Industrial Vehicle Steering Limit Angle Detection During Travel

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Solution Overview

Problem

Existing steering control systems for industrial vehicles like forklift trucks face challenges in accurately detecting wheel angles at steering limit positions without stationary steering, leading to increased tire wear and operator discomfort, especially in mechanically linked systems.

Innovation Solution

A control apparatus that includes a wheel angle detector, a travel determining device, and a control calculation device to determine if the vehicle is traveling at a specified speed, calculating the average and maximum variation of the wheel angle over time, and renewing the reference steering limit angle based on these conditions, allowing accurate detection without stationary steering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the wheel angle is detected at steering limit positions by stationary steering, then the reference steering limit angle can be determined, but the tire wear is accelerated and a force greater than the restoring force of the tire needs to be applied

Engineering Contradiction:

Improvewheel angle detection accuracyVSAvoidtire wear

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary detection of steering limit positions by detecting the operator's steering intention in advance, rather than waiting for the vehicle to come to a stop. The wheel angle detector continuously monitors steering wheel angle, and when the operator's steering intention is detected, the system starts detecting the steerable wheel angle to determine the steering limit position during vehicle travel, thereby avoiding stationary steering and reducing tire wear.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces the mechanical stationary steering method with an electronic detection system. Instead of mechanically stopping the vehicle and manually steering to limit positions, the system uses a wheel angle detector to electronically detect the operator's steering intention and automatically detects the steerable wheel angle during travel, substituting mechanical operations with electronic sensing and control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If the steering wheel is turned automatically without manipulation by the operator, then the wheel angle can be detected at steering limit positions, but the operator may feel uncomfortable

Engineering Contradiction:

Improvewheel angle detection accuracyVSAvoidoperator comfort

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The system applies preliminary anti-action by detecting the operator's steering intention in advance and preparing to detect the steering limit position, but only actually performing the automatic wheel angle detection when the operator's intention is confirmed. This prevents unexpected automatic steering movements while ensuring accurate detection when needed, thereby maintaining operator comfort while achieving measurement precision.

Inventive Principle:

Principle #9Preliminary anti-action

3Measurement precision

If the vehicle cannot be used for its intended purpose during detection of wheel angle at steering limit positions, then the reference steering limit angle can be determined, but productivity is reduced

Engineering Contradiction:

Improvesteering limit angle determinationVSAvoidvehicle usage time

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The system performs preliminary detection of steering limit positions during normal vehicle operation by continuously monitoring the wheel angle and detecting the operator's steering intention. This allows the reference steering limit angle to be determined in advance during actual use, rather than requiring separate calibration stops, thereby maintaining productivity while achieving accurate steering limit angle determination.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention enables continuous detection of steering limit positions during normal vehicle operation. The wheel angle detector continuously monitors the steering wheel angle, and when the operator's steering intention is detected, the system immediately starts detecting the steerable wheel angle without interrupting vehicle use. This continuous operation ensures that useful action (vehicle operation) continues uninterrupted while still achieving the calibration function.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS10017206B2Apparatus for controlling steering of industrial vehicle and method therefor

Publication Date: 2018.07.10 TOYOTA INDUSTRIES CORP

AI summary

An apparatus and a method for controlling steering of an industrial vehicle includes a wheel angle detector, a travel determining device, and a control calculation device that calculates a wheel angle average and a maximum variation of wheel angle in the specified period and learns a reference steering limit angle. The control calculation device determines that the steerable wheel is in a steering limit state if an actual traveling speed is maintained at the specified speed or higher for the specified period of time or longer, the average wheel angle in the specified period of time is at a specified angle or greater, and the maximum variation of wheel angle in the specified period of time is at a specified value or less. The control calculation device renews the reference steering limit angle if the steerable wheel is determined to be in the steering limit state.