Electric Wheelchair Brake Torque Control for Agility
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Solution Overview
Problem
Conventional electric wheelchairs continue to coast after the user releases the hand rims, leading to reduced agility in confined spaces, as the auxiliary power is not effectively attenuated quickly enough.
Innovation Solution
Implementing a brake mode that applies a brake torque in the opposite direction of the wheel rotation when no torque is applied to the hand rim, using a control system with torque sensors and motors to quickly decelerate the wheel, thereby suppressing coasting and enhancing agility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If auxiliary power is quickly attenuated after user releases hand rims, then agility of electric wheelchair is improved, but coasting is not sufficiently suppressed
Solution Approach 1:
The control device applies brake torque in advance to counteract the coasting motion. When the user releases the hand rims, the control device detects the release and immediately applies brake torque to the wheel in the opposite direction of rotation, preventing the wheel from continuing to rotate due to inertia. This preliminary anti-action effectively suppresses coasting and improves agility in confined spaces.
Solution Approach 2:
The control device changes the torque parameter from auxiliary drive torque to brake torque based on the operational state. By detecting when the user releases the hand rims, the system transitions the motor torque from a positive value (assisting motion) to a negative value (braking), thereby controlling the wheel's deceleration and suppressing coasting behavior.
2Speed
If brake torque is applied to decelerate wheel rotation, then coasting is suppressed and agility is improved, but energy consumption increases
Solution Approach 1:
The brake torque is applied partially and temporarily only when needed - specifically when the user releases the hand rims and coasting occurs. The brake torque is not continuously applied but rather as a targeted intervention to suppress coasting. This partial action minimizes energy consumption while achieving the agility improvement in confined spaces.
Solution Approach 2:
The brake torque is applied periodically or intermittently based on the operational conditions. The control device continuously monitors the hand rim torque and applies brake torque only during the specific period when the user releases the hand rims and coasting is detected, rather than maintaining continuous braking. This periodic application reduces overall energy consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces coasting and increases the agility of the electric wheelchair by quickly decelerating the wheels when no torque is applied, allowing for more precise control and operation in limited spaces.
Implementation Method 1
a motor 15L, 15R and a control device 8. The control device 8 makes the motor 15L, 15R apply auxiliary power to the wheel 21L, 21R in accordance with a torque applied to a hand rim 13L, 13R. The control device 8 makes the motor 15L, 15R apply brake torque to the wheel 21L, 21R when no torque is applied to the hand rim 13L, 13R
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Comprised are a hand rim, a wheel rotated by receiving a torque applied to the hand rim, and a drive controller configured to apply auxiliary power in accordance with the torque applied to the hand rim to the wheel, the drive controller decelerates rotation of the wheel rotating in a state where no torque is applied to the hand rim, by performing a brake mode in which a brake torque acting in a direction reverse to a rotation direction of the wheel is applied to the wheel.