Study on Velocity and Acceleration/Deceleration Planning for CNC Controller
DDA插值法則進而提出 Cubic DDA插值法則。應用高次的DDA插值，對
In the motion control, the reference command to the servo system directly influences the contouring error. The generation of the reference command includes path planning and the acceleration/deceleration planning. In order to obtain more accurate contouring path, we have to develop a higher order interpolation curve rather than a simple linear one. On the other hand, when the speed command varies drastically, the servo motor will consequently provide large torque to meet the change, and that will always cause the system to vibrate because of large jerk is induced. Therefore, it is necessary to develop an appropriate acceleration/deceleration planning for smooth and accurate motion. According to the concept of pre-acceleration/deceleration scheme, several kinds of acceleration/deceleration curve including linear curve, S-curve, and linear plus S-curve are discussed and compared. Considering the planning of speed curves within every two consecutive blocks together, we also examine several kinds of blended speed curves. The performance of different blended curves are compared in the view of corner error; an error control strategy is also developed by adjusting the acceleration time or the time-delay between two consecutive blocks. At last, every algorithm is simulated to verify its feasibility. In this thesis, we also extend the algorithm of liner and parabolic DDA to a new higher order one, called cubic DDA.
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