This study presents a temperature-feedback approach to control the radius of curvature of an arc-shaped shape memory alloy wire. The nonlinear properties of the shape memory alloy such as phase transformation and its dependence on temperature and stress make shape memory alloy actuators difficult to control. Tracking a desired trajectory is more challenging than controlling just the position of the shape memory alloy actuator since the desired path is continuously changing. Consequently, tracking the desired strain directly or tracking the parameters such as temperature and electrical resistance that are related to strain with a model is a challenging task. Temperature-feedback is an attractive approach when direct measurement of strain is not practical. Pulse width modulation is an effective method for shape memory alloy actuation, and it can be used along with a compensator to control the temperature of the shape memory alloy. Using the constitutive model of the shape memory alloy, the desired temperature profile can be obtained for a given strain trajectory. A pulse width modulation–based nonlinear proportional–integral–derivative controller with a feed-forward heat transfer model is proposed to use temperature-feedback for tracking a desired temperature trajectory. The proposed controller is used during the heating phase of the shape memory alloy actuator. The controller proves to be effective in tracking stepwise and continuous trajectories.

中文翻译：

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基于脉冲宽度调制的温度跟踪用于形状记忆合金执行器的反馈控制

本研究提出了一种温度反馈方法来控制弧形形状记忆合金线的曲率半径。形状记忆合金的非线性特性，例如相变及其对温度和应力的依赖性，使得形状记忆合金致动器难以控制。跟踪所需的轨迹比仅控制形状记忆合金致动器的位置更具挑战性，因为所需的路径不断变化。因此，直接跟踪所需应变或使用模型跟踪与应变相关的温度和电阻等参数是一项具有挑战性的任务。当直接测量应变不切实际时，温度反馈是一种有吸引力的方法。脉宽调制是形状记忆合金驱动的有效方法，它可以与补偿器一起使用来控制形状记忆合金的温度。使用形状记忆合金的本构模型，可以为给定的应变轨迹获得所需的温度分布。提出了一种具有前馈传热模型的基于脉宽调制的非线性比例积分微分控制器，以使用温度反馈来跟踪所需的温度轨迹。在形状记忆合金致动器的加热阶段使用所提出的控制器。控制器证明在跟踪逐步和连续轨迹方面是有效的。提出了一种具有前馈传热模型的基于脉宽调制的非线性比例积分微分控制器，以使用温度反馈来跟踪所需的温度轨迹。在形状记忆合金致动器的加热阶段使用所提出的控制器。控制器证明在跟踪逐步和连续轨迹方面是有效的。提出了一种具有前馈传热模型的基于脉宽调制的非线性比例积分微分控制器，以使用温度反馈来跟踪所需的温度轨迹。在形状记忆合金致动器的加热阶段使用所提出的控制器。控制器证明在跟踪逐步和连续轨迹方面是有效的。