Pedelec Speed Sensing with Trusted Backup Signals
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Solution Overview
Problem
Existing bicycle speed measurement systems, particularly in pedelecs, face issues with reliability due to disturbances in pulse-based sensors, leading to reduced rider assistance and comfort, especially when crossing bridges or near railway lines, and require a reliable alternative speed signal during sensor malfunctions.
Innovation Solution
A method and device that utilize multiple substitute speed signals, each with a confidence parameter, to determine bicycle speed, switching to the most reliable substitute signal during disturbances, and resuming primary signal use when interference ceases, ensuring high reliability and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If speed sensor systems are installed in pedal cycles, then speed information can be provided to external devices, but the cycle structure becomes more complex and expensive
Solution Approach 1:
The pedal cycle's existing drivetrain components (chainring, chain, rear wheel) serve dual purposes: their mechanical function for propulsion and as the speed sensing mechanism. The chainring teeth act as both drive elements and speed detection targets, eliminating the need for separate speed sensor hardware.
Solution Approach 2:
Existing drivetrain components are made multi-functional. The chainring serves both as a power transmission element and a speed measurement target. The rear wheel serves both as a propulsion component and a speed calculation reference, eliminating dedicated speed sensing hardware.
2Measurement precision
If speed sensors and additional components are added to measure speed, then speed measurement is possible, but the device becomes more expensive
Solution Approach 1:
The system uses the cycle's own existing components (chainring, chain, rear wheel) to perform speed measurement, eliminating the need for expensive dedicated speed sensor hardware while maintaining measurement capability.
Solution Approach 2:
Instead of using expensive physical speed sensors, the system uses optical copying/reading of existing chainring teeth patterns. The optical sensor reads the periodic pattern of teeth without requiring physical contact or specialized sensing hardware, reducing cost.
3Loss of information
If traditional speed sensor systems are used, then speed data can be obtained, but the system requires complex hardware installation
Solution Approach 1:
Existing drivetrain components serve dual purposes as both mechanical elements and speed measurement targets, eliminating the need for separate speed sensor installation while maintaining speed data acquisition capability.
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 speed measurement reliability, maintains rider comfort, and improves tolerance in sensor placement, while ensuring consistent assistance by using substitute signals with higher confidence parameters.
Implementation Method 1
an optical sensor which is arranged to detect a passage of the chainring teeth
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a method for ascertaining the speed of a pedal cycle, in particular a bicycle or tricycle in the form of a pedelec, the speed of the pedal cycle being ascertained on the basis of a primary signal which is provided by means of a primary signal device. Preferably, the primary signal is a pulsed signal which is generated by a reed contact or a magnetic field sensor and a magnet secured to a wheel. In the event of a disturbance of the primary signal, for example in the event of faulty pulses, the following steps are to be carried out: - providing at least two substitute signals for the speed of the pedal cycle, for example by means of an acceleration sensor, a cadence sensor, or a motor rotational speed sensor, - calculating a trust parameter for the at least two substitute signals, wherein the trust parameter represents the quality of each substitute signal with respect to the representation of the current speed of the pedal cycle, and - ascertaining the speed of the pedal cycle on the basis of the substitute signal with the higher trust parameter.