Single-Actuator Trunk Exoskeleton With Cable-Pulley Lumbar Support
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Solution Overview
Problem
Existing exoskeleton systems fail to effectively reduce muscle forces in a wearer's back during lumbar flexion, such as stooping or bending, while allowing comfortable movement during other activities like walking or climbing.
Innovation Solution
A trunk supporting exoskeleton system with a supporting trunk frame, thigh links, and an actuator that generates extension torques between the thigh links and the trunk frame when the wearer bends forward, using a system of pulleys and lines to distribute forces and allow for comfortable movement during non-reciprocal leg motions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a powered exoskeleton system is designed to reduce muscle forces during lumbar flexion, then back support effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent combines the functions of multiple actuators into a single powered actuator located at the trunk. This single actuator uses a cable-pulley system to simultaneously control both thigh links, merging what would traditionally require separate actuation systems into one integrated unit, thereby reducing overall system complexity while maintaining back support effectiveness
Solution Approach 2:
The cable-pulley mechanism acts as an intermediary between the single trunk-mounted actuator and the thigh links. The cables transmit force from the actuator to the thigh links, and the pulleys enable directional control and mechanical advantage, allowing one actuator to effectively control multiple joints through this intermediate transmission system
2Reliability
If the actuator generates extension torques during lumbar flexion, then muscle force reduction is improved, but ease of operation during natural movements deteriorates
Solution Approach 1:
The actuator dynamically adjusts its operation based on the wearer's movement state. During lumbar flexion, the actuator generates extension torques to support the back. During natural walking or climbing movements, the actuator allows free movement by not generating resistive torque, thus adapting its behavior to different operational modes and maintaining ease of operation
Solution Approach 2:
The actuator operates periodically based on the detection of lumbar flexion events. It remains inactive during normal activities and activates only when lumbar flexion is detected, providing support in a periodic manner that matches the intermittent nature of stooping or bending tasks, thereby not interfering with continuous natural movements
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 system reduces muscle forces in the wearer's back during lumbar flexion by providing support during stooping and bending, while enabling comfortable walking, ascending, and climbing without impeding natural leg movements.
Implementation Method 1
the actuator can generate an actuator resistive torque between the actuator housing and the actuator shaft. The actuator resistive torque between the actuator housing and the actuator shaft can generate tensile forces in the housing line and the shaft line, thereby generating extension torques between the respective first and second thigh links and the supporting trunk frame
Implementation Method 2
The shaft pulley can be coupled to the actuator shaft. The housing pulley can be coupled to the actuator housing. The shaft line can have a first end wound onto the shaft pulley and a second end coupled to the first thigh link
Data Source
AI summary
Some embodiments described herein are directed to a trunk supporting exoskeleton for reducing muscle forces in a wearer's back during forward lumbar flexion. The trunk supporting exoskeleton can include a supporting trunk frame, a first thigh link, a second thigh link, an actuator, a shaft pulley, a housing pulley, a shaft line, and a housing line. The actuator can include an actuator housing and an actuator shaft. When the wearer is bent forward relative to a vertical gravitational line in a sagittal plane, the actuator can generate an actuator resistive torque between the actuator housing and the actuator shaft. The actuator resistive torque between the actuator housing and the actuator shaft can generate tensile forces in the housing line and the shaft line, thereby generating extension torques between the respective first and second thigh links and the supporting trunk frame.