Tanto 2

Looking at http://www.tantorobot.com/http://www.tantorobot.com/ this is one cool robot.

1 thing to add, I been wondering, where you will fit an active weapon to get it though robot wars rules IF series 8 goes ahead.

Did you know that South Today advertised the Brighton model world with the robots from robot wars appearing, who says the BBC (south) dont care for robot wars :)

how much did craig pay you to post this? for RW7 tanto had a little spinning disc on the front. as im assuming he built it for the live events, it dont need a weapon.

we were on the bench next to tanto at brighton (well we shared the table). craig spent most of the time building it there :P but he had problems with the drive gears not meshing correctly (or something like that anyway).

Im not going to say anything bad about tanto, as a certain score line may appear as it did at the weekend :sad:

Lol at Alan. It looks nice. Perhaps the wedge might be a little steep. For some reason it reminds me of Tsunami without the weapon.

The wedge is intentionally steep- you bounce off perpendicular to the wedge angle- so its more of a hitting thing. Incidentally, its a similar angle to storm 2, and youll notice that in many cases things bounce of the front of storm 2, instead of riding up the wedge.

Oh boy is that 36V & ETEK motors I spy in the pics.

Thats an awfull lot of power but how can they get it down on to the floor with only two wheels.

Richard
Team Mayhem

They lift it up onto a trolley and lower it down gently!

wow Ive got a thread!
its brand new as far as I know its the first heavyweight built to FRA rules. No stupid active weapon rule. there isnt a weapon or one planned either, Im building it to be stronger Ive just bought a piece of titanium 0.550 thick to cover the front.
yes its 36v in the pic but thats its live event set up the fighting or all out set up is 48v, how to get that on the floor? well we have ideas.
Matty were you at brighton? obviously missed us throwning the robot out of the arena.
as for brighton yes we had problems with gearing down to a miss engineering. At least Im not using the robots r us in it anymore

Craig, 2 things.. your drive, my FP technology...

If I can build a Heavyweight class FP system inside 5 kg, Im sure the weight will allow it inside Tanto2.

Hmmm, was this why Craig bought the 140*140 ram you hade for sale earlier?

But as Tanto only has two wheels, whats stopping the nose from lifting off the ground when it accelerates?

Mario- God knows Ive tried to persuade him :)

Christian- the 140 x 140 is for something different.

Christian- Electronics

Traction control?

We are toying with traction control, but that doesnt really help keep the nose on the ground. In the speedos which are being developed, theres an accelerometer to measure tilt, and so apply power so as to keep the nose on the ground. we may however want to nose to rise a couple of inches up in the air, so we can make full use of the spikes on the front of the wedge, and the accelerometer will allow us to do that too. Its anaologous to adjusting the gain on your gyro- we should be able to adjust the tilt control.

Fantastic idea guys

....so many bits to go wrong :)

oh I love traction control, so much wasted power and grip......

anyone know what slip angles are?
nope.
I love traction control (on otherpeoples machines)

ps... this is a hint to ask me for advice on making efficient traction control.

Ill bite, James (especially since some of my more obscure designs would be a bit lacking in the physical traction department). Care to start a discussion/advice session in hints & tips? (Hmm, we dont have a section thats for nonspecific weights; unless admin are so inclined, I guess we default to heavyweight.)

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Fluppet

Ed, Ive had this conversation with you before :)...
... I do not design Robot wars electronics which rely on sensitive Chips- I do have a modicum of common sense. As I have explained to you before, should any of the modules (for example the accelerometer) stop working, the 2 processors will simply work without them. Should 1 of the processors fail, the other one will take over its job. The whole speedos are designed for things to go wrong! Short of an axe chopping the thing in half, weve tried to think of every eventuality!

Andrew- Basics of traction control (and this will include slip angles :) :-

Contrary to popular beleif, a robot is not generating the most force if its wheels are spinning- the most traction from a wheel is obtained when the wheel is only just on the verge of slipping. So if you want to most traction when pushing another machine, you want to reduce the power of the motor (assuming the wheels have been slipping) untill the wheels are only just about to spin.

A slip angle is the angle at which the surface of the wheel will just break contact with the surface that it is on. The slip angle therefore depends on the surface youre running on, the amount of pressure on the wheel etc. For most traction, you must apply power to your wheels so that they only just begin to slip- this is the slip angle. I invite james to explain this far better than I because Im not very good at explaining such concepts, and hes had a lot more experiance with this kind of thing that I have.

yeah, here is the secret, Ive been sitting on it for a few years, but as Im not going to do traction control, I might as well let the cat out of the bag now.

To achieve efficient traction control you need the following.

a realtime feedback loop, measuring wheelspeed (or motorspeed), lateral g, groundspeed.

you also need data about your wheels on the required surface, this can be simulated on a rig, but finetunin must be built in.

Right, the way this works.....

in a straight line, the robot will accellerate and decelerate when the tyres are operating within their maximum effective slip angle.

to find out the value of this (this also explains what a slip angle is) you need to run the wheel on a rig. this rig is set to measure the torque of the motor, and the torque on a slave shaft which simulates the floor of the arena. This way you can measure grip of the tyres.

accellerating the motor should accellerate the slave shaft at the same rate. If the slave shaft accelerates slower than the motor, you have wheelspin. A torque comparrison gives you a graph of how much wheelspin you get.

you will find that, from when the speeds first vary (ie, wheelspin first occurs) to a noticable difference in torque, there is a gentle squeeling. This is a tell tale that the tyre is working at its hardest, and is within its slip angle (the theory being, the wheel turns, say 367 degrees for the slave shafts 360, so it is an angle of 7 degrees different caused by the slipping.

so what does this mean?

if you look at the graph, you will see that the accelleration did not drop for this area of slip. Beyond about 7 degrees (this is an example for a go kart tyre) the torque on the slave drops suddenly. this is where you need the traction control. Regualr traction control cuts in as soon as the wheel speed is different. this ignores this area of slip, and so automatically looses it.

by having groundspeed, and motor speed, you can program the traction control to allow for the slip angle, as derived from your rig tests, and so maximize your available traction. This works in deceleration to, as for example F1 abs was working within slipangles, unlike car ABS.

to maximize lateral grip, you need sensitive g-sensors, but best avoid thse, as they will get confused when storm 2 hits you.

there we go, a nice description of why previos traction control didnt provide enough of an advantage to make it viable, it cut off the bit where most grip was produced.

oh, before everyone starts looking at this, think about one more thing.
Tornado pushing on the side of... um... Smidsy, for example.
Cant move him eh, wheels are not gripping? traction control would not help here, what would help is spinning the wheels up for a second, which covers the floor in tyre rubber, then push again and voila, more grip.

traction control, Ill never use it. :)

I cant honestly say Im interested in putting on a weapon but Im sure me and Eddy will argue and Ill end up with some kind of weapon. Its gonna have spikes it that counts?
Traction control well Im not saying anything as too what Ive got in mind.
The angle is too steep? its 45 degree I think thats perfectly ok. When Tanto catches any edge on the wedge it tends to turn it over.

Craig, no I wasnt at Brighton! Seeing as Im only 14, getting anyone to drive me anywher is abot as easy as threading a piece of rope through the eye of a needle, so Iam impressed that you managed to throw something out the ring, though without seeming rude (It could in fact be a rare compliment! :wink:) I wonder whether it was the wedge that enabled that or the sheer brute force of the thing, aided by the shape!
As for a weapon, Why not have an Aggrobot3 Style wheel underneatth, that way you can raise the nose, and if it stops working, youve still got the wedge and brute force to carry you through.

Oh, and on a final note, is James the first person to become an advanced roboteer?! Congratulations if he is, and alos is ther a higher rank than that?!

just updated the tanto 2 bit
its not a good site i know but we do the best with what we have

Thanks James. I was aware that maximum acceleration usually happens with some slippage, but hadnt seen it expressed in those terms before. I presume a fair bit can be done just by sticking a strain gauge on the driveshaft and seeing how much force you *should* be applying to it compared to the change in drive speed? Im a bit wary of the idea of predicting how much traction ought to be available allowing for heating/wearing tyres, fairy liquid and so on.

Other thoughts - can anything be done with the mechanism from an optical mouse to measure floor speed? (If some optics cant scale up, itd only help for antweights).

However, this is off-topic; perhaps a move to tip swa^H^H^H^H^H^H^Hhints and tips might be better if people want to discuss it further.

Several of my designs (sorry, vapour builder here) would benefit from having some intelligence on board; once the programmability is there I may as well add some engine management. :-)

(Speaking of which, whoever came up with the traction control for the Focus didnt presume that you want to accelerate if your wheels are spinning; kills the engine revs until youre out of the torque band, not helpful, better to balance the clutch and keep the revs - if not torque - high.)

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Fluppet

Andrew- Ive been playing with optical mouse technology for that very reason. It was useless at 20mph, but certainly for ants it would do fine. A small wheel with an odometer seems to be the best option.

Cool - I look forward to seeing how well it works. I suspect the technique should scale up to higher weight/speeds if a bonus lens was stuck in front of the sensor (think fisheye), but that would be a bit fiddly to set up and might be too damage prone.

If you get it working on an antweight, Id be interested in giving it a go, though, if nobody else tries it first (or they do, and it works). Might be helpful in my plans for a self-built robotic vacuum cleaner, too (the ones you can buy cant do stairs, and I like a challenge).

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Fluppet

Ive been looking at optical mice too, in fact I have obtained some code to interface a PS/2 optical mouse to a PIC, although I havent actually tried it yet. My research indicates that the highest speed they would work at is about 2mph. I would be interested to know how you get on with them.

I think traction control on an ant is a little bit silly :-) Would be fun tho. The prob with ants is that the weight limit isnt quite enough to stick in our own pic based circuits and PCBs, and start playing with things like that, unless youre willing to go down the SMT route which I most certainly am not :-)

Having said the above, I am now determined to build traction control for an ant :) The odometers from a ball mouse for the wheels, the optical sensor from another mouse for the real time feedback, and a PIC circit as small as i can get it, which will sit in-line between the Rx and servos (itll do the mixing as well). Im doing it to see if i can, not to win any competitions:-)

I approve - and Ill watch out for it! Ive always thought robot combat should be about interesting designs, rather than the tried and tested. (Hence Im a fan of Tip Top, in spite of the drive mechanism blatantly being a bit of a daft idea.)

--
Fluppet

Another advantage is that it can serve as a cheap test platform to try different ideas and software for Tantos traction control. Yey, fun.

seen as Tanto 2 was having some serious speed controller issues Ive had to fork out and buy some proper controllers made for eteks (48330esc)
with these new controllers Ive had to toy with positioning and decided it would be just as easy to build a whole new robot
So in te words of the trade ive done a grim reaper and built another new robot. This one is pretty much interchangable almost everything can be changed. Currently she has 2 fronts a full wedge front and my Storm 2 front. ;)
best bit is on its lightest setup it weighs 73Kg so for the first time I will have a weapon that may actually do something.
Pictures wont be on the site til after the world champs now (I have shared some pics with key indaviduals and I know who u are should anyone show the pics Ive sent consider yourselves female when I get hold of ya)

Craig

Your always trying to grab my man-hood :sad: lol

different reason Dave ;) lol

I was goning to keep Tanto under wrapes til the World Champs but now its a different matter

Will post new Pics and other info within the next few days before I go to billing

For once Im upto 100kg mark shes 97kg and armoured like a brick, responsive and reliable which has been my major problem but with the new controllers and BEC Im much more confedent in her.

That said Im going to make another new heavy next year called Tantalus involving some pneumatics and big motors watch this space

Craig, this is a big what if....

.....consider yourselves female when I get hold of ya

erm.......what about me? :proud:

didnt send u a pic Karoline no problem

yeah, but what if?? :)

then Ill kung fu yaw ass all the way to Hong Kong
thats what if :) lol

The Island or Kowloon? I shall outrun you by jumping on a tram to Central, hopping on the Star Ferry and getting lost in the fish market in Tsim Sha Tsui.....
Kick my ass all the way to HK? If you pay Ill go :)