Wearable Robot Sitting Stability via Distance Tolerance Control
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Solution Overview
Problem
Wearable robots for paraplegic patients face instability during sitting motions due to varying object heights, lacking a method to accurately detect objects behind the robot and maintain balance for safe sitting.
Innovation Solution
A lower body supporting robot system with a distance calculator, including sensors and a controller, calculates vertical distances to objects and the ground, determining a tolerance distance to adjust the robot's joints and links for stable sitting, using a drive device to adjust angles and positions for secure seating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the robot performs a predetermined sitting motion, then the control operation is simple, but the sitting stability deteriorates when object height varies
Solution Approach 1:
The system performs preliminary detection of the object behind the robot using a distance sensor before executing the sitting motion. The controller calculates the distance between the robot and the object, and determines the appropriate sitting depth in advance, ensuring stable sitting while maintaining simple control operation.
2Stability of the object's composition
If the robot automatically controls sitting based on detected object distance, then sitting stability improves, but the device complexity increases
Solution Approach 1:
The system uses a distance sensor to detect the object behind the robot and provides feedback to the controller. The controller calculates the distance and automatically adjusts the sitting depth based on this feedback, achieving stable sitting with relatively simple control logic.
3Device complexity
If the robot measures distance to ground surface only, then the measurement system is simple, but the sitting control accuracy deteriorates
Solution Approach 1:
The system introduces an intermediary calculation process where the controller computes the distance between the robot and the object based on the measured distance to the ground surface and the object's position. This intermediary step improves sitting control accuracy without requiring additional complex measurement hardware.
Data Source
AI summary
A lower body supporting robot system includes a lower body mechanism being worn on a user's lower body, the lower body mechanism including a plurality of joints and links and a drive device, a distance calculator for measuring a first distance that is a vertical distance to an object located therebelow and a second distance that is a vertical distance to a ground surface, a memory for storing a limit distance that is a vertical distance between the distance calculator and the ground surface when the lower body mechanism is in a lowest sitting posture, and a controller for calculating a tolerance distance that is a difference between the second distance and the limit distance, comparing the first distance with the tolerance distance, and controlling the drive device so that the distance calculator moves by the first distance when the first distance is less than the tolerance distance.