Steering Angle Sensor Bracket Layout Resistant to Vertical Wheel Motion
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Solution Overview
Problem
Existing steering angle measurement systems in vehicles, particularly in autonomous vehicles, face challenges in accurately measuring the steering angle without being affected by vertical motion of the wheel assembly, as they often rely on physical shafts that may not be present in all wheel assemblies, leading to potential measurement errors and issues like 'bump steer'.
Innovation Solution
The proposed solution involves an apparatus comprising a reference bracket, a rotating bracket, and an angle sensor, where the measurement ends of both brackets are rotatably coupled about a rotation coupling point, ensuring the angle sensor remains aligned with the steering axis during vertical motion. This configuration includes the mounting end of the rotating bracket with the suspended wheel mount and the mounting end of the reference bracket with the suspension arm, maintaining a fixed spatial relationship with the steering axis, thus preventing measurement errors from vertical motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If physical shafts are used for mounting angle sensors in wheel assemblies, then the sensor mounting is simplified, but measurement errors occur due to absence of shafts in some wheel assemblies and bump steer effects
Solution Approach 1:
The patent introduces a virtual reference point (intersection of steering axis and rotation axis) as an intermediary element. Instead of directly mounting the sensor on physical shafts that may not exist, the system uses this virtual point to define the orientation of the reference bracket, enabling accurate measurement without requiring physical shafts for mounting.
Solution Approach 2:
The patent transitions from relying on one-dimensional physical shafts to using a three-dimensional geometric construction. By defining the reference bracket's orientation through the intersection point of two axes (steering axis and rotation axis) in 3D space, the system eliminates the need for physical mounting shafts while maintaining measurement accuracy.
2Ease of operation
If angle sensors are mounted on physical shafts in wheel assemblies, then installation is simplified, but the sensors become susceptible to vertical motion effects and bump steer
Solution Approach 1:
The virtual reference point (intersection of steering axis and rotation axis) serves as an intermediary that decouples the sensor mounting from the physical shafts. The reference bracket is oriented relative to this virtual point rather than physical shafts, making the measurement system immune to vertical motion and bump steer effects while keeping installation straightforward.
Solution Approach 2:
The patent extracts the reference for sensor orientation from the physical shafts themselves and relocates it to a virtual reference point defined by the intersection of the steering axis and rotation axis. This separation allows the sensor to be mounted on existing structural elements while maintaining measurement stability independent of vertical motion.
3Ease of manufacture
If the reference bracket is not properly aligned with the steering axis during vertical motion, then manufacturing is simpler, but measurement errors occur due to misalignment
Solution Approach 1:
The patent uses three-dimensional geometric relationships to define the reference bracket's orientation. By specifying that the reference bracket be perpendicular to the steering axis at the intersection point with the rotation axis, the system creates a unique orientation in 3D space that remains consistent during vertical motion, eliminating alignment errors without complicating manufacturing.
Solution Approach 2:
The reference bracket is pre-oriented during manufacturing to be perpendicular to the steering axis at the defined intersection point. This preliminary alignment ensures that the bracket maintains correct orientation during subsequent vertical motion of the wheel assembly, preventing measurement errors without requiring complex adjustment mechanisms.
Data Source
AI summary
An apparatus for measuring the steering angle of a wheel assembly including a suspended wheel mount and at least one suspension arm, the apparatus including a reference bracket, a rotating bracket and an angle sensor, the reference bracket and the rotating bracket each respectively including a measurement end and a mounting end, wherein the measurement ends of the reference and rotating brackets are rotatably coupled about a rotation coupling point such that the brackets can rotate with respect to one another, wherein the mounting end of the rotating bracket is coupled with the suspended wheel mount and the mounting end of the reference bracket is coupled with the suspension arm, and wherein the mounting end of the reference bracket is positioned on a plane defined by a steering axis of the suspend-wheel mount and a rotation axis between the suspension arm and the suspended wheel mount.