Tendon-Sheath Actuation with Rigid Rod Guidance to Reduce Backlash
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Solution Overview
Problem
The existing tendon-sheath driving methods for robots suffer from significant backlash and reduced precision due to loosening and bending of the slave tendon, which is not directly actuated by a motor.
Innovation Solution
A tendon-sheath driving apparatus is designed with a flexible sheath, a tendon, a rod with higher rigidity, and a pipe also with higher rigidity, where the tendon moves through the sheath and pipe as the rod is actuated, guided by the pipe to prevent buckling and maintain precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the slave tendon is driven by force applied from the master tendon, then the robot can be actuated remotely, but the slave tendon loosens and bends causing significant backlash and reduced precision
Solution Approach 1:
The patent introduces a rod as an intermediary component between the master and slave tendons. This rigid rod transmits the actuation force more effectively while maintaining tendon tension, preventing the slave tendon from loosening and bending, thus reducing backlash and improving actuation precision while preserving remote actuation capability
Solution Approach 2:
The patent employs a composite structure combining flexible tendons with a rigid rod. This composite approach allows the system to benefit from both the flexibility of tendons for remote actuation and the rigidity of the rod for precise force transmission, resolving the contradiction between ease of operation and measurement precision
2Device complexity
If the slave tendon is exposed to the outside, then the structure is simpler, but friction increases and backlash occurs reducing precision
Solution Approach 1:
The patent nests the rod within a protective housing or conduit that guides the slave tendon. This nested structure protects the tendon from external friction while maintaining a relatively simple overall design, thus preserving structure simplicity while improving actuation precision by reducing friction and preventing tendon bending
Data Source
AI summary
Disclosed is a tendon-sheath driving apparatus. A tendon-sheath driving apparatus according to an embodiment of the disclosure includes: a sheath having a predetermined length, being flexible and having a hollow shape; a tendon placed inside a hollow of the sheath; a rod coupled to an outer surface of a first side of the tendon, and having higher rigidity than the sheath; and a pipe coupled to an outer surface of a first side of the sheath, and having higher rigidity than the sheath, wherein the tendon is moved through the sheath and the pipe as the rod is moved being guided by the pipe while a portion of the rod is placed inside the pipe.