Multilevel Storage Retrieval System Lift Interface Sorting
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Solution Overview
Problem
Existing material handling systems face inefficiencies in the transfer and sorting of items between storage levels, particularly in multilevel storage and retrieval systems, where multiple lift strokes are often required to sort and retrieve items for load-out, leading to decreased throughput.
Innovation Solution
The system optimizes item transfer by sorting items at a lift interface and picking them with a common lift stroke, matching the order of sorted items to a load stream, and using autonomous transport vehicles and lift modules to efficiently move items between storage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple lift strokes are used to sort and retrieve items, then items can be transferred between storage levels, but the throughput of the system decreases
Solution Approach 1:
The system performs preliminary sorting of items at the lift interface before the lift stroke begins. Items are pre-positioned and organized in the correct sequence on the lift platform, so that when the lift reaches the destination level, items can be rapidly discharged in the correct order without requiring additional sorting operations or multiple lift strokes. This preliminary organization action eliminates the time penalty associated with multiple sequential operations.
Solution Approach 2:
The system maintains continuous useful action by ensuring that the lift is always engaged in productive work - either transporting items or discharging them in sequence. The sorting and sequencing operations are integrated into the lift stroke itself rather than being separate preparatory steps, so the lift continuously moves items through the system without idle time or redundant strokes. This continuity maximizes throughput by eliminating non-value-added time in the lift cycle.
2Productivity
If items are sorted during outbound flow after being transported by gantry crane or paternoster lift, then items can be directed to correct destinations, but additional sorting steps decrease throughput
Solution Approach 1:
The system merges the sorting function with the transport function by integrating sorting mechanisms directly into the lift platform. Items are sorted and sequenced on the lift itself during the transport operation, rather than requiring separate sorting stations at the destination. This consolidation of sorting and transport into a single integrated operation eliminates additional sorting steps and maintains system throughput.
Solution Approach 2:
The lift platform serves multiple functions: it transports items between storage levels, sorts items in the correct sequence, and discharges items to the appropriate destinations. By making the lift a multi-functional device that performs transport, sorting, and sequencing operations, the system eliminates the need for dedicated sorting equipment and additional sorting steps, thereby maintaining high throughput while achieving proper item distribution.
3Productivity
If lifts perform multiple lift strokes to pick items needed for load-out, then all required items can be collected, but the rate of item transfer decreases
Solution Approach 1:
The system performs preliminary sequencing of items on the lift platform before the lift stroke completes. As items are loaded onto the lift during ascent, they are automatically or manually arranged in the correct discharge sequence. This preliminary ordering allows the lift to discharge multiple items in a single stroke at the destination level, eliminating the need for multiple sequential lift strokes to collect all required items for a load-out.
Solution Approach 2:
The system transitions from sequential vertical transport (one item or small batches per lift stroke) to batch processing by organizing multiple items in spatial sequence on the lift platform. By arranging items in the correct order along the lift platform in advance, the system enables parallel discharge of multiple items in a single lift stroke, effectively adding a spatial dimension to the transport process that increases the rate of item transfer.
Data Source
AI summary
A product order fulfillment system includes multiple decks arrayed at different levels and defining multilevel decks, at least one autonomous transport vehicle on each of the decks, and configured for holding and transporting a pickface on each deck, at least one lift, traversing and connecting more than one level of the decks, and arranged for lifting and lowering the pickface from the decks, and at least one pickface transfer station on each deck interfacing between the transport vehicle and the at least one lift to effect transfer of the pickface between the transport vehicle and the at least one lift, the at least one lift defines a fulfillment stream of mixed case pickfaces outbound from the multilevel decks to a load fill, at least one stream of the fulfillment stream has an ordered sequence of streaming pickfaces wherein the ordered sequence of streaming pickfaces is based on another fulfilment stream.