Hip Joint Angle Trigger for Step Assist Device
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Solution Overview
Problem
Conventional step assist devices are limited in their ability to assist rehabilitation patients with injured legs, as they require the foot to touch the ground for weight-based actuator control, making it difficult for such patients to perform step movements effectively.
Innovation Solution
A step assist device that detects the hip joint angle and provides assistive forces based on a predetermined assistance plan, allowing for controlled step movements without the need for ground contact, using motors and sensors to adjust forces dynamically during the swinging and kicking phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If weight-based actuator control is used, then the control activation can be triggered by ground contact, but rehabilitation patients with injured legs cannot perform step movements effectively because their foot cannot appropriately touch the ground
Solution Approach 1:
The patent changes the trigger parameter from weight-based detection to hip joint angle detection. The hip joint angle sensor detects when the angle exceeds a predetermined threshold, which occurs during the natural swinging motion of the leg. This parameter change allows rehabilitation patients to perform step movements without needing to make appropriate ground contact, as the trigger is based on hip joint motion rather than foot weight bearing.
2Measurement precision
If weight-based control trigger is used, then the system can detect step initiation, but the activation condition is limited and requires foot ground contact
Solution Approach 1:
The patent replaces the mechanical weight-based detection system with an angular detection system using a hip joint angle sensor. Instead of measuring the force or weight applied during ground contact, the system measures the angular position of the hip joint. This substitution maintains precise detection of step initiation while eliminating the requirement for ground contact, thereby improving movement freedom during rehabilitation training.
Data Source
AI summary
When performing actuator control using weight on the bottom of the foot as a trigger, the foot of the user must appropriately touch the ground in order for the weight to be sensed. Therefore, the activation condition for starting the actuator control is limited and, for example, a rehabilitation patient who has one injured leg has difficulty training their step movement using this step assist device. Provided is a step assist device including a providing section that provides an assist force to a step movement of a user; a detecting section that detects a hip joint angle, which is an angle of aperture of a hip joint of the user; and a control section that begins controlling the providing section when the hip joint angle exceeds a predetermined threshold value, according to an assistance plan set in advance for the step movement of a single step of the user.