This page describes my first autonomous mini-sumo, Drone...
I added a few movies of Drone pushing some wooden blocks out of my test sumo ring...
These are all AVI movies, 640 x 480, taken with my Logitech Quickcam Pro. This is what I consider to be very basic, rudimentary behaviour for a mini-sumo bot. Note that each wooden block weighs about 200 grams, so there is a total of about 600 grams of weight for Drone to push around (which it does with no problems whatsoever).
|First, here's the CAD drawing of the design.
You can see the SRF-04 sonar mounted on the front -- I'm not using that on the real bot, since the beam pattern is close to 90 degrees at 30". Instead, I'm using a couple Sharp analog IR range-finders.
This robot will be controlled with a single PIC 16F876.
|And here it is, mostly done. I haven't mounted
any of the sensors, and the main board is just a temporary one until I get some software
written and figure out how everything will work. But, the hardware on this robot is
It weighs in at a hefty 475 grams without any weight added, so by the time I add the sensors, it should be very close to 500 grams. There are a number of places where I can change out some materials for lighter stuff if the weight goes over.
You can see the 28-pin PIC 16F876 here, and the small 8-pin chip just behind it is a Dallas Semiconductor (now Maxim) DS-275 serial converter chip.
|Another view, showing the back. The 9V battery
runs the electronics, and there are 4 AAA bateries at the bottom (the red & black wire
running down) to run the motors.
The wiring, once I figure out where everything is going to be and do the final PCB, is going to be a lot neater...
I'll be replacing the stock motors with much more powerful "Torque Tuned Motor" as soon as I get my order from Tower Hobbies...
|Here's a side view. To give a sense of scale,
from the floor to the top of the h-bridge heat sink is about 4 1/4".
The switch near the front (the one that points up) is the power sdwitch for the electronics. It provides power to the LM2940 5-volt regulator right behind it, and there is also a little blue power indicator LED, just behind that, which is on in this picture.
The switch closer to the back (pointing directly at the camera) is the motor power switch, and it also has a blue power indicator LED, which is also on here.
|And finally, the opposing robot's view :-)
And yes, it can push a 500 gram block of wood around without too much trouble... In fact, with some RC car sticky stuff on the tires, it can push a 1 kilogram block of wood around without too much trouble...
|Here's a view of the inside of one of the wheels, showing the hex insert where the axle goes.|
|Here's a picture with the base started. I have the front piece to attach yet... I'm using 1/16" aluminum plate.|
|Here's the back view... I'm using 1/2" Delrin rod for the uprights.|
|And finally, for the unbelievers who don't seem to believe it is possible to put those big fat tires into 10 cm with the Tamiya Gearbox, well, here's the proof...|
|As a base, I'm using the standard Tamiya twin gearbox set, which I got from HVW Technologies (which is local to me in Calgary). I've replaced the useless hexagonal output shafts with brass axles I machined on my lathe & milling machine.|
|Here's more detail of one of the axles. I machined it from a solid piece of 1/2" hexagonal rod. I used hex rod since the wheels I am using have a hex mounting hole. I had to machine the matching end part down from 1/2" to 12mm, since the wheels are metric. The big end of the shaft is drilled and tapped for a #8-32 bolt.|
|Here's a picture of the tires & wheels I am using. I got these at a local hobby shop, and the tires are made from a very soft compound, so they have tons of grip. I don't think traction is going to be a limiting factor with this robot... Plus, they look way cool :-)|
|Here's a view of the tires mounted on the twin gearbox. Everything fits just nicely...|
|Here's another view of the same thing...|
If you have any comments or questions, please feel free to contact me at Jon@huv.com