Self-Mixing Laser Sensor System for Vehicle Traction Measurement
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Solution Overview
Problem
Existing vehicle sensor systems are bulky and impractical for measuring vehicle movement parameters, particularly traction between wheels and surfaces, due to their size and complexity.
Innovation Solution
A compact sensor system utilizing laser sensors with self-mixing interference, rotation sensors, and an analyzer circuit to determine vehicle velocity components and rotational velocities, allowing for accurate measurement of traction by analyzing rotational velocities in relation to velocity components, with optional additional sensors for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical measurement apparatus is used to measure vehicle movement parameters, then measurement capability is provided, but the apparatus becomes bulky and impractical
Solution Approach 1:
The patent combines multiple sensor functions (laser sensor for velocity measurement, rotation sensor for wheel rotational velocity, and analyzer circuit for data processing) into an integrated compact system. The laser sensor and rotation sensor work together to measure vehicle movement parameters, with the analyzer circuit processing data from both sensors to determine velocity components and traction, thereby achieving comprehensive measurement capability in a compact form factor.
Solution Approach 2:
The patent replaces bulky mechanical measurement apparatus with optical measurement methods. Specifically, it uses laser sensors that employ optical interference patterns and Doppler shifts to measure velocity, and rotation sensors that use optical principles to measure wheel rotational velocity. This substitution of mechanical systems with optical systems enables compact sensor design while maintaining measurement precision.
2Measurement precision
If multiple sensors are added to improve measurement accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The analyzer circuit serves multiple functions: it processes data from both the laser sensor and rotation sensor, determines velocity components, calculates traction forces, and provides output to both vehicle control systems and driver information systems. This multi-functionality reduces the need for separate dedicated circuits for each measurement task, thereby managing complexity while maintaining high measurement precision.
Solution Approach 2:
The system uses feedback from both the laser sensor (vehicle velocity) and rotation sensor (wheel rotational velocity) to cross-validate measurements and improve traction calculation accuracy. The analyzer circuit continuously processes feedback data from both sensors to determine traction forces, and this feedback mechanism allows the system to compensate for individual sensor limitations, enhancing measurement precision without requiring excessive numbers of sensors.
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
The system provides precise measurement of traction and vehicle dynamics, enhancing vehicle stability and control by integrating with vehicle control systems for improved braking efficiency and driver information systems.
Implementation Method 1
determining a surface-induced Doppler shift from the incident and collected light and determining at least one of a motion property of the travel vehicle and a surface property of the travel surface based on the determined surface-induced Doppler shift
Implementation Method 2
at least one laser sensor working with self-mixing interference
Data Source
AI summary
A sensor system is described, using self-mixing laser sensors (10) and an analyzer circuit (30) in order to determine the velocity of a vehicle, such as a car, and the rotational velocity of a wheel (20) of the car. Deviations between the velocity of the vehicle and the rotational velocity of the wheel (20) can be used to determine sliding of the wheel (20) and, finally, the traction or, more specifically, the coefficient of driving friction between the wheel (20) and the surface the car is driving on. Furthermore, a vehicle control system is described, initiating test accelerations of a wheel (20) by means of a control circuit (50) and control means (300, 400) in order to determine the coefficient of driving friction during driving. The test accelerations initiate short periods of sliding of the wheel (20) and the sliding is detected by means of the sensor system.