eBike Speed Estimation Using IMU Kinematics and Plausibility Checks
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Solution Overview
Problem
Existing methods for determining the speed of single-track vehicles like eBikes, which rely on pulse-based sensors, fail to accurately detect speed when sensors are faulty, and lack a reliable plausibility check for speed values.
Innovation Solution
A method utilizing acceleration and rotation rate sensors to measure vehicle accelerations in multiple directions and rotation rates around two axes, determining the driving situation, and calculating speed using kinematic equations, with a plausibility check comparing speed values from different sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pulse-based sensors are used to measure speed, then the device complexity is reduced and cost is lowered, but the reliability of speed determination deteriorates when sensors are faulty
Solution Approach 1:
The patent changes the measurement parameters from simple pulse counting to multi-axis acceleration and rotation rate measurements. By using an inertial measurement unit (IMU) that captures acceleration in three directions and rotation rates about two axes, the system obtains richer kinematic data that can be processed through equations of motion to determine speed, thereby improving reliability without excessive complexity increase
Solution Approach 2:
The patent introduces equations of motion as an intermediary computational layer between the raw sensor measurements and the final speed determination. This mathematical intermediary processes the acceleration and rotation rate data to derive speed values, enabling cross-validation and plausibility checks that enhance reliability while maintaining manageable system complexity
2Device complexity
If pulse-based sensors are used for speed measurement, then the device complexity is lowered, but the measurement precision deteriorates due to inability to detect faulty signals
Solution Approach 1:
The patent makes the inertial measurement unit serve multiple functions: it simultaneously measures acceleration in three directions and rotation rates about two axes. This multi-functional sensor platform provides redundant information that can be cross-checked for consistency, improving measurement precision by detecting and identifying faulty signals through plausibility checks of the kinematic relationships
Solution Approach 2:
The patent implements feedback through plausibility checks that continuously verify the consistency of measured accelerations and rotation rates against the equations of motion. When inconsistencies are detected, the system can identify potential sensor faults and adjust or reject problematic measurements, thereby maintaining high measurement precision
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
Enables accurate and cost-effective speed determination and plausibility checking, effectively detecting faulty speed signals and improving reliability in various driving conditions.
Implementation Method 1
measuring the acceleration of the vehicle in at least three directions using the acceleration sensor
Implementation Method 2
measuring a rotation rate of the vehicle about at least two rotation axes using the rotation rate sensor
Data Source
AI summary
A method for determining a speed value of a single-track vehicle, in particular an eBike, is disclosed. The vehicle has at least one acceleration sensor and one rotation rate sensor. The method includes (i) measuring the acceleration of the vehicle in at least three directions using the acceleration sensor, (ii) measuring a rotation rate of the vehicle about at least two rotation axes using the rotation rate sensor, (iii) determining a driving situation of the vehicle based on the measured accelerations and rotation rates of the vehicle, and (iv) determining the speed value of the vehicle using a system of equations describing the kinematics of the vehicle, the determined driving situation and the measured accelerations and rotation rates of the vehicle.