ASRS Vehicle Queuing Using Proximity-Based Cell Entry Control
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Solution Overview
Problem
In automated storage and retrieval systems, congestion occurs around frequently visited cells like ports due to the uncertainty of container handling vehicle positions, leading to delays and inefficient bandwidth usage as vehicles wait for position updates from the central control system.
Innovation Solution
Implementing a proximity sensor system on container handling vehicles to detect when another vehicle is beyond a predetermined distance, allowing the central control unit to command the first vehicle to move into a target cell without waiting for the second vehicle's updated position, thereby reducing queuing times and optimizing bandwidth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the central control system waits for position updates from container handling vehicles before allowing movement, then collision safety is ensured, but queuing delays increase and bandwidth efficiency decreases
Solution Approach 1:
The system performs preliminary safety checks using proximity sensors before movement is initiated. The proximity sensor on the first vehicle detects the position of the second vehicle in advance, and the central control unit receives this information beforehand to pre-authorize movement without waiting for continuous position updates during the approach.
Solution Approach 2:
The proximity sensor acts as an intermediary device that provides position information about the second vehicle to the central control unit. This intermediary measurement system enables the control system to make informed decisions about authorizing movement without requiring direct continuous communication between vehicles.
2Productivity
If the central control system requires continuous position updates from all vehicles, then accurate traffic management is achieved, but communication bandwidth is wasted
Solution Approach 1:
The system applies different communication requirements to different vehicles based on their local situation. Only the first vehicle (which needs to move) and the second vehicle (which is blocking) are involved in the proximity detection and authorization process. Other vehicles continue normal operations without requiring updated position information, thus conserving bandwidth.
Solution Approach 2:
The first vehicle's proximity sensor independently detects the position of the second vehicle and provides this information to the central control unit. This self-service measurement approach eliminates the need for the second vehicle to actively report its position, reducing communication overhead while maintaining accurate traffic management.
3Reliability
If vehicles must wait for blocking vehicles to completely clear target cells before moving in, then collision prevention is simplified, but traffic flow efficiency decreases
Solution Approach 1:
The system dynamically adjusts the safety condition for movement based on real-time proximity measurements. Instead of requiring the blocking vehicle to completely clear the target cell (static condition), the system allows movement when the distance between vehicles exceeds a predetermined threshold (dynamic condition), enabling smoother traffic flow while maintaining collision prevention.
Data Source
Figure 1
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AI summary
The invention concerns a method of operating an automated storage and retrieval system (1), wherein the method comprises: - detecting with the central control unit (14) that access of a first container handling vehicle (2) to a target cell (12), which is one of the plurality of grid cells, is blocked by a second container handling vehicle (2), - transmitting a data signal (16) from the central control unit (14) to the vehicle control unit (15) of the first container handling vehicle (2) commanding the first container handling vehicle (2) to move into the target cell (12) when the second container handling vehicle (3) is beyond said predetermined distance (D). Furthermore, the invention relates to an automated storage and retrieval system comprising container handling vehicles comprising a central control unit configured to perform the aforementioned method.