ELC 4332/5 Lab Hardware

ELC 4332/5: Control Systems Labs

Introduction to Lab Hardware

Material taken from: Quanser DC Motor Control Trainer – USB QICii Laboratory Workbook.Last Modified: John Miller, 6/9/14

Objective

This exercise will introduce you to the Quanser DC Motor Control Trainer (DCMCT) and the QICii software used to control it.

Introduction

A system’s dynamic equations may be determined in several ways. They may be found by deriving the equations knowing the parameters such as mass, spring constants, resistor values, etc. They may also be found by a technique similar to the process used in linearization, in which all parameters except one are held constant and that parameter is varied. Then the output is observed, and the equation relating the two is determined. This lab focuses on the first technique (called “first principles modeling”), but it requires knowledge of the mass, spring constants, resistor values, etc. Therefore, it will be necessary to determine these parameters for the DCMCT in order to develop its transfer function.

DC Motor Control Trainer (Hardware)

Figure 1 gives an overview of the hardware used in these labs. The main board consists of a DC motor, electronic control circuitry, connectors, and a daughterboard that houses the USB interface.

Figure 1. Quanser DCMCT.

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Other Connectors

DC Motor

Disc Load

USB Connector

White “Reset” button

Black “User Switch”

LEDs

ELC 4332/5 Lab Hardware

QICii Software

Figure 2 shows what the QICii software screen looks like. The black boxes at top left and the graphs on the right are updated in real time. The white boxes on the left are the inputs. Table 1 lists and describes the numbered items.

Figure 2. Screen shot of the QICii software.

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Menu for choosing exercise

Connect to hardware

Start/stop experiment

Auto-scale both axes

Stop graphs (experiment continues)

ELC 4332/5 Lab Hardware

Table 1. QICii software nomenclature.

ID# Label Parameter Description Unit1 Speed ωm Motor Output Speed (numeric display) rad/s2 Current Im Motor Armature Current (numeric display) A3 Voltage Vm Motor Input Voltage (numeric display) V4 Signal

GeneratorType of Generator for the Input Voltage Signal

5 Amplitude Generated Signal Amplitude (input) V6 Frequency Generated Signal Frequency (input) Hz7 Offset Generated Signal Offset (input) V8 Speed ωm Scope with Actual (red) and Simulated (blue)

Motor Speedsrad/s

9 Voltage Vm Scope with Applied Motor Voltage (red) V10 K K Motor Model Steady-State Gain (input) rad/(V*s)11 τ τ Motor Model Time Constant (input) S12 Tf Tf Time Constant of Filter for Measured Signal s

Module Startup

1. Connect the DCMCT to both power and USB. LED2 should light up, while LED3 should flash on and off repeatedly.

2. Press the “Reset” (white) button (LEDs shouldn’t change), then the black “User Switch.” LED2 and LED3 should turn off.

3. Launch the QICii software (if you haven’t already), and select Modeling in the drop-down menu.

4. Click the “Connect to data source” (hardware) button next to the drop-down menu. The controller should start running, LED2 should light up, and LED3 should stay off.

5. The following default parameters should be loaded when you start the module:

Signal Type

Amplitude (V)

Frequency (Hz)

Offset (V)

K (rad/V.s)

τ (s)

Tf

(s)Square 2.0 0.4 0.0 10.0 0.2 0.01

IMPORTANT! When changing the input parameters (for the signal generator or model), you must press Enter for the change to take effect.

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ELC 4332/5 Lab Hardware

Initial Experimental Tests

Answer the follow questions and record the required data:

6. Set the Amplitude to 0 and vary the Offset over its full range. What do you observe about the steady-state speed and current?

The current remains almost constant at 0 amp, but the speed increases and decreases with the increase or decrease in the offset voltage input, the signs also change accordingly

7. What is the maximum allowed voltage (Offset) input? What is the speed at this input?

Max offset +5 V Speed = 73 rad/sec

8. Set the Offset to 0 and the Amplitude to 2 V. Measurements can be taken from the graphs

by clicking the magnifying glass icon , holding down Ctrl, and clicking and draging on the graph. Use this method to measure the period and the amplitude of the of the actual (red line) speed of the motor.

Period = 2.518 Amplitude = 25.8

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