I have already had electric and gas rc cars, buggy, monster truck... And I wanted to build my self a tracked monster that could go quite fast, climb about anywhere, something unstopable... So I started to build a tracked monster. I started by the electric system.
it will be about 25 kilos, 60cm long, 30cm wide and 25cm high.
The whole system is is controlled by only two servos.
It will have one motor for each track, steel chassis, golf caddy battery, tracks made of timing belts and U alumunium profile, transmission by car' s water pump...
motors are 12V 24Amps at stall and 6Amps running free.
At this point I have only finished the electric system and I am going to start the chassis, tracks and suspension soon.
Dannyv, this should help you. Its the simple version of the system.
For exemple if you push the “left” button it will only comand the “motor right+” and the “motor left-” relays. So the left motor will turn forwards and the right motor will turn backwards, so the robot will “pivot steer” to the left. Diodes are there so as the microswitches controls the right relays and not all the relays in the same time. All the other diodes are there for the soft star and pwm system, to use 1 unit for the 2 motors.
This is probably a stupid question, but couldn’t this be done using say a H-bridge driving some massive MOSFET transistors? Am I wrong thinking that you only have full on or stop, -or can you PWM the speed?
In fact, I’ m sure there are many other ways to make it work!
It works like a h-bridge but I’ m using only 2 relays instead of 4 for a h-bridge. I’ m not using transistors because I don’t realy know how they work and how much power they can resist to… The PWM unit has an integrated soft start, motors take speed untill the chosen speed is reached. Max speed can be adjusted on the side of the wooden box with a button. If you are doing speed or if you are doing trial, climbing you change speed… The important is that my system is working way under the limits of the parts, even if it does take a lot of place, I must admit!
Hope you understand everything, because this it not my language.
Don’t get me wrong, I think your relay setup is great and something I haven’t seen before here at LMR. I would only like to mention that for example the MOSFET IRFZ44N is rated to handle 49A at 55V and might be though enough to handle the job.
Je suis Canadien,Québécois. Il n’y a pas beaucoup de roboticiens ici qui parlent francais je pense. J’ai débuté avec PICAXE il y a quelques mois pour m’amuser un peu et ensuite je me suis procuré Arduino pour l’étudier pour éventuellement l’utiliser sur un robot.
Could we please stick to English for all posts so that it is available to all of us. Norwegian: Ellers så blir det bare tull og tøys her inne, lettere om alle skriver på engelsk synes nå jeg.
Agreed - English is the sticky lingo of choice here
Of course, exchanging pleasantries in your native tongue can be a welcome variation. But in order to keep this forum available by every man (and searchable by machines), we need to stick to one common language.
So far I did not see any technical stuff floating by in French. Well, none that wasn’t translated later anyway. Thanks for that. I get the feeling les francophones understand le point. Dankuwel.
He told me he’ s Canadian and that not many “robotitians” speak french, he started by having fun with PICAXE, then he bought a ARDUINO to learn how it works and use it on a robot. He will follow my work.
I’ m sorry if you thought we were “talking in private”. Sorry
I was looking for an idea to make wheels to go inside the tracks, to support the weight of the chassis, I first thought of skateboard wheels or castorweels but they are quite expensive. And I found this polyamide cylinder for 3,95 euros (5,16 dollars) on Conrad.fr. Only need to cut it and drill it properly! This is used to make castorwheel rims, it is very hard and looks very resistant. It may be usefull for others… Exists in many sizes
little belt between motor and axe, bearing, and the big belt (I won’t put this one, it’s cut) turning against the floor with alumunium U not shown here. The tracks won’t have the same shape of bomb squad robot.
That looks like it is going to be one fine looking track system. Will you include a method to tension the tracks? This could be important, especially as the rubber tracks wear.
Working on a much smaller scale then you are, I added a tensioner pulley to the tracks for GRAB-E. It is similar to your approach with adjusting front-upper wheel, but instead of messing around with the main wheels, I just added the tensioner pulley.
BEFORE:
AFTER: (note tenioner pulley at rear-middle of track)
