ASRS Vehicle Proximity Control for Port Cell Congestion
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Solution Overview
Problem
In automated storage and retrieval systems, congestion occurs around frequently visited cells like ports due to uncertainty in the position of container handling vehicles, leading to delays and inefficient use of bandwidth, as vehicles wait for confirmation from the central control system before moving into target cells.
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 vehicle to move into the target cell without waiting for confirmation, thereby reducing queuing times and optimizing bandwidth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the central control system waits for confirmation from vehicles before commanding movement, then position accuracy is improved, but productivity deteriorates due to queuing delays
Solution Approach 1:
The system performs preliminary positioning actions by having vehicles report their positions proactively before the control system needs to make dispatch decisions. This allows the control system to have accurate position information available in advance, eliminating the need to wait for confirmation after initiating movement commands.
Solution Approach 2:
The system implements a feedback mechanism where container handling vehicles automatically report their position and status to the central control system. This continuous feedback loop ensures the control system has up-to-date information for making optimal dispatch decisions without introducing delays.
2Reliability
If vehicles wait for central control confirmation before moving, then system reliability is improved, but loss of time increases due to queuing delays
Solution Approach 1:
Vehicles perform self-reporting of their position and status information to the central control system. This self-service approach eliminates the need for the control system to actively query each vehicle for status updates, reducing communication overhead and waiting time while maintaining reliable information accuracy.
Solution Approach 2:
The system executes preliminary information exchange by having vehicles report their status before the control system needs to make decisions. This preliminary action ensures that when the control system needs to issue commands, all necessary information is already available, eliminating delays.
3Measurement precision
If the system uses centralized control for all vehicle commands, then measurement precision is improved, but device complexity increases due to bandwidth requirements
Solution Approach 1:
Vehicles autonomously report their position and status information to the central control system, eliminating the need for continuous active monitoring and command-query cycles. This reduces the communication bandwidth requirements and simplifies the control system architecture while maintaining accurate position monitoring.
Solution Approach 2:
The system uses efficient feedback mechanisms where vehicles transmit relevant status information only when changes occur or at scheduled intervals. This selective feedback approach maintains monitoring accuracy while reducing overall communication traffic and system complexity.
Data Source
AI summary
A method of operating an automated storage and retrieval system includes: a rail system including a first set of parallel rails arranged in a horizontal plane and extending in a first direction, and a second set of parallel rails arranged in the horizontal plane and extending in a second direction which is orthogonal to the first direction, which first and second sets of rails form a grid pattern in the horizontal plane including a plurality of adjacent grid cells, a central control unit configured to receive, transmit and process data signals of a plurality of container handling vehicles for handling storage containers of the automated storage and retrieval system. Each container handling vehicle includes a vehicle body, a wheel assembly provided on the vehicle body, the wheel assembly being configured to move the vehicle along the rail system in both of the first direction and the second direction, a vehicle control unit configured to receive data signals from, transmit data signals to and process data signals of the central control unit, and a proximity sensor system configured to detect another container handling vehicle of said plurality of container handling vehicles and determine whether or not it is within a predetermined distance. The method includes detecting with the central control unit that access of a first container handling vehicle to a target cell, which is one of the plurality of grid cells, is blocked by a second container handling vehicle, transmitting a data signal from the central control unit to the vehicle control unit of the first container handling vehicle commanding the first container handling vehicle to move into the target cell when the second container handling vehicle is beyond said predetermined distance.