Tube Mechanism With 3-Axis Rotary Joints Structure to Achieve Variable Stiffness Using Positive Pressure
Tube Mechanism With 3-Axis Rotary Joints Structure to Achieve Variable Stiffness Using Positive Pressure
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DOI：
10.1109/lra.2023.3234767
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发表时间：
2024-01
影响因子：
5.2
通讯作者：
Issei Onda;M. Watanabe;K. Tadakuma;Kazuki Abe;S. Tadokoro
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文献类型：
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作者：
Issei Onda;M. Watanabe;K. Tadakuma;Kazuki Abe;S. Tadokoro
对软机器人的研究探索了改变机器人结构刚度的机制。柔性-刚体混合方法结合了软材料和高刚度结构，是实现变刚度机构的常用方法。尤其是正压法，由于它可以消除对行驶压力的限制，近年来引起了人们的极大关注。此外，它还可以根据内部压力改变保形力。在这项研究中，设计了一种由三轴旋转球关节和单腔组成的变刚度机构，该机构通过正压摩擦力实现。该样机在不施加压力时可以任意改变关节角度，在施加正压时可以保持关节角度不变。通过建立保持关节角度所需力矩的理论模型，对保持力矩进行了有限元建模分析，并测量了在内压作用下，保持力矩在俯仰和侧倾方向的变化。基于理论模型、测量和有限元分析的相互作用，确定了在每一内压下，滚压方向的保持力矩大约是俯仰方向的π/2倍。进一步，我们通过两两的数值比较评估了保持力矩的有限元值、理论值和实测值。我们的方法将有助于为软机器人应用设计有效的加强机构。
Studies on soft robotics have explored mechanisms for switching the stiffness of a robot structure. The hybrid soft-rigid approach, which combines soft materials and high-rigidity structures, is commonly used to achieve variable stiffness mechanisms. In particular, the positive-pressurization method has attracted significant attention in recent years as it can eliminate the constraints on driving pressure. Moreover, it can change the shape holding force according to internal pressure. In this study, a variable stiffness mechanism, comprising 3-axis rotary ball joints and a single chamber, was devised via frictional force using positive pressure. The prototype can change joint angles arbitrarily when no pressure is applied and can hold joint angles when positive pressure is applied. Using a theoretical model of the torque required to hold the joint angle, we simulated the holding torque using finite element modeling analysis and measured the holding torque in the pitch and roll directions when internal pressure was applied. Based on the interaction of the theoretical model, measurement, and FEM analysis, it was confirmed that the value of the holding torque in the roll direction was approximately π/2 times larger than that in the pitch direction for each value of the internal pressure. Further, we evaluated the FEM value, theoretical value, and measured value of the holding torque by performing pairwise numerical comparisons. Our approach will aid the design of effective stiffening mechanisms for soft robotics applications.