Geobot

built by Chris Schur

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Target Environment Locomotion Method
Outdoors, all terrain Treads
Sensors / Input Devices Actuators / Output Devices
Tread odometry sensors
very high impact bumpers
quadrate sonar array
overtilt sensor
ground sensor switch
devantech digital compass
DC drive motors
sample collector arm
Control Method Power Source
Autonomous Battery
CPU Type Operating System
PIC 16F877a and 16F628 None
Programming Lanuage Weight
BASIC 25 lbs
Time to build Cost to build
7 months $500
URL for more information
http://www.schursastrophotography.com/robotics/geobotfinal.html
Comments
The purpose of this project was to design an outdoor robot capable of navigation through rough rocky terrain to a predetermined collecting area, obtain rock and soil samples from that area, then return them safely to the point of origin.

The distance of travel is selected from dip switches on the main processor board. We can select 0, 20, 100 feet. The power switch is thrown, and the robot initializes the arm position to the "stow" position for stable travel. The processor takes an initial compass bearing reading which is maintained within 2 degrees for the travel to the destination. Essentially, the robot is pointed toward the collection area, and let loose. The robot is programmed to proportionally avoid obstacles in its path along the way, and always resumes the original bearing after reacting to say a large rock or some insurmountable brush. Upon arrival at its destination which is determined by total distance odometry, the robot stops, and performs the collection sequence. The arm is lifted to a safe height, and the Geobot backs up about a foot. The ground is sampled for a second time just incase the first sample was incomplete or on top of a rock. The robot actually measures the point it touches the ground before sampling with a series of contact switches on the scoop. So what happens if the ground is NOT detected? The robot is programmed to alert the operator and wait for instructions. The arm is then stowed and the robot reverses the bearing from the original to return back to the starting point. Rotating the robot to the reverse bearing ended up being quite a mathematical adventure.

The robot then returns to the home position, again avoiding any obstacles and maintaining the reverse bearing for the distance set at the time of initial release. The odometer resets at the destination and counts back down to zero on the return trip. Upon arrival at home base, the robot stops and waits for the specimen removal from the scoop.

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