Processing Line Backlog Control With Feed Forward Speed Balancing
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Solution Overview
Problem
Existing processing lines experience jerky or start-stop operations due to discreet speed levels, requiring operator intervention and resulting in inefficient use of space and longer conveyor lengths.
Innovation Solution
A model-based speed and backlog control system that utilizes real-time calculations and feedback to automatically adjust machine speeds, incorporating a PID control and a feed forward control mechanism to maintain optimal backlog levels, reducing the need for operator interaction and minimizing conveyor length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional photo electric eye control systems are used to control machine speeds, then the processing line can operate with discrete speed levels, but this causes fault-inducing jerky or start-stop operation and requires operator intervention
Solution Approach 1:
The control system continuously monitors the actual backlog level and compares it to the desired backlog setpoint, using this feedback to dynamically adjust machine speeds. This closed-loop feedback mechanism eliminates the need for operator intervention while maintaining smooth operation by preventing both excessive accumulation and starvation conditions.
Solution Approach 2:
The system transitions from discrete speed levels to continuous speed adjustment, allowing machines to operate at any speed within their range. This dynamic speed control enables smooth acceleration and deceleration, eliminating jerky start-stop operations while maintaining the desired backlog level.
2Device complexity
If traditional control systems with discrete speed levels are used, then speed control is simplified, but this results in longer conveyor lengths and greater space occupation
Solution Approach 1:
The system changes the control parameter from discrete speed levels to continuous speed values, and from open-loop control to closed-loop feedback control. This allows the conveyor length to be minimized while maintaining proper backlog levels, as the continuous speed adjustment can respond more precisely to backlog conditions.
3Productivity
If machine speeds are manually adjusted by operators, then discrete speed levels can be maintained, but this reduces productivity and requires operator attention
Solution Approach 1:
The control system automatically balances machine speeds and maintains desired backlog levels without operator intervention. The system monitors backlog conditions and self-adjusts speeds in real-time, freeing operators for other value-added tasks while maintaining optimal productivity.
4Reliability
If continuous speed adjustment is implemented, then operation smoothness is improved, but this increases control system complexity
Solution Approach 1:
The control system uses feedback from backlog level measurements to continuously adjust machine speeds. This feedback mechanism enables smooth continuous operation while managing complexity through a structured control approach that automatically adapts to changing conditions.
Data Source
AI summary
A processing line includes a conveyor for conveying product from upstream processing equipment to downstream processing equipment. Data structures stored in a memory of a controller comprise a backlog set point for a product type to be processed. A product sensor for the conveyor is enabled to generate signals representative of a number of the products moving on the conveyor from the upstream processing equipment for delivery to the downstream processing equipment. A conveyor speed sensor for the conveyor is enabled to generate signals representative of a speed of the conveyor. A backlog measurement based upon the product sensor signals and the conveyor speed sensor signals is determined. The backlog measurement is compared to the backlog set point to determine a difference in backlog. The controller is enabled to generate signals for controlling the processing line based upon the difference in backlog and additional information related to the product type.