Wheelchair Control System Using Touchpad and Accelerometer
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Solution Overview
Problem
Existing wheelchair control systems lack efficient and precise control mechanisms for navigating corners and maintaining stability, particularly in electric wheelchairs powered by two motors, as they rely on mechanical adjustments that are not adaptable to electronic variations in wheel speed.
Innovation Solution
A wheelchair control system incorporating a microcontroller, power drive electronics, a power supply, and an input device such as a touch screen or accelerometer, which calculates velocity commands and adjusts motor speeds differentially to enable smooth turning and stability monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If mechanical adjustments are used for wheel speed control, then the control mechanism is simple, but the adaptability to electronic variations in wheel speed is poor
Solution Approach 1:
The patent replaces mechanical adjustment mechanisms with an electronic control system. A microcontroller receives input from a touchpad and generates pulse width modulation (PWM) signals to control the speed of each motor independently. This electronic substitution enables precise adaptation to varying wheel speed requirements while maintaining a relatively simple overall system architecture.
Solution Approach 2:
The system changes the control parameter from mechanical position adjustment to electronic pulse width modulation duty cycle. By varying the PWM duty cycle, the microcontroller can precisely control motor speed electronically, providing adaptability to different wheel speed variations without mechanical complexity.
2Measurement precision
If independent motor control is implemented for precise turning, then the turning precision is improved, but the control system complexity increases
Solution Approach 1:
The control system is segmented into independent control channels for each motor. The microcontroller independently controls the left and right motors based on touchpad input, allowing precise differential steering. This segmentation enables precise turning control while keeping each control channel relatively simple.
Solution Approach 2:
The microcontroller acts as an intermediary between the touchpad input and the motor control. It processes the touchpad signals and generates appropriate PWM outputs for each motor, enabling precise turning control through software algorithms without requiring complex hardware control circuits.
3Measurement precision
If electronic control with microcontroller is used, then the control precision and adaptability are improved, but the device complexity and cost increase
Solution Approach 1:
The microcontroller serves multiple functions: reading touchpad input, calculating differential motor speeds, generating PWM signals, and potentially implementing safety features. This multi-functionality consolidates what could be multiple separate control components into a single device, improving control precision while limiting the increase in overall system complexity.
Data Source
AI summary
A method and apparatus for wheelchair control. The position and distance of a touch point on a touch pad is used to set speed and wheel differential control. The two major wheels of the wheelchair are controlled according to these set quantities. Exceeding either of two horizontal accelerations measured by an accelerometer limits the set speed. Wheelchair control is shut down upon exceeding a vertical acceleration limit.