雙軸機械手臂之適應性模糊滑動模式控制
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2011
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Abstract
本研究之目的是針對機械手臂之循軌控制提出適應性模糊滑動模式控制。於系統模型部份已知的情況下，運用極點配置法來設計標稱控制器給予機械手臂之理想動態，並透過滑動模式干擾估測器及適應性模糊補償器將系統的不確定性及外部干擾予以補償。
利用滑動模式干擾估測器來提昇整體控制架構之初始性能，並對於未知的干擾給予快速有效的補償，以提升控制架構的強健性能。適應性模糊補償器透過自訂適應性法則，將控制系統中的未知干擾建模於模糊規則庫；當建模完成便可依據系統之狀態，查得目前的系統干擾，以達到即時的干擾補償，因此可進一步改善滑動模式干擾估測器補償的相位落後問題。
本文實驗平台之架構上，採用美國德州儀器公司(Texas Instruments, TI)所生產之TMS320C6713 DSP搭配具FPGA之自製擴充子板為實驗平台。在FPGA方面，以硬體描述語言(VHDL)撰寫Encoder, A/D與D/A等週邊界面程式；在控制器實現上，利用TI所提供的Code Composer Studio (CCS)環境下以C/C++撰寫控制器程式並下載到DSP上執行。經由自製的雙軸機器手臂實驗平台進行追圓軌跡控制，結果顯示能有效提升循軌的表現及降低循軌誤差。
A scheme of adaptive fuzzy sliding-mode control is proposed in this paper to deal with highly nonlinear dynamics of robotic manipulators for trajectory tracking. By using a simplified model, a nominal controller is obtained by pole placement design to specify ideal closed-loop dynamics. Then, an adaptive fuzzy compensator augmented with a sliding-mode disturbance observer (SDOB) compensates for system uncertainties and external disturbances. The SDOB ensures well transient performance and compensates well for unknown perturbation. In addition, the adaptive fuzzy compensator is used to model an unknown disturbance according to the proposed adaptive law. When the perturbation has been well modeled, the control system can efficiently compensate for the disturbance, avoiding the phase-lag problem associated with the SDOB. The experimental system for studies on a two-link robotic manipulator tracking a circular trajectory contains a DSP/FPGA system, which is the control kernel. We use C language and very-high-speed hardware description language (VHDL) as tools for developing a servo control system. The experimental results show that the proposed scheme improves the tracking performance and decreases the tracking error.
A scheme of adaptive fuzzy sliding-mode control is proposed in this paper to deal with highly nonlinear dynamics of robotic manipulators for trajectory tracking. By using a simplified model, a nominal controller is obtained by pole placement design to specify ideal closed-loop dynamics. Then, an adaptive fuzzy compensator augmented with a sliding-mode disturbance observer (SDOB) compensates for system uncertainties and external disturbances. The SDOB ensures well transient performance and compensates well for unknown perturbation. In addition, the adaptive fuzzy compensator is used to model an unknown disturbance according to the proposed adaptive law. When the perturbation has been well modeled, the control system can efficiently compensate for the disturbance, avoiding the phase-lag problem associated with the SDOB. The experimental system for studies on a two-link robotic manipulator tracking a circular trajectory contains a DSP/FPGA system, which is the control kernel. We use C language and very-high-speed hardware description language (VHDL) as tools for developing a servo control system. The experimental results show that the proposed scheme improves the tracking performance and decreases the tracking error.
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Keywords
機械手臂, 適應性模糊補償器, 干擾估測器, Robot manipulator, Adaptive fuzzy compensator, Disturbance observer