Guide Pulley Torque Transmission Across Nonparallel Hinge Axes
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Solution Overview
Problem
Existing wearable robots face challenges in torque transmission over nonparallel and hingable axes, leading to increased spatial extent and dependency of cable tension on angular configuration, which can hinder user mobility and comfort.
Innovation Solution
A device utilizing coaxial torque transmission with guide pulleys parallel to the hinge axis, maintaining constant member path length and independent tension, allowing for limited spatial extent and reduced inertial forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a guide pulley with axis parallel to the joint rotational axis is used for torque transmission, then the spatial extent perpendicular to the joint rotational axis is limited, but the cable path length becomes dependent on the angular configuration of the joint, causing tension variations
Solution Approach 1:
The patent introduces an intermediary component - a guide pulley with axis perpendicular to both the first hinge axis and the rotational axis of the input pulley. This intermediary guide pulley mediates the cable path between the input and output pulleys, enabling torque transmission while maintaining cable path length independence from joint angular configuration, thus resolving the tension variation issue
Solution Approach 2:
The patent changes the orientation dimension of the guide pulley axis to be perpendicular to both the hinge axis and the input pulley axis. This dimensional arrangement creates a spatial configuration where the cable wraps around the guide pulley in a manner that decouples the cable path length from the joint's angular configuration, maintaining constant tension
2Adaptability or versatility
If intermediate guide pulleys on vertical axes are used to transmit motion between non-parallel axes, then motion transmission is achieved, but the device complexity and spatial extent increase
Solution Approach 1:
The guide pulley serves multiple functions simultaneously: it guides the cable, transmits torque between non-parallel axes, and maintains constant cable path length. This multi-functionality reduces the need for separate components for each function, thereby simplifying the overall device structure while achieving motion transmission between non-parallel axes
Solution Approach 2:
The patent combines the functions of torque transmission and cable guidance into a single integrated pulley system. The guide pulley is merged with the torque transmission path, eliminating the need for separate intermediate transmission mechanisms and reducing overall device complexity
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
Enables efficient torque transmission with minimal spatial impact and independent cable tension, enhancing user comfort and mobility in wearable robots.
Implementation Method 1
a first guide pulley (1) with a pulley rotational axis (11) in essence perpendicular to the first hinge axis (10)... a second guide pulley (2) with a pulley rotational axis (12) in essence perpendicular to the first hinge axis (10)
Data Source
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AI summary
The current invention concerns a device and a method for transmitting torque. The device may comprise an elongated and bendable torque transmission member, e.g. a cable, and a hinge element along which the member is guided via one or more guide pulleys. The hinge element may comprise a first and a second base element hingedly attached and comprising a first hinge axis. The first element may comprise a first guide pulley with pulley rotational axis in essence perpendicular to the first hinge axis. The second element may comprise a second guide pulley with pulley rotational axis in essence perpendicular to the first hinge axis. The positions of the first guide pulley in the first element and the second guide pulley in the second element may be configured to guide a portion of the member in essence coaxial to the hinge axis. In a preferred embodiment, the device is a wearable robot, e.g. an exoskeleton.