Motor Vehicle Radar Sensor Calibration via Phase Difference
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Solution Overview
Problem
Existing driver assistance systems for motor vehicles, particularly those using radar sensors, face challenges in accurately calibrating sensors due to assembly tolerances and environmental factors, leading to systematic angle errors that affect measurement precision.
Innovation Solution
A method involving a computing device that continuously receives and processes signals from two reception devices of a sensor while the vehicle moves relative to an object, determining measurement angles based on phase differences and relative orientations, with calibration achieved by comparing measured angles to known reference angles during a predetermined reference time, allowing for correction of systematic errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor calibration is performed using conventional methods with static vehicle positioning, then calibration can be completed, but assembly tolerances and environmental factors cause systematic angle errors that reduce measurement precision
Solution Approach 1:
The patent transforms the calibration process from a static procedure to a dynamic one by performing calibration measurements while the vehicle is in motion. The sensor captures reflection signals from objects at multiple different positions and orientations, allowing the system to identify and correct systematic angle errors that occur under various dynamic conditions rather than relying on a single static calibration point.
Solution Approach 2:
The system employs feedback by continuously comparing measured angles against expected geometric relationships during vehicle movement. The calibration process uses the collected measurement data to generate correction values that compensate for systematic errors, and this feedback loop ensures that the sensor maintains accurate angle measurements throughout its operational range.
2Reliability
If the vehicle remains stationary during calibration, then the calibration process is simpler, but the calibration does not account for environmental factors and assembly tolerances that affect sensor performance during actual vehicle operation
Solution Approach 1:
The system performs preliminary data collection and analysis by capturing multiple reflection signals at different vehicle positions before finalizing the calibration. This preliminary action allows the system to pre-identify systematic errors and prepare correction values that will be applied during actual operation, ensuring reliable calibration without requiring complex real-time adjustments.
Solution Approach 2:
The calibration process utilizes changes in vehicle position, orientation, and sensor viewing angles as variable parameters. By systematically varying these parameters during the calibration drive and analyzing how measurement angles change relative to expected geometric relationships, the system can identify systematic errors across the entire measurement range rather than at a single fixed parameter state.
3Measurement precision
If multiple measurement positions are used during calibration, then systematic angle errors can be identified and corrected, but the calibration process requires extended vehicle movement and time
Solution Approach 1:
The calibration process maintains continuous data acquisition throughout the vehicle's movement through the calibration area. Rather than performing discrete measurements at isolated positions, the sensor continuously captures reflection signals while the vehicle moves, ensuring that no useful calibration data is lost and that systematic errors are captured across the complete range of motion in a single continuous operation.
Solution Approach 2:
The system performs calibration at periodic intervals during normal vehicle operation or during scheduled calibration drives. By incorporating calibration measurements into regular operational cycles rather than requiring separate dedicated calibration sessions, the system can maintain measurement precision without significant additional time loss.
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 enables reliable and precise calibration of sensors during vehicle movement, correcting for assembly tolerances and environmental influences, ensuring accurate angle measurements and improved sensor performance across the entire capture region.
Implementation Method 1
radar sensors serve to detect an object in a surrounding region of the motor vehicle. The radar sensors can be part of different driver assistance systems that assist the driver in guiding the motor vehicle.
Implementation Method 2
the radar sensor emits a sensor signal in the form of an electromagnetic wave. This sensor signal is then reflected at the object to be detected and received again by the radar sensor as an echo.
Implementation Method 3
For the purposes of obtaining a reception signal, the reflected transmission signal is initially down-mixed into the baseband and subsequently sampled by means of an analogue-to-digital converter.
Implementation Method 4
a measurement angle between the sensor and the object is determined on the basis of a phase difference between the reception signals
Data Source
AI summary
A method for calibrating a sensor of a motor vehicle includes, while the motor vehicle is moved relative to an object, continuously receiving a reception signal by a computing device from two reception devices of the sensor, the reception signal describing a sensor signal that is emitted by the sensor and reflected at the object. A measurement angle between the sensor and the object is determined based on a phase difference between the reception signals. A relative orientation between the sensor and the object is determined continuously based on the reception signals, and a reference time at which the relative orientation corresponds to a predetermined reference orientation for which a reference angle between the sensor and the object is known is determined by the computing device. The measurement angle is determined for the reference time, and the sensor is calibrated based on a comparison between the measurement angle for the reference time and the reference angle.