Robotic perception Flashcards
What are the types of sensor?
Proprioceptive sensor
Exteroceptive sensor
Passive sensor
Active sensor
Define proprioceptive sensor
Measure internal values of sensor
Exteroceptive sensor
Acquires info about the robots environment
-distance, light intensity and sound
Define active and passive sensors
Passive: measures ambient environment entering sensor
Active: emits energy into environment
How we do represent uncertainty?
We consider the whole system vs the uncertainty of one sensor
What models can we use for statistical representation?
Gaussian model
Error propagation law
Give the function of wheel and motor sensors and the type of sensor it is
-Uses optical to detect the angle of the joint/motor
-proprioceptive
Give the function of heading sensors and the type of sensor it is
-determine orientation and direction of the robot
proprioceptive: measure the incline of the robot and gyroscopes
exteroceptive: magnetic compass
Explain the function of magnetic compasses
-measure the Earths field to determine the magnet relative to the north
-detects strength and direction of the magnetic field
-common in outdoor environments
Explain the function of gyroscopes
Measure the rate of rotation around an axis
-can be mechanical (spinning mass)
-can be optical
-useful in environments where magnetic fields are unreliable
Explain how accelerometers work and explain MEMS
-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
Explain what an IMU does and the components
-inertial measurement units
-IMUs provide pose estimation: position, roll,pitch,yaw
-IMUs include accelerometers and gyro’s
Explain active ranging
-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
Give some types of active ranging systems
-Ultrasonic ranging
-Laser ranging
-Radar ranging
How does triangulation work?
-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
Explain how structure light 2D works
Position sensitive device recovers depth information about the environment
-Use a CCD
-measure distance to illuminated light from origin of sensor
compared to the system, what is key about sensor performance?
The sensor must be much faster than the system so that delays are negligible
What are desirable features of sensors?
High accuracy - small systematic error
High precision - low random error
Wide operating range - high accuracy and position over a wide range of values
Why do we want a linear transfer function?
A non-linear transfer function introduces some distortion
Define the dynamic range of a sensor
The lower and upper signal limits in dB
