Backward Movement Control for Articulated Vehicles

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Solution Overview

Problem

The existing system for assisting backward movement of articulated vehicles struggles with maintaining the intended curvature, leading to difficulties in reaching a desired position due to changes in the target hitch angle caused by its own operation, making it challenging for the vehicle to follow the driver's intended path.

Innovation Solution

A backward movement control device that calculates and sets a target virtual steered angle for the tractor's wheels, allowing the trailer to be steered as if it were a rigid vehicle, ensuring the virtual steered angle converges to the target, thereby improving the vehicle's ability to follow the intended path.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the curvature regulator calculates the target hitch angle based on the current steered angle and target curvature, then the trailer can be guided along the reference path, but the convergence of the hitch angle to the target value decreases because the target value changes due to the regulator's own operation

Engineering Contradiction:

Improvebackward movement controlVSAvoidhitch angle convergence

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent introduces a virtual steered angle as an intermediary variable to bridge the tractor's actual steered angle and the trailer's desired path. Instead of directly controlling the hitch angle (which causes convergence issues), the system controls the virtual steered angle that indirectly determines the trailer's movement, thereby resolving the circular dependency problem

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The control system is segmented into independent functional modules: a virtual steered angle calculator that computes the virtual steered angle based on tractor and trailer states, and a curvature regulator that uses this virtual angle to determine the target hitch angle. This segmentation allows each module to operate independently without causing convergence issues

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If the hitch angle regulator executes feedback control to adjust the steered angle command, then the current hitch angle can follow the target hitch angle, but the system becomes complex and difficult to control

Engineering Contradiction:

Improvepath following precisionVSAvoidcontrol system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The virtual steered angle serves as an intermediary that simplifies the control architecture. By expressing the trailer's desired path in terms of the virtual steered angle (which has the same geometric relationship as a rigid vehicle's steering angle), the system reduces the complexity of coordinating tractor and trailer steering actions

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the control parameter from the actual hitch angle to the virtual steered angle. This parameter transformation allows the system to use simple trigonometric relationships (similar to rigid vehicle steering) to control the articulated vehicle, thereby reducing control complexity while maintaining path following precision

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If the driver specifies the target curvature through the input device, then the intended path can be controlled, but the system cannot accurately maintain the curvature due to the coupled motion of tractor and trailer

Engineering Contradiction:

Improvepath specificationVSAvoidcurvature maintenance

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The virtual steered angle acts as an intermediary that translates the driver's curvature specification into appropriate tractor steering commands. It mediates between the desired path (specified by curvature) and the actual articulated vehicle dynamics, enabling accurate curvature maintenance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system uses feedback control where the current virtual steered angle (calculated from actual tractor and trailer positions and orientations) is compared with the target virtual steered angle (derived from the specified curvature). This feedback loop continuously adjusts the steering commands to maintain the desired path accuracy

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20240239409A1Backward movement control device for articulated vehicle, computer-readable medium storing backward movement control program for articulated vehicle, and backward movement control method for articulated vehicle

Publication Date: 2024.07.18 JTEKT CORP

AI summary

A backward movement control device performs a backward movement control of an articulated vehicle including a tractor that includes steered wheels and a trailer towed by the tractor. The tractor is equipped with a steering control device that executes feedback control for causing a steered angle of the steered wheels of the tractor to follow a target steered angle. The backward movement control device includes a control unit configured to calculate the target steered angle such that a virtual steered angle follows a target virtual steered angle when a backward movement operation of the articulated vehicle is performed. The virtual steered angle is a steered angle of steered wheels that are virtually present in the trailer if the trailer is regarded as a rigid vehicle. The target virtual steered angle is a target value of the virtual steered angle that is set through a specific operation by an operator.