Introduction

Assessment

Getting Started

Terminology

Equipment

Training Lab

Experiment 1

Experiment 2

Experiment 3

Experiment 4

Experiment 5

Optional Experiment

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Armature - The moving part of an alternator, generator or motor.

Armature Control - Abbreviated term for armature voltage control of a DC motor, which describes the usual method of changing the speed of a DC motor by controlling the magnitude of applied armature voltage.

Constant - a number representing a quantity assumed to have a fixed value

Controller - a device or set of devices to manage, command, direct or regulate the behaviour of other devices or systems

Delay Time - The delay time (Td) is the time taken for the response to reach 50% of its final value

DC Motor - A DC motor is an electric motor that runs on direct current (DC) electricity

Field Control - Method of controlling DC motor speed by varying the field current in the shunt field windings.

Gain Margin - The gain margin is defined using the overall open loop system transfer function. To measure the gain margin, you can use compare the error signal and the feedback signal inside the closed loop system for a sine wave input. Note that if the system only has two poles, the gain margin would be infinite.

Adjust the frequency until the phase shift between the two signals is -180 degrees. The gain margin is the ratio of magnitude of the error signal to the feedback signal.

 

Linear - Relationship between input and output in which the change in output varies in direct proportion to the change in input

 Load - A load of a motor is anything that causes force to be exerted on the rotor.

Percentage Overshoot - The maximum overshoot (Mp which occurs at time tp) is the maximum peak value of the output (c(t)) signal measured from the final steady state value of the signal c(t). The percentage overshoot is the ratio of the maximum overshoot to the final steady state value expressed as a percentage.

Percent overshoot 

 

Phase Margin -  The phase margin is defined using the overall open loop system transfer function. To measure the phase margin, you can compare the error signal and the feedback signal inside the closed loop system for a sine wave input.

Adjust the frequency until the magnitude of the two signals is the same. The phase margin is obtained from the phase difference between the two signals.

Position Error Constant - The error constant Kp specify the steady state response characteristics and you need to choose the right frequency for the input signal to give time for the error signal to settle down.

The position error constant can be measured using a square wave input. When the input step signal has a peak to peak magnitude of A V instead of being a unit step, the value of Kp becomes



Resonant Peak & Resonant Frequency - The resonant frequency and resonant peak are defined using the closed loop frequency response. To measure these two quantities you measure the input (sinewave from the function generator) and output of the closed loop system. The resonant frequency is the one where the closed loop gain has a peak value. This frequency is the resonant peak of the closed loop system.

 

Rise Time -  The rise time (Tr) is the time taken for the signal to rise from 10% of its final value to 90% of its final value.

Rotating Shaft - a revolving rod that transmits power or motion.

Settling Time - The settling time is the time required for the response curve to reach and stay within a 5% range about its final steady state value.

Square Wave Input - The function generator only produces asymmetrical square waves.

Torque - Turning force, equal to force times radius

Velocity Error Constant -  The error constant Kv specifies the steady state response characteristics to a ramp input and you need to choose the right frequency for the input signal to give time for the error signal to settle down.

The velocity error constant can be determined by measuring the steady state error to a triangular wave input. First put in as large a triangular wave as possible. The peak to peak ramp rate of the input will be + and - 2fA Volts per second where A is the peak to peak amplitude of the triangular wave and f = 1/T is its frequency in Hz. Measure the steady state error ess under this triangular input in one direction and the velocity constant can then be determined using