Pulley-Integrated Cable Actuator for Wearable Robots
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Solution Overview
Problem
Conventional wearable robots with cable-driven systems are bulky and heavy due to the use of separate pulleys and motors, leading to increased system volume and protrusion from the body, which compromises user comfort and control performance.
Innovation Solution
A pulley-integrated cable actuator design that integrates pulleys and bearings directly into the motor, reducing system volume and weight by integrating a sun gear shaft, planet gear set, and ring gear-integrated pulley within a compact frameless motor, allowing for a smaller and lighter wearable robot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If separate pulleys and motors are used in cable-driven wearable robots, then the system can provide sufficient driving force, but the system volume and weight increase, causing protrusion from the body and reduced user comfort
Solution Approach 1:
The patent merges the pulley and motor into a single integrated actuator unit. The pulley is positioned at the output end of the motor shaft, eliminating the need for separate mounting structures, bearings, and housing. This integration directly reduces system volume while maintaining the driving force capability through the combined mechanical structure.
Solution Approach 2:
The integrated actuator serves multiple functions simultaneously: the motor provides rotational driving force, the pulley transmits this force to the cable, and the integrated structure eliminates the need for separate mounting and support components. This multi-functionality reduces the overall number of parts and system volume while maintaining full driving capability.
2Reliability
If separate pulleys and motors are used in cable-driven wearable robots, then the system can operate reliably, but the weight increases, making the wearable robot bulky and inconvenient for daily use
Solution Approach 1:
By combining the pulley and motor into a single integrated unit, the patent eliminates redundant components such as separate mounting brackets, additional bearings, and separate housing structures. This merging reduces the total weight of the actuator system while maintaining operational reliability through the direct mechanical connection between the motor shaft and pulley.
3Force
If conventional motor and pulley assemblies are used, then sufficient driving force can be generated, but the actuator protrudes up to 7 cm from the wearer's back, creating obstacles and reducing comfort
Solution Approach 1:
The integration of the pulley with the motor shaft eliminates the need for extended mounting structures and separate component arrangements. This results in a compact actuator assembly that minimizes the distance from the wearer's back, reducing protrusion to a minimal extent while preserving the full assistive force generation capability through the direct-drive configuration.
4Ease of manufacture
If separate pulleys and motors are used, then the system can be designed with standard components, but the overall system complexity and number of parts increase
Solution Approach 1:
The patent integrates the pulley and motor into a single manufactured unit, reducing the total number of discrete parts and assembly steps. While the integrated actuator itself may require custom manufacturing, the overall system complexity is reduced by eliminating multiple separate components, mounting structures, and associated fasteners, leading to simpler assembly and maintenance procedures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The pulley-integrated cable actuator significantly reduces the volume and weight of wearable robots, enhancing user comfort by minimizing protrusion and improving control performance, while being applicable to various cable drive mechanisms beyond wearable robots.
Implementation Method 1
a base motor; a sun gear shaft of which the lower end portion is coupled to the center of the base motor, rotating by the motor rotation
Implementation Method 2
a planet gear set consisting of multiple planet gears that mesh with the sun gear; and a ring gear-integrated pulley where a ring gear is formed on the inner side, meshing with the planet gear
Implementation Method 3
a pulley for winding a cable is formed on the outer side
Data Source
AI summary
The present disclosure relates to a pulley-integrated cable actuator and an operation method thereof, more particularly to an actuator for operating cables. The pulley-integrated cable actuator includes: a base motor; a sun gear shaft of which the lower end portion is coupled to the center of the base motor, rotating by the motor rotation, and provided with a sun gear; a planet gear set consisting of multiple planet gears that mesh with the sun gear; and a ring gear-integrated pulley where a ring gear is formed on the inner side, meshing with the planet gear, and a pulley for winding a cable is formed on the outer side. The sun gear meshes with the inner space of the planet gear set. The ring gear is integrated with the pulley. The planet gear set is placed inside the pulley, minimizing the volume.