形状记忆合金手指系统的输出力自适应控制

Adaptive force control of robotic finger actuated by shape memory alloy

中文关键词  形状记忆合金  迟滞非线性  扩张状态观测器  自适应控制

英文关键词  shape memory alloy (SMA)  hysteresis nonlinearity  extended state observer  adaptive control

中文摘要

      形状记忆合金(SMA)是智能材料中的一种, 具有功率重量比大、质量轻、无噪音等特性. 作为驱动器有利 于结构的小型化和轻型化. 然而SMA的非线性、多映射的迟滞特性严重影响了输出力的精确控制. 为此, 本文提出 了基于扰动补偿策略的自适应控制方法用于SMA输出力的精确控制. 首先, 搭建了SMA驱动的手指实验装置, 建立 了机理模型; 其次, 采用状态观测器对系统的总扰动进行了实时估计; 最后, 基于机理模型设计了自适应控制器, 并 进行了阶跃信号、正弦信号、抗负载扰动实验. 实验结果表明, 基于扰动补偿的自适应控制方法不需要系统精确建 模, 参数调节方便. 在保证系统稳定和跟踪精度的同时, 具有较强的鲁棒性.

英文摘要

      Shape memory alloy (SMA), one of smart materials, has the characteristics of large power-to-weight ratio, light weight, and no noise, etc. Due to the miniaturization and light weight, SMA is often used as the material of smart actuators. However, the nonlinearity, multi-value properties, i.e., hysteresis, of SMA material, will seriously affect the precise control of the output force. To this end, this paper proposes an adaptive control method, in which the hysteresis, the uncertain dynamics and external disturbance are treated as the total disturbance of the system, to achieve the precise control of SMA output force. Firstly, the finger experiment setup actuated by SMA was constructed and the mechanism model was established. Then the extended state observer was used to estimate both the states and the total disturbance of the system in real time. Finally, the adaptive controller was designed based on the mechanism model. The tracking experiment of the step signal and the sinusoidal signal were demonstrated, meanwhile, the load disturbance rejection experiment was also implemented. The experimental results show that the adaptive disturbance compensation control method does not require accurate system modeling, and the controller parameters adjustment is convenient. More interestingly, The proposed algorithm not only ensures the system stability and tracking accuracy but also guarantees the robustness.