08M2 Tricycle Bot: First Test

erco

erco

Senior Member
Today's uber-simple bot is an ugly but quite functional duckling using an 08M2. Quick prototype shown here. We're going to 3D print an improved version of this chassis to use in a robot camp. Two 9g servos, one continuous rotation drives, one steers. And a 1 PPR mechanical encoder. Easy peezy, works every time. Just have to calibrate servo turning radius to match up to a 360 degree turn with an integer multiple of my wheel circumference. In this case, 12 wheel revolutions per circle. Accelerates & decelerates. First test was this figure 8 course. Bot will soon have IR and ultrasonic sensors and audio output. Maybe light tracking too.

Video thumbnail shows bare chassis before the electronics were added. So hideous that it's beautiful.

 
I like the simplicity of these tricycle bots and may have to build one. Your videos are always fun to watch. I really enjoyed the tour of your robot room.

Thanks,
Rick
 
Finally got around to testing my idea for a simple low-tech, single I/O pin, line-following sensor on Trike bot. Two CdS (cadmium sulphide) photocells in series, making a voltage divider read by an ADC, looking down at a line illuminated by a single center mounted green LED. About as stupid simple as it gets, but it works. Lots of variables: vehicle geometry, sensor geometry (view and location), how much illumination from the LED, line width, and of course, the software.

It wouldn't be anyone's first choice for a timed line following competition, but it's about as minimal as I can think of. On an 08M2, every I/O pin counts.


Code: 
servo 2, 132 ' drive servo 132stop 175fwdmax 100reversemax
b1=144' servo center position
servo 4, b1 ' steer servo center144  leftmax62  rightmax235
servopos 2, 140' drive fwd
main:
readadc 1,b0  'read photocell voltage divider
if b0<95 then let b1=b1+1 max 235  
elseif b0>120 then let b1=b1-1 min 62
endif
servopos 4,b1
pause 5 ' damps oscillation
goto main
 
Sadly,the collection belonged to my mother-in-law's husband who passed this last week. When I saw that trike, I couldn't help but photograph it juxtaposed with the "duck bill dipper". I knew I was going to post it here.

I have a couple of the Armatrons around; one of them with a powered parallel port interface. My son was blessed in his upbringing. Neat stuff.
 
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