Wearable Robot Control Unit for Stair Climbing Load Reduction
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Solution Overview
Problem
Wearable robots impose a greater load on users when walking up stairs due to existing control methods that are not effectively adaptable to varying terrain, leading to reduced usefulness and efficiency.
Innovation Solution
A method and system that utilize joint angle and torque sensors to differentiate between flat walking and stair climbing, adjusting the operation mode and applying appropriate torque to reduce the load on the user by setting the knee joint angle to 0° using a cosine function, thereby optimizing control and reducing user burden.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing control methods are used for wearable robots, then the robot can operate during typical walking, but the load on the wearer increases significantly when ascending stairs
Solution Approach 1:
The control method dynamically adjusts the robot's operation mode based on real-time detection of walking terrain. The system transitions between flat walking mode and stair climbing mode by monitoring knee joint angle and torque values, allowing the robot to adapt its control strategy to the current terrain conditions. This dynamic adaptation enables the robot to maintain appropriate support torque during stair climbing, reducing the load on the wearer's legs while preserving natural walking capability on flat surfaces.
Solution Approach 2:
The system changes control parameters (operation mode, support torque) based on detected terrain conditions. When stair climbing is detected through knee joint angle and torque thresholds, the system switches to a different control parameter set optimized for stair climbing, providing enhanced support torque to reduce the wearer's load. This parameter adaptation resolves the contradiction by tailoring the robot's mechanical assistance to the specific walking condition.
2Force
If the robot provides support torque during stair climbing, then the load on the wearer is reduced, but the complexity of the control system increases
Solution Approach 1:
The control system continuously monitors knee joint angle and torque as feedback signals to determine the current operation mode. This feedback mechanism allows the system to automatically adjust support torque without requiring complex manual intervention or multiple sensors. The feedback from existing joint sensors is sufficient to trigger mode transitions, simplifying the overall control architecture while maintaining effective torque support during stair climbing.
Solution Approach 2:
The robot uses its own existing joint angle and torque sensors to detect terrain conditions and autonomously determine when to provide enhanced support torque. This self-service capability eliminates the need for external terrain detection systems or complex control algorithms, allowing the robot to self-regulate its support torque based on real-time joint state feedback, thereby reducing control system complexity.
3Productivity
If the robot is designed to assist during stair climbing, then the wearer's walking performance improves, but the robot's response time to terrain changes increases
Solution Approach 1:
The system continuously monitors knee joint angle and torque values, preparing to transition to stair climbing mode as soon as threshold conditions are met. This continuous preparation eliminates detection delays, allowing the robot to respond immediately when stair climbing begins. The preliminary monitoring of joint parameters ensures that the robot is ready to adjust support torque without waiting for explicit terrain confirmation, thus minimizing response time while maintaining high walking performance.
Data Source
AI summary
A method for controlling a wearable robot includes deducing a knee joint angle value of a robot using a joint angle sensor in a control unit, comparing the deduced knee joint angle value with a reference knee joint angle value previously stored in the control unit, deducing a thigh angle value using a thigh angle sensor in the control unit when the deduced knee joint angle value exceeds the reference knee joint angle value, comparing the deduced thigh angle value with a reference thigh angle value previously stored in the control unit, and setting an operation mode of the robot to a lift-up mode in the control unit when the thigh angle value exceeds the reference thigh angle value.