The Compensation Strategies in Multi-axis Contouring Accuracy for Real-Time NURBS Curve

• Main Authors: Li-Yeh Chen, 陳立業
• Other Authors: Chin-Sheng Chen
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/756q2z

碩士 === 國立臺北科技大學 === 自動化科技研究所 === 93 === The objective of this thesis is to improve high-speed multi-axis motion contour accuracy based on a reliable multitasking real-time kernel. Therefore, this thesis will finish the following objects: 1.) constructing a real-time control system. 2.) command generator of multi-dimension motion trajectory 3.) multi-axis motion controller. By using the PC-based approach in motion control, the hardware and software flexibility are gained. Then, we should port a real-time multitasking kernel into PC-based platform to implement the motion control algorithm. The real-time operation system (RTOS) uC/OS-II is firstly ported in PC as the target RTOS because it has simple architecture and relatively easy to modify. Traditionally, the motion trajectory is approximated by many line and circular segments. Such approximation may result in several problems such as large contour error, increase of NC program size and data transfer load , etc. A real-time NURBS interpolator is proposed to overcome the above drawbacks. The corresponding position, velocity and acceleration commands are directly feed into the servo control loop. In the improved strategies of single axis, thesis proposed a feedback controller and feedforward control to improve the tracking performance. Unfortunately, good tracking performance for each individual axis doesn’t guarantee that the contour error will be reduced for multi-axis motion. The cross-coupling controller is developed to improve contouring accuracy by contouring error vector. Furthermore, the hybrid controller of feedforward and CCC are integrated to fit the high speed and high accuracy motion contour requirement. Finally, the above improved strategies in contouring accuracy for high speed motion control are verified by simulation and experimental results.