Rolling Mill Setpoint Compensation for Actuator Limit Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing roll stand control systems face performance limitations due to temporal variability in setpoints, leading to power deficits in actuators, which cannot be adequately compensated by known control circuits, resulting in instability and quality issues during the rolling process.
Innovation Solution
The method involves monitoring the time profile of setpoints against threshold values to initiate preventive corrections, ensuring the master actuator operates within its performance limits by adjusting the setpoint with calculated correction components, and utilizing multiple slave control circuits to compensate for any actuator deficiencies, thereby maintaining optimal operating points and reducing oversize lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the setpoint for the first controlled variable is made time-varying to compensate for changes in process variables, then the rolling process can adapt to process changes, but the actuator reaches its performance limit and cannot execute the setpoint accurately
Solution Approach 1:
The invention applies preliminary action by proactively monitoring the setpoint trajectory and detecting when it approaches the actuator's performance limit before the limit is reached. The correction is initiated in advance by reducing the setpoint when the slope exceeds a threshold, preventing the actuator from entering a non-executable state and maintaining position accuracy throughout the rolling process
Solution Approach 2:
The invention implements feedback by continuously monitoring the setpoint's time derivative (slope) and comparing it against a predefined threshold. When the slope exceeds the threshold indicating approaching performance limits, the system provides feedback by automatically reducing the setpoint to bring it back within the actuator's executable range, creating a closed-loop control mechanism
2Manufacturing precision
If the setpoint is reduced to stay within actuator performance limits, then the actuator can execute the setpoint accurately, but the rolling stability and product quality deteriorate
Solution Approach 1:
The invention applies dynamics by making the setpoint adaptive rather than static. The setpoint is dynamically adjusted based on real-time monitoring of its slope characteristics. When the slope exceeds the threshold, the setpoint is reduced to maintain executability; when the slope is acceptable, the original setpoint is maintained to preserve rolling stability and product quality
Solution Approach 2:
The invention implements parameter changes by modifying the setpoint parameter based on its derivative (slope). The system changes the setpoint value dynamically - reducing it when the slope indicates approaching performance limits and maintaining it when conditions are favorable - thereby optimizing both actuator accuracy and rolling stability under different operating conditions
3Manufacturing precision
If multiple slave control loops are added to compensate for actuator deficits, then the system can maintain control accuracy, but the device complexity increases
Solution Approach 1:
The invention applies segmentation by dividing the control system into a hierarchical structure with one master control loop and multiple slave control loops. The master loop handles the primary controlled variable with setpoint management, while slave loops handle secondary controlled variables. This segmentation allows the system to maintain high control accuracy through coordinated multi-loop control while keeping each individual loop relatively simple and manageable
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method for operating a rolling mill 100, to which a first and at least one further control loop for controlling various control variables are assigned. According to the invention, the temporal profile of the setpoint SMset* for the first or master control variable is monitored to determine whether the setpoint falls outside a predetermined tolerance range T. If so, the invention provides for the calculation of a corrected, i.e., reduced or increased, setpoint for the master control variable, thereby ensuring that the setpoint returns to the tolerance range. Furthermore, according to the invention, the calculated correction components for the master control variable are also used to calculate a compensation component for the setpoint of a slave control variable.By ensuring, according to the invention, that the setpoint remains within the tolerance range, it is ensured that at least one master actuator 132 of a master control loop 130 does not reach its physical performance limits.