Blaster Mapper
Kyle Patel and Richard Uhrie
EENG 383
Objective
● Sonar Obstacle Mapping Rover
● Two components
o
o
Computer hosting mapping engine
HCS12 control system and hardware
Source:
http://www.clker.com/cliparttreasure-map-1.html
Approach
Separate into three different Phases
1) Maps immediate surroundings
2) Maps a trajectory in front of it
3) Maps a given radius (“room”)
Source: thinkgeek.com
Hardware List
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HCS12
2 DC Motor Wheels
1 Servo Motor
2 Sonar Modules
2 XBee Modules
2 LiPo Batteries
Sourece: sparkfun.com
Physical Diagram
Wiring Diagram
Computer Backend
● WPF Project with C# coding
● Uses Dijkstra's algorithm with modification for quickest
route
● Explores adjacent tiles and then goes to next tile
sequence that can be visited
● Data sent through serial communication through 12 byte
packets of sensor data and 1 byte packets of
commands
Source:
http://www.clipartbest.com/seri
al-port-icon
HCS12 Code
● Complex interconnection of simple
subsystems
o
SCI, RTI, Hardware Flag Polling, PWM
● Multiple devices sharing HCS12 resources
o
o
required module switching behavior
code sections are compartmentalized
source: http://www.ibmsystemsmag.com
Timing
Sonar Development
● Technical Documents specify a 45 degree
spread angle on the sonar.
o
Max range with mapping accuracy ~0.5 units of
resolution(would result in most data being
erroneous)
● Solution: attach funnel to front of sonar
o
o
Increased accuracy to 32.5 degrees(~1.1 units)
Decreased max range of pulse
Source:
http://pixgood.com/communistsymbols-fist.html
Problems
● XBee adapters
● Tire slippage
o Resolved by adding weight and rubber bands
● Sonar inaccuracies
o Take average values
● Next tile in mapping
might not be closest
● Not Enough pins to best use encoders
o Polling with state tracking used instead
Source:
http://www.newdirectionsaromatics.com/
heavy-duty-rubber-bands-p-1262.html
Questions?