Trajectory Design And Optimization Of Steel Marking Mechanism

The motion control of the traditional steel marking mechanism usually calls the PLCopen standard motion control block in the PLC,or realizes the basic motion control by setting some parameters in the process of using the electronic gear control block or the function of electronic gear and electronic cam.Its limitation is that the system provides few types of trajectory planning algorithms,especially in terms of motion stability,it can not provide trajectory planning algorithms that meet the requirements.For example,single axis motion control only supports trapezoidal and S-type acceleration and deceleration,and multi axis motion control can only ensure the position and speed relationship between each axis.Based on the above reasons,this paper develops the bottom motion control function block supporting complex trajectory planning algorithm,which is used as a supplement to the standard block to meet the requirements of more identification tasks,especially in the situation of high precision and high stability.It is worth noting that the function block of the proposed trajectory planning algorithm can also be applied to the motion control of NC machine tools and multi axis robots.In order to facilitate the follow-up verification of the designed trajectory planning algorithm,a steel identification mechanism test platform is built,which takes the rectangular coordinate robot as the motion mechanism and the laser marker as the actuator,and carries out motion control and execution control through Beifu PLC,in which the selection basis of PLC controller and servo motor is emphatically introduced.The forward and inverse kinematics of the rectangular coordinate robot is analyzed,and its kinematics model is built by using the MATLAB robot toolbox.The key points in the task space are inversely solved to the joint space for trajectory planning.In view of the complex problem that the traditional B-spline curve does not pass through the original control points and reversely solves the new control points,the method of adding auxiliary control points is improved,and the cubic and quartic new B-spline curves are taken as examples.The results show that the new B-spline can pass through the original control points accurately and the operation is simple.Through the combination of polynomials of different degrees,the interpolation method of "445" combined polynomials is obtained,and compared with the kinematic simulation of "434" trajectory,it shows the unique advantages of "445" trajectory in stability.When planning the point-to-point trajectory in joint space,firstly,the classification of S-shaped curve is analyzed,and the influence of contour shape on triangular S-shaped curve is introduced.The single axis and multi axis trajectory planning algorithms of third-order combined S-shaped curve and fourth-order combined S-shaped curve are emphatically introduced,and the correctness of the algorithm is verified by simulation in MATLAB.Finally,taking the actual project task as the background,this paper explains the selection of trajectory planning method and the implementation process of trajectory planning algorithm in Beifu PLC.The point-to-point positioning accuracy is compensated three times,and the motion results show the effectiveness of the proposed algorithm.