Powered Lower Limb Device Stumble Recovery Control
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Solution Overview
Problem
Existing lower limb prostheses lack the ability to provide proper joint kinetics and kinematics, leading to instability and increased risk of falls, especially on uneven terrain, as they cannot react appropriately to stumbling perturbations.
Innovation Solution
A control system and methodology for powered lower limb devices with at least one powered joint that detects stumble events and implements recovery responses, such as elevating or lowering strategies, to enhance balance and stability during standing and walking, using sensors like accelerometers and strain gages to adjust joint torques and angles accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive prostheses are used, then device complexity is reduced, but stability and ability to respond to stumbling perturbations deteriorates
Solution Approach 1:
The patent replaces passive mechanical prosthetic joints with powered joints actuated by motors, enabling active control of joint kinetics and kinematics. This substitution allows the prosthesis to dynamically adjust to terrain and provide stumble recovery responses, resolving the contradiction between simplicity and stability.
Solution Approach 2:
The control system continuously monitors user intent through sensors (EMG, accelerometers, gyroscopes) and autonomously adjusts joint torques and positions to maintain stability. The system self-regulates during normal walking and automatically activates stumble recovery strategies without user intervention, enhancing reliability while managing complexity through intelligent control.
2Reliability
If powered joints are added to provide active control, then stability and stumble recovery improve, but device complexity increases
Solution Approach 1:
The control system is segmented into distinct functional modules: intent detection module (processing EMG and sensor data), state estimation module (determining gait phase and stability), and control module (selecting appropriate stumble recovery strategies). This segmentation manages complexity by organizing control functions into manageable, independent components that can be developed and tested separately.
Solution Approach 2:
The prosthesis employs dynamic control where joint torques and stiffness are continuously adjusted based on real-time sensor feedback and detected user intent. The system transitions between different control modes (normal walking, stumble detection, recovery execution) to provide context-appropriate responses, enabling high reliability without requiring overly complex static control mechanisms.
3Ease of manufacture
If passive prostheses are used, then ease of manufacture is improved, but adaptability to uneven terrain and stumbling events deteriorates
Solution Approach 1:
The powered prosthesis changes operational parameters (joint torque, stiffness, velocity) in real-time based on terrain conditions and detected user intent. The control system adjusts these parameters dynamically during normal walking and dramatically during stumble recovery, providing adaptability to uneven terrain while maintaining manufacturability through standardized motor and sensor components.
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
Systems and methods are provided for controlling a lower limb device having at least one powered joint. The method includes detecting a stumble event based on one or more sensor signals associated with an overall motion lower limb device, classifying the stumble event based on sensor signals following the sensor signals associated with the stumble event, and selecting a stumble recovery strategy for the lower limb device based on the classification of the stumble event.