Walking Assist Device Hip Differential Angle Control
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Solution Overview
Problem
Existing walking assist devices struggle to provide effective cyclic assistance to users with asymmetric disabilities, as they require complex parameter settings and accurate identification of healthy and disabled limbs to compute optimal assist forces, which is challenging due to non-cyclic motion patterns.
Innovation Solution
A walking assist device with a control unit that computes differential angles and phases between the user's hip joints, allowing for the computation of assist forces without requiring complex parameter settings, using differential angle computation, phase estimation, and oscillator phase synchronization to provide appropriate cyclic assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase estimation is performed using data from each joint measurement in users with asymmetric disabilities, then the device can provide assist force, but the phase estimation becomes inaccurate due to non-cyclic motion patterns of the disabled limb
Solution Approach 1:
The patent applies asymmetry by treating the healthy and disabled limbs differently in the phase estimation process. Instead of requiring symmetric cyclic motion from both limbs, the system uses the cyclic motion of the healthy limb as the primary reference and compensates for the asymmetric characteristics of the disabled limb through differential angle computation and phase adjustment mechanisms.
Solution Approach 2:
The patent introduces an intermediary approach by using the differential angle between the two limbs as a mediating parameter. Rather than directly measuring phase from the non-cyclic disabled limb, the system computes the difference between healthy and disabled limb angles, which preserves the cyclic characteristics needed for accurate phase estimation while accommodating the asymmetric disability.
2Measurement precision
If the device requires complex parameter settings and identification of healthy/disabled limbs to compute optimal assist force, then assist force accuracy improves, but device complexity and ease of operation deteriorate
Solution Approach 1:
The patent implements self-service by enabling the system to automatically identify and adapt to the user's asymmetric disability without requiring manual configuration. The control unit automatically detects which limb is healthy and which is disabled through the measurement data, and automatically adjusts the phase estimation parameters accordingly, eliminating the need for complex manual parameter setting.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the phase estimation parameters based on the detected asymmetric conditions. The system modifies the reference phase and differential angle computations adaptively according to the user's specific disability pattern, maintaining accuracy without requiring fixed complex parameters to be pre-configured.
3Ease of operation
If assist force is applied based on inaccurate phase estimation from disabled limb motion, then the device can operate, but the assist force does not match the user's motion and may destabilize gait
Solution Approach 1:
The patent implements feedback by continuously monitoring the actual motion of both limbs and comparing it with the estimated phase from the healthy limb. The system uses this feedback to adjust the assist force timing and magnitude in real-time, ensuring that the assistance remains synchronized with the user's actual gait pattern and maintains stability even in the presence of asymmetric disabilities.
Data Source
AI summary
Provided is a walking assist device including a main frame configured to be worn by a user, a power unit mounted on the main frame, a pair of power transmission members for transmitting assist force provided by the power unit to femoral parts of the user and a control unit for controlling an operation of the power unit, wherein the control unit comprises a differential angle computation unit for computing a differential angle between angular positions of the femoral parts of the user about respective hip joints of the user; a differential angle phase computation unit for computing a differential angle phase according to the differential angle; and an assist force computation unit for computing an assist force to be applied to the user according to the differential angle phase.