Research And Experiment On Calibration Technology Of Robot Processing Equipment With CNC-like Characteristics

With the continuous development of China’s manufacturing industry,the problem of rising labor costs is becoming more and more obvious.The traditional labor-intensive industries are under great pressure.Compared with CNC machine tools,robots have low investment cost,large working space and multi-axis flexibility advantage.The repetitive positioning accuracy of the robot is high,but the absolute positioning accuracy of only millimeters limits its application in some fields.Calibration technology is currently one of the most effective ways to improve the absolute positioning accuracy of robots.When the robot is machining,the inverse kinematics is calculated by the control model,and the actual model machining is used,and there is an error caused by the inconsistency of the robot model.For the calibration of the robot body error,the existing method of measuring the end points of multiple groups of robots and correcting the error of the robot body by solving the equations.Although the error correction at the position of the measurement target point can be realized,since the calibration robot body error cannot be decoupled,the error still exists at a position other than the measurement target point.The single-axis rotation method can realize the decoupling calibration of the robot geometric parameters and zero error.Using the laser tracker as a measuring tool,by rotating the axes of the robot and recording the position information of the end points of the robot,six sets of spatial points are obtained,and the space circle fitting method was used to fit the center and axis of the space circle where each axis space point is located,the actual robot model was established,and the pole length,offset and zero position of the actual robot model were obtained.When a single circle was fitted,a small attitude error will brought a large position error.When uniaxial rotation,two sets of spatial points were measured per axis,and the center of the fitted center was connected as the robot axis.Using the double circle fitting,the actual robot model was obtained,and the actual model was processed to obtain the geometric parameters and zero position information.When the robot was machining,the inverse model was obtained by using the processed model,and the obtained joint angle compensation corresponds to the zero position.Through simulation and machining experiments,the feasibility of decoupling and calibrating the robot body error by the single-axis rotation method was verified.