Steering Angle Sensor Using Magnetic Loop Counting
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Solution Overview
Problem
Existing steering angle sensors require multiple gears and sensors to accurately measure steering wheel angles beyond 360°, leading to increased production costs and potential errors when the power supply stops, as they fail to account for the actual angle of the steering wheel upon restart.
Innovation Solution
A sensor-based angle sensing system comprising a sensing unit, processing unit, and storage unit that determines the number of loops and relative angle of the steering wheel from a datum point, allowing for accurate angle calculation even after power interruption, using a single sensor and a keyway design on the steering column to limit rotation and prevent errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple gears and sensors are used to sense steering wheel angle beyond 360°, then the sensing range is improved, but the device complexity and production cost increase
Solution Approach 1:
The patent replaces the mechanical gear system with a magnetic field-based sensing system. A magnet is attached to the steering wheel and a magnetic sensor detects its position, eliminating the need for multiple gears and mechanical sensors. This substitution allows unlimited rotation sensing while reducing mechanical complexity.
Solution Approach 2:
The magnetic sensor serves multiple functions: detecting steering angle, determining rotation loops, and identifying position relative to datum point. This single sensor replaces what would traditionally require multiple specialized sensors and gear mechanisms, achieving versatility without proportionally increasing device complexity.
2Measurement precision
If multiple gears and sensors are used to accurately measure steering wheel angle, then measurement precision is improved, but production cost increases
Solution Approach 1:
The patent replaces expensive mechanical gear assemblies and multiple precision sensors with a simple magnet and single magnetic sensor. This substitution maintains measurement precision for angles beyond 360° while dramatically reducing production costs by eliminating complex mechanical components.
Solution Approach 2:
The patent uses inexpensive components (a simple magnet and single magnetic sensor) instead of expensive mechanical gear systems. The magnet is a low-cost component that can be easily attached to the steering wheel, making the overall system more cost-effective while achieving the required measurement precision.
3Use of energy by moving object
If the power supply stops, then energy consumption is reduced, but the ability to reflect actual steering wheel angle is lost
Solution Approach 1:
The patent establishes a datum point on the steering wheel before operation begins. This preliminary reference position allows the system to determine rotation loops and calculate actual steering angle after power restart, even though power was interrupted. The microcontroller counts magnetic sensor transitions to track rotations from this predetermined reference.
Solution Approach 2:
The patent introduces a magnet as an intermediary between the steering wheel and the magnetic sensor. This magnet retains its position on the steering wheel throughout power interruptions, serving as a persistent reference that allows the system to reconstruct the actual steering angle after restart without requiring continuous power.
4Ease of manufacture
If a single sensor is used instead of multiple sensors, then production cost is reduced, but measurement capability for angles beyond 360° is limited
Solution Approach 1:
The patent replaces multiple mechanical sensors with a single magnetic sensor that can detect the magnet's position regardless of rotation angle. This substitution enables the single sensor to measure angles beyond 360° by counting magnetic field transitions, achieving unlimited sensing range while maintaining low production cost.
Solution Approach 2:
The patent adds the dimension of time to the sensing measurement. Instead of relying solely on spatial position like traditional sensors, the magnetic sensor detects changes in the magnetic field over time as the steering wheel rotates. By counting these temporal transitions, the system calculates total rotation angle beyond 360° with a single sensor.
Data Source
AI summary
An angle sensing system for sensing a rotating angle of a steering wheel includes a sensing unit, a processing unit, and a storage unit. The sensing unit detects the rotating angle of a steering column connected to the steering wheel and outputting a sensing signal based on the rotating angle. When the steering column rotates for a circle, the sensing signal presents a non-continuous status. The processing unit calculates the relative angle in a single loop of the steering column based on the sensing signal and the number of loops according to the number of the non-continuous status. The storage unit stores the information of the relative angle and the number of loops. Based on the number of loops and the relative angle, the rotating angle of the steering wheel is detected.