Research On The Precise Contour Control Technology Of SCARA Robot

With the steady development of the science and technology,It has led the extensive research on high-precision motion control of industrial robots.The error of contour tracking is a universal problem in industrial equipment such as various industrial robots.The traditional motion control of robots is mainly to control the motion axis independently.However,during the process of contour tracking,the trajectory of contour tracking is resulted from multi-axis movement.And the precision of contour tracking is resulted not only from the precision of multi-axis movement,but also from the precision of independent axis movement.Independent control of axis is difficult to improve the contour tracking accuracy and reduce the tracking error in the case of multi-aixs motion control.Although cross-coupling control is multi-axis control,it is difficult to calculate cross-coupling factor and it could not be widely promoted.In terms of this problem,this article makes a detailed analysis of contour tracking.On the basic of existing theory of industrial robots motion control,this article presents a theory of PID control based on the position domain.By dividing the motion axis into the reference axis and the serve axis,the motion of the serve axis is controlled by the motion of the reference axis.and applies it to the SCARA robot for experiments.By using position domain PID control algorithm and LinuxCNC as control system,position domain control theory is applied to SCARA robot to adjust its tracking error.In the case of multi-axis control,the contour tracking accuracy is improved and the contour tracking error is reduced.The main contents of this paper are as follows.(1)First of all,this article transforms the PID control algorithm from the time domain to the position domain by analyzing the PID control of the traditional time domain and combining the theory of position domain control.Then,it makes the initial modelling of the position domain PID control module model through the combination of SCARA robots used in this article.(2)Secondly,based on the establish of D-H coordinate system,It presents the forward kinematics and inverse kinematics equation of the robot.According to the defined overall scheme of position domain PID control,it presents the hardware conditions and software scheme of the PID control.Then,according to the established position domain PID control model,the SCARA robot position domain controlling algorithm is presented.(3)Finally,It tested the improvement condition of contour tracking performance of the multi-degree-of-freedom robot with the position domain PID controlling algorthem.It mainly included tracking error processing test,SCARA robot contour tracking performance comparison test under the control of time domain and position domain PID algorithm.Based on the above development and research,this article completed the design of position domain PID controlling algorithm based on the SCARA robot.The actual control experiment shows that the contour tracking performance of the SCARA robot with the position domain PID control is better than the traditional time domain PID control.The positon domain PID controlling algorithm improves the contour tracking performance of the SCARA robot.