Conduct Model-Based Control Design with LabVIEW
PrintControl design engineers today face a variety of challenges. Whether they are aerospace engineers designing control systems to launch satellites or chemical engineers developing chemical control processes, engineers seek easier, faster ways to design and implement high-performance controllers. While competition pushes machine builders to produce faster machines, smaller components for semiconductor and biotechnology force higher precision. Additionally, increasing fuel costs and government regulations require higher efficiencies for passenger vehicles and large equipment. These changes mean that companies traditionally not involved in model-based control design find it thrust upon them. Companies that were already involved in control design now are forced to produce higher-performing control systems than ever before.
Trade Many Design Tools for One Environment
Traditional approaches demand engineers use one environment for control design, another for simulation, a third for analysis, and yet another for real-time implementation. Not only does this require engineers to learn the intricacies of many different design tools, it also causes them to waste time integrating multiple tools that they could spend designing better products. By using a single environment for system identification, control design, simulation, analysis, and real-time implementation, engineers need learn only a single environment and eliminate time wasted on tool integration. This makes it easier for engineers introducing control design into their product life cycles to get started. For experienced control design engineers, using a single environment gets their products to market faster and helps them focus on higher-speed, higher-precision control systems rather than on tool integration issues.
With the introduction of control design add-on tools for LabVIEW, National Instruments now delivers a single graphical environment for system identification, control design, simulation, and analysis. Without changing their code, engineers can download control algorithms and simulated systems to real-time hardware for rapid control prototyping or hardware-in-the-loop (HIL) simulation. Because LabVIEW is also a full-featured graphical programming language, engineers can use the same environment for creating custom functionality in their control applications. LabVIEW and the add-on control design tools reduce the integration burden and lower the learning curve to help experienced control design engineers refine their control strategies and engineers developing new control design applications benefit from model-based control design.
Take Advantage of NI Control Design Innovation
NI is committed to continuous innovation in control and control design. Before 2004, NI had tools for PID and fuzzy logic control implementation. NI also provided the LabVIEW Simulation Interface Toolkit, so engineers can directly import The MathWorks, Inc. Simulink® models into LabVIEW and use interactive graphical user interface technology to implement them in real-time hardware and instrumentation. In 2004, National Instruments multiplied its control design offering with the release of three new add-ons -- the LabVIEW System Identification Toolkit, LabVIEW Control Design Toolkit, and LabVIEW Simulation Module. The National Instruments broad control design portfolio simplifies plant model and control system development, system analysis with offline simulations, and control system implementation in real-time hardware. Using this interactive, graphical technology, engineers new to the process can easily adapt open-loop control systems or PID closed-loop control systems to more advanced control systems.
PID controllers are appropriate for some applications requiring simple system control. For PID controller development, engineers can use the LabVIEW Control Design Toolkit to work in an interactive environment to vary the PID gains and immediately view time responses, including step responses as well as frequency-response information. After developing these gain parameters, engineers implement them using the LabVIEW PID Control Toolkit. With this toolkit, engineers can specify the PID parameters in the LabVIEW environment and use the LabVIEW Real-Time Module to easily implement the controller in NI real-time hardware, such as CompactRIO, Compact FieldPoint, or PXI. Control engineers can use this tool to develop custom graphical user interfaces so operators can tune PID controllers as desired. The PID Control Toolkit also provides functionality for fuzzy logic control system design and implementation.
systems or connect to real-world I/O for controller implementation or hardware-in-the-loop testing.
Obtain Tighter Control with NI Bundle
For more complex applications requiring tighter control, engineers may want to use classical or modern model-based control design. Over the last several years, NI has invested heavily to optimize LabVIEW and address these applications. As these applications moved into closed-loop control, NI responded with a broad range of software and hardware to facilitate more productive development and implementation of high-speed, high-precision control systems. The NI LabVIEW Control Design and Simulation Bundle includes four toolkits and one module that extend the LabVIEW function set to system identification, control design, and simulation. With the LabVIEW System Identification Toolkit, engineers can use real-world I/O to develop dynamic system models of linear single input, single output (SISO) or multiple input, multiple output (MIMO) systems. The NI LabVIEW State Diagram Toolkit provides a state diagram editor to represent state machine logic in state diagram form for implementation in a LabVIEW graphical block diagram. The LabVIEW Control Design Toolkit offers a flexible, interactive set of tools, such as interactive Bode plots and root locus plots with pole-zero analysis, to develop and analyze control systems. In addition to providing LabVIEW functionality, the System Identification and Control Design toolkits also include separate, stand-alone tools for interactively analyzing real system data and designing control systems. These stand-alone tools -- the LabVIEW System Identification Assistant and the LabVIEW Control Design Assistant -- integrate with National Instruments SignalExpress for I/O. Engineers can convert the applications they build in the stand-alone tool to LabVIEW block diagrams so they can add custom functions, perform simulation, and integrate I/O.
With the LabVIEW Simulation Module, engineers can use the same LabVIEW environment for simulation that they used for system identification and control design. It provides a means to represent dynamic systems, such as high-fidelity, nonlinear systems, in block diagram form and to simulate system behavior over time within the LabVIEW environment. Engineers easily can convert these offline simulations to real-time implementations simply by replacing simulated signals on the block diagram with built-in LabVIEW I/O functions. National Instruments I/O is widely used in control and control design applications, as evidenced by Control Design readers awarding the magazine's 2004 Reader's Choice Award for Data Acquisition Hardware and Software to NI. Using the LabVIEW Real-Time Module, engineers can connect simulations of systems and control algorithms to this I/O on real-time targets for rapid control prototyping and HIL simulation or implementation.
Finally, engineers using Simulink can take advantage of LabVIEW interactive graphical user interface technology and real-time implementation through the LabVIEW Simulation Interface Toolkit. With the Simulation Interface Toolkit, engineers can easily map LabVIEW user interface controls and indicators to Simulink parameters and signals to instrument models. The Simulation Interface Toolkit also helps engineers needing real-time implementation use a compiled Simulink model in the LabVIEW block diagram. This means that engineers can reduce cost and increase I/O options for deployment because they can use any NI real-time target -- CompactRIO, Compact FieldPoint, PXI modules, Compact Vision System, PCI boards, and even desktop PCs. LabVIEW Real-Time supports FPGA, high-speed 18-bit data acquisition, image acquisition, motion control, controller area network, and serial (RS232/RS485) I/O natively.
Create Control Systems Easier and Faster
National Instruments has invested hundreds of man-years in developing revolutionary add-on software and hardware tools to abstract complex tasks -- including I/O, system identification, control design, simulation, and real-time implementation -- so that engineers can focus on creating tight control systems with high precision rather than wrestling with manual control system analysis or complex real-time targets. These tools combine to provide a single environment for control design engineers to use through the entire process of analyzing dynamic systems, developing controllers, and implementing closed-loop control systems. Along with the close tie to hardware, this means that engineers spend minimal time on integration and spend more time on creating high-performance control applications and getting them to market faster.
Kim Lankford
LabVIEW Control Design Senior Product Manager
kim.lankford@ni.com
Simulink® is a registered trademark of The MathWorks, Inc.
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