Electric Wheelchair Dynamic Obstacle Avoidance Control
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Solution Overview
Problem
Conventional electric vehicles, such as wheelchairs and power-assisted carts, face challenges in safely navigating around obstacles, particularly when the operator is unfamiliar with the vehicle's operation, leading to potential collisions due to erroneous maneuvers or insufficient virtual repulsive forces when passing between closely spaced obstacles.
Innovation Solution
The electric vehicle incorporates an omnidirectional design with obstacle sensors, a control system that calculates a virtual repulsive force inversely proportional to the obstacle's distance, and a resultant force calculation to automatically adjust the vehicle's path to avoid obstacles, ensuring safe passage between obstacles without limiting the virtual repulsive force, even when the operating force exceeds a predetermined level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the virtual repulsive force is increased to improve obstacle avoidance, then the obstacle avoidance capability is improved, but the vehicle cannot pass between closely spaced obstacles
Solution Approach 1:
The virtual repulsive force is made dynamic by adjusting its magnitude based on the operating force detected by the operating force detection section. When the operating force exceeds a predetermined threshold, the magnitude of the virtual repulsive force is reduced, allowing the vehicle to pass between closely spaced obstacles while still maintaining obstacle avoidance capability when the operating force is within normal ranges.
Solution Approach 2:
The magnitude of the virtual repulsive force is changed as a parameter based on the detected operating force. The control section adjusts the force magnitude dynamically: when operating force is low, full virtual repulsive force is applied for strong obstacle avoidance; when operating force exceeds the threshold, the virtual repulsive force magnitude is reduced to enable passage between obstacles.
2Ease of operation
If the virtual repulsive force is limited to allow passage between obstacles, then the passage capability is improved, but the obstacle avoidance capability is reduced
Solution Approach 1:
The system dynamically adjusts the virtual repulsive force based on real-time detection of operating force. The control section continuously monitors the operating force and adjusts the force magnitude accordingly, ensuring that obstacle avoidance capability is maintained when needed while allowing passage when the operator intends to move between obstacles.
Solution Approach 2:
The operating force detection section provides feedback to the control section about the magnitude of force applied by the operator. The control section uses this feedback to adjust the virtual repulsive force magnitude, creating a closed-loop control system that balances obstacle avoidance and passage capability based on operator intent.
3Ease of operation
If the operating force threshold is set low to allow easier passage, then the passage capability is improved, but the obstacle avoidance is compromised
Solution Approach 1:
The predetermined threshold value for the operating force is set to an appropriate level that balances passage capability and obstacle avoidance. This threshold parameter is carefully chosen so that normal operating forces remain above the threshold (maintaining obstacle avoidance), while exceptional forces needed for passage between obstacles can exceed it when necessary.
Data Source
Figure 1A~1B
Figure 1C
Figure 2
AI summary
An electric wheelchair (11) includes a body portion (12), an operating section (13) to detect an operation by an operator, an obstacle sensor (14) to detect an obstacle existing in the vicinity of the body portion (12), an obstacle determination section (15) to form a search region (21) extending from the body portion (12) in an operating direction, and to determine an obstacle existing in the search region (21), as the obstacle to be avoided, a virtual repulsive force calculation section (16) to calculate a virtual repulsive force to move the body portion away from the obstacle determined by the obstacle determination section, a resultant force calculation section (17) to calculate a resultant force composed of an operating force and the virtual repulsive force, and a control section (18) to control a movement of the body portion so that the body portion is moved in a direction of the resultant force.