Electric Vehicle Rotation Center Control for Tight Cornering
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Solution Overview
Problem
Conventional omni-directional electric wheelchairs face difficulties in navigating corners smoothly, leading to complex turning orbits and user discomfort, especially in tight spaces like corridors or intersections.
Innovation Solution
The electric wheelchair employs a mode-switching mechanism that allows for independent control of wheel rotation and translation, using a joystick to generate target speeds and rotation centers, enabling easier cornering by adjusting the rotation center position based on speed thresholds and operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rotation center is set at the user's head position, then the user feels comfortable when rotating, but the turning orbit becomes complicated making it difficult to turn corners
Solution Approach 1:
The patent applies dynamics by making the rotation center position changeable rather than fixed. The control unit dynamically adjusts the rotation center position based on operation mode and speed thresholds, allowing the system to adapt between two positions: one optimized for user comfort during rotation and another optimized for cornering maneuvers.
Solution Approach 2:
The patent changes the parameter of rotation center position based on operating conditions. By switching between different rotation center positions according to speed thresholds and operation modes, the system optimizes performance for different maneuvers without requiring mechanical changes.
2Device complexity
If the rotation center position is fixed, then the control system is simple, but the vehicle cannot easily navigate corners in tight spaces
Solution Approach 1:
The control system dynamically adjusts the rotation center position based on speed thresholds and operation modes. This allows the system to maintain simplicity in structure while achieving complex maneuvering capabilities through software-based parameter adjustment.
Solution Approach 2:
The single control system serves multiple functions by implementing different rotation center positions for different operation modes. The same control unit handles both comfortable rotation (first position) and easy cornering (second position) without requiring separate control mechanisms.
3Ease of operation
If the vehicle rotates about the user's head, then the user experiences natural rotation sensation, but the turning radius becomes too large for tight corridors
Solution Approach 1:
The patent changes the rotation center position parameter based on speed thresholds. When speed exceeds the threshold (indicating a need for tighter turning), the system switches to the second rotation center position that provides a smaller turning radius, enabling navigation through tight corridors while maintaining natural rotation sensation when appropriate.
Data Source
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AI summary
An omni-directional electric vehicle (11) includes: a body (12) having a chair portion (23); an operation detection unit (13) which detects an operation direction and an operation amount of an operation input; a travel control information generation unit (14) which generates, based on the operation direction and the operation amount, travel control information including (i) a target straight-movement speed for moving the body (12) in a forward/backward direction and (ii) a target rotation speed for rotating the body (12) about a rotation center; and a control unit (15) which drives a movement mechanism of the body (12) according to the travel control information. The travel control information generation unit (14) changes, based on the target straight-movement speed, the rotation center for the target rotation speed from a reference position which is set virtually and fixedly to the body (12) in the forward/backward direction.