变刚度柔性夹持装置的研究进展

Review on compliant gripper with adjustable stiffness

变刚度柔性夹持装置既保留了软体驱动器的柔顺特性,又有效提高了夹持装置的夹持力。根据结构及驱动方式的不同,变刚度柔性夹持装置主要可分为包含内骨骼或外骨骼结构、基于干扰(阻塞)效应、内嵌低熔点合金或聚合物等3个种类。包含内骨骼或外骨骼结构的夹持装置无法实现刚度的灵活调节;基于干扰效应的夹持装置的两种典型结构中,层干扰比颗粒干扰的刚度调节范围更大,但其结构更复杂,导致制造困难;而内嵌低熔点合金或聚合物的夹持装置,其最大缺陷为响应时间过长,且对设备和驱动器的绝缘以及耐热性能的要求较高。通过分析和总结目前变刚度夹持装置的研究现状,指出目前在该研究领域被忽视的关键问题主要包含3个方面:1)缺少变刚度机理方面的深层次研究;2)缺少变刚度柔性夹持装置可靠性和寿命的研究;3)缺少变刚度柔性夹持装置的应用研究。

Compliant gripper not only retains the compliance of soft actuator,but also lifts up the gripping force efficiently.Compliant gripper with adjustable stiffness can be mainly classified into three categories according to different structure and actuation pattern including endoskeleton or exoskeleton based,jamming effect based,and low-melting alloy or polymer based.Flexible adjustment of stiffness cannot be realized by endoskeleton or exoskeleton-based gripper.For the two typical structures of jamming effect-based gripper,the range of stiffness adjustment of layer jamming based structure is larger than that of granular jamming-based structure;however,the structure of layer jamming based gripper is more complicated leading to more complicated fabrication process.The major defect of low-melting alloy or polymer-based gripper is its long movement response time as well as the required high insulativity and heat resistance for the actuator.By analyzing and concluding state-of-the-art of compliant gripper,the key questions which have been neglected in this research field are raised mainly including three aspects as follows:the lack of deep research in the theory of adjustable stiffness mechanism,the lack of research in the reliability and lifetime of compliant gripper with adjustable stiffness,and the lack of research in the application of compliant gripper with adjustable stiffness.