Automatic Steering Override Control at Full Wheel Lock

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Solution Overview

Problem

In work vehicles with automatic steering, excessive torque is generated when steered wheels are turned beyond a fully turned state, leading to potential motor damage and reduced operator operability due to the need for large forces to switch to manual steering.

Innovation Solution

A control method that determines whether the steered wheels are in a fully turned state using a turning angle determination condition, which includes torque and steering angle thresholds, to prevent further automatic steering and limit motor torque, thereby preventing override states and motor damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the threshold value of torque for override state determination is set to be large, then automatic steering cancellation is avoided, but excessive torque generation is prolonged and motor damage risk increases

Engineering Contradiction:
Improveautomatic steering stabilityVSAvoidmotor damage risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary determination of fully turned state using turning angle determination processing before excessive torque can cause damage. By detecting when the steered wheel has reached its maximum turning angle in advance, the system can prevent further torque application that would lead to motor damage while maintaining reliable automatic steering operation within normal ranges.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by continuously monitoring the steering angle and torque conditions, then adjusting the automatic steering control accordingly. When the turning angle determination condition is met (indicating fully turned state), the system provides feedback to cancel or modify automatic steering, preventing excessive torque generation while maintaining stable operation during normal conditions.

Inventive Principle:
Principle #23Feedback

2Reliability

If the threshold value of torque for override state determination is set to be large, then automatic steering cancellation is avoided, but force required for manual steering operation increases

Engineering Contradiction:
Improveautomatic steering stabilityVSAvoidsteering wheel operability
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system determines the fully turned state in advance using turning angle criteria before the operator needs to take over manual control. By identifying when the wheel is already at maximum angle, the system can prevent situations where both automatic steering and manual operation would contend for the same mechanical range, thereby reducing the force required for manual steering intervention.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system provides feedback about the steered wheel's angular position to the control mechanism, enabling intelligent adjustment of automatic steering behavior. When the feedback indicates a fully turned state, the system modifies its control output to assist rather than resist manual operation, thereby reducing the force burden on the operator while maintaining automatic steering stability during normal operation.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4446200A1Control method of work vehicle, work vehicle control program, work vehicle control system, and work system
Publication Date: 2024.10.16 YANMAR HLDG CO LTD
  • EP4446200A1 patent drawingFigure 1
  • EP4446200A1 patent drawingFigure 2
  • EP4446200A1 patent drawingFigure 3

AI summary

[Problem] To provide a control method of a work vehicle, a work vehicle control program, a work vehicle control system, and a work system, by which appropriate determination of an override state becomes possible. [Solution] A control method of a work vehicle (10) is a control method of a work vehicle (10) having an automatic steering mode for automatically steering a steered wheel (111) using a motor (421). The control method includes: in the automatic steering mode, controlling the motor (421); determining whether the work vehicle (10) is in an override state on the basis of a determination condition related to torque generated in the motor (421); and changing the determination condition. (Figure 4)