Im looking to make the next robot with large wheels similar to a car (500 mm diameter) the wheels will be exposed what do the forum recommend,
1/ a ridged wheel that wont bend.
2/ a more flexible wheel that distorts with the knocks and springs back.
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Im looking to make the next robot with large wheels similar to a car (500 mm diameter) the wheels will be exposed what do the forum recommend,
1/ a ridged wheel that wont bend.
2/ a more flexible wheel that distorts with the knocks and springs back.
Prime example. The wheels from Tough As Nails.
The originals still are in use. Yes, that one lost that the rim in Series 7. The same that got a nibble a few months before from Kan-Opener in Rijswijk.
Flexible wheel are my reply then.
Have flexable ones...........barbarous are another example with flexy wheels.
its swings and roundabouts Craig, TAN has flexy wheels and will degrade under attack but will stay on (mostly)
My (Tanto) has hard more solid wheels they with stand alot of punishment tyres can degrade but wheels stay on,
I would suggest a solid centre slightly larger than the dia of the body of the robot (assuming u go invertable like tanto) with soft tyres that way if u loose your tyres it will still work.
but with 500mm your proberbly better going for flexible lighter wheels
hells teeth 3 with the monochassis made from stainless had huge wheels. we tried to make them rigid and brace them but still bent. still it did run well. i would go for flex too. i liked that robot too.
What plastic makes good flexible wheels?
been sat here thinking of how to make some flexi wheels. here is my plan.
get some nice 15mm polypropolene and cut out 2 circles of whatever dia you wish. lets say 400mm. then drill a hole for the shaft. mabee 30mm holow shaft fot a bit of strength. make a carrier to hold the 2 pieces of poly to the shaft a bit like a kart setup. space out the 2 pieces of poly to about 80mm. between the poly put in springs so the 2 pieces will have flex but then add a bit of strength. then get a nice thick piece of tyre and screw it to the 2 pieces of poly around the outside. when the wheel flexes the tyre should flex with it.
is that a bit too much work for some flexi wheels???????
nylon
HDPE
Its what is used on TAN, still the same wheels since series 7.
dont like my genius plan then :sad:
Its genius, doesn€™t include gaffer tape though
Shane I dont know about the springs, but the rest seems quite brilliant!!!!!!!!!!!!
I was thinking about using the ctr of a car wheel say 200mm dia then bolting the plastic to each side of that (with spacers to get the 80mm) then fitting some type of tyre perhaps a Motorcycle tyre what do you think?
I have bought some trailer hubs for the stub axels they are quite light but very strong the stud pattern is 100mm 4 stud.
HDPE has several advantages in this application.
Easely worked, very light, flexible but springy, even limited self repair capacity, and contradictionary to the easy worked and softness, very tough. Easely damaged, almost impossible to destroy. What is demonstraded in the TAN wheels, in use since 2002, and its not that TAN was left in the shed for all those years.
These wheels are made from a 12mm HDPE plate, turned to fit in the thin walled 16 drainage pipe, with a bit of messuring and tapping with a hammer the plate was at the right depth straight and then welded in.
Then we put the wheel in a large chuck on the lathe and finished it so it was straight in all dimensions, a nice centring hole to fit the custom Hubs Kos turned and milled to perfection.
The first set of wheels used the surface of a rather soft and worn cartyre fixed with short wide head woodscrews. But the thickness of rubber and steel braid in it makes this a very heavy option. Also, car tyre is made for cars, not 100 kg robots,the grip is less than optimal.
Other option we tried.
Running surface from a wheelbarrow wheel. Not grippy enough, but very light.
And since then we have a formula One style mounted set of wheels.
But the best result on wheel surface coating was my first experiment in that respect, the billet HDPE backwheel from Project Two: Hexem, what was fitted with the softest compound dirtbike mud tyre we could lay hands on. Kevlar reinforced, thin rubber, high studs and so grippy it glued itself to the floor.
But the main disadvantage, and the reason we didnt do that on TAN, was the pricetag, and TAN would have needed 2 of these tyres.
the idea of the springs between the poly would let it flex but tie the 2 bits together. if you did it with quite strong springs it would allow flex. would absorbe energy when another robot impacted with them too. if i were to redesign the wheels for that version of hells teeth knowing what went wrong i would do them like that. but then experimenting with other ideas is a good thing too. :)
now i get it thanks Shane.:)
Things seem to be moving on ok with The Saint Mk2 Ive sorted out the hubs modified from car trailer units, and the drive will be my Bosch750 motors with a 19:1 ratio. It looks like the wheels will be about 550 - 600 mm Dia made from HDPE about 15mm thick would that sound about right?
Also if the robot flipped it may get stuck on the face of the wheel, how do I stop this, I know some robots have domes spun from steel like Stinger, is this the best solution? Where would I get them from or made? Thanks guys.
:)
Other option, think War Chariot style blades on the wheels.
One source of steel domes are LPG tanks. The ends are dome shaped.
Pulveriser used these.
craig i have some 20 to 1 gearboxs if your interested. used with bosch750 in hells teeth3. i will bring them to swindon you can have a look. might be of some use.
Mario thanks for the idea for the dome, I will look out for some tanks, also old air compressor tanks as they have two domed ends!
Shane please do bring the gear boxes They sound very interesting if not for saint 2 then saint 3! If you know of any Bosch 750 motors anyone has. I need those too, but I know they are like hens teeth at the moment Jonno wanted some a few weeks ago but I think he had to buy new.
:uhoh:
I did some measurements on the Saint regarding the drive
I have 2 Bosch750 motors with a sidewinder speed controller and standard Hawker bateries16Ah I think.
The battery voltage measured at 24.7 volts with no load
The volts going to the motor on full speed measured 22.7 volts
The voltage at the battery terminals under full speed was 23.8volts
I think I am loosing about 1to 1.2 volts through the speed controller is this ok?
both myself with the new ripper, and beast are now using sidewinder speed controllers and have both thought that we have lost some speed due to the speed controller, compared to the roboteQ.
This might explain it. I am planning on putting the roboteQ in ripper for swindon and am going to compare it.
Interesting what you say though !
John
While its true there will be some voltage drop in the speed controllers, even at full speed (unloaded) the volt drop from a sidewinder or robotec should be way less than 0.1 volts. Its more likely something else. The most common is that you are not using the full range of the RC signal, could also be very thin wiring / bad contacts. The first is easy to check. Put the transmitter stick at full speed, then adjust the trims, if it speeds up then youve solved your problem. The other common reason of driving slow in an arena is that you are hitting the speed controllers current limit. Be careful when adjusting the sidewinders current limit as too far can turn it off.
Were your voltage measurements at the motor terminals and the battery terminals or at the input and output to the speed controller?
Lets assume that your no load current for your drive is a total of 30A (is this reasonable?) then this would mean that if theres a 1 volt drop across the whole system (minus motor and battery) your system has a resistance of 33milliohms.
That seems reasonable to me.
Thanks guys
The trim thing I don€™t think this is a problem as the radio is Spectrum and I have adjusted the travel to elevator aileron to125%. But I will do the test tonight and will keep you posted.
The readings were taken at the battery terminals, and motor readings taken at the connector plugs fitted to the motor the nearest possible point to the motors. The wires are those supplied by the motor manufacturers and the Sidewinder tails everything else is the Technobots big cable 16mm stuff.
I would like to say that I don€™t have a big problem with the Sidewinder performance, it works well, I have had one of my Bosch motor drive chain seize up and the sidewinder was un harmed, even if the Bosch was un touchable for quarter of an hour because of the extreme heat this event generated. I can live with 22.7volts at the motors if that is reasonable I don€™t think another 1.3 volts would make much difference to my fight record!!!!!!!!!!!!!!!
Hiya,
Yeah i just wanted to add..... we dont have a problem... it was just something that we noticed, and coincidenly said to each other.
We may be completely wrong. The side winder is a nice small it of kit!!
John
Yep
I just done the tests and Battery with no load was 25 volts, battery under load is 24.1 volts, and input to motor is 23.1 volts at the plug.
I also tested the volts under load at the speed controller tails they were
24.1 volts input
23.1 volts output
So I don€™t think it€™s the resistance in the rest of the circuit, has any one measured the input to output volts, on their speed controllers to see if this volt drop is there on all speed controllers. I don€™t think it will matter to me but I would be interested in people€™s ideas as to where this missing volt has gone!!!
:uhoh:
I think its something to do with the spectrum if im honest. I noticed a change in speed when using the specktrum... i think i played with the end points and it was ok... so i think Jonno and John Lear just need to read some books and setup teir specktrums and sidewinder current/slew limits correctly.... LOL
Mr Stu
It probably is the spektrum. I had similar problems in Hive at the UK champs. Although mine were somewhat worse.
24V going into the speedos but only a max of 11v coming out to the motors.
Got home, took the spektrum to its extremes with the travel and bingo problem sorted.
This is one of the major reasons I dont like the spektrum. I only have one around in case my 40meg stuff gets damaged.
ive got no idea.... it works so ill leave it alone !
Someone did tellme about the speckrum causing a reduction.... it might have been stu.... i did mess about with the settings but gave up, as i didnt want to mess it up, and it didnt appear to make any difference.
When I put the roboteQ in over the next week ill have to measure the voltage as i am curious now.
I bet the 1 volt is being lost, it is being used to power the little hampster on its wheel inside !! :)
john
You could try calibrating the Sidewinder ....
QUOTE:-
Different radio systems have slightly different center points and travel ranges. To adjust
the Sidewinder to your radio a small button is located near the Status LED on the circuit
board to activate the radio calibration function. To calibrate the Sidewinder to your radio
systems set all your trims to center and press and hold the button for at least 2 seconds
(remove the front plate to access the button) while the radio is transmitting. The Status
LED will blink rapidly during calibration. Move the radio controls to their full extent
several times. When finished center the controls and press the button again. The
Sidewinder is now calibrated. You can verify proper calibration by observing the motor
LEDs. Both should be off with the controls centered. We recommend you disconnect
any motors from the Sidewinder during calibration.
http://www.robotpower.com/downloads/RobotPower_Sidewinder_quickstart.pdfhttp://www.robotpower.com/downloads/...quickstart.pdf
http://www.robotpower.com/images/sidewinder-bare-top-labels-sm.jpghttp://www.robotpower.com/images/sid...-labels-sm.jpg
thank you Woody,
I was going to offer the same advice.
It is also worth recalibrating if changing any part of the robot control system, such as reciever, transmitter, or motors. I certainly does no harm, and I have been advised by Robot Power that correcting the calibration will cure 90% of customers problems.
Tried all kinds of things
Re-set the Sidewinder, and changed the settings on the Spectrum that is the ELE and AIL Travel adjustment settings (For the RH stick) tried it at 100%, 115%, 125% and 150% no difference in output to the motor, when I went below the 100% mark to 90% the power was reduced but only in one direction?? I don€™t know why that should happen unless it is to do with the one stick operation; this is set up on the Sidewinder!!
Still mysteries like this are what make this game such fun. Like I say I can live with the power output as it stands. If anyone has any other ideas let me know or alternatively have a play when we meet at Swindon.
Just a thought when I get Saint Mk 2 going I was thinking of running the Bosch motors at 36 volts will this be ok? Or should I try to reduce the power to the motors via the Spectrum ELE and AIL Travel adjustment settings? That is if I can get the same voltage backwards and forwards.
Thanks Craig
:)
Mr Stu i dont need to read books you set it up for me:)
ONE big problem is i do have to stop in beast to fire (same setup on roboteq you dont)there is a 9v batter in line as well as 24v
Little john said the sidewinder is slower not me as i dont drive it compared to the roboteq,
not convinced yet as awaiting the new sidewinder befor i mess with the spectrum ( but could do a test swap back to 40 meg but No thanx
James please ans your email if you can see this thread you can see email im sure yes thats a dig!
(Message edited by jct on January 15, 2008)
over in ireland i converted back to 24v from 36v after i had to revert to Stus sidewinder ( thanks again :) )
I did find the same problem, that it wouldnt fire my 2 fire burkets while driving, i too had to stop before i could fire.
To the pneumatic experts.... i noticed a slight drop in flipper performance too..... maybe because it was sub 0 temperatures.... but woul firing a burket on 36v open it quicker hence get better flow??? I was just wondering.
woody or mario im sure you know the answer?
Im reverting back to the roboteQ for Ripper EVo and back to 36v as the sidewinder is going in something else.
John
whats it going in jonno?
my new toy? :proud:
something new, thats all im saying for now...
No your toy needs something a bit bigger :)
John
hehe thats what i thought :P
I wouldnt have thought the Burkert was opening slower ...rather as you suggest the low air temperature... the bottle pressure drops down to 500 psi @ zero degrees celsius and 250 psi @ minus 10 degrees celsius etc.
ok, just wondered / hoped !! :)
John
Oh it was easily Zero degress ain Ireland... so 500psi - no wonder the flippers were pants unless they go the heaters/hair dryers out.
LOL @ John - well next time let me at ur Current and Slew rate and specktrum settings and we can sort it correctly this time, same to jonno when he uses the sidewinder in his new toy.
But hurry up and get building my new big big big big toy for Swindon :talker:
Mr Stu