Buffer Load Sequencing Control With Recirculation Hold Logic
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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 prevent system blockages, 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 holding loads for recirculation, selects loads based on availability and sequence numbers, and assigns recirculation status to optimize load placement and reduce blockages, ensuring loads are sequenced in ascending order on input levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inlet elevator continuously transfers loads to inlet levels, then the throughput of the system increases, but the risk of system blockage increases due to improper load sequencing
Solution Approach 1:
The control unit continuously monitors the status of inlet levels, recirculation levels, and load sequence numbers, using this feedback information to dynamically adjust inlet elevator operations. When a load would violate ascending sequence order, the control unit receives feedback about the current level status and modifies the transfer decision, preventing blockages while maintaining high throughput.
Solution Approach 2:
The system dynamically adjusts the behavior of the inlet elevator based on real-time conditions. The control unit changes the elevator's operation mode between continuous transfer and standby/recirculation based on the current state of buffer levels and load sequencing requirements, optimizing both productivity and reliability under varying conditions.
2Reliability
If recirculation levels are added to increase buffer capacity, then the system can handle more loads without blockage, but the device complexity and ground footprint increase
Solution Approach 1:
The patent introduces a vertical dimension by stacking inlet levels and recirculation levels vertically rather than expanding horizontally. This allows the system to increase buffer capacity without proportionally increasing ground footprint, managing complexity through vertical integration of multiple functional levels.
Solution Approach 2:
The recirculation levels serve multiple functions: they act as additional buffer storage capacity, provide a recirculation path for loads that need repositioning, and help maintain ascending sequence order on inlet levels. This multi-functionality increases reliability without requiring separate dedicated components for each function.
3Manufacturing precision
If the inlet elevator prioritizes transferring loads to maintain ascending sequence order, then sequencing accuracy improves, but the output rate of sequenced loads decreases
Solution Approach 1:
The control unit performs preliminary assessment of load transfer decisions by evaluating future sequence requirements before executing transfers. It anticipates sequencing needs and proactively manages load placement on inlet levels, ensuring ascending order compliance while minimizing delays to output rate through advance planning of transfer operations.
Solution Approach 2:
The system maintains continuous useful action by coordinating inlet elevator transfers with outlet elevator operations and recirculation processes. The control unit ensures that load sequencing operations on inlet levels are continuously optimized to feed the outlet elevator without interruption, maintaining both sequence accuracy and high output rate through seamless operational continuity.
Data Source
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: if the inlet elevator has the status "waiting for recirculation", meaning that there is at least one load to be recirculated in the system (204), put on hold (205) until the transfer of at least one load to be recirculated onto the recirculation level; otherwise: selection (206 to 211) of a load at the exit of an inlet conveyor or at the exit of the recirculation level; if the selection (213) of one of the entry levels succeeds, generation (219) for the entry elevator of a transfer mission of the selected load on the selected level, otherwise assignment (216) to it of the status "waiting for recirculation", selection (218) among the entry levels of a level to be recirculated (assignment of the status "to be recirculated" to the load(s) on it) (without generation for the entry elevator of a transfer mission).