What Is A Simulation Model?

A simulation model is a model, built on a computer, which represents a system or a process. Most simulation models have a graphical animation (preferably 3-D) representing what is modeled. Simulations are built using a simulation software package such as Simul8, SLX, GPSS, Witness, or AutoMod (our preferred package). A highly detailed simulation will accurately reflect what is modeled in order to make simulation runs or experiments to predict system performance and behavior.

Our discrete event simulations are developed with the AutoMod Software by Applied Materials. This software allows a 3-dimensional animation to be created incorporating system characteristics. Data regarding customer throughput, volume and timeframes are incorporated to develop a working demonstration of system performance.

There is literally no limit to what can be simulated. Usually costly material handling or manufacturing systems are good candidates for simulation. The modeling efforts allow a system to be built and tested on a computer at a minimal cost compared to putting actual equipment out on the floor and testing it. Some examples of the types of systems for simulation modeling are explained below.

Manufacturing Systems
• Parts Production
• Operator or automated work cells
• Assembly processes
• Assembly systems

The simulation modeling of manufacturing systems is beneficial in determining and experimenting with production throughput capabilities. The systems capability for Jobs Per Hour (JPH) is key and simulation modeling will help in ensuring the highest rate of production for your system.

Material Handeling Systems
• Distribution centers
• Postal sortation
• Parcel and freight
• Storage and retrieval

Pieces Per Minute (PPM) is the key with these types of systems. Simulation modeling will help in creating smooth and balanced system operations. The system flow is tested and tweaked to ensure a high rate of system utilization during processing times.

When a typical simulation model is built it will be based on actual system layouts, operations, and controls. The model will behave as the system does. The models can use real world data for a thorough analysis.

A 3-dimensional model is built that incorporates the system behavior from conveyor speed to controls algorithms. The model is built to scale and will accurately reflect hardware characteristics such as speed, space and rate. When real world data is plugged into a simulation we get real world results.

The Purpose of Simulation Modeling

The purpose of simulation modeling is to reduce risk and costs through efficient and accurate system installations that do not require expensive modifications when the systems are supposed to have already been up and running.

Simulations serve a constructive purpose through the entire cycle of a system's life; from the original concepts to the observation of daily operations of an installed system. A proper simulation can be used for the testing of concepts or designs; providing animations of systems; examining systems operational characteristics or performing experimentation. The role of simulation modeling can be divided in the three essential categories of Sales and Conception, Design Verification, and Experimentation.

Sales
• Emphasis on animation
• Animation allows proposed system to be seen in action
• A clear understanding of the system can be derived
• Proven concepts can be shown
• A rough verification can be performed on system design

Design Verification
• Highly detailed simulation model
• Emulates the system design and control to be as close to actual as possible
• Allows the system design to be tested to verify that it will meet throughput goals
• Statistics can be gathered on almost any aspect of the system ranging from overall
   throughput to specific machine or resource utilizations
• Actual data and schedules can be incorporated in simulation model

Experimentation
• The most valuable portion of a simulation study to customer and system design engineers
• "What if" scenarios can be built into the base simulation model
• Sensitivity analysis for equipment (sort machines, buffers, accumulation)
• Effects of changes in system design or control may be studied and viewed
• A user interface can be developed to allow easy manipulation of model input data
  and chart separate model results

The value of a valid and proper simulation model is priceless. When a system is run and understood via a simulation model it will save time and money for the system vendor and user. Having the right staff to build a simulation is the key. With the experience of PSC you get that staff.