Multi-axis motion system is widely applied in commercial industrial machines such as precision CNC machine tools, Robot manipulator and laser cutting machines, etc. Contour accuracy plays a major role for the multi-axis servo motion system. The contour machining accuracy is related to the synthesis of single-axis position accuracy and multi-axis linkage accuracy. Only improving the single-axis tracking performance cannot effectively guarantee the machining accuracy of multi-axis system. The primary objective of this study was to design a contour control method to improve single-axis tracking accuracy and multi-axis contour accuracy. A control strategy that combines a sliding mode tracking controller, a disturbance observer and an adaptive fuzzy PID cross coupled controller is proposed. Sliding mode control is simple and has strong robustness to parameter changes and disturbance, which is especially suitable for control of such as non-linear multi-axis motion system. Besides, disturbance is inevitable in practical application, which degrades the motion accuracy. In order to eliminate the influence of external disturbance and uncertainty, disturbance observer is adopted to accurately estimate external disturbance and reduce the chattering phenomenon of sliding mode control, then improve the single-axis tracking accuracy. In order to further consider the coordination between different motion axes and improve the contour accuracy, the PID cross coupled control is used. Owing to conventional PID control cannot satisfy the multi-axis servo motion system with nonlinearity and uncertainty, an adaptive fuzzy method with on-line real-time PID parameters adjustment is proposed. The three-axis motion platform driven by PMLSM is used as the control object, to analysis the influence of disturbance observer on sliding mode control signal and analysis adaptive fuzzy PID cross coupled control performance respectively. The disturbance observer is used to observe the disturbance signal and estimate the disturbance well. The chattering of the sliding mode control signal is obviously improved. Next, compared with the conventional PID-CCC control, adaptive fuzzy PID- CCC control can significantly reduce the tracking error, the contour accuracy is also obviously improved. The disturbance observer can effectively eliminate the influence of external disturbance, reduce the chattering of sliding mode control, and ensure the single-axis accurate tracking. The self-adaptive fuzzy PID cross coupled controller can eliminate the influence of the dynamic characteristics mismatching and parameter difference of each axis, and improve contour accuracy. The simulation results clearly demonstrate the effectiveness of the proposed control method.

多轴运动系统广泛应用于精密数控机床、机器人机械手、激光切割机等商用工业机械中。多轴伺服运动系统的轮廓精度起着重要作用。轮廓加工精度与单轴位置精度和多轴联动精度的综合有关。仅提高单轴跟踪性能并不能有效保证多轴系统的加工精度。本研究的主要目的是设计一种轮廓控制方法来提高单轴跟踪精度和多轴轮廓精度。提出了一种结合滑模跟踪控制器、扰动观测器和自适应模糊PID交叉耦合控制器的控制策略。滑模控制简单，对参数变化和扰动具有较强的鲁棒性，特别适合非线性多轴运动系统等控制。此外，在实际应用中，干扰是不可避免的，这会降低运动精度。为了消除外部扰动和不确定性的影响，采用扰动观测器准确估计外部扰动，减少滑模控制的抖振现象，提高单轴跟踪精度。为了进一步考虑不同运动轴之间的协调性，提高轮廓精度，采用PID交叉耦合控制。针对传统PID控制不能满足非线性和不确定性的多轴伺服运动系统的问题，提出了一种实时在线调整PID参数的自适应模糊方法。以PMLSM驱动的三轴运动平台为控制对象，分别分析扰动观测器对滑模控制信号的影响和自适应模糊PID交叉耦合控制性能。扰动观测器用于观察扰动信号并很好地估计扰动。滑模控制信号的抖振现象明显改善。其次，与传统的PID-CCC控制相比，自适应模糊PID-CCC控制可以显着减小跟踪误差，轮廓精度也明显提高。扰动观测器可以有效消除外界扰动的影响，减少滑模控制的抖振，保证单轴精确跟踪。自适应模糊PID交叉耦合控制器可以消除各轴动态特性不匹配和参数差异的影响，提高轮廓精度。仿真结果清楚地证明了所提出的控制方法的有效性。