Behavior-Based Robotics: Interacting Mobile Robots
Arun Mahendra - Dept. of Math, Physics & Engineering, Tarleton State University
Mentor: Dr. Mircea Agapie
Abstract
Calculating Destination Coordinates
In robotics, behaviors are simple algorithms that connect inputs
(sensory data) and outputs (motion commands). The interaction between a
behavior-driven robot and the environment enables the robot to perform
relatively complex tasks. In this project we extend the behavior-based
approach to include multiple robots. We develop an interactive behavior
which enables one robot to follow the other, using a simple method of
communication. For validation, we are using the AmigoBot™
hardware/software platform, building upon our previous work in behaviorbased mobile robots. We describe our successful experiments involving
two AmigoBots™ in a realistic (cluttered) environment. Several scenarios
of motion are investigated, demonstrating the robustness of our method.
Geometry problem: Line passing through the center of a circle
AmigoBot
Follower: Flow of Control
ActionGoto
100 ms
(X-Xp)2 + (Y-Yp)2 = r2
Main_Ctrl()
(Xp,Yp)
r
Each robot communicates with a PC across a (802.11) wireless network.
Information packets are sent every 100 milliseconds.
¶
Get_TrigX()
Get_TrigTh()
Get_TrigY()
(Xr,Yr)
Wireless Communication
For implementation purposes, the following calculations are used:
Ultrasonic
Sonar
Read_FileY()
Read_FileX()
Pilot
(Xp,Yp)
Pilot
AmigoBot
Follower
r
α
ΔY
Multiple robots use a central PC as a hub to communicate among
themselves. Pilot writes into a file, follower reads that file.
Eight sonar units built into the robot constitute the input sensors. The
robot identifies external obstacles and wall-to-follow by processing inputs
from these sensors. When these sensors return a reading, it is processed
and as a reaction, a state transition in the system occurs. Different states
reflect different reactive behaviors.
CONCLUSIONS
 This project proves that behavior-driven robots can interact
using a simple method of communication.
Pilot: Conceptual flow of control
 Observation: The follower looses track of the pilot when the
pilot is not in the follower’s line of sight.
Piloting Modes
Robot
WallFollow Behavior Mode
Collision Avoidance
Simple Turn
Explore
Sensors and Positions
WritePosTo
File()
FUTURE WORK
 Extended the project to include multiple follower robots.
α
(Xr,Yr)
…..
ArRobotX
…..
…..
ΔX
 Develop a follower-sensing behavior for the pilot … explain
InputKeyHandler
Xp-Xy
Wander Mode
Obstacle Avoidance
…..
WritePosTo
File()
Experimentally, a translational speed of 200 mm/sec was found ideal for
navigating without colliding with objects.
Distance traveled @ 200 mm/sec before a packet arrives = 200 *.1 =
20mm.
The “blind distance” covered in this case is only 20mm, which is very
small.
 Develop a behavior to enable the follower to follow the pilot
even when they don’t have line of sight.
…..
ArRobotX
…..
…..
2
Cos( )=ΔX/(√ΔX +ΔY )
α
Xintersection = ΔX – r.Cos( )
α
Sin( )=ΔY/(√ΔX2+ΔY2)
α
Yintersection = ΔY – r.Sin( )
Implementation using C++
TeleOperation Mode
Obstacle Avoidance
…..
WritePosTo
File()
α
2
a little more!
¶ Amigobot
…..
ArRobotX
…..
…..
is a member of the Pioneer family of mobile robots
manufactured by ActiveMedia Robotics.
For additional information please contact:
Mircea Agapie
Dept. of Math, Physics & Engineering
Tarleton State University
agapie@tarleton.edu