Wheelchair with independently adjustable wheels for slope stability
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Solution Overview
Problem
Electric Powered Wheelchairs (EPWs) face challenges in safety due to loss of traction and stability when encountering uneven terrain, steep slopes, and architectural barriers, leading to potential injuries or accidents, especially as the user base increases with the aging population and injured military personnel.
Innovation Solution
The wheelchair features a frame with independently controllable wheels and a control system that includes sensors and actuators to maintain seat orientation relative to gravity, allowing for self-leveling, curb climbing, and traction control, enabling safe navigation over various terrains and obstacles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional wheelchairs are used on uneven terrain and slopes, then basic mobility is maintained, but loss of traction and stability occurs leading to tipping and injury
Solution Approach 1:
The patent implements dynamically adjustable wheel parameters including variable diameter drive wheels that can expand or contract, and steerable rear castor wheels that can pivot independently. These dynamic adjustments allow the wheelchair to adapt to varying terrain conditions, maintaining stability and traction on slopes and uneven surfaces where traditional fixed-wheel designs would fail
Solution Approach 2:
The system continuously monitors terrain conditions and adjusts multiple parameters simultaneously: wheel diameter, wheel position, caster angle, and drive torque. These parameter changes enable the wheelchair to optimize its mechanical properties for different surface conditions, preventing loss of traction and maintaining reliable stability across diverse environments
2Adaptability or versatility
If wheelchairs encounter architectural barriers like curbs and steps, then mobility is blocked, but with proper design the wheelchair can safely traverse these obstacles
Solution Approach 1:
The adjustable caster wheels can pivot to steerable angles and the drive wheels can change diameter dynamically during obstacle approach and traversal. This dynamic reconfiguration allows the wheelchair to climb curbs and steps safely by adjusting its wheel geometry in real-time, converting the static tipping hazard into a controllable climbing operation
Solution Approach 2:
The system detects upcoming obstacles using sensors and performs preliminary adjustments to wheel parameters before contact is made. The wheelchair pre-positions its wheels and adjusts caster angles in advance of curb or step encounters, ensuring stable traversal and preventing tipping hazards before they can occur
3Reliability
If the wheelchair maintains independent wheel control for terrain adaptation, then stability and orientation are improved, but device complexity increases
Solution Approach 1:
The patent employs a multi-functional actuator system where a single integrated control mechanism manages multiple wheel parameters simultaneously. The actuators perform multiple functions including diameter adjustment, position control, and steering, reducing the need for separate dedicated mechanisms for each function and managing the inherent complexity through consolidation
Solution Approach 2:
The system incorporates sensors that continuously monitor seat orientation, wheel position, and terrain conditions, feeding this data back to the control system. This feedback loop enables automatic adjustments to maintain proper seat orientation relative to gravity, reducing the complexity of manual control and improving reliability through closed-loop control
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E
AI summary
A wheelchair includes a frame, a seat attached to the frame, a first forward wheel on a first side of the frame and a second forward wheel on a second side of the frame, a first rearward wheel on the first side of the frame and a second rearward wheel on the second side of the frame, a first drive wheel on the first side of the frame positioned intermediate between the first forward wheel and the first rearward wheel and a second drive wheel on the second side of the frame positioned intermediate between the second forward wheel and the second rearward wheel, and actuators to independently control the vertical position of the first forward wheel relative to the frame, the vertical position of the second forward wheel relative to the frame, the vertical position of the first rearward wheel relative to the frame, the vertical position of the second rearward wheel relative to the frame, the vertical position of the first drive wheel relative to the frame and the vertical position of the second drive wheel relative to the frame.