E-Bike Speed Estimation Using Inertial Sensors and Kinematics
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Solution Overview
Problem
Existing methods for determining the speed of single-track vehicles, such as eBikes, rely on pulse-based sensors which can be defective or malfunctioning, leading to incorrect speed calculations, and lack a reliable alternative for plausibility checking.
Innovation Solution
A method utilizing acceleration and rotation rate sensors to measure vehicle accelerations in multiple directions and rotation rates around axes, determining the driving situation, and calculating speed through kinematic equations, with a plausibility check using additional speed sensors and reliability indicators like Kalman filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pulse-based sensors are used to measure speed, then speed measurement is simple and cost-effective, but the sensors can be defective or malfunctioning leading to incorrect speed calculations
Solution Approach 1:
The patent changes the measurement parameters from pulse-based wheel rotation detection to acceleration and rotation rate measurements using inertial sensors. This allows speed determination through kinematic equations rather than direct pulse counting, providing an alternative measurement approach that is both cost-effective and reliable for verifying pulse sensor accuracy
Solution Approach 2:
The patent implements a feedback mechanism where the speed determined from acceleration and rotation rate measurements is used to verify the plausibility of speed values from pulse-based sensors. This cross-verification provides reliability checking while maintaining the simplicity of pulse sensor implementation
2Device complexity
If pulse-based sensors are used for speed measurement, then the system is simple, but there is no reliable alternative for plausibility checking
Solution Approach 1:
The patent introduces acceleration sensors and rotation rate sensors as intermediary measurement devices that provide an independent method for determining speed. These intermediaries enable plausibility checking of the primary pulse-based speed measurement without requiring direct modification of the simple pulse sensor system
Solution Approach 2:
The patent substitutes mechanical pulse-based speed measurement with an inertial measurement system using acceleration and rotation rate sensors. This substitution provides a physics-based alternative method for speed determination that can verify the accuracy of mechanical pulse sensors
3Reliability
If acceleration sensors and rotation rate sensors are used to determine speed, then an alternative method for speed determination is provided, but the device complexity increases
Solution Approach 1:
The patent makes the inertial measurement system multi-functional by using acceleration and rotation rate sensors for both primary speed determination and verification of pulse sensor accuracy. This universal approach allows the same sensors to serve multiple purposes, reducing the need for additional dedicated verification hardware
Solution Approach 2:
The patent merges the speed determination function with the verification function by using the same acceleration and rotation rate sensors for both tasks. This combining of functions reduces overall system complexity compared to having separate independent systems for measurement and verification
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, detecting incorrect speed signals and providing a reliable alternative to pulse-based sensors, improving speed calculation precision and reliability.
Implementation Method 1
measuring an acceleration of the vehicle in at least three directions by means of the acceleration sensor
Implementation Method 2
measuring a rotation rate of the vehicle about at least two axes of rotation by means of the rotation rate sensor
Data Source
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AI summary
The invention relates to a method for determining the speed of a single-track vehicle, in particular an e-bike, wherein the vehicle has at least one acceleration sensor and one yaw rate sensor, comprising the steps of: - measuring the acceleration of the vehicle in at least three directions using the acceleration sensor, - measuring the yaw rate of the vehicle about at least two axes of rotation using the yaw rate sensor, - determining the driving situation of the vehicle based on the measured accelerations and yaw rates of the vehicle, and - determining the speed of the vehicle based on a system of equations describing the kinematics of the vehicle, the determined driving situation, and the measured accelerations and yaw rates of the vehicle.