OHT Vehicle Step Difference Detection via Inclination Correction

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Solution Overview

Problem

Existing article transferring apparatuses, such as Overhead Hoist Transport (OHT) devices, face challenges in accurately measuring step differences on travel rails, especially during acceleration and deceleration, due to inclination-induced errors in displacement sensor measurements, leading to potential damage and accuracy deterioration.

Innovation Solution

An article transferring apparatus equipped with a vehicle traveling along a ceiling-mounted travel rail, featuring a step difference measurement unit with first and second displacement sensors and an inclination sensor, which corrects measurement errors using the inclination angle to calculate actual distance values, allowing for accurate detection of step differences and controlling the vehicle's speed or bypassing critical points when thresholds are exceeded.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If displacement sensors are used to detect step difference of travel rail, then step difference can be detected, but measurement accuracy deteriorates during acceleration and deceleration sections due to vehicle inclination

Engineering Contradiction:

Improvestep difference detection accuracyVSAvoiddetection reliability during acceleration/deceleration

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces an inclination sensor as an intermediary device to detect the vehicle's inclination angle during acceleration and deceleration. This inclination angle information is then used to correct the displacement sensor measurements, thereby compensating for the measurement errors caused by vehicle inclination and maintaining detection accuracy throughout the entire travel process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a feedback mechanism where the inclination sensor continuously monitors the vehicle's inclination angle and provides this information back to the control system. The control system then uses this feedback to dynamically adjust the displacement sensor readings through correction calculations, ensuring accurate step difference detection even during dynamic acceleration and deceleration phases.

Inventive Principle:

Principle #23Feedback

2Productivity

If vehicle speed is increased to improve productivity, then transfer efficiency increases, but vibration and damage risk increase due to step differences in travel rail

Engineering Contradiction:

Improvearticle transfer efficiencyVSAvoidvibration and damage risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent uses real-time feedback from displacement sensors and inclination sensors to monitor the vehicle's position and inclination during travel. When step differences are detected, the control system receives feedback signals and automatically adjusts the vehicle speed or triggers bypass maneuvers, allowing the system to maintain high productivity while preventing vibration-induced damage through dynamic response.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies dynamic control by continuously adjusting the vehicle's operating parameters (speed, trajectory) based on real-time sensor data. During normal conditions, the vehicle operates at optimal speed for productivity. When step differences are detected through sensor feedback, the system dynamically modifies speed and path to minimize vibration and damage risk, thus balancing productivity with safety throughout the transfer process.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables precise detection of step differences, minimizes sensor misdetection, and ensures safe operation by adjusting speed or bypassing problematic sections, thereby reducing the risk of damage and maintaining accuracy during transfers.

Implementation Method 1

measuring distances values to a traveling surface of the travel rail by a first displacement sensor and a second displacement sensor arranged at a predetermined interval along a travel direction

Methodology Applied

Scientific EffectDisplacement sensor measurement:

Implementation Method 2

an inclination sensor unit for detecting an inclination angle of the vehicle and providing the inclination angle value to the controller

Methodology Applied

Scientific EffectInclination detection:

Data Source

PatentUS20230211957A1Article transferring apparatus, method of measuring step difference of travel rail, and transferring system

Publication Date: 2023.07.06 SYSTEM ENGINEERING MEGA SOLUTION CO LTD

AI summary

Disclosed is an article transferring apparatus, including: a vehicle traveling along a travel rail installed on a ceiling; a hoist module connected to the vehicle and transferring an article; a step difference measurement unit which is installed in the vehicle, and measures a step difference of the travel rail by measuring distances values to a traveling surface of the travel rail by a first displacement sensor and a second displacement sensor arranged at a predetermined interval along a travel direction; and a controller for determining whether there is a step difference of the travel rail by correcting an error between a first measurement value of the first displacement sensor and a second measurement value of the second displacement sensor according to an inclination of the vehicle.