基于流量调节的水下轻巧软体机械臂的液压驱动与控制

海洋中蕴藏着总量巨大的自然资源，对于人类有着不可替代的经济和科学价值。在海洋的探索和开发中，水下机械臂是理想的工具。新兴的水下软体机械臂凭借自身的高柔顺性和高适应性等特点，尽管能够克服目前主流的水下刚性机械臂存在的质量大、成本高、安全性和自由度有限等局限性，但是固有的极高自由度带来的非期望形变也给建模造成了较大的困难，从而影响了其在实际应用场景的表现。在不同的水下软体机械臂驱动原理中，液压驱动不仅在响应速度、负载能力、控制精度等方面取得了良好的平衡，而且具备对于水下环境的适应性。然而，主流的基于泵-阀系统开关控制的液压驱动方法受限于离散状态切换的不连续特性，难以兼顾软体机器人的精确控制和快速响应。

为提升水下软体机械臂的性能表现，推动其走向实际应用，本研究课题完成了以下三方面的工作：首先，针对主流液压驱动方法的局限性，本研究课题提出了基于流量调节的液压驱动方法，借助蠕动泵实现了相应的液压驱动框架，并且通过实现同时具备精确控制和快速响应特性的软体驱动器位置/输出力控制，验证了方法的有效性。其次，针对水下软体机械臂高自由度导致的建模困难，本研究课题提出了平面绑定过约束设计，提高了软体机械臂的抗屈曲与剪切形变能力，进而提升了建模的精度。最终，本研究课题通过将基于流量调节的液压驱动方法和平面绑定过约束设计结合，实现了软体机械臂关节位置的轨迹跟踪。

The ocean harbors vast resources with irreplaceable economic and scientific value for humanity. In the exploration and exploitation of the ocean, underwater robotic arms serve as ideal tools. Emerging underwater soft robotic arms, with characteristics including high flexibility and adaptability, can overcome the limitations of mainstream rigid underwater robotic arms, such as heavy weight, high cost, limited safety, and degrees of freedom (DoFs). However, the inherent high DoFs also introduce unexpected deformations, posing significant challenges in modeling and affecting their performance in real-world applications. Among various actuation principles for underwater soft robotic arms, hydraulic actuation achieves a good balance in terms of response speed, load capacity, and control precision, while also demonstrating adaptability to the underwater environment. Nevertheless, the prevailing hydraulic actuation methods based on pump-valve systems with switch control are constrained by the discontinuous nature of discrete state transitions, making it difficult to balance precise control and rapid response of soft robots.

To enhance the performance of underwater soft robotic arms and promote their practical application, this research addresses three main issues as follows. Firstly, to overcome the limitations of prevailing hydraulic actuation methods, a flow-regulating hydraulic actuation method was proposed. Utilizing peristaltic pumps, a hydraulic actuation framework is implemented, validating the proposed method by enabling precise control and rapid response in position/force control of soft actuators. Secondly, to overcome the modeling difficulty caused by high DoFs, a planar-bundled and overly-constrained (PBOC) design was proposed, which improves the arm’s resistance to buckling and shearing, thereby enhancing modeling accuracy. Eventually, position trajectory tracking of the soft robotic arm joints was implemented by integrating the flow-regulating hydraulic actuation method and the PBOC design.

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