Walking Assistance Device Gait Control via Dynamics Model
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Solution Overview
Problem
Existing walking assistance devices face challenges in accurately controlling gait phases and balance for users with reduced muscular strength or joint issues, particularly due to difficulties in real-time acquisition of ground reaction force information and sensitivity to pressure changes.
Innovation Solution
A method involving a walking assistance device with a first frame, a second frame, and a joint, utilizing an angle sensor and inertial measurement unit to measure angles and velocities, updating a dynamics model, and determining forces and torque equivalents to control the device based on gait phases and balance, thereby adjusting the joint angle to assist the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ground reaction force sensors are used to accurately detect gait phases, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the ground reaction force measurement function from dedicated force sensors and implements it through calculation based on inertial measurement unit data and dynamics model. This removes the need for complex force sensing while maintaining the ability to determine gait phases accurately.
Solution Approach 2:
The patent replaces mechanical/physical force sensors with a computational approach using inertial measurement and dynamics modeling. The force equivalent is calculated through mathematical processing of acceleration data rather than direct physical measurement, simplifying the hardware system.
2Measurement precision
If pressure sensors are used to detect ground reaction forces, then measurement precision is improved, but sensitivity to pressure changes causes reliability deterioration
Solution Approach 1:
The patent removes pressure sensors from the system and extracts the necessary force information through calculation. By using inertial measurement unit data combined with dynamics model, the system avoids the reliability issues of pressure sensor sensitivity while maintaining accurate gait phase detection.
Solution Approach 2:
The patent implements a feedback mechanism where the dynamics model is continuously updated with inertial measurement data, and the calculated force equivalent feeds back into gait phase determination. This closed-loop approach improves reliability by using consistent data sources and mathematical relationships rather than sensitive physical sensors.
3Measurement precision
If real-time ground reaction force data is acquired, then gait phase determination accuracy is improved, but device complexity increases
Solution Approach 1:
The patent extracts the force measurement capability from direct sensing and achieves it through calculation. The inertial measurement unit data is processed through updated dynamics models to derive force equivalents, eliminating the need for complex real-time force data acquisition hardware.
Solution Approach 2:
The patent introduces dynamics model updating as an intermediary process between inertial measurement and gait phase determination. This mediator translates acceleration data into force information through mathematical relationships, avoiding direct force sensing complexity while maintaining accuracy.
Data Source
AI summary
A method for controlling an ankle-type walking assistance device may include measuring an angle of a joint of the walking assistance apparatus, calculating an angular velocity and a linear velocity of a frame of the walking assistance device using an inertial measurement unit (IMU) attached to the frame, generating a dynamics model for the walking assistance device based on the angle of the joint, the angular velocity and the linear velocity of the frame, calculating a disturbance applied to the walking assistance device based on the dynamics model, and controlling the walking assistance device based on the calculated force, equivalent, or wrench.