Robotic Laboratory, BeiHang University, HaiDian District, Beijing 100191, China.
Sensors (Basel). 2012;12(6):7682-700. doi: 10.3390/s120607682. Epub 2012 Jun 7.
With the progress of miniaturization, shape memory alloy (SMA) actuators exhibit high energy density, self-sensing ability and ease of fabrication, which make them well suited for practical applications. This paper presents a self-sensing controlled actuator drive that was designed using antagonistic pairs of SMA wires. Under a certain pre-strain and duty cycle, the stress between two wires becomes constant. Meanwhile, the strain to resistance curve can minimize the hysteresis gap between the heating and the cooling paths. The curves of both wires are then modeled by fitting polynomials such that the measured resistance can be used directly to determine the difference between the testing values and the target strain. The hysteresis model of strains to duty cycle difference has been used as compensation. Accurate control is demonstrated through step response and sinusoidal tracking. The experimental results show that, under a combination control program, the root-mean-square error can be reduced to 1.093%. The limited bandwidth of the frequency is estimated to be 0.15 Hz. Two sets of instruments with three degrees of freedom are illustrated to show how this type actuator could be potentially implemented.
随着微型化的进步，形状记忆合金（SMA）执行器具有高能量密度、自感测能力和易于制造的特点，非常适合实际应用。本文提出了一种使用 SMA 丝对的反作用来设计的自感测控制执行器驱动器。在一定的预应变和占空比下，两根丝之间的应力保持恒定。同时，应变-电阻曲线可以最小化加热和冷却路径之间的滞后间隙。然后通过拟合多项式来对两根丝的曲线进行建模，以便可以直接使用测量电阻来确定测试值与目标应变之间的差异。应变到占空比差值的滞后模型已被用作补偿。通过阶跃响应和正弦跟踪证明了精确控制。实验结果表明，在组合控制程序下，均方根误差可降低到 1.093%。估计频率的有限带宽为 0.15 Hz。通过两个具有三个自由度的仪器实例说明了这种类型的执行器如何能够潜在地实现。
