Bio-inspired Curved Sole Balance Controller for Exoskeletons
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Solution Overview
Problem
Current full-mobilization exoskeletons for spinal cord injury patients are bulky, expensive, and require crutches for balance, limiting their usability in daily activities and mobility, especially on uneven terrain.
Innovation Solution
A balance control system using two actuated degrees of freedom (knee and hip flexion/extension) with embedded sensors to stabilize the exoskeleton without an actuated ankle, allowing users to stand and walk without crutches by adjusting the center of mass and center of pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an exoskeleton uses multiple actuated degrees of freedom to provide balance, then stability is improved, but device weight and complexity increase significantly
Solution Approach 1:
The invention extracts the balance function from the traditional multi-actuated exoskeleton system and implements it separately through a passive curved foot sole mechanism. The curved sole (with radius of curvature between 0.3-0.6 times user height) naturally provides balance stabilization through its geometry without requiring active actuators at the ankle or other joints, thus removing the weight penalty while maintaining stability.
Solution Approach 2:
The invention applies curvature to the foot sole, creating a passive balance mechanism through the curved geometry. The specific radius of curvature (0.3-0.6 times user height) is designed to match human biomechanics and provide natural balance stabilization during standing and walking, eliminating the need for heavy actuated balance systems.
2Ease of operation
If an exoskeleton uses 10-12 actuated degrees of freedom to enable crutches-free walking, then mobility independence is improved, but device weight increases to 38-60 kg
Solution Approach 1:
The invention extracts the balance stabilization function from the actuated joint system and implements it passively through the curved foot sole geometry. This allows the exoskeleton to achieve crutches-free operation with significantly fewer actuators (only 4 DoFs at hips and knees), reducing weight from 38-60 kg to a much lighter configuration while maintaining mobility independence.
Solution Approach 2:
The curved foot sole provides self-service balance stabilization without requiring active control or additional actuators. The passive geometric design automatically adapts to user movements and terrain, enabling crutches-free operation through the inherent properties of the curved sole rather than through active mechanical assistance.
3Ease of manufacture
If a exoskeleton uses a flat foot sole design, then manufacturing is simpler, but standing stability without crutches is insufficient
Solution Approach 1:
The invention transitions from a flat foot sole to a curved foot sole with a specific radius of curvature (0.3-0.6 times user height). This curvature provides the necessary standing stability without crutches while remaining manufacturable through conventional processes, as the curved geometry can be created using standard molding or bending techniques.
4Stability of the object's composition
If an exoskeleton uses a fully curved foot sole, then rolling smoothness and balance are improved, but manufacturing complexity increases
Solution Approach 1:
The invention specifies a particular range for the radius of curvature (0.3-0.6 times user height) that optimizes both balance performance and manufacturability. This parameter range ensures sufficient balance stability while remaining compatible with standard manufacturing processes, avoiding the need for complex custom fabrication.
Data Source
AI summary
The invention concerns a method of performing automatic standing balance of a user in a full mobilization exoskeleton with at least a foot and using at least two actuated degrees of freedom, wherein a controller uses information provided from sensors to produce corrective movements in the actuated degrees of freedom, wherein an estimation of the center of mass of the system comprising user and exoskeleton is made and the controller applies corrective measures on the actuated degrees of freedom to influence the position of the center of mass with respect to a center of pressure with the ground on which the exoskeleton is standing. The invention also concerns a device using the method according to the invention.