Pedal Sensor Cross-Validation for Electric Bicycle Drive Safety
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Solution Overview
Problem
Existing bicycle electric drive control systems using pedal torque and speed sensors are prone to errors due to mechanical load and environmental factors, leading to unsafe driving operations.
Innovation Solution
A method that compares pedal speed and torque sensor signals to validate each other, detecting sensor errors by linking both variables and generating an error signal if they differ, ensuring safe operation by determining the condition of the pedal sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If pedal sensors are used to detect torque and speed for controlling the electric drive, then the electric drive can be controlled based on rider power, but sensor errors due to mechanical load and environmental factors lead to unsafe driving operations
Solution Approach 1:
The system continuously monitors both torque and speed sensor signals and compares them against each other and against expected physical relationships. When a discrepancy is detected (such as non-zero torque with zero speed when the bicycle is moving, or inconsistent power calculations), the system generates feedback to trigger error handling procedures, thereby maintaining safety while preserving automatic control functionality.
2Measurement precision
If sensors are positioned on the crank or pedals for direct torque and speed detection, then accurate power measurement is achieved, but the sensors are exposed to high mechanical load and environmental effects causing high susceptibility to errors
Solution Approach 1:
The system performs preliminary validation checks on sensor readings before using them for control decisions. By anticipating potential sensor errors and checking for physically impossible conditions (such as torque without corresponding speed, or power values that exceed mechanical limits), the system prevents faulty sensor data from causing unsafe operations, thereby maintaining measurement precision while compensating for sensor vulnerability.
3Productivity
If sensor errors are not detected, then continuous operation is maintained, but incorrect activation of the electric drive can endanger the cyclist or his environment
Solution Approach 1:
The control system implements continuous feedback monitoring of sensor signals against physical constraints and expected operational patterns. When sensor errors are detected through this feedback mechanism, the system responds by disabling the electric drive or triggering warning signals, thereby preventing dangerous situations while maintaining continuous operation under normal conditions.
Data Source
Figure 1
AI summary
The invention relates to a method for detecting the state of pedal sensors of a bicycle with an electric drive. According to the invention, the rotational speed sensor signal is provided by means of a rotational speed sensor (22) of the pedal sensors, and a torque sensor signal is provided by means of a torque sensor (20) of the pedal sensors. A first pedal driving state is determined on the basis of the rotational speed sensor signal, and a second pedal driving state is provided on the basis of the torque sensor signal. The first pedal driving state is compared with the second pedal driving state and an error signal is provided if the first pedal driving state differs from the second pedal driving state. The invention furthermore relates to a control device designed to control an electric drive of an electric bicycle. The control device comprises pedal sensors which are designed to detect rotational speed and torque of a pedal drive. The control device comprises an evaluation circuit which has a threshold value comparator which compares the signals of the rotational speed sensor and of the torque sensor with a first and second threshold value, respectively, in order to detect a first and second pedal driving state, respectively. The evaluation circuit furthermore has an error detection circuit which is designed to compare the first pedal driving state with the second pedal driving state, and which provides an error signal when the states differ.