Tim Gellner, director of operational consulting at systems integrator Maverick Technologies, Columbia, Ill., says better graphics with higher resolution aren’t needed. “The sole function of graphic displays is to provide the operator with timely, easily digestible information about the process being controlled and to facilitate the operator’s ability to make the correct decisions when a process upset occurs,” says Gellner. “Unless better graphics can enhance this functionality, they may just be glitz. On the other hand, when using simulation tools for analyzing work streams and product flows through a facility for optimization purposes, the more realistic the graphics, the better the simulation, and the higher the impact.”
Greg McMillan, principal consultant, Emerson Process Management, adds that, “Graphics aren’t as important for process and control system design studies, but they sure help sell the idea and impress users—particularly the ones holding the purse strings.”
Jonathan Phillips, Arena Simulation product manager at Rockwell Automation agrees. “Simulations with detailed animation aid in selling whatever is presented,” he says. “Also, they can help when the audience may not have a great understanding of the system or isn’t focused on its minute details, such as an engineer presenting a proposal to accountants about a capital expenditure.”
Discrete automation simulations generally have better graphics than process modeling. “Discrete automation simulations benefit from detailed visualization,” says Hosni Adra, product manager/partner at CreateASoft. “Graphics help identify where a robot can be positioned in relation to parts and other equipment to improve efficiency and performance.”
For example, CreateASoft built a Simcad simulation of a 300,000 sq ft warehouse. “The company needed to improve efficiency of its put-away process with available material handling equipment,” explains Adra. (Go to www.controlglobal.com/0810_SimWarehouse.html for this video.)
Proposed changes included moving racks further apart and losing one rack of capacity, but the Simcad simulation showed it would work. So, the company reduced head count and improved velocity, and reduced put-away time from 7 hours to 3.5 hours. In the video, you can see simulated robots, AGVs and people scurrying around the warehouse.
Likewise, Molded Fiber Glass (MFG) in Ashtabula, Ohio, produces parts from polyester resins and fiberglass reinforcements (FRP). Robert Morrison, MFG’s founder, says they used Simcad to model a composites manufacturing plant. “The model required tracking multiple variables including cycle times, labor costs, and manpower utilization,” he says. “The goal was to detect and identify bottlenecks, and reduce overall production costs. Using Simcad’s graphical interface, MFG built the model representation of the manufacturing line, and then added manpower allocation and cost detail.”
Using results from Simcad’s animation and line analysis, MFG found its bottlenecks, adopted a proces flow that saved one man hour per part, maintained current production rates, and reduced labor required at the plant.
Driving a Simulator
Tomorrow’s engineers, accustomed to the fast response of computer games, will be bored with traditional process simulators.
“Traditional simulation requires an operator to generate and pass code to a computing engine, which then has to be compiled,” explains Adra. Once the simulation starts, changes can’t be made in a traditional simulator.
The first step in a dynamic simulation, then, seems to be automating the way a simulation is set up.
“ExperTune’s PlantTriage software uses active-model capture technology to develop process models from normal operating data,” says George Buckbee of ExperTune. “The software monitors the process 24x7, finding, qualifying and storing models in a database, so they’re ready for use. This software helps engineers develop a detailed understanding of the dynamic process response. With these models, they can choose control strategies and tuning for optimum process results.”
For instance, Eli Lilly pulled historical data, and fed it into ExperTune’s PID Loop Optimizer to develop dynamic process models of a bioreactor. These model pairings were then used to develop an MPC controller. It was tested offline in a simulator before implementation in the real reactor.
As for “driving” a simulator, many “traditional” simulators can do it. Gellner says, “Even in simple loop-back simulations you can modify parameters on the fly by testing controllers’ responses under well-defined and documented scenarios.”
However, vendors don’t promote dynamic simulation very well. Perhaps because it’s new ground, and many vendors are busy preparing next-generation simulators. Vikas Dhole, vice president of engineering product management at AspenTech, agrees this is possible, but yet scarce. “On-demand decision support provided via real-time simulations is available,” Dhole says. “The challenge is combining a simulation tool’s technical capabilities with a graphical interface that can interpret data quickly and easily. Though these two elements are converging, less than a handful of commercial players are able to support such product development, and even fewer have something available currently.”