Project 09-006: Mini Sumo

[Liam_McQuellin]

Got some pictures of it so far. Havnt really touched it much. Still have a long way to go. Hows yours coming along? Im tempted just to be slack and use the relays with a picaxe, at least that way i can program some complex behaviour into it, and improve both the opponent and edge detection circuity.

Mine is ok. I am going to make a PCB to mount it all on. It will make it easier to replace parts in the long run, especially when I am at a competition.

If you used a motor controller, you would totally eliminate the need for the relays. This is probably the path that I am going to take as I have found the relays rather finicky. When the turn and reverse behaviour is initiated, I have found that the relays seem to latch which stalls the motors. I then have to short the circuit to get it going again which is less than ideal.

What I am going to do now is use a L298 motor driver and an arduino to program my robot, may as well add some proper sensors as well.

[Liam_McQuellin]

Oh good idea,

Ive used the L298 before, should work well. Im tempted just to start again with a more effective design. Biggest issue im having is traction. Used some elastic bands and CA'd them on to the plastic wheels but the traction was limited. I think i saw a good gearbox setup and my local electronics store. Should still be quick and provide a good amount of torque. Unfortunately, there are no sumo comps in Australia (that i know of) so i dont really have much to keep my going this this kind of project.

Liam

Yeah, the relay brain is good at a very basic level but if you want to compete then you do need to do more. I'm still keeping the cost of my robot right down though I will use new motors as the GM3s are awfully slow, so I am looking at either some Pololu 50:1 HP or maybe even just using the SuperTec HPX F/BB servos and modifying them. They have superb torque and are pretty fast.

IF you want to enter it into some competitions then you can always send it over and I will enter it for you.

Sam

[Liam_McQuellin]

Ive used some BB servos with great results. I had some Hitec BB MG servos and the gears have never failed.

I would send you a bot to enter for me if you were okay with that. Would defiantly get me more interested in building a working bot. I need to make myself my own ring to program it more efficiently. Do you know were i can get some details on the dimensions on the ring they use in the competitions?

Liam

Yeah, there is a great post here.

You are more than welcome to send your robot to me. I don't enter all competitions but if I plan to enter one then I will let you know and you can decide whether you want it entered or not.

Programming a sumo is definitely more efficient than the relay solution. I am using the stripduino as my MCU as it is cheap and easy to build, I recommend you have a look

[Liam_McQuellin]

Thanks mate Now I know what I'm doing this weekend.

Ive never had a play with any of the Arduino line. I really need to learn some more, it seems to be overtaking in functionality compared to the PICAXE range.

I had a go at bread-boarding my picaxe L298 circuit and it works well. Ive been googling for bot designs to see what works and what doesn't. Still having a look too see if it would be better to use servos or a gearbox. Ill probably end up going with servos and program an interrupt sequence so its quick to respond to inputs. Problem with using a servo and a picaxe is it uses the internal clock to provide the 75-225 ms pulse, so the picaxe is paying more attention to providing an output than monitoring its input. Even worse when using a ultrasonic transducer. The Arduino is sounding better and better

What progress have you made on your bot so far?

Oh, id love to send you a bot once i have one i am happy with Thanks very much.

Yeah, that is a great post from Dave Cook. He seems to make projects look very simple and provides great instructions.

Have a look at the Stripduino and see what you think. It is low cost so if you are not happy with the arduino way then you have not invested too much money. I also have some information on how to make an ISP lead using an RS232 port and some header sockets (costs less than £2.50) which is much cheaper than using a USBtinyISP and you can still use a RS232-USB converter if you don't have the legacy port.

So for about £10 you can have a complete MCU with all the programming leads and environments. Can't say better than that

Gah, not RS232 as I said before but a 25-way D sub connector Replace any RS232s for 25 way D Subs

[Liam_McQuellin]

Do you know were i can get one?

What language to the Arduino's use?