Single-Track Vehicle Sensor Plausibility Checking via Gear Ratios
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Solution Overview
Problem
Sensor malfunctions in eBikes can cause the propulsion assistance to remain activated beyond the maximum speed due to incorrect speed measurements, leading to potential safety issues and inefficiencies.
Innovation Solution
A method and device for checking the plausibility of sensor signals by estimating gear ratios between wheel speed and pedal cadence, using statistical parameters like variance and histograms to determine a reliability indicator, which is compared to a threshold to detect sensor malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor signals are used to determine speed for propulsion assistance control, then the eBike can provide motor assistance, but sensor malfunctions may cause incorrect speed measurements leading to safety issues
Solution Approach 1:
The system continuously monitors the gear ratio calculated from sensor signals (wheel speed and pedal cadence) and compares it against expected values. When the gear ratio deviates from expected ranges, it triggers a feedback mechanism to deactivate propulsion assistance, creating a closed-loop safety system that responds to sensor anomalies without requiring redundant sensors.
Solution Approach 2:
The gear ratio serves as an intermediary parameter that mediates between the raw sensor signals (wheel speed, pedal cadence) and the propulsion assistance control. By calculating the gear ratio as an intermediate value and checking its plausibility, the system can detect sensor malfunctions indirectly without needing additional direct speed sensors.
2Reliability
If gear ratio estimation is performed continuously to detect sensor faults, then sensor malfunction detection improves, but computational requirements increase
Solution Approach 1:
Instead of continuously performing complex sensor validation algorithms, the system performs partial action by calculating the gear ratio only when necessary (during propulsion assistance operation) and using simple statistical checks (variance, histogram) rather than comprehensive analysis. This selective partial validation reduces computational energy consumption while maintaining effective sensor monitoring.
Solution Approach 2:
The system changes the parameter being monitored from raw sensor values (wheel speed, pedal cadence) to the derived gear ratio parameter. This parameter transformation simplifies the detection logic, as the gear ratio naturally reflects the relationship between sensors and their expected mechanical connection, making fault detection more computationally efficient through simpler statistical comparisons.
3Reliability
If redundant sensors are added to verify speed measurements, then sensor reliability improves, but device complexity and cost increase
Solution Approach 1:
The system uses the existing sensor data (wheel speed and pedal cadence sensors already present in the eBike) to perform self-validation through gear ratio calculation. Rather than requiring external redundant sensors, the system makes the existing sensors serve dual purposes: both for normal propulsion control and for mutual verification through the gear ratio relationship, achieving self-service validation.
Solution Approach 2:
The gear ratio calculation serves multiple functions simultaneously: it provides the mechanical transmission ratio for control purposes and acts as a validation mechanism for sensor reliability. This multi-functionality allows the existing sensors to perform both their primary function and a secondary verification function, eliminating the need for dedicated redundant sensors.
Data Source
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AI summary
The invention relates to a method for verifying the plausibility of a sensor signal from a single-track vehicle, comprising the following steps: - Estimating gear ratios between the wheel rotation speed of a wheel and the pedaling frequency of a pedal unit and/or the drive speed of a drive of the single-track vehicle at several times, - Determining a value of a reliability indicator based on the estimated gear ratios, wherein the value of the reliability indicator is determined using a statistical parameter, in particular a variance, of the estimated gear ratios and/or a histogram of the estimated gear ratios, - Verifying the plausibility of the sensor signal by comparing the value of the reliability indicator with a threshold value, wherein the threshold value corresponds to a maximum permissible value of the reliability indicator.