Prosthetic Joint Mode Transition Optimization
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Solution Overview
Problem
Modern computer-controlled prosthetic devices face challenges in accurately transitioning between stiff and loose modes, leading to discomfort and undesirable gait patterns in amputees, as the transition is often triggered at inappropriate times, and manual adjustments become laborious and costly with increasing complexity.
Innovation Solution
A prosthetic joint system with a state controller, sensor system, and controllable actuator that utilizes movement data to determine the correct mode transitions, aided by an optimization unit that generates data files to adjust decision values for precise mode changes, preventing premature transitions and ensuring accurate support during gait.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the prosthetic joint uses event-based triggering for mode transitions, then the device can respond to gait events, but the transitions occur at inappropriate times causing discomfort and undesirable gait patterns
Solution Approach 1:
The system performs preliminary actions by progressing through additional intermediate states (Setup Swing Flexion, Setup Terminal Stance) before executing the actual mode transition. This preliminary progression ensures the joint is in the correct preparatory state, preventing premature or inappropriate transitions while maintaining gait adaptability.
2Reliability
If the prosthetic joint defaults to stiff mode for safety, then stability is improved, but the transition to loose mode does not occur when it should, resulting in peg-legged pirate gait
Solution Approach 1:
The system implements dynamic mode transitions by using multiple intermediate states that progress through different stiffness levels. The joint dynamically adjusts its stiffness based on the specific gait phase detected, transitioning smoothly from stiff to loose mode through intermediate states rather than abrupt switches, thereby maintaining both safety and gait naturalness.
3Measurement precision
If the prosthetic device becomes more sophisticated with more control variables, then gait accuracy is improved, but manual adjustment becomes laborious and time-consuming
Solution Approach 1:
The system performs self-service by automatically optimizing its control variables through iterative analysis of gait data. The optimization unit automatically adjusts the numerous control variables based on recorded gait patterns, eliminating the need for manual adjustment while maintaining high gait accuracy and reducing setup time.
4Manufacturing precision
If additional intermediate states are added to the control system, then mode transition precision is improved, but device complexity increases
Solution Approach 1:
The control system uses segmentation by dividing the mode transition process into distinct intermediate states (Setup Swing Flexion, Setup Terminal Stance, etc.). Each state has specific entry and exit criteria, making the complex transition process manageable and precise while organizing complexity into structured, named phases rather than a monolithic control system.
Data Source
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AI summary
The present invention relates to a prosthetic device including a prosthetic joint which accurately transitions between a loose mode and a stiff mode to more accurately mimic a human gait. The prosthetic joint includes a state controller which utilizes a sensor to detect prosthetic joint movement data, and compares it with prosthetic joint movement decision values to determine when a solenoid should be energized to place the prosthetic joint in the loose mode. An optimization unit connects to the prosthetic joint in a prosthetic joint system. The optimization unit generates a plurality of data files containing prosthetic joint movement data corresponding to an amputee walking without stumbling. By iteratively analyzing the prosthetic joint movement data, the optimization unit adjusts the prosthetic joint movement decision values to ensure that the prosthetic joint does not prematurely enter a stumble recovery state.