Mobile robot project
Autonomous Floor Mapping
2010 - 2011 spring
Abstract
Simulation can be used to reduce the time and cost to develop a new technology. This paper describes the development of an autonomous floor mapping robot. In order to reduce the cost of building prototypes to test the program, we used the Simbad 3D simulator. To test in a more realistic environment, we established a way to control objects in a virtual world Second Life. Then, for the hardware part, we built a low cost robot with cheap but accurate Sharp IR sensors with a regular optical mouse.
Introduction
Motivations
Robots need maps for efficient paths planning
Mapping is costly
US $6,000 for SICK LMS-200
Need a platform to test our algorithm for floor mapping
Software
Hardware
Objectives
Algorithm
Easy to implement
Practical
Robot platform
Arduino based . easy to extend and customize
Cheap sensors for 2D scanning
Easy and cheap way to track robot’s location
Algorithm
Initialization
Divide the environment into grids
Go straight
While going straight, perform a 180-degree before moving to the new grid
Record whether the left, right, and front grids are occupied or not
Continue steps 2-4 until the front grid is occupied, then enter the main loop
Main Loop
WHILE (unexplored grid exists)
IF no block in front & not explored in front
IF no block on left & not explored on left
turn left
go straight
ELSE
go straight
ELSE
IF no block on left & not explored on left
turn left
go straight
ELSE IF no block on right & not explored on right
turn right
go straight
ELSE
Breath first search to find an unexplored grid
Assumptions
The mapping environment must have a closed boundary
Required to terminate the main loop
Each grid is as large as the robot
Software SimulatioSimbad 3D Robot Simulator
software simulator
Advantages:
Source code is available → modify the code to create our own interface and environment
Very fast to obtain the sensors’ readings
Location and orientation of the robot are accurately obtained
Second Life
Virtual World for the simulation
Problems
Hard to track location accurately
Hard to obtain the map of the surroundings
It takes one minute to do a 180-degree scan
Cannot map the environment reliably and autonomously
Real robot
Hardware Components
Control
Two Arduino boards
Sensing
Three Sharp IR analog distance sensors (10 .- 80 cm)
Computer mouse
Digital compass
Communication
Two Xbee modules
Assembled Robot
Scanning, Tracking, talking
IR Sensors for Scanning
Mouse for Tracking
Robot moves in incremental steps
Mouse keeps track of robot’s movement and helps adjusting the robot’s path
Xbee for Communication
Two Xbee modules
On robot
Connected to computer
Xbees are used to send
commands from computer to robot
sensors’ readings from robot to computer for processing
Results and Summary
Results
IR sensors give really good readings
Useful for pose estimation (future work)
Incremental steps and mouse make robot go very straight
Magnetic fields nearby interfere with compass’s readings
Robot does not turn left or right perfectly
Discussion
Using software simulations to experiment with algorithms
Extendable robot for US $400
Xbee, mouse, multiple IR sensors, compass, …
Accurate 2D scans can be accomplished for under US $65
Computer mouse is used beyond its intended purposes
Summary
Easy-to-implement mapping algorithm
Simbad 3D Robot Simulator for simulation
Cheap robot platform for testing
IR sensors for scanning
Mouse and compass for tracking
Xbee for wireless communication
Publication
H. Nguyen, A. Eguchi, D. Hooten, "In Search of a Cost Effective Way to Develop Autonomous Floor Mapping Robots,"9th IEEE International Symposium on RObotic and Sensors Environments (ROSE 2011), 2011, Montreal, Canada. pp.107-112. [View Download]