Tan U-Xuan, Latt Win Tun, Widjaja Ferdinan, Shee Cheng Yap, Riviere Cameron N, Ang Wei Tech
School of Mechanical and Aerospace Engineering, Nanyang Technological University.
Sens Actuators A Phys. 2009 Mar 16;150(1):116-123. doi: 10.1016/j.sna.2008.12.012.
With the increasing popularity of actuators involving smart materials like piezoelectric, control of such materials becomes important. The existence of the inherent hysteretic behavior hinders the tracking accuracy of the actuators. To make matters worse, the hysteretic behavior changes with rate. One of the suggested ways is to have a feedforward controller to linearize the relationship between the input and output. Thus, the hysteretic behavior of the actuator must first be modeled by sensing the relationship between the input voltage and output displacement. Unfortunately, the hysteretic behavior is dependent on individual actuator and also environmental conditions like temperature. It is troublesome and costly to model the hysteresis regularly. In addition, the hysteretic behavior of the actuators also changes with age. Most literature model the actuator using a cascade of rate-independent hysteresis operators and a dynamical system. However, the inertial dynamics of the structure is not the only contributing factor. A complete model will be complex. Thus, based on the studies done on the phenomenological hysteretic behavior with rate, this paper proposes an adaptive rate-dependent feedforward controller with Prandtl-Ishlinskii (PI) hysteresis operators for piezoelectric actuators. This adaptive controller is achieved by adapting the coefficients to manipulate the weights of the play operators. Actual experiments are conducted to demonstrate the effectiveness of the adaptive controller. The main contribution of this paper is its ability to perform tracking control of non-periodic motion and is illustrated with the tracking control ability of a couple of different non-periodic waveforms which were created by passing random numbers through a low pass filter with a cutoff frequency of 20Hz.
随着诸如压电材料等智能材料的致动器越来越受欢迎，对这类材料的控制变得至关重要。固有滞后行为的存在阻碍了致动器的跟踪精度。更糟糕的是，滞后行为会随速率变化。一种建议的方法是采用前馈控制器来线性化输入与输出之间的关系。因此，必须首先通过感知输入电压与输出位移之间的关系来对致动器的滞后行为进行建模。不幸的是，滞后行为取决于单个致动器以及诸如温度等环境条件。定期对滞后进行建模既麻烦又昂贵。此外，致动器的滞后行为也会随使用年限而变化。大多数文献使用一系列与速率无关的滞后算子和一个动态系统对致动器进行建模。然而，结构的惯性动力学并非唯一的影响因素。一个完整的模型会很复杂。因此，基于对具有速率的唯象滞后行为的研究，本文针对压电致动器提出了一种带有普朗特 - 伊什林斯基（PI）滞后算子的自适应速率相关前馈控制器。这种自适应控制器是通过调整系数来操纵间隙算子的权重实现的。进行了实际实验以证明自适应控制器的有效性。本文的主要贡献在于其能够对非周期性运动进行跟踪控制，并通过对一些不同的非周期性波形的跟踪控制能力进行了说明，这些波形是通过将随机数通过截止频率为20Hz的低通滤波器生成的。
