Nagal Naresh, Srivastava Shikhar, Pandey Chandan, Gupta Ankur, Sharma Atul Kumar
Department of Mechanical Engineering, Indian Institute of Technology Jodhpur, Jodhpur 342037, Rajasthan, India.
Polymers (Basel). 2022 Jul 27;14(15):3037. doi: 10.3390/polym14153037.
Hard-magnetic soft materials belong to a class of the highly deformable family of smart materials and provide a promising technology for flexible electronics, soft robots, and functional metamaterials. When hard-magnetic soft actuators are driven by a multiple-step input signal (Heaviside magnetic field signal), the residual oscillations exhibited by the actuator about equilibrium positions may limit their performance and accuracy in practical applications. This work aims at developing a command-shaping scheme for alleviating residual vibrations in a magnetically driven planar hard-magnetic soft actuator. The control scheme is based on the balance of magnetic and elastic forces at a critical point in an oscillation cycle. The equation governing the dynamics of the actuator is devised using the Euler-Lagrange equation. The constitutive behaviour of the hard-magnetic soft material is modeled using the Gent model of hyperelasticity, which accounts for the strain-stiffening effects. The dynamic response of the actuator under a step input signal is obtained by numerically solving the devised dynamic governing equation using . To demonstrate the applicability of the developed command-shaping scheme, a thorough investigation showing the effect of various parameters such as material damping, the sequence of desired equilibrium positions, and polymer chain extensibility on the performance of the proposed scheme is performed. The designed control scheme is found to be effective in controlling the motion of the hard-magnetic soft actuator at any desired equilibrium position. The present study can find its potential application in the design and development of an open-loop controller for hard-magnetic soft actuators.
硬磁软材料属于一类高可变形的智能材料家族，为柔性电子、软体机器人和功能超材料提供了一项很有前景的技术。当硬磁软致动器由多步输入信号（阶跃磁场信号）驱动时，致动器在平衡位置附近表现出的残余振荡可能会限制其在实际应用中的性能和精度。这项工作旨在开发一种指令整形方案，以减轻磁驱动平面硬磁软致动器中的残余振动。该控制方案基于振荡周期中临界点处磁力和弹力的平衡。使用欧拉 - 拉格朗日方程设计了致动器动力学的 governing 方程。硬磁软材料的本构行为使用超弹性的 Gent 模型进行建模，该模型考虑了应变强化效应。通过使用 [具体数值求解方法] 对设计的动态 governing 方程进行数值求解，得到了致动器在阶跃输入信号下的动态响应。为了证明所开发的指令整形方案的适用性，进行了全面的研究，展示了诸如材料阻尼、期望平衡位置序列和聚合物链可扩展性等各种参数对所提出方案性能的影响。发现所设计的控制方案在控制硬磁软致动器在任何期望平衡位置的运动方面是有效的。本研究可以在硬磁软致动器的开环控制器的设计和开发中找到其潜在应用。
