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What’s the pneumonic for adding the proportional term?



What’s the pneumonic for adding the integral term?



What’s the pneumonic for adding the derivative term?



What does brush bounce do to a motor?

Limits maximum speed
Not good electrical contact
It’s a consequence of the commutator and springs forming a dynamic system


Name some devices that have open loop control

Cooling fan on a microchip, drill, brushed motor in a toy car


Name some devices that have PID control

Robotic arm
Industrial furnace
Cruise control on a car


Name some devices that have bang bang control

Refrigerator, heating system in house, electric oven


What’s the pneumonic for increasing PID in proportional term?



What’s the pneumonic for increasing PID in integral term?



What’s the pneumonic for increasing PID in derivative term?



True statements about kickback

A kickback diode should be able to withstand the stall current of the motor

Inductive kickback is larger for larger inductance

Fast recovery diodes should be used when mitigating kickback


Describe kickback graph from left to right

No snubber, diode and zener, zener only, diode and resistor, diode only


True facts about piezoelectric ceramics

Very brittle, exhibit hysteresis, expensive compared to other actuators, they have limited range of motion typically up to several millimetres at best, not affected by magnetic field, consume very little power, can be cycled over 100 million times, have a fast response


True facts about inchworm and ultrasonic based motors

Ultrasonic motors have smooth continuous motion

Ultrasonic motors use a travelling wave to induce motion in the rotor

Point of contact between piezo element and rotor in ultrasonic motors exhibits elliptical motion

Inchworm motors use a grasp-push-release approach to create pseudo-continuous motion

The operational frequenct of ultrasonic motors is typically tens of khz

Inchworm motors have higher fees rates

Inchworm piezo motors have larger ranges of motion


What does a photodiode do?

Measures the intensity of an illuminated object


What does an ultrasonic sensor do?

Measures the distance of an object


What does a strain gauge do?

Measures the bending of a beam


What’s the definition of an infrared sensor?

A sensor that emits light and then measures the intensity of the reflected light


What’s the definition of a photodiode?

A sensor that, when under an applied load, develops an electrical charge proportional to that load


A device that is composed of a semiconductor junction housed in an optically clear package that allows incident light to fall directly on the junction


What’s the definition of accuracy?

The largest expected error between actual signal output and ideal output signal


What is the definition of non linearity?

The maximum deviation of the sensor output with respect to a straight line fit of input signal versus output signal of the sensor


What’s the definition of hysteresis?

The difference between the output of a sensor depending on whether the input is rising or falling


True facts about sensorless communication

Back EMF is used to sense the position of the rotor

Measurement of coil inductance can be used to determine rotor position

It is possible for the motor to rotate in the wrong direction at start up

The motor must be rotating relatively quickly for this method to work


Facts about shape memory alloys

Expensive, generate large forces, dont require electrical power, high energy density, relatively slow response as compared to other actuators


Facts about shape memory alloys structure

When in austensite form, shape memory alloys can withstand very high strains without plastic deformation

When the crystal structure is martensite, the material may be deformed as desired

The martensite start temp is lower than the austensite finish temp

The shape of a shape memory alloys is trained at the annealing temp

Large forces are generated as the crystalline structure changes from martensite to austensite


True facts about torque ripple

Torque ripple decreases for higher frequency PWM signals

Torque ripple is a function of the motor coil inductive time constant


What’s the definition of a hall sensor?

A sensor in which a magnetic field creates a voltage across a conductor carrying a current


What’s the definition of noise?

The part of the sensor output that does not contain information about the input physical signal being measured


What’s the definition of an encoder?

A sensor that utilises a slotted disk to interrupt a beam of light


What’s the definition of sensitivity?

The change of output electrical signal to a unit change in the input signal