the optical sensor of the robot phoenix-1 aleksey dmitriev
TRANSCRIPT
The optical sensor of the robot Phoenix-1
Aleksey Dmitriev
Introduction
The presented work is devoted to the
description of the optical sensor designed
and experimentally verified as a part of the
students’ project of a mobile robot.
Optical sensor overview
MathCAD
D1...DnThe optical sensor
Showingphase
α1...αn
DB
Teachingphase
Testingphase
The optical sensor
Objectives and criteria The primary objective of the sensor is to measure a
displacement of a contrast stripe from the image center.
Performance of recognition and control algorithms was the main criteria of the optical sensor design.
The principal idea of stripe recognition algorithm is based on the assumption that stripe has homogeneous color and high contrast with the background.
Stripe recognition (1/2)The optical sensor should estimate size D, representinga displacement of the white stripe center from the imagecenter.
Stripe recognition (2/2)The displacement D is calculated with the method ofcentre of mass.
n
ii
n
ii
c
L
iLN
0
0
*
where Nc – pixel number that corresponds to white stripe center, Li – brightness of i pixel in a measuring stripe, n – number of pixels (length) of a measuring stripe .
0NND c
Sample frameThe sensor consists of several measuring stripes which
indications are used by the algorithm of the robot control.
Each stripe has its own parameters: offset from the image center, width and height.
Sample movieThis is a sample movie taken during one of experiments.
Experiments’ result The control algorithm is based on PID-regulator. Indications of the optical sensor and output data of the
control algorithm are used for teaching a neural network.
k 0 4
Revealed issuesThe control system is very sensitive to a camera position.
Conclusion: we should install a cam angle sensor.
Conclusion
The optical sensor has been successfully used on the
teaching stage of “teaching by showing” methodology.
During the tests the algorithm has shown good working
capacity. The speed of the algorithm is at very high
level that allows to write it even to low-performance
microprocessors.
Contact info
Aleksey Dmitriev
SUAI, Saint-Petersburg, Russia