Brushless Vernier Motor Steering Wheel Feedback
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Solution Overview
Problem
Steering by wire systems lack effective haptic feedback to drivers, as they do not provide direct mechanical connection between the steering wheel and road wheels, making it difficult to convey road conditions such as stone or icy surfaces to the driver.
Innovation Solution
A handwheel actuator assembly using a brushless permanent magnet Vernier motor with a radial or axial configuration, where the rotor is directly or indirectly connected to the steering wheel hub, providing a 1:1 gear ratio and allowing for torque feedback to the driver through an electric motor, which can simulate road conditions by applying torque to the steering wheel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a steer by wire system is used to eliminate the direct mechanical connection between steering wheel and road wheels, then the complexity of the mechanical linkage is reduced, but the driver loses haptic feedback about road conditions
Solution Approach 1:
The patent implements a feedback mechanism where a torque sensor detects the steering torque applied by the driver, and this information is fed back to the control system which adjusts the motor torque accordingly. This closed-loop feedback system recreates the haptic feedback that would normally be provided through direct mechanical connection, allowing the driver to feel road conditions through the steering wheel while maintaining the benefits of steer-by-wire architecture
Solution Approach 2:
The patent introduces an intermediary control system that mediates between the driver's steering input and the motor's steering output. This intermediary system includes a torque sensor, control unit, and motor that work together to translate the driver's mechanical input into electrical control signals, which then drive the motor to provide both the steering action and the haptic feedback, effectively replacing the direct mechanical linkage with an intelligent intermediary system
2Loss of information
If feedback torque is applied through an electric motor in steer by wire system, then haptic feedback is provided to the driver, but the motor must be precisely controlled to accurately simulate road conditions
Solution Approach 1:
The control system uses feedback from the torque sensor to continuously monitor the driver's steering input and adjusts the motor torque in real-time to match the desired haptic feedback characteristics. This feedback control mechanism simplifies the overall control strategy by using the driver's own input as the reference signal, reducing the need for complex lookup tables or sophisticated control algorithms
Solution Approach 2:
The system uses the driver's own steering torque input as the primary signal for generating the feedback torque. By measuring the driver's input torque and using this same signal (after appropriate processing) to drive the feedback motor, the system essentially uses the driver's action to service its own feedback requirement, reducing the need for additional sensors or complex control logic
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 solution effectively provides haptic feedback to the driver by simulating road conditions, enhancing the user experience and safety by conveying road surface information through torque applied to the steering wheel, even in the absence of a direct mechanical connection.
Implementation Method 1
a feedback torque generator comprising an electric motor which has a stator and a rotor... the motor comprises a brushless permanent magnet Vernier motor
Implementation Method 2
permanent magnet Vernier motor... the rotor has a larger diameter than the stator... The rotor and stator share a common axis of rotation and face each other across a circumferential air gap
Data Source
AI summary
A handwheel actuator assembly 600 for a steer by wire steering system of a vehicle is disclosed. The assembly 600 comprises a steering wheel 601 and a feedback torque generator. The steering wheel 601 has at least one hand grip portion rotatable around an axis of rotation of the steering wheel 601 which can be gripped by a driver and a hub 602 that supports the hand grip portion. The feedback torque generator comprises an electric motor which has a stator 609 and a rotor 610. The rotor 610 is directly or indirectly fixed to and rotates with the hub of the steering wheel 601 and the stator 609 is secured to a fixed part of the vehicle body such that it cannot rotate relative to the vehicle body. The motor comprises a brushless permanent magnet Vernier motor.