Offline, RCP, and HIL Configurations (Control Design and Simulation Module)

The following sections provide an overview of the process you might use to simulate a dynamic system. The following sections also describe examples of offline simulations, rapid control prototyping (RCP) configurations, and hardware-in-the-loop (HIL) configurations.

Offline Simulation

An offline simulation is one that is not connected to any hardware. You use the LabVIEW Control Design and Simulation Module to simulate all parts of the dynamic system, including the controller, the system you want to control, and any inputs or outputs. The following figure represents a simulation of an offline control system.

If you are running an offline simulation on a Windows computer, National Instruments recommends you place a checkmark in the Synchronize Loop to Timing Source checkbox on the Timing Parameters page of the Configure Simulation Parameters dialog box for optimal performance.

Rapid Control Prototype Configuration

An RCP configuration replaces the simulated system with an actual system. Use this configuration to test multiple controller algorithms without building the controller again every time you make a change. In this situation, the simulated controller is connected to hardware actuators and hardware sensors. To convert an offline simulation to an RCP configuration, remove the system model from the simulation. Replace the system input with an output from a hardware device, and replace the system output with an input from a hardware device.

The following figure represents an RCP configuration.

In the previous figure, the simulated controller uses National Instruments real-time hardware, such as a DAQ device, to send data to the hardware system.

Hardware-in-the-Loop Configuration

A HIL configuration involves the actual controller providing input to a simulated system. Use this configuration to test a controller on a system without actually having that system available. For example, if you were testing an engine control unit (ECU) for a car, you could test the ECU without having to build the car multiple times. HIL configurations also are useful for testing controllers under extreme conditions that you cannot replicate conveniently in a laboratory.

To convert an offline simulation to a HIL configuration, remove the controller model from the simulation. Replace the controller input with an output from a hardware device, and replace the controller output with an input from a hardware device. The result is similar to the RCP configuration, except with the controller model, not the system model, replaced with physical hardware inputs and outputs.

The following figure shows a HIL configuration of the example in the previous figure.

In the previous figure, the controller uses National Instruments real-time hardware, such as a DAQ device, to send data to the simulated system.