Metal thickness control model based inferential sensor

Abstract

A rolled sheet metal mill controller for controlling thickness of sheet metal produced by rolls of the mill, the controller comprising one or more processors and code stored on media readable by the one or more processors to control the thickness of the produced sheet metal, the controller including an input coupled to receive multiple measured mill parameters including produced sheet metal thickness that is time delayed from the production of the sheet metal, multiple models of the sheet metal mill, wherein the sheet metal thickness is modeled as an input varying delay, and at least one internal disturbance model based on one or more of the multiple measured parameters coupled to the input, a Kalman filter based on the multiple models, and an output coupled to control a gap between the rolls that produce the rolled sheet metal.

1 . A rolled sheet metal mill controller for controlling thickness of sheet metal produced by rolls of the mill, the controller comprising one or more processors and code stored on media readable by the one or more processors to control the thickness of the produced sheet metal, the controller comprising:
 an input coupled to receive multiple measured mill parameters including produced sheet metal thickness that is time delayed from the production of the sheet metal;   multiple models of the sheet metal mill, wherein the sheet metal thickness is modeled as an input varying delay, and at least one internal disturbance model based on one or more of the multiple measured parameters coupled to the input;   a Kalman filter based on the multiple models; and   an output coupled to control a gap between the rolls that produce the rolled sheet metal.   
     
     
         2 . The rolled sheet metal mill of  claim 1  wherein the multiple models include a rolling model with a corresponding input of roll torque. 
     
     
         3 . The rolled sheet metal mill of  claim 1  wherein the multiple models include a gap control model with a corresponding input of rolling force. 
     
     
         4 . The rolled sheet metal mill of  claim 1  wherein the multiple models include a main drive model with a corresponding input of roll speed. 
     
     
         5 . The rolled sheet metal mill of  claim 1  wherein the communication delay is a function of a variable transport delay input. 
     
     
         6 . The rolled sheet metal mill of  claim 1  wherein one or more internal disturbances that are modeled are selected from the group consisting of backup and work roll eccentricity, work roll thermal crown, work roll mechanical wear, and backup roll bearing flotation. 
     
     
         7 . The rolled sheet metal mill of  claim 1  wherein the Kalman filter is based on the models and is robust to known parametric uncertainties. 
     
     
         8 . The rolled sheet metal mill of  claim 1  wherein the Kalman filter includes filter parameters adjusted as a function of measured mill parameter values from operation of the sheet metal mill. 
     
     
         9 . A method of programming a controller for a rolled sheet metal mill, the method comprising:
 obtaining a physical representation of the rolled sheet metal mill;   identifying available measurements for generating inferential estimates of internal states of the rolled sheet metal mill;   correlating key internal disturbances to the available measurements to model the rolled sheet metal mill;   generating a Kalman filter based on the model; and   adding the Kalman filter to the controller such that the controller is programmed to provide closed loop control thickness of sheet metal produced by the sheet metal mill.   
     
     
         10 . The method of  claim 9  and further comprising testing the controller as a function of operation of the rolled sheet metal mill. 
     
     
         11 . The method of  claim 10  and further comprising adjusting Kalman filter parameters responsive to the testing. 
     
     
         12 . The method of  claim 10  wherein the multiple models include a rolling model with a corresponding input of roll torque. 
     
     
         13 . The method of  claim 10  wherein the multiple models include a gap control model with a corresponding input of rolling force. 
     
     
         14 . The method of  claim 10  wherein the multiple models include a main drive model with a corresponding input of roll speed. 
     
     
         15 . The method of  claim 10  wherein the communication delay is a function of a variable transport delay input. 
     
     
         16 . The method of  claim 10  wherein one or more internal disturbances that are modeled are selected from the group consisting of backup and work roll eccentricity, work roll thermal crown, work roll mechanical wear, and backup roll bearing flotation. 
     
     
         17 . A rolled sheet metal mill controller comprising:
 a processor;   a sensor; and   a memory device coupled to the processor and having a program stored thereon for execution by the program processor to:
 receive an input of multiple measured mill parameters from the sensor including produced sheet metal thickness that is time delayed from the production of the sheet metal; 
 process multiple models of the sheet metal mill, wherein the sheet metal thickness is modeled as an input varying delay, and at least one internal disturbance model based on one or more of the multiple measured parameters coupled to the input; 
 execute a Kalman filter based on the multiple models; and 
 provide an output coupled to control a gap between the rolls that produce the rolled sheet metal. 
   
     
     
         18 . The controller of  claim 17  wherein the multiple models include a rolling model with a corresponding input of roll torque, a gap control model with a corresponding input of rolling force, and a main drive model with a corresponding input of roll speed. 
     
     
         19 . The controller of  claim 17  wherein the communication delay is a function of a variable transport delay input. 
     
     
         20 . The controller of  claim 17  wherein one or more internal disturbances that are modeled are selected from the group consisting of backup and work roll eccentricity, work roll thermal crown, work roll mechanical wear, and backup roll bearing flotation.