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Vine-Inspired Twining Actuator: Cylindrical Hyper-Form-Closure Envelopment by Single Actuated Linkage
Jinnong Liao1, Qihua Zhou2, Yonglin Wang1
1State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China.
Biomimetics (Basel, Switzerland)
|February 26, 2026
Summary
This study introduces a novel N-layer Reverse Four-Bar Linkage for enhanced grasping. The innovative design overcomes limitations of traditional linkages, enabling stable grasping of diverse objects for industrial automation.
Area of Science:
- Robotics and Mechanical Engineering
- Kinematics and Mechanism Design
Background:
- Traditional linkage mechanisms face limitations in enveloping angles and complexity.
- Multi-loop designs often suffer from reduced reliability and structural interference.
Purpose of the Study:
- To establish the kinematic general formula for the N-layer Reverse Four-Bar Linkage.
- To analyze the relationship between envelope angle and the number of closed-loop layers (N).
- To investigate the impact of structural parameters on mechanism configuration and stability.
Main Methods:
- Derivation of the kinematic general formula for the N-layer Reverse Four-Bar Linkage.
- Analysis of envelope angle variation with increasing layers (N).
- Prototype development utilizing slotted shaft-thrust bearing composite joints and stepped arrangement to mitigate interference.
Main Results:
- The N-layer Reverse Four-Bar Linkage exhibits self-similar topological characteristics under specific symmetric length and internal-angle constraints.
- A six-layer (N=6) prototype achieved a 450° theoretical envelope angle.
- The prototype successfully demonstrated hyper form closure grasping for cylindrical objects (35-110 mm diameter).
Conclusions:
- The N-layer Reverse Four-Bar Linkage offers a versatile and reliable grasping solution for industrial automation.
- The developed mechanism overcomes multi-link interference issues, enabling large envelope angles.
- This design facilitates stable grasping of objects with varying sizes and shapes.
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