Magnetic Encoder Direction Detection via Phase-Shifted Signal Gradient
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wheel speed sensors face challenges in determining the relative movement direction of an encoder object with sufficient resolution and speed, particularly in autonomous driving applications where higher resolution is necessary for tasks like autonomous parking.
Innovation Solution
The apparatus employs a magnetic field sensor and processing circuit to generate two phase-shifted sensor signals based on the magnetic field, calculating an angle using the arctangent of their quotient, and determining the movement direction by analyzing the gradient of this angle between a switch-on time and threshold values, allowing for immediate output of the movement direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional wheel speed sensors are used to detect relative movement direction, then basic speed detection is achieved, but measurement precision and response speed are insufficient for autonomous driving applications
Solution Approach 1:
The system pre-calculates threshold value angles and prepares the angle calculation framework before actual movement detection begins. By having the arctangent calculation and threshold comparison ready in advance, the system eliminates computation delays during critical movement detection moments, achieving both high precision and fast response required for autonomous parking applications
2Measurement precision
If higher resolution is implemented to enable autonomous parking applications, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system achieves higher resolution by changing the measurement parameters - specifically by calculating the angle using arctangent of the quotient of two sensor signals and comparing it against threshold value angles. This parameter-based approach enables autonomous parking resolution requirements without adding complex hardware, maintaining simplicity while achieving the needed measurement precision
3Measurement precision
If the angle is calculated continuously to determine movement direction, then measurement precision is improved, but use of energy increases
Solution Approach 1:
Instead of continuous angle calculation, the system performs angle calculation and threshold comparison only periodically or event-driven - specifically when the calculated angle reaches a threshold value angle. This periodic action maintains measurement precision by capturing all directional changes while dramatically reducing computational energy consumption compared to continuous calculation
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
This approach enables rapid and accurate determination of the movement direction, even under noisy conditions, by generating a pulse in the output signal when the angle reaches a threshold, effectively addressing the need for higher resolution in autonomous driving applications.
Implementation Method 1
a magnetic field sensor (14) which is designed in order to generate two sensor signals based on a magnetic field
Data Source
AI summary
An apparatus, for determining a relative direction of a movement of an encoder object depending on a magnetic field which is generated or influenced by the encoder object. A magnetic field sensor generates two sensor signals based on the magnetic field, that indicate a profile of the magnetic field in the event of a relative movement between the encoder object and the magnetic field sensor, that fluctuate around a mean value and are phase-shifted 90° to one another. The processing circuit calculates an angle based on the two sensor signals, and determines the relative direction of the movement of the encoder object based on a gradient of the angle between a switch-on time of the apparatus and a threshold value angle which is reached thereafter or based on a gradient of the angle between the situation of two successive threshold value angles being reached.