Sensors

Question 1

What is a potentiometer

Answer 1

The voltage output of the circuit is proportional to the displacement of the mechanical components.

A sliding contact moves along resistor coils

Question 2

Whats a Pro of potentiometers?

Answer 2

Cheap and easy

Question 3

Whats a con of potentiometers?

Answer 3

Wear over time

Does not handle shock, vibrations, moisture, and high temperature well

Question 4

What is a LVDT?

Answer 4

Linear Variable Differential Transformer

There are 3 coils. A voltage is applied to the middle coil. The position of a central coil determines the voltage induced into the other two coils, which represents the position.

Question 5

What is a pro and con of LVDTs?

Answer 5

Con:

Versatile and robust
Reliable in harsh environments due to no contact deisgn.

Pro:

High cost
Large

Question 6

What is an application of LVDTs on the frigate

Answer 6

CRPP

Question 7

What is a Linear Encoder?

Answer 7

Employs optical or magnetic gratings that supply a stream of digital signals which are affected what you are measuring, then read by a read head.

Question 8

What is the difference between absolute and incremental linear encoders?

Answer 8

Absolute encoders use a home position sensor so do not lose position when switched off.

Incrememntal encoders onyl measure the change in position.

Question 9

What is a radial encoder?

Answer 9

Radar position

Question 10

What is a pro and con of linear encoders?

Answer 10

Pro: High precision

Con: Fragile, only for slow movement

Question 11

What is an angular potentiometer?

Answer 11

Same as a linear potentiometer but the wire wound resistor is circular

Question 12

Answer 12

Question 13

What are resolvers

Answer 13

Use a rotating core surrounded by stators, like a generator.

Used for high rpm applications

Question 14

What is an ADC converters?

Answer 14

Reads analog and converts to digital

Question 15

What are 3 types of proximity sensors?

Answer 15

Inductive, capactivie, sonar, radar, optical

Question 16

How does a capactive accelerometer work?

Answer 16

Contain a mass on a spring which pushes two capactive plates togther when it moves. As the capictance changes, the acceleration can be determined.

Question 17

How does a piezoelectric accelerometer work?

Answer 17

The mass on the spring presses on a piezoelectric crystal. Piezoelectric crystals output electrical charge when placed under mechanical stress.

Question 18

If you were desinging a fire and forget missile, which sensor would you use to get real-time updates on the missile’s attitude?

Answer 18

Rotary encoder using a gyroscope as reference: Precise, robust, does not need to contact the reference, which would disturb the gyro.