Container Vehicle Routing With Partial Path Locking in Storage Grids
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Solution Overview
Problem
Existing automated storage and retrieval systems face inefficiencies in routing and rerouting container handling vehicles due to the need for complete route planning, which can lead to delays and limited route alternatives, especially in dynamically changing environments.
Innovation Solution
A method that calculates routes on the fly, allowing partial route locking for a set time interval, enabling frequent rerouting and increased route alternatives by using multi-agent pathfinding algorithms while avoiding route conflicts and optimizing journey times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complete route planning is performed for container handling vehicles, then route conflicts are avoided, but routing time increases and route alternatives are limited
Solution Approach 1:
The patent segments the route planning process into discrete time intervals, where only routes needed for the current time interval are planned and locked. This allows the system to avoid planning complete routes in advance, reducing routing time while maintaining conflict avoidance through interval-based route locking.
Solution Approach 2:
The system dynamically adjusts route planning by continuously updating routes for each time interval based on current vehicle positions and system state. This dynamic approach replaces static complete route planning with adaptive incremental planning, reducing time loss while maintaining reliability through continuous monitoring and adjustment.
2Reliability
If complete route planning is performed for container handling vehicles, then route conflicts are avoided, but number of route alternatives decreases
Solution Approach 1:
By segmenting route planning into time intervals, the system maintains multiple route alternatives within each interval while locking only the necessary routes for conflict avoidance. This segmentation preserves adaptability by allowing route re-planning in subsequent intervals, unlike complete route planning which locks all routes in advance.
Solution Approach 2:
The system performs partial route planning by planning and locking only the portion of routes needed for the current time interval rather than complete routes. This partial action maintains sufficient route alternatives for future intervals while achieving conflict avoidance for the current period.
3Reliability
If routes are locked for container handling vehicles, then route conflicts are prevented, but adaptability to changing traffic conditions decreases
Solution Approach 1:
The system implements dynamic route locking by releasing locks at the end of each time interval and re-planning routes based on updated traffic conditions. This dynamic approach maintains conflict prevention during each interval while enabling adaptation to changing conditions between intervals, unlike static long-term route locking.
Solution Approach 2:
The system uses periodic route planning and locking at defined time intervals, where routes are locked for conflict prevention during each interval and then re-evaluated in the next interval. This periodic action balances conflict prevention with adaptability by regularly updating routes based on current traffic conditions.
Data Source
AI summary
A method, control system 500 and computer program for routing and rerouting of container handling vehicles 201 handling storage containers 106 in an automated storage and retrieval system comprising a framework structure 100 forming a three-dimensional storage grid structure 104 for storing the storage containers 106 in storage columns 105, the framework structure including a grid-based rail system 108 arranged above the storage columns 105 with the rail system 108 providing available routes for the container handling vehicles 201 handling and transferring the storage containers 106 to and from the storage columns 105, and wherein each container handling vehicle 201 comprises a first set of wheels configured to move the vehicle along a first lateral direction (X) of the grid-based rail system and a second set of wheels configured to move the vehicle along a second lateral direction (Y) of the grid-based rail system (108), the second direction (Y) being perpendicular to the first direction (X), the movements of the container handling vehicles being controlled by a control system 500, that determines which tasks are to be done by specified container handling vehicles 201, destination locations for performing the tasks and which routes the container handling vehicles 201 are to travel on the rail system 108. The method comprises the following steps performed by the control system 500 when executing the computer program: running 410 a multi-agent pathfinding algorithm, MAPF, in the control system 500 for establishing and assigning routes on the rail system 108 for the container handling vehicles 201 from their current locations to assigned tasks at destination locations; determining 420 how far the container handling vehicles 201 can travel on a first part of the assigned routes within a set time interval, the first part being shorter than the assigned routes to the destinations; locking 430 the first parts of the assigned routes that the container handling vehicles 201 can travel within the set time interval; instructing 440 the container handling vehicles 201 to move from their current locations to an end location on the assigned locked routes; repeating steps above.