Trailer Articulation Angle Estimation Using Wheel Speed Signals
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Solution Overview
Problem
Existing methods for determining the articulation angle between a towing vehicle and a trailer are costly and prone to errors due to the use of articulation angle sensors, and there is a need for a more reliable and cost-effective solution.
Innovation Solution
Estimate the articulation angle based on wheel speeds of the towing vehicle and trailer using existing sensors, such as those used for brake control, without the need for direct articulation angle sensors, by calculating distances and angles based on instantaneous centers of velocity and wheel speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If articulation angle sensors are used to measure the articulation angle, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical articulation angle sensor with a computational method that uses wheel speed sensors and geometric relationships. The articulation angle is calculated by determining the instantaneous center of velocity and using the relationship between wheel speeds and articulation angle, thereby substituting a mechanical measurement system with a computational one that uses existing sensor data.
Solution Approach 2:
The patent creates a virtual model of the vehicle-trailer system's kinematics to estimate the articulation angle. By copying the physical relationships between wheel speeds, instantaneous center of velocity, and articulation angle into a computational model, the system can derive the articulation angle without direct physical sensing.
2Measurement precision
If articulation angle sensors are used to measure the articulation angle, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent uses inexpensive wheel speed sensors that are already part of the brake control system instead of expensive articulation angle sensors. The wheel speed data, which is continuously generated anyway for braking purposes, is repurposed to calculate articulation angle, effectively using a cheap existing resource instead of investing in expensive new sensing hardware.
Solution Approach 2:
The patent makes the existing wheel speed sensors serve multiple functions: they provide data for brake control operations and simultaneously provide the necessary input for articulation angle estimation. This multi-functionality eliminates the need for dedicated articulation angle sensors, reducing overall system cost.
3Reliability
If articulation angle sensors are used, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical articulation angle sensor with a computational method that uses wheel speed sensors and geometric relationships. The articulation angle is calculated by determining the instantaneous center of velocity and using the relationship between wheel speeds and articulation angle, thereby substituting a mechanical measurement system with a computational one that uses existing sensor data.
4Device complexity
If wheel speed sensors are used to estimate articulation angle, then device complexity is reduced, but measurement precision may worsen
Solution Approach 1:
The patent introduces the instantaneous center of velocity as an intermediary concept that connects wheel speed measurements to articulation angle estimation. By using this intermediate geometric construct, the system can translate wheel speed data into accurate articulation angle information through well-defined kinematic relationships.
Solution Approach 2:
The patent transforms the problem from directly measuring articulation angle to measuring wheel speeds and calculating articulation angle through parameter transformation. By changing the measured parameters from angular position to linear velocity, the system leverages more reliable and easier-to-obtain sensor data while maintaining estimation accuracy through mathematical relationships.
Data Source
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AI summary
The present invention relates to a method for estimating an articulation angle (ϕ) between a towing vehicle (10) and a trailer (20) with respect to a pivot (K), comprising the steps of: determining a distance (r) between an instantaneous center of velocity (P) of the towing vehicle (10) and a center of at least one axle (R) of the towing vehicle (10) representative for a rotation of the towing vehicle (10) about the instantaneous center of velocity (P) of the towing vehicle (10) and/or a distance (rT) between an instantaneous center of velocity (D) of the trailer (20) and a center of at least one axle (T) of the trailer (20) representative for a rotation of the trailer (20) about the instantaneous center of velocity (D) of the trailer (20), determining at least one instantaneous speed (vR, vT, vTL, vTR) representative for a wheel speed of at least one wheel of the towing vehicle (10) and/or the trailer (20), wherein the at least one instantaneous speed (vR, vT, vTL, vTR) refers to the at least one determined distance (r, rT), and estimating the articulation angle (ϕ) based on the at least one determined instantaneous speed and the at least one determined distance (r, rT).