VisSim/Real-TimePRO

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The Windows Solution for Hardware-in-the-Loop Systems

VisSim/Real-Time is a VisSim option that lets you connect your VisSim model directly to the external world through digital and analogue I/O blocks. With VisSim/Real-Time, hardware-in-the-loop (HIL) systems can be configured and executed by interfacing VisSim plant or controller models with real-world hardware, such as manufacturing plants, chemical processes, motors, pumps and electric drives. VisSim/Real-Time supports analogue and digital I/O boards from Measurement Computing, National Instruments, Advantech and ACS Tech80. No code generation or programming is required to configure and use VisSim/Real-Time.

VisSim/Real-Time is used successfully in a wide variety of industries to :

• Develop and validate control strategies

• Perform off-line tuning of controllers against a real-time plant
• Perform real-time control of actual plant
• Train the system operators on a real-time plant simulation rather than actual plant

With VisSim/Real-Time, engineers can perform real-time simulation, data acquisition and control directly from Windows 9x/NT/2000/XP. There is no code generation or programming involved. There is virtually no difference between running a regular VisSim simulation and a real-time HIL system.

A list of computer I/O boards that can be used to interface your PC to real world hardware can be found here.

Configuring a Hardware-in-the-loop System

Connecting VisSim to the real world is simple:

• Select the I/O card(s) from the list of supported boards
• Install the I/O card(s)
• Place realTime dataIn and dataOut blocks into the VisSim diagram for each I/O channel to be accessed
• Right click each realTime block to configure as analogue, digital, counter, volts, encoder, PWM, 4-20 ma or thermocouple in the dialogue box
• Select "run in real-time" in the simulation properties dialogue

• Click "Go"

VisSim/Real-Time lets you execute your VisSim based control algorithm to control a physical plant in real-time up to 20 kHz sampling rates. This lets you rapidly prototype different control strategies.

Off-line tuning of controllers is done by developing a plant model that runs in real-time. Then plant I/Os are connected to the control hardware via VisSim/Real-time to fool the controller under test to thinking it is connected to a real plant. By leveraging VisSim's fast execution speed, this is an excellent way to check out controller performance against an accurate plant model.

When the control validation is complete, the control hardware is disconnected from the plant model and connected directly to the real plant. This process ensures faster, safer and less costly system and equipment ramp-ups. Off-line tuning is especially useful in the process control industries as it enables validation of controller design without any equipment shut down. It is an important technique for use with sensitive equipment where a poorly designed or untested controller could result in costly damage to the equipment.

The Motor and Drive Systems Division of General Electric (GEMIS), based in Salem, Virginia, USA, is one of the world's largest manufacturers of electrical drive systems. Using VisSim and VisSim/Real-Time, GEMIS engineers recently completed prototyping a Resonance Eliminator Controller (REC) for industrial drive systems used in metals rolling applications. The goal of the controller, according to Emil Kuelz and Sandy Gurian, System Engineers for GEMIS, is to reduce resonance vibrations in the shafts and rolls of the mechanical system. Kuelz and Gurian modeled the motor and mechanical system in VisSim, and then incorporated the REC. The REC computes a motor torque correction signal from shaft torque measurement, which in turn is applied to the mechanical system at a specific resonant frequency.

To test the design, Kuelz and Gurian used two PCs, each running VisSim/Real-Time. One PC contained the motor and mechanical system simulation; the other, the REC. VisSim's A-D/D-A real-time interface allowed the two models to exchange information. This configuration verified that controller performance would not be degraded by either time delays introduced by the A-D/D-A conversions or the precision of the 12-bit DAC. "The simulation results assured us that the REC would function properly when attached to the actual motor and mechanical system," said Kuelz.

After verification, Kuelz and Gurian disconnected the PC with the REC from the PC with the motor and mechanical system simulation, and reconnected it to the real motor and mechanical system in GEMIS's in-house laboratory. The first time the REC was turned ON, it totally eliminated the mechanical system resonance.

By developing and testing the REC in VisSim and VisSim/Real-Time, Kuelz and Gurian focused exclusively on proving the viability of the design. "The risks of connecting an unproved design to a large horse power electrical drive and mechanical system are great," said Kuelz. "If incorrectly designed and not thoroughly tested, it can cause motor, shaft, and coupling failure, resulting in a process outage costing millions of dollars."

HIL simulation is a critical requirement for the chemical, petrochemical, power, paper & pulp, pharmaceutical and food process industries. The cost of inefficient control strategies or poor product/controller transitions is enormous. Companies like DuPont (Non-Woven and AFS Spruance facility, Richmond, Virginia, USA) are successfully using VisSim/Real-Time to validate, tune and monitor their process control equipment. Read the DuPont case study here.

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