Dynamic Actuator Limiting Positions for Wheelchair Safety
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Solution Overview
Problem
Existing wheelchair control systems lack the ability to dynamically adjust movable parts based on current circumstances and the limiting positions of other parts, potentially compromising user safety and comfort.
Innovation Solution
A control system comprising a controller with a mathematical model of the kinematics of movable parts and actuators, allowing for dynamic alteration of limiting positions through input signals and electronic circuitry in actuators, enabling flexible and safe customization of settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If static end positions are set for actuators using micro switches, then the device complexity is reduced and ease of manufacture is improved, but the adaptability and user safety are compromised because the settings cannot be dynamically adjusted based on current circumstances
Solution Approach 1:
The patent applies dynamics by transitioning from static micro switch-based end position limits to dynamic software-controlled limiting positions. The controller dynamically adjusts the limiting positions of actuators based on real-time conditions such as wheelchair speed, current configuration of other movable parts, and safety parameters. This allows the system to adapt to varying operational circumstances while maintaining comprehensive control through the mathematical model of kinematics.
2Ease of operation
If the backrest is allowed to reach its maximal recline end position, then the comfort and adjustability are improved, but the user safety is compromised when driving at certain speeds due to excessive inclination
Solution Approach 1:
The patent applies parameter changes by dynamically modifying the limiting position parameter of the backrest actuator based on operational conditions. When the wheelchair is stationary or moving slowly, the backrest can reach its full recline position for maximum comfort. When the wheelchair exceeds a certain speed threshold, the controller automatically adjusts the limiting position parameter to prevent excessive inclination, thereby maintaining safety while preserving comfort capabilities when appropriate.
Solution Approach 2:
The system implements feedback by continuously monitoring the wheelchair's operating conditions (such as speed) and using this information to dynamically adjust the limiting positions of actuators. The controller receives feedback about the current state and modifies the backrest limiting position accordingly, creating a closed-loop control system that balances comfort and safety based on real-time conditions.
3Ease of operation
If the seat is moved forward to a new position, then the user comfort is improved for that particular setting, but the optimal end position of the backrest changes and the static micro switch setting becomes suboptimal
Solution Approach 1:
The patent applies dynamics by making the end position of the backrest actuator dynamically dependent on the position of the seat actuator. When the seat is moved forward, the controller automatically recalculates and adjusts the optimal limiting position of the backrest based on the mathematical model of kinematics. This ensures that the backrest and seat maintain proper coordination and relationship for optimal user comfort across all possible seat positions, rather than being fixed independently.
Data Source
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AI summary
The invention relates to a control system for controlling a wheelchair having movable parts. The control system comprises a controller and a number of actuators for effectuating movements of the movable parts. The controller comprises a mathematical model of the kinematics of the movable parts and their respective at least one actuator, means for receiving an input signal from one or more of the actuators, and means for setting, based on the mathematical model, limiting positions of the actuators in response to the determined input signal. The invention also relates to a corresponding wheelchair and method of controlling a wheelchair.