Continuous motion solution for numerical control devices

In the continuous trajectory, the "inflection point" judgment method is as follows: V1 is the speed of the machine tool at the contact point A, V2 is the speed of the machine tool at the contact point B, and V3 is the speed of the machine tool at the contact point C. Let the interpolation period be T, and the angle between the straight line segment trajectory AB of the machine tool in the z-axis direction and each axis is α2, β2, γ2, respectively. If the speed of the machine tool is constant at this time, the speed direction, that is, the speed becomes In the direction of the straight line AB, if any value is greater than Q, it is considered that the joint of the adjacent upper and lower trajectories is “inflection point”. At this time, the machine cannot directly change the speed direction after the end speed V1 of the above trajectory is executed. A trajectory, that is to say, it needs to be decelerated when reaching the end point of the upper trajectory OA until the speed of the machine speed satisfies the condition described in Equation 1.

If there is a circular arc curve in the trajectory, the tangential slope of the starting point and the ending point of the arc curve should be determined separately, because the starting speed direction and the ending speed direction of the circular arc are different. Then, in the same way, it is judged whether the intersection of the trajectory is an "inflection point". The specific steps of the method How should we find these "inflection points" during the exercise? Just like driving, we can only decelerate before we know that there is a sharp turn ahead. By the same token, we should know whether the intersection of this trajectory and the next trajectory is the “knee point” when the machine is executed to this trajectory. If so, where should we start to decelerate and then calculate the trajectory and the coordinate axes? Angle (if it is an arc, the angle between the start and end tangent and the coordinate axis needs to be calculated) until all the tracks in the array have been processed. The next step is to find the length of each segment of the array (not the total length, but the length of the individual segments). Then, from the unprocessed trajectory, whether it is a straight line, or whether the upper trajectory is a straight line, the lower trajectory is an arc, or the upper trajectory is a lower arc, the lower trajectory is a straight line, or the upper and lower trajectories are all circular arcs. Then the acceleration calculation is performed according to the given acceleration (equivalent to simulating the motion process with software) until the end of the trajectory, and the velocity value of the point is obtained (in this process, it is also necessary to determine whether the speed exceeds the set maximum speed) When the trajectory is processed, the length of the trajectory is added to the All_length variable (All_length is used to save the total length of the continuous trajectory segment, which is useful when calculating the deceleration point later).

Always do deceleration. According to the matching motion, we can find the deceleration point according to the uniform acceleration motion or the equation of the arithmetic progression. Then we save the processed N(N<60) trajectory parameters and the obtained deceleration point in the array dispoased, then The data is transmitted to the lower computer, and then the upper computer sends N segments of unprocessed trajectory parameters to the array no_disposal. After the lower computer obtains the processed data, the interpolation algorithm is used to calculate the interpolation amount to control the operation of the machine tool, and each time The interpolation amount is added up and compared with the deceleration point to see if it should continue to accelerate or evenly. If the accumulated amount Length>=Down_length starts to decelerate according to the set acceleration, repeat (1) to (6) until all the tracks are completed. The machine tool can continuously perform acceleration and deceleration. Another problem is that if there is no "knee" in the no_disposal array track, we should not store these 60 segments in the array dispoased, in order to prevent the "inflection point" after the 60 segments, and we There is not enough long distance to slow down to V1, which will result in lost or overtravel. We should select a point in the 60 segments as the end point. The basis for selecting the end point is to leave the length required to decelerate from the end point speed to the starting speed F according to the uniform deceleration motion.

Summary Although this method of processing is not the best way, it is relatively simple and easy to implement, and can be used in CNC systems where the accuracy requirements are not very high. We have successfully applied this method to our machines and machined more complex workpieces. In this paper, the basic principle of the auto disturbance rejection controller is studied, and the auto disturbance rejection controller is successfully applied to the servo system design of a certain servo tracking device. The actual system test data shows that the servo system's various indicators meet the requirements when using the auto-disturbance-proof controller, and they are better than the traditional PID controller, which solves the contradiction between the system's rapid response and overshoot, and overcomes the problem. The system model is difficult to establish the difficulties brought by the system design, and also makes the system have better immunity and robustness. In addition, the research work of this thesis also has important reference value for the application of model-free control methods in practical systems.

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