AUTOMATION BUILDING ENERGY AND INDUSTRIAL

Overview


For engineers who need to identify system behavior and design controllers to obtain the best possible closed loop system characteristics, National Instruments (NI) provides LabVIEW based software tools and flexible, low cost hardware solutions. This is a superior alternative to expensive fixed-functionality systems. Unlike these embedded, inflexible alternatives, NI products provide an easy to use, integrated graphical environment and built-in compatibility across a broad range of data acquisition and control hardware devices.







Table of Contents

1.1. Introduction

2.2. Identifying the System

3.3. Controller Design

4.4. Simulating the Closed Loop System

5.5. Driving the Motor with the closed loop system

6.6. Conclusions

1. Introduction

This article describes the process of designing a closed loop control system, or plant, using the NI System Identification and Control Design Assistants. A DC Motor will be the plant (Figure 1).





Figure 1: The Quanser Engineering Trainer (QET) will be the plant for which we will design a closed loop controller.





The Quanser Engineering Trainer will be used in velocity mode. A voltage signal commands the motor to move and the tachometer output determines the velocity. The motor system is connected to a National Instruments CompactDAQ device, shown in figure 2, where Analog Input Channel 0 of a 9211 Analog input module (AI0) is connected to the tachometer and Analog Output Channel 0 of a 9233 Analog output channel (AO0) is connected to the motor command input. For demonstration purposes, you can replace the DC motor with an RC circuit.







Figure 2: CompactDAQ system