Knee Angle Sensor Stimulation for Foot Raising
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Solution Overview
Problem
Individuals with spastic hemiparesis face mobility issues due to limited dorsiflexion movement during walking, leading to increased risk of stumbling and falling, as existing devices are bulky, require shoe-mounted sensors, and result in muscular fatigue from quasi-permanent stimulation.
Innovation Solution
A stimulation device with sensors on the lower limb to measure knee flexion angle, electrodes for muscle stimulation, and a processing unit that activates electrodes only during the swing phase, increasing intensity with knee angle decrease, eliminating the need for a heel sensor and reducing electrical consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electric stimulation is applied continuously to raise the foot, then the foot raising function is maintained, but muscular fatigue increases and energy consumption rises
Solution Approach 1:
The stimulation device applies electrical stimulation periodically during the swing phase of walking rather than continuously. The processing unit detects knee flexion angle and triggers stimulation only when the knee is flexed beyond a threshold angle, creating periodic stimulation cycles that match the walking pattern. This reduces energy consumption while maintaining foot raising function during the critical swing phase.
Solution Approach 2:
The device uses the user's own knee movement to trigger stimulation. The processing unit monitors the knee flexion angle and automatically activates stimulation when the knee flexes beyond the threshold, eliminating the need for external control or continuous power application. The system serves itself by using biomechanical signals to control its own operation.
2Measurement precision
If heel sensors are used to detect walking phase, then stimulation timing is accurate, but device bulk increases and shoe mounting is required
Solution Approach 1:
The invention extracts the sensing function from the heel area and relocates it to the knee joint. By measuring knee flexion angle with sensors mounted on the thigh or calf, the system eliminates the need for heel-mounted pressure sensors and shoe modifications. The knee angle measurement provides sufficient information to determine swing phase without requiring heel contact detection.
Solution Approach 2:
The knee angle sensor serves multiple functions: it detects swing phase for timing stimulation, provides information about knee position for control decisions, and can potentially monitor overall gait pattern. This multi-functional approach replaces the specialized heel sensor system with a more versatile knee-based sensing solution.
3Reliability
If stimulation intensity is increased to ensure proper foot raising, then dorsiflexion effectiveness improves, but energy consumption increases
Solution Approach 1:
The stimulation intensity is made dynamic rather than fixed. The processing unit adjusts the stimulation parameters based on the detected knee flexion angle, applying higher intensity when the knee is deeply flexed during swing phase when foot raising is most critical, and reducing or stopping stimulation when the knee is extended. This dynamic adjustment maintains effectiveness while reducing overall energy consumption.
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 device accurately triggers muscle stimulation for proper foot raising, reduces device bulk, and minimizes fatigue by stimulating muscles only when necessary, enhancing dorsiflexion movement and reducing energy consumption.
Implementation Method 1
sensors (3) on the lower limb (20) which measure the angle of flexion of the knee (22)
Implementation Method 2
at least two electrodes (4) on the lower limb (20) facing the muscle(s) to be activated in order to electrically stimulate said muscle(s)
Data Source
AI summary
A stimulation device for activating at least one muscle involved in raising the foot while an individual is walking, comprising sensors which are to be placed on a lower limb of the individual, permitting calculation of a flexion angle of the knee; electrodes which are to be placed on the one or more muscles to be activated and able to electrically stimulate the one or more muscles, and a processing unit with computing means for calculating the value of the flexion angle of the knee on the basis of the measurement signals and for determining the oscillation phase in a walking cycle of the individual, and control means for the electrodes, the control means being designed to activate the electrodes only in the oscillation phase of a walking cycle of the individual, such that the electrodes generate an electrical stimulation with an intensity depending on the flexion angle of the knee, the intensity increasing as the flexion angle of the knee decreases, during the re-extension of the knee during the oscillation phase.