Electric Bicycle Wheel Circumference Auto-Calibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining the wheel circumference of a drive wheel in electric bicycles require manual measurement or pre-programmed values, leading to inaccuracies in speed calculation and performance when tire changes occur, especially when converting from street tires to studded tires.
Innovation Solution
A method that automatically determines the wheel circumference by detecting the rotational speed and acceleration profile over a predetermined period, using an acceleration sensor calibrated when the vehicle is stationary, and calculating the distance traveled to accurately determine the wheel circumference, which is then used to adjust the drive motor control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wheel circumference is manually measured or pre-programmed, then the speedometer functions can operate, but inaccuracies occur when tire changes are made
Solution Approach 1:
The system automatically determines the wheel circumference by utilizing data from existing sensors (rotational speed sensor and acceleration sensor) without requiring manual measurement or external intervention. The control unit calculates the wheel circumference based on the relationship between rotational speed, acceleration, and distance traveled, enabling the system to self-adjust when tires are changed.
Solution Approach 2:
The system dynamically changes the wheel circumference parameter based on actual operating conditions. By continuously monitoring rotational speed and acceleration, the control unit calculates and updates the wheel circumference parameter to reflect actual tire conditions, whether street tires or studded tires are installed.
2Device complexity
If the wheel circumference is fixed in the control unit, then the system is simple, but speed calculation becomes inaccurate after tire conversion
Solution Approach 1:
The control unit performs multiple functions using existing components. The rotational speed sensor and acceleration sensor, originally designed for other purposes, are also used to determine wheel circumference. This multi-functional approach avoids adding dedicated measurement devices while maintaining accuracy.
Solution Approach 2:
The system uses feedback from rotational speed and acceleration sensors to continuously monitor and calculate the actual wheel circumference. This feedback mechanism allows the control unit to detect changes in tire circumference and adjust speed calculations accordingly, maintaining accuracy without complex manual programming.
3Ease of manufacture
If manual programming of wheel circumference is required, then initial setup is simple, but adjustment effort increases when changing tires
Solution Approach 1:
The system automatically determines the wheel circumference by utilizing data from existing sensors (rotational speed sensor and acceleration sensor) without requiring manual measurement or external intervention. The control unit calculates the wheel circumference based on the relationship between rotational speed, acceleration, and distance traveled, enabling the system to self-adjust when tires are changed.
Solution Approach 2:
The system performs preliminary determination of wheel circumference using existing sensor data before any manual intervention is needed. By continuously monitoring rotational speed and acceleration during normal operation, the system proactively identifies and calculates the actual wheel circumference, eliminating the need for post-tire-change programming.
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 method ensures accurate speedometer functions and motor performance by automatically adjusting for changes in tire circumference, eliminating the need for manual programming and reducing errors in wheel circumference settings.
Implementation Method 1
an acceleration of a vehicle in a longitudinal direction of the vehicle by means of an acceleration sensor
Implementation Method 2
a speed of a drive wheel of the vehicle by means of a speed sensor
Implementation Method 3
determine the distance traveled by the vehicle during the period of time as a function of the acceleration detected
Implementation Method 4
determine a wheel circumference of the drive wheel of the vehicle as a function of the detected rotational speed and the determined route
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
Method for determining the circumference (U) of a drive wheel (160) of a vehicle (100), wherein the following steps are performed during a specified time interval (t): recording (210) a rotational speed (n) of the drive wheel (160) and recording (220) an acceleration (a) of the vehicle (100) in the direction of the longitudinal axis (170) of the vehicle (100). Subsequently, a distance (s) traveled by the vehicle (100) is determined (240) as a function of the acceleration (a) recorded during the time interval (t), and then the following step is performed: determination (250) of the circumference (U) of the drive wheel (160) as a function of the recorded rotational speed (n) and the determined distance traveled (s).