Speed Sensor Error Analysis for Electric Bicycles
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Solution Overview
Problem
Existing speed detection systems for two-wheelers, particularly electric bicycles, face issues with sluggish detection during slow movements, potential manipulation, and inability to determine direction of movement, along with challenges in accurately evaluating magnetic field sensor signals due to distance and wheel installation errors.
Innovation Solution
A method and analysis unit that uses a camera to record a side view of the two-wheeler, determining the attachment location of a magnetic sensor and evaluating magnetic field strength over time to detect errors such as incorrect sensor placement, wheel alignment, and magnet strength, generating error messages for necessary adjustments or replacements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic field sensor signals are used for speed detection, then non-contact distance and installation position measurement is achieved, but the detection becomes sluggish during slow movements and manipulation is easily possible
Solution Approach 1:
The system continuously monitors the magnetic field sensor signals and compares them against expected patterns. When anomalies are detected (such as signals that could result from manipulation or sluggish detection during slow movements), the system provides feedback to identify and correct these issues, ensuring reliable speed detection throughout the entire operating range
2Measurement precision
If magnetic field sensor signals are used for speed detection, then non-contact measurement is achieved, but the direction of movement cannot be determined
Solution Approach 1:
The system employs asymmetric evaluation of magnetic field sensor signals by analyzing the sequence and pattern of signal changes during wheel rotation. By evaluating the temporal pattern and direction of signal transitions, the system can distinguish between forward and reverse rotation, thereby determining the direction of movement while maintaining non-contact measurement capability
3Productivity
If magnetic field sensor signals are evaluated to determine wheel rotation, then speed information is obtained, but errors occur due to distance, wheel installation, and sensor placement
Solution Approach 1:
The system performs preliminary evaluation of magnetic field sensor signals to identify potential errors before they affect speed measurement accuracy. By analyzing signal characteristics in advance and detecting anomalies related to distance, wheel installation, or sensor placement, the system can correct these errors proactively, ensuring accurate speed detection throughout operation
Solution Approach 2:
The system replaces direct mechanical measurement of wheel rotation with non-contact magnetic field sensor evaluation. This substitution eliminates mechanical wear and contact issues while enabling more precise and reliable speed detection through magnetic field analysis, though it introduces the need for sophisticated signal evaluation to compensate for distance and installation variations
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
Enhances the accuracy and reliability of speed detection by identifying and correcting sensor placement, wheel alignment, and magnet strength issues, ensuring proper functioning of the speed detection system.
Implementation Method 1
a first magnetic field sensor (120) which is coupled directly or indirectly to the frame (180) of the two-wheeler (100)... the speed detection system requires a first magnetic sensor which is coupled directly or indirectly to the frame of the two-wheeler
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method, to a computer program, and to an analysis unit, by means of each of which an error analysis can be performed if one of the components used in a speed-sensing system of the type described at the beginning for a vehicle or a two-wheeled vehicle, in particular an electric bicycle, does not function properly. For the error analysis, an image of the bicycle in a side view is captured by means of a camera. By means of the image data, the distance between a magnetic field sensor and the wheel is determined, there being a magnet mounted on the wheel. If the distance between the wheel and the magnetic field sensor exceeds a certain distance, an error message is output. In addition, the magnetic field intensity can be sensed by means of a further magnetic field sensor during a complete revolution and can be compared with at least one threshold value.