Stacker Crane Transport Control for False Abnormality Detection
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Solution Overview
Problem
Conventional automated storage systems experience efficiency decreases due to erroneous detection of article abnormalities by sensors, often triggered by packaging films or labels, leading to unnecessary transport stops.
Innovation Solution
A transport device equipped with a transporter, transfer device, abnormality detector, counter, and movement controller that reduces speed when an abnormality is detected, allowing continued transport if the abnormality is no longer recognized, and enters an abnormal-stop state only after multiple occurrences or when the counter reaches a threshold, thereby reducing erroneous detection and mechanical load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor detects an article abnormality immediately, then the article abnormality can be detected quickly, but erroneous detection occurs due to packaging films or labels
Solution Approach 1:
The system performs preliminary actions by reducing the moving speed before making a final abnormality determination. When the abnormality detector first detects an abnormality, the movement controller reduces the transporter's speed and waits for re-detection. This preliminary speed reduction allows the system to verify whether the abnormality is real or erroneous before stopping transport, thereby improving detection accuracy while maintaining operational reliability.
2Reliability
If the transporter stops immediately upon abnormality detection, then safety is ensured, but transport efficiency decreases due to unnecessary stops
Solution Approach 1:
Instead of immediately stopping the transporter upon abnormality detection, the system first reduces the moving speed as a preliminary action. This allows verification of the abnormality through re-detection at reduced speed. Only if the abnormality is confirmed after speed reduction does the system stop the transporter. This approach ensures safety by confirming real abnormalities while avoiding unnecessary stops that would reduce transport efficiency.
Solution Approach 2:
The system implements feedback by re-detecting abnormalities after reducing the moving speed. The movement controller monitors whether the abnormality detector still detects the abnormality at the reduced speed. This feedback mechanism allows the system to distinguish between real abnormalities (which persist after speed reduction) and erroneous detections (which disappear), thereby making informed decisions about whether to stop transport and maintaining both safety and efficiency.
3Measurement precision
If the moving speed is reduced when abnormality is detected, then erroneous detection is reduced, but transport time increases
Solution Approach 1:
The speed reduction is implemented as a preliminary verification step rather than a permanent slowdown. The system reduces speed only temporarily to allow re-detection and verification of the abnormality. If no abnormality is detected after speed reduction, the system resumes normal speed immediately. This preliminary action approach minimizes the time lost while still achieving accurate abnormality detection by only slowing down when necessary for verification.
Data Source
AI summary
A stacker crane includes a transporter, a slide fork, first to third sensors, a counter, and a main controller. The transporter moves from a shelf on which an article is supported to an empty shelf. The slide fork is mounted on the lift stage and transfers the article to and from the shelf. The first, second and third sensors recognize an abnormality of the article moved by the movement of the transporter. The counter counts the number of event occurrences. When an abnormality is recognized by the sensor, the main controller reduces a moving speed of the transporter, and when no abnormality is recognized by the sensor upon reduction in the moving speed, the movement of the transporter is continued. When the number of event occurrences reaches a first threshold, the stacker crane is brought into an abnormal-stop state.