Steering Angle Offset Compensation for Autonomous Trajectory Control

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Solution Overview

Problem

Automated driving systems face challenges in accurately compensating for steering wheel angle offsets due to wheel misalignment or sensor degradation, which can lead to accidents, especially on uneven roads, as existing solutions are not robust enough for fully autonomous driving modes.

Innovation Solution

A device comprising a lateral controller and a trajectory tracking analysis module that detects road conditions without longitudinal slope or lateral inclination, providing a steering angle error value to an automatic steering wheel angle offset compensation module, allowing real-time identification and correction of steering wheel angle shifts, with two adjustment modes for quick and fine corrections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If a vehicle model-based compensation device is used to calculate yaw angular speed and compensate for steering wheel angle offset, then the offset can be determined relatively quickly, but the compensation takes into account road inclination which leads to undesirable behavior on uneven roads

Engineering Contradiction:
Improvecompensation determination timeVSAvoidcontrol law robustness
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The patent segments the steering angle offset compensation process into two distinct parts: a quick compensation phase using vehicle model-based calculation, and a precise calibration phase using actual steering angle sensor data. This segmentation allows the system to quickly respond to offset changes while maintaining accuracy by periodically calibrating against real sensor measurements, thus resolving the contradiction between speed and reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements feedback by continuously monitoring the steering angle sensor data and comparing it with the vehicle model calculations. When discrepancies are detected, the system adjusts the compensation values accordingly. This feedback mechanism ensures that the compensation remains accurate and reliable even on uneven roads, while maintaining quick response times through the use of pre-calibrated models.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If manual calibration of the steering system is performed to correct angle shifts, then alignment accuracy can be improved, but maintenance time and costs increase

Engineering Contradiction:
Improvesteering angle alignment accuracyVSAvoidmaintenance time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent enables the steering system to perform self-calibration by automatically detecting offset errors through the trajectory tracking analysis module and compensating for them using the compensation module. This self-service capability eliminates the need for frequent manual calibrations by service technicians, thereby maintaining high alignment accuracy while significantly reducing maintenance time and costs.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system continuously monitors steering angle measurements and trajectory deviations, providing feedback that triggers automatic compensation when offset errors are detected. This feedback-driven automatic calibration replaces manual intervention, maintaining measurement precision while reducing the time and cost associated with manual maintenance operations.

Inventive Principle:
Principle #23Feedback

3Extent of automation

If sensors are used to calculate steering commands, then automated control can be achieved, but sensor degradation over time leads to measurement errors

Engineering Contradiction:
Improveautomated driving control capabilityVSAvoidsensor measurement accuracy
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the trajectory tracking analysis module continuously monitors the actual vehicle trajectory and compares it with the planned trajectory. When sensor degradation causes measurement errors, the system detects the resulting trajectory deviations and automatically compensates by adjusting the steering commands, thus maintaining reliable automated control despite sensor aging.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces reliance on potentially degrading mechanical sensors with a model-based compensation approach. By using vehicle dynamics models and trajectory tracking analysis, the system substitutes direct sensor measurements with calculated estimates that are less susceptible to sensor degradation, thereby maintaining automated control reliability over time.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP4037948B1Device for controlling the steering angle of a self-driving motor vehicle
Publication Date: 2023.11.22 AMPERE SAS
  • EP4037948B1 patent drawingFigure 1
  • EP4037948B1 patent drawingFigure 2~3
  • EP4037948B1 patent drawingFigure 4~5

AI summary

The invention relates to a device (1) for controlling the steering angle of a motor vehicle, comprising a lateral controller (14) which is suitable for outputting a command to at least one actuator of a vehicle steering system (15) acting on the steering angle of the vehicle directional wheels by means of the rotation angle of the vehicle steering wheel so as to follow a trajectory in an automated driving mode, the device being characterised in that it further comprises a module (11) which is for analysing the tracking of the trajectory and which can detect road conditions without any longitudinal gradient and without any lateral inclination and which, when such road conditions are detected, can output a current error value for the steering angle of the vehicle directional wheels to a module (16) for automatic compensation of any angle offset of the steering wheel, which module is connected with the lateral controller.