Trunk Exoskeleton with Adaptive Torque for Lumbar Support
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Solution Overview
Problem
Conventional back support devices fail to differentiate between walking and bending or sitting, leading to discomfort and hazards as they require the wearer's legs to push against the device, restricting unrestricted movement.
Innovation Solution
A trunk supporting exoskeleton with torque generators that couple the trunk to thigh links, generating torque only when the wearer bends forward beyond a predetermined angle, reducing muscle forces in the back by imposing a resisting torque between the trunk and thighs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional passive spring resistance is used to create torque between torso and legs, then the probability of injury of the L5/S1 area of the spine is greatly reduced, but the wearer cannot walk or sit comfortably since the wearer's legs must push against the devices during these activities
Solution Approach 1:
The exoskeleton employs a torque generator that dynamically adjusts resistance based on the trunk's angular position. When the trunk is upright, no resistance is applied, allowing free movement for walking and sitting. When the trunk bends forward beyond a predetermined angle, the torque generator activates to provide supporting torque, reducing spinal injury risk. This dynamic activation resolves the contradiction by making the device adaptive to different postural requirements.
Solution Approach 2:
The system changes the resistance parameter conditionally based on trunk angle. The torque generator monitors the angle between the trunk and vertical gravity line, and only imposes resisting torque when the trunk passes beyond a predetermined angle from vertical. This parameter-based control allows comfortable walking and sitting (low resistance) while providing injury prevention (high resistance) when bending occurs.
2Force
If passive spring resistance is applied continuously to counteract trunk gravity weight, then spinal support is provided during bending, but the wearer's legs must push against the devices during walking and sitting, restricting unrestricted movement
Solution Approach 1:
The torque generator provides dynamic force modulation based on real-time trunk angle detection. The system transitions from a static continuous resistance model to a dynamic conditional resistance model, where force is applied only when the trunk bends forward beyond a predetermined angle. This enables the exoskeleton to adapt to different movement scenarios, providing spinal support during bending while allowing unrestricted walking and sitting.
Solution Approach 2:
The exoskeleton system monitors its own operational state through angle sensors and automatically activates or deactivates torque generation based on detected postural conditions. The system serves itself by detecting when support is needed (trunk bending) and when it should remain passive (walking, sitting), eliminating the need for manual control and enabling automatic adaptation to movement requirements.
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 comfortable walking and sitting by minimizing muscle forces in the back during forward lumbar flexion, allowing unrestricted movement without the need for the wearer's legs to push against the device.
Implementation Method 1
Conventional systems utilize a passive, spring resistance to create a torque between the wearer's torso and legs
Implementation Method 2
moment is created during a bend to counteract the moments from a wearer's trunk gravity weight
Data Source
AI summary
A trunk supporting exoskeleton comprises: a supporting trunk; thigh links configured to move in unison with a wearer's thighs; and first and second torque generators located on both left and right halves of the wearer substantially close to the wearer's hip. The torque generators couple the supporting trunk to the thigh links, and generate torque between the thigh links and the supporting trunk. When the wearer bends forward such that a predetermined portion of the supporting trunk passes beyond a predetermined angle from vertical, a torque generator(s) imposes a resisting torque between the supporting trunk and the thigh link(s), causing the supporting trunk to impose a force against the wearer's trunk, and the thigh link(s) to impose a force onto the wearer's thigh. When the predetermined portion does not pass beyond the predetermined angle, the torque generators impose no resisting torques between said supporting trunk and respective thigh links.