海水液压软体机械爪抓取特性研究

In order to deal with the challenges of environmental compatibility, grasping adaptability and interactive security faced by the existing underwater robotic claw, a soft robotic claw driven by seawater hydraulics is proposed in this project and its grasping characteristics are investigated. The soft actuator is integrated after material selection and structural design of the inner skeleton and the flexible skin. The driving characteristics of the soft actuator under different ambient pressure are revealed by means of simulation and experiment methods. And the material constitutive model of the soft actuator is established successively. Then, the working mechanism of the soft actuator can be clarified. The grasping force model of the soft robotic claw driven by seawater hydraulics is established, and the valve-controlled soft robotic claw system is simulated to explore the effects of different working condition parameters on the grasping force and the deformation of the soft robotic claw. Additionally, a nonlinear robust predictive control method for grasping force control is studied. The soft robotic claw driven by seawater hydraulics is developed and its relevant performance test system is built, so that the grasping characteristic tests under atmospheric environment and back pressure environment would be carried out to verify the theoretical results, respectively. Meanwhile, the grasping force model is corrected by taking use of the test results to show the accurate mapping relationship between the grasping force and working pressure. Based on the experimental, theoretical and simulation results, the optimal matching relationship between the structure parameters of the soft robotic claw driven by seawater hydraulics and the system parameters is obtained, and the grasping force can be controlled quickly and precisely. This project will help provide theoretical and technical support for improving the performance of underwater soft robotic claw in China.

为了应对当前水下机械爪面临的环境相容性、抓取形态适应性及交互安全性等多重挑战，本项目提出一种海水液压软体机械爪结构，并对其抓取特性进行研究。通过对内骨架和柔性皮肤进行材料筛选与结构设计集成软体驱动器，仿真联合试验揭示不同环境背压下软体驱动器的驱动特性，建立软体驱动器材料本构模型，阐明软体驱动器的工作机理；建立软体机械爪抓取力模型，构建阀控软体机械爪系统仿真模型，探索不同工况参数对软体机械爪抓取力以及手指变形的影响，提出抓取力的非线性鲁棒预测控制方法；研制海水液压软体机械爪样机并搭建其性能试验系统，开展大气环境及背压环境下的抓取特性试验，验证理论结果的有效性，同时，利用试验结果校正抓取力模型，揭示抓取力与工作压力间的精确映射关系；综合试验、理论与仿真结果，获取软体机械爪结构与系统参数的最佳匹配关系，实现抓取力的快速、精确控制。本项目将为提升我国水下软体机械爪性能提供理论和技术支撑。

水下机器人搭载的末端手爪是执行水下作业任务的重要工具，而传统采用的刚性手爪通常结构复杂、环境相容性差，与抓取对象的形态适应性和安全交互性不尽理想。为解决上述难题，本项目提出了一种海水液压软体机械爪结构。该软体机械爪由三个海水液压软体驱动器组成，能够最大限度模仿人手的抓取功能。首先进行了海水液压软体驱动器的结构设计，初步确定了满足低压大变形和高压小变形两种工况要求的软体驱动器内骨架和柔性皮肤材料。随后，构建了软体驱动器材料的本构模型和软体机械爪的抓取力模型，通过有限元仿真分析方法研究了低压大变形工况和高压小变形工况下不同结构参数或系统参数对内骨架与软体驱动器受力及变形特性的影响，优选出软体驱动器的材料构成，揭示了不同工况下软体驱动器的驱动特性，阐明了软体驱动器的作动机理。在上述研究基础上，完成了海水液压软体机械爪与阀控系统的集成设计，探究了关键结构参数对集成装置系统动态特性的作用规律，建立了关于软体机械爪阀控系统的Simulink仿真模型，应用模型预测控制（MPC）技术实现了海水液压软体机械爪变形的快速和稳定控制。最后，研制出海水液压软体机械爪样机并搭建了其性能试验系统，分别开展了软体驱动器及其内骨架的变形特性试验，以及软体机械爪对不同形状物品的抓取特性试验。综合试验、理论与仿真结果，验证了本研究提出的海水液压软体机械爪设计理论的可行性。本项目提出的海水液压软体机械爪相关设计理论与方法有望为提升现有水下作业工具执行末端的综合性能提供理论和技术支撑。