OHT Hand Unit Tilt Compensation for Precise Load Port Placement

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Solution Overview

Problem

The misalignment of positioning pins and recesses in transfer containers due to tilt during unloading by OHT vehicles leads to improper placement on load ports, causing contamination and process disruptions in semiconductor manufacturing.

Innovation Solution

An OHT vehicle system with a displacement measuring means and controller to determine the degree of tilt and correct the position of the transfer container, ensuring accurate alignment with load port positioning pins through horizontal and vertical adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the OHT vehicle unloads the transfer container while it is tilted, then the unloading process is faster, but the positioning pin and recess become misaligned causing placement errors

Engineering Contradiction:

Improveunloading speedVSAvoidplacement precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system performs preliminary tilt detection using displacement measuring means before the unloading operation. The controller calculates the tilt degree and determines the necessary position correction in advance, allowing the hand unit to adjust its position proactively rather than reactively, ensuring precise alignment is achieved before placement occurs

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements a feedback mechanism where the displacement measuring means continuously monitors the position of the transfer container relative to the hand unit. The controller processes this feedback information to calculate tilt degree and dynamically adjusts the hand unit's position through the slide unit, creating a closed-loop control system that ensures precise placement despite tilt conditions

Inventive Principle:

Principle #23Feedback

2Ease of operation

If the transfer container is held without position correction, then the operation is simpler, but the recess cannot be aligned with the positioning pin

Engineering Contradiction:

Improveoperational simplicityVSAvoidalignment precision

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The system employs self-service through automatic tilt compensation. The displacement measuring means autonomously detects container tilt, the controller automatically calculates correction values, and the slide unit self-adjusts the hand unit position without manual intervention. This automated self-correction mechanism maintains alignment precision while keeping operations simple

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system replaces manual mechanical adjustment with an automated control system. Instead of requiring operators to physically adjust the hand unit position, the controller uses displacement measurement data to automatically command the slide unit, substituting human mechanical operation with an automated electromechanical system that achieves higher precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12362214B2OHT vehicle and method of controlling operation of same

Publication Date: 2025.07.15 SYSTEM ENGINEERING MEGA SOLUTION CO LTD

AI summary

Proposed are an OHT vehicle and a method of controlling the operation of the same. More particularly, proposed is a technology in which when a hand unit of an OHT vehicle loads a transfer container and unloads the same to a destination load port, an error between a recess of the transfer container and a positioning pin of the load port caused by the tilt of the transfer container is resolved through position correction of the hand unit, thereby enabling the transfer container to be accurately placed on the load port.