and evaluation methods are used to evaulate the trajectory accuracy of the SR4C robot and the actual trajectory compensation effect of the robot is verified,which is a reference basis for providing the trajectory accuracy of the six-degree-of-freedom industrial robot.