Exoskeleton Torque Control via Sagittal Foot Distance
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Solution Overview
Problem
Existing exoskeleton systems struggle to accurately identify walking phases without specialized sensors, leading to inadequate or inappropriate assistance during rehabilitation exercises for patients with locomotor deficits, particularly in cases of partial motor impairment or gait abnormalities.
Innovation Solution
A method that uses the distance between a subject's feet along the sagittal plane to identify three walking phases, utilizing existing angle encoders in the exoskeleton joints to determine assistive torques without additional sensors, allowing for continuous and phase-specific assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If specialized sensors (force sensors in sensorised insoles, accelerometers) are used to determine walking phases, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the essential information needed for gait phase detection (foot position relative to sagittal plane) from complex sensor systems and implements it using only the angle encoders already present in the exoskeleton joints. This eliminates the need for specialized sensors while maintaining measurement precision.
Solution Approach 2:
The exoskeleton's existing angle encoders, which are already installed for joint control, are repurposed to detect gait phases. The system serves itself by using its own operational sensors for dual purposes (control and detection), eliminating the need for additional specialized sensors.
2Ease of operation
If assistive torques are provided as fixed-duration pulses after detected state changes, then ease of operation is improved, but adaptability deteriorates
Solution Approach 1:
The system continuously monitors the distance between feet and dynamically adjusts torque delivery based on real-time gait phase detection. This feedback mechanism allows the system to adapt torque timing and magnitude to the patient's actual movement status rather than using fixed pulses.
Solution Approach 2:
The control system transitions from static fixed-duration torque pulses to dynamic torque delivery that continuously adapts to the detected gait phase. The assistive torques are adjusted in real-time based on the patient's movement progress through different gait phases.
Data Source
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AI summary
Method for determining the torque to be delivered by the motorised joints (10, 11, 12, 13) of a lower limb exoskeleton during the walk of a subject with locomotor deficits (3), which method provides for setting the torque to be delivered by the motorised joints (10, 11, 12, 13) based on the various phases of the walk, a step being provided for determining the state of the walk moment by moment. The determination of the state of the walk is made by detecting the distance along the sagittal plane between the two feet of the patient (3), so as to identify three conditions, of which a right foot condition forward, an aligned foot condition and a left foot condition forward, the motorised joints (10, 11, 12, 13) being configured to detect the distance along the sagittal plane between the two feet of the subject (3).