EV Road Surface Detection Using Wheel-Rotor Speed Error
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Solution Overview
Problem
Existing methods for determining road surface properties in electric vehicles are inefficient and often require additional sensors, making it difficult to accurately assess traction properties and road conditions without significant noise interference.
Innovation Solution
A method and device that utilize high-frequency detection of wheel position and rotor speed, either with a rotary encoder or through sensorless estimation, to determine rotor position and speed errors, which are then evaluated to provide road surface properties, leveraging existing wheel sensors and field-programmable gate arrays for enhanced signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors are used to detect road surface properties, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies the self-service principle by utilizing the electric machine's own operational parameters (rotor position and speed) to detect road surface properties. The control unit processes signals already present in the electric machine system, eliminating the need for separate road surface sensors. This allows the system to serve dual purposes: controlling the electric machine and detecting road conditions, thereby improving measurement precision without adding device complexity.
Solution Approach 2:
The patent implements multi-functionality by enabling the electric machine's control system to perform both its primary function of motor control and the secondary function of road surface property detection. The same rotor position and speed signals used for motor control are also processed to determine road surface characteristics, allowing one system to serve multiple purposes and avoiding additional sensor requirements.
2Measurement precision
If high-frequency detection is used to improve signal accuracy, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The system utilizes the electric machine's existing control signals and operational parameters for high-frequency detection, rather than implementing separate detection systems. The control unit processes rotor position and speed signals that are already being monitored for motor control, thereby achieving high-frequency detection without the additional energy consumption that would result from separate sensor systems.
Solution Approach 2:
The patent merges the road surface detection function with the existing electric machine control system. By combining the processing of rotor position and speed signals for both motor control and road surface property determination, the system achieves high-frequency detection while avoiding the duplicate energy consumption that would occur with separate detection systems.
Data Source
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AI summary
The invention relates to a method for determining at least one road characteristic (40) for an electric vehicle (50), in which a wheel position (φ 1, φ 2) and/or a wheel speed (n1, n2) of at least one wheel (54) of the electric vehicle (50) is detected at high frequency by means of at least one wheel sensor (56), and a rotor position (φ EM) and/or a rotor speed (n EM) of an electric machine (52) coupled to the at least one wheel (54) is detected at high frequency by means of a rotary encoder (57) or is estimated without a rotary encoder. Starting from the detected wheel position (φ 1, φ 2) and/or wheel speed (n1, n2) a rotor position and/or rotor speed (formula (I)) of the electric machine (52) is estimated, and a rotor position error (e φ EM) and/or rotor speed error (e n EM) is determined from the estimated rotor position and/or the estimated rotor speed (formula (I)) and the rotor position (φ EM) and/or rotor speed (n EM) detected or estimated without a rotary encoder. The determined rotor position error (e φ EM) and/or the determined rotor speed error (e n EM) are evaluated over time, and, starting from an evaluation result, at least one road characteristic (40) is determined and is provided as a road characteristic signal (41). The invention also relates to a device (1) for determining at least one road characteristic (40) for an electric vehicle (50).