Buffer Storage Load Sequencing with Recirculation Priority Control
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Solution Overview
Problem
Buffer storage and load sequencing systems face challenges in optimizing the control of entry elevators to balance the output rate of sequenced loads and reduce the risk of system blockage, particularly in selecting loads and destination levels while ensuring ascending sequence order compliance.
Innovation Solution
An iterative control method for the entry elevator that prioritizes recirculating loads and selects destination levels based on scoring rules to optimize load sequencing and reduce blockage risks, including assigning a 'load to be recirculated' status to optimize the choice of input levels for subsequent loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the entry elevator prioritizes transferring loads to inlet levels to increase output rate, then the productivity increases, but the risk of system blockage increases due to improper sequence ordering
Solution Approach 1:
The control unit performs preliminary assessment of inlet level sequences before transferring loads. It evaluates whether placing a load on a specific inlet level will maintain ascending sequence order, and only authorizes transfers that satisfy this condition, preventing blockages before they occur
Solution Approach 2:
The system continuously monitors the sequence numbers of loads on each inlet level and uses this feedback information to dynamically control entry elevator transfers. The control unit adjusts transfer decisions based on real-time sequence state, ensuring productivity while preventing blockages
2Reliability
If the system allows recirculation of loads to prevent blockage, then the reliability improves, but the complexity of load selection and destination level selection increases
Solution Approach 1:
The control logic is segmented into distinct evaluation steps: first assessing whether a direct transfer to an inlet level is possible while maintaining sequence order, and only if that fails, evaluating recirculation options. This modular approach manages complexity by breaking down the decision process
Solution Approach 2:
The system dynamically adjusts the recirculation decision based on real-time conditions. The control unit evaluates sequence numbers, inlet level states, and recirculation needs adaptively, rather than following a fixed rigid protocol, allowing flexible management of complexity
3Productivity
If the entry elevator transfers loads to multiple inlet levels simultaneously, then the productivity increases, but the difficulty of maintaining ascending sequence order increases
Solution Approach 1:
The control unit continuously receives feedback on the sequence numbers of loads placed on each inlet level and uses this information to make informed decisions about subsequent transfers. This real-time monitoring ensures ascending sequence order is maintained across multiple concurrent transfers
Solution Approach 2:
Before authorizing a transfer to any inlet level, the control unit preliminarily verifies that the sequence number relationship will be maintained. This pre-validation prevents sequence disorganization while enabling parallel transfers to multiple levels
Data Source
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AI summary
A method for controlling a buffer storage/load sequencing system, receiving unsequenced loads, providing at least one load sequence, and comprising a buffer storage unit (comprising inlet levels (FIFOs in one direction) and at least one recirculation level (another FIFO in the opposite direction)) and an inlet elevator and an outlet elevator positioned opposite the inlets and outlets of the aforementioned levels. A control unit iteratively controls the inlet elevator.At each iteration (even if load(s) to be recirculated in the system): selection (204 to 209) of a load at the output of an input conveyor or at the output of the recirculation level; if the selection of one of the input levels succeeds (211), generation (217) for the input elevator of a transfer mission of the selected load on the selected level, otherwise selection (216) among the input levels of a level to be recirculated and assignment of the status "to be recirculated" to the load(s) on it (without generation for the input elevator of a transfer mission).