Wire Guide for Robot Arm Joints
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Solution Overview
Problem
Wearable robot arms with multiple joints driven by wires face excessive weight due to multiple motors, leading to reduced working efficiency as the wearer becomes fatigued, and existing wire-driven systems cannot adjust wire length with changes in link angles, affecting operational accuracy.
Innovation Solution
A robot arm design featuring a wire guide with a rotational plate and idle rollers that allows the wire to pass through the center of joints, maintaining constant wire length despite changes in link angles, ensuring accurate control and reduced operational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple motors are provided in each joint of the wearable robot arm, then the robot arm can achieve precise control and sufficient driving force, but the weight of the robot arm becomes excessively increased
Solution Approach 1:
The patent merges multiple motor functions into a single driving unit located at one end of the robot arm. This single driving unit controls multiple joints through wires, eliminating the need for separate motors at each joint. The merging reduces the overall weight while maintaining the driving capability through the wire transmission mechanism.
Solution Approach 2:
The patent introduces wires as intermediary elements to transmit driving force from the single driving unit to multiple joints. The wires act as mediators that carry the driving force across different joints, enabling precise control without requiring physical motors at each joint location, thus reducing weight while maintaining power transmission.
2Weight of moving object
If the robot arm uses a wire-driven system with a small number of driving units, then the weight of the robot arm is decreased, but the length of the wire changes when relative angles of links are changed
Solution Approach 1:
The patent introduces a dynamic wire guide that can rotate along with the joint angles. This dynamic adjustment allows the wire guide to maintain the wire's path through the center of rotation, ensuring that the wire length remains constant even when joint angles change. The rotatability of the wire guide adapts to different arm configurations.
Solution Approach 2:
The patent replaces the conventional fixed wire routing mechanism with a rotational plate-based wire guide system. This substitution allows the wire guide to dynamically adjust its position and orientation, maintaining optimal wire tension and length consistency through geometric design rather than rigid mechanical constraints.
3Device complexity
If the wire length changes when link angles change, then the robot arm structure is simple, but the control accuracy of target links deteriorates
Solution Approach 1:
The rotational plate wire guide dynamically adjusts its position to maintain wire length consistency. By rotating along with the joint, it ensures that the wire always passes through the center of rotation, preventing length changes that would compromise control accuracy. This dynamic adaptation maintains precision without adding significant structural complexity.
Solution Approach 2:
The rotational plate wire guide serves multiple functions: it guides the wire, maintains wire length consistency, and adapts to different joint angles. This multi-functionality achieves both structural simplicity and control accuracy by combining several functions into a single versatile component.
Data Source
AI summary
Disclosed herein is a robot arm including a first joint portion connected to an end portion of a wire and operable to rotate when the wire is pulled, a second joint portion connected to the first joint portion through a link, and a wire guide composed of a rotational plate rotatably installed at the second joint portion and a pair of idle rollers provided to continuously contact the rotational plate, in which the wire passes between the idle rollers.