Robotic perception

Question 1

What are the types of sensor?

Answer 1

Proprioceptive sensor
Exteroceptive sensor
Passive sensor
Active sensor

Question 2

Define proprioceptive sensor

Answer 2

Measure internal values of sensor

Question 3

Exteroceptive sensor

Answer 3

Acquires info about the robots environment
-distance, light intensity and sound

Question 4

Define active and passive sensors

Answer 4

Passive: measures ambient environment entering sensor
Active: emits energy into environment

Question 5

How we do represent uncertainty?

Answer 5

We consider the whole system vs the uncertainty of one sensor

Question 6

What models can we use for statistical representation?

Answer 6

Gaussian model
Error propagation law

Question 7

Give the function of wheel and motor sensors and the type of sensor it is

Answer 7

-Uses optical to detect the angle of the joint/motor
-proprioceptive

Question 8

Give the function of heading sensors and the type of sensor it is

Answer 8

-determine orientation and direction of the robot
proprioceptive: measure the incline of the robot and gyroscopes
exteroceptive: magnetic compass

Question 9

Explain the function of magnetic compasses

Answer 9

-measure the Earths field to determine the magnet relative to the north
-detects strength and direction of the magnetic field
-common in outdoor environments

Question 10

Explain the function of gyroscopes

Answer 10

Measure the rate of rotation around an axis
-can be mechanical (spinning mass)
-can be optical
-useful in environments where magnetic fields are unreliable

Question 11

Explain how accelerometers work and explain MEMS

Answer 11

-detects changes in speed and direction
-MEMs uses a small mass suspended by micro-springs. The mass in response to acceleration
-the equation of motion for the system is:
F = mx_2dot + cx_dot + kx

Question 12

Explain what an IMU does and the components

Answer 12

-inertial measurement units
-IMUs provide pose estimation: position, roll,pitch,yaw
-IMUs include accelerometers and gyro’s

Question 13

Explain active ranging

Answer 13

-A technique used to measure distances
-Typically emits a signal which is then recieved
-The time between emission and recieving is used to calculate distance
-Doppler shift

Question 14

Give some types of active ranging systems

Answer 14

-Ultrasonic ranging
-Laser ranging
-Radar ranging

Question 15

How does triangulation work?

Answer 15

-Measures the distance between 2 baseline points
-Measures angle from each baseline point to target
-Use trigonometry to find distances and coordinates of target point

Question 16

Explain how structure light 2D works

Answer 16

Position sensitive device recovers depth information about the environment
-Use a CCD
-measure distance to illuminated light from origin of sensor

Question 17

compared to the system, what is key about sensor performance?

Answer 17

The sensor must be much faster than the system so that delays are negligible

Question 18

What are desirable features of sensors?

Answer 18

High accuracy - small systematic error
High precision - low random error
Wide operating range - high accuracy and position over a wide range of values

Question 19

Why do we want a linear transfer function?

Answer 19

A non-linear transfer function introduces some distortion

Question 20

Define the dynamic range of a sensor

Answer 20

The lower and upper signal limits in dB