Pal, an obedient autonomous truck
@ July 15, 2008
Hey, a home for my robot, Pal.
I'm tired of carrying my electric RC truck around from hill to hill while working it up in the dirt. just seems kinda of humiliating to both of us, ya know?
Also, I think one of the best/simplest ways to instill a sense of awareness in a robot is for it to know where you are. towards that goal i''m adding some ultrasonics and some brains to it so it will follow it's control unit around like an obediant doggy.
The latest posts appear after this one, look down at the bottom for the Block Diagrams early discussion.
I'm using ultrasonics mounted on the truck and the handheld transmitter to act as a beacon so the truck knows where the master is... maybe can also make it race in circles around a central fixed beacon
michael
@ Thu, 2011-12-29 09:05
Did you finish this? If so,
Did you finish this?
If so, we want updates!
@ Mon, 2009-02-16 17:54
Great work so far!
@ Sat, 2009-02-14 21:05
Omni Directional antenna measurements
i'm testing the omni-directional antennas now. the small quickly built one seems problematic at this point. the large fully adjustable one is definetly functional though.
i only alinged everything by eye and did all testing with the one configuration of the ant.
i was rotating the antenna on a 360 degree rotation servo, and it was not rotating perfectly flat, so the circles are off-center. plus, i was only 40 inches away so i was very sensitive to this effect.
i tried measurements at 2, 3 and 5 degree inc to test out the system repeatability and at different dwell times at each point of rotation.
it's amazing how the details repeat so well. even after starting at a different point in the rotation. i'm anxious to try this at say 10 feet instead of 3 and see if the pattern smooths out, but i'll need more gain from my prototype circuit. (the PCB design has programmable gain in it)
@ Sat, 2009-01-31 06:27
Omni Directional Ultrasonic Antenna Ver 2.0
here's my attempt at a small antenna. i Have made a bigger one that is fully adjustable, but i wanted to see how small these could be made.
have not tested this at all yet. i think i would like to put three of these on the car and do time-differential location instead of the panning servo. the panning servo would look coo, but can't work as well. time-diff will locate on one pulse.
the blue disks are 1.75" in diameter. the "parabolic" cone is made from modeling clay by hand. my 3D printer is on the blink...
@ Sat, 2009-01-31 15:01
exciting DIY tech!
I love the look of this. Awaiting field test results!
Anxiously!
@ Tue, 2009-01-13 05:55
Omni Directional Ultrasonic Antenna
This is really important to the design and still not resolved...
i need an Omni ant on the robot to transmit the initiating signal to the hand-held controller. with the panning receiver version of orientation determination, that uses the normal 20degree receving element for it's directionality. but if i implement the much more efficient interaural time delay method of angle determination, then i need three more omni antennas for each of the three receivers mounted on the robot. a diagram would be good to insert here, but i am also working on major house repairs.... :-)
my main thought has been to point the trans. or receiver straight up and hang an inverted cone above it. the cone should have a 45 degree cut to it, in this case. i saw this done in a university experiment, but couldn't find any other approaches.
not sure how to make this cone though. maybe with a 3D printer service. maybe i can fab it up in google sketch-up. not sure of the details and i'll need something soon.
the other idea is to radially contain the above idea with a couple of horz. disks, one at the base, or top of the cone, and one around the opening of the trans/receiver. i suppose they should be seperated by a wavelength or two. or three. this could make things worse, or could help. testing would be necessary.
@ Tue, 2009-01-13 04:15
I like what your doing
@ Tue, 2009-01-13 04:05
Ckt Board on truck
Sort of. just a printout of the board layout and where it will fit on the truck.
i'll bring up the four supports in the center to some sort of scaffolding to hold up the panning turret that will protrude up through the trucks body.
or, there will be three receivers mounted around the truck instead of the scanning turret.
@ Tue, 2009-01-13 04:00
Schematics, as the are now
these are certainly subject to changing. if you notice any glaring error, tell me. i'll being getting these made up some day real soon now. they deserve a cleaning up in various ways, but i may never get to that. this is a prototype afterall...
@ Tue, 2009-01-13 03:51
Circuit Board Layout
Ok, i'm laying out a board now using Orcad. i'm going to add three analog ultrasonic receiver channels instead of the one needed for this design. this way i can implement the Time delay method of orientation by using 3 receivers instead of the panning single receiver. obviously it would respond much more quickly, but then it wouldn't have that cool Kitt car effect...
anyway, since i'm laying out the board may as well plan for the future. this thing is now 4" by 5", and it's kinda crowded. i can't fuss over the design too much if i'm only going to be making 4 boards or so, so i'm not worrying about it much.
here each analog channel also has a programmable gain feature, though i don't have that in my prototype, and i'm not sure i'll really need it since i'm not ever listening for actual echoes, my overall signal strength shouldn't be an issue. but then i'll want it to reach even further, or maybe use this board for another ultrasonic application.
here's the circuit board layout and how it would mount on the RC truck i'll be using.