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|Target Environment||Locomotion Method|
|Sensors / Input Devices||Actuators / Output Devices|
|Sharp IR||hacked futaba servos|
|Control Method||Power Source|
|CPU Type||Operating System|
|Intel 80x86||Windows 95/98/NT/2K/CE...|
|Time to build||Cost to build|
|URL for more information|
|Tetherbot is a technology demonstrator, like his predecessor Followbot. The main technologies that he demonstrated were: IR Object Avoidance. Servo Control from the PC (Windows NT 4.0). and Algorithm Testbed. All were very successful and Tetherbot will continue to be used in Genetic Algorithm Research.
Power - since it's tethered I was able to use an old PC power supply. It supplies +5VDC and ground via two unused wires in the RJ-45.
Locomotion - x2 "Hacked" Futaba 3003 DC Servo Motors. The hack I used was to replace the potentiometer with a voltage divider consisting of two 1/4 watt 2.2k resistors.
Sensors - 2 Hi-Output IR LED's from Radio Shack and 1 Sharp 40 kHz IR receiver Module. A schematic of the circuit can be found here.
Control - PC Parallel Port. Because this is under Windows NT and the OS does not have direct access to the I/O. I am using DriverLINX by Scientific Software Tools, Inc. I also used a bit of code that allows me to measure how long my PC takes to perform For-Next operations. This was very helpful in sending the correct Microsecond pulse to the servo motors, mainly since VB's timer is only Millisecond resolution.
To do this I have employed a genetic algorithm that consist of one gene. That gene contains a sequence of directions that tetherbot needs to move. The genes are tested for fitness by the whether Tetherbot realizes he has espaped or the directions from the gene have been exausted.