Steering Shaft Rotation Limiting for Emergency Personal Mobility Control
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Solution Overview
Problem
Personal mobility devices, such as electric kickboards and bicycles, can cause injuries during emergency situations due to rapid rotation around the steering axis, leading to collisions with the user's legs during sudden braking or tripping.
Innovation Solution
A steering limiting device is integrated into the personal mobility system, featuring a posture sensor and a controller that activates a magneto-rheological fluid or viscoelastic fluid mechanism to limit the rotation of the steering shaft when rapid changes in posture are detected, preventing excessive rotation and potential injuries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the steering shaft is allowed to rotate freely for normal operation, then the ease of operation is improved, but the reliability deteriorates in emergency situations due to rapid rotation causing injury
Solution Approach 1:
The steering limiting device dynamically changes the rotational characteristics of the steering shaft based on operating conditions. During normal operation, the steering shaft rotates freely for easy control. During emergency situations detected by the posture sensor, the device activates the MR fluid or viscoelastic fluid mechanism to limit rotation speed, thereby preventing injury while maintaining ease of operation under normal conditions.
Solution Approach 2:
The invention changes the physical parameters of the steering system by using magneto-rheological fluid or viscoelastic fluid whose viscosity or rigidity can be altered. When a magnetic field is applied to the MR fluid or when rapid rotation is detected, the fluid's properties change from fluid-like to solid-like, thereby limiting the rotation speed of the steering shaft and improving safety during emergencies.
2Reliability
If a steering limiting device is added to prevent injury, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The steering limiting device is nested within the existing steering shaft structure. The MR fluid or viscoelastic fluid is contained within the steering shaft housing, and the locking members are integrated into the shaft support portion. This nesting approach allows the safety function to be added without significantly increasing the overall device complexity or requiring a completely separate system.
Solution Approach 2:
The steering limiting device operates autonomously by detecting posture changes through the posture sensor and automatically activating the MR fluid or viscoelastic fluid mechanism. The system self-regulates the steering shaft rotation based on detected emergencies without requiring external intervention, thereby improving safety while minimizing the need for additional complex control systems.
3Speed
If magneto-rheological fluid is used to limit rotation, then the response speed is improved, but the use of energy increases due to magnetic field generation
Solution Approach 1:
The magnetic field generation for the MR fluid is activated periodically or event-driven rather than continuously. The controller activates the magnetic field only when emergency situations are detected by the posture sensor, allowing the MR fluid to change properties on demand. This periodic activation maintains fast response speed when needed while significantly reducing overall energy consumption compared to continuous magnetic field generation.
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
The system effectively limits steering shaft rotation in emergency situations, thereby reducing the risk of injury to the user by detecting rapid posture changes and applying a magnetic or viscoelastic response to restrict movement, ensuring safer operation.
Implementation Method 1
a magneto-rheological (MR) fluid accommodated in the fluid accommodating groove, and an excitation coil provided in the housing to selectively provide a magnetic field to the MR fluid according to the control signal of the controller. The MR fluid may change into a solid property to limit the rotation of the steering shaft when a current is applied to the excitation coil according to the control signal of the controller to generate the magnetic field.
Data Source
AI summary
A personal mobility and a control method thereof may include a main body, a steering shaft rotatably coupled to the main body, a steering limiting device configured to limit rotation of the steering shaft, a posture sensor provided to detect a change in posture of the main body, and a controller configured to selectively generate a control signal to control an operation of the steering limiting device to limit the rotation of the steering shaft when the controller determines that the posture of the main body changes at a speed exceeding a predetermined speed.