Hi. I am new to robot building. What are possible setups for the drive system? What motors and gearboxes do people use and roughly what works together?
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Hi. I am new to robot building. What are possible setups for the drive system? What motors and gearboxes do people use and roughly what works together?
For a relatively simple system, I known 800W scooter motors with sprockets and chains to be used to good effect which is relatively affordable. Beyond that, you could go with big CIM motors, NPC or Ampflow motors with gearboxes on them or even go brushless though they can be quite fiddly. In theory, wheelchair motors also work but they tend to be underpowered for this level I feel. Speed controllers, in terms of brushed motors, usually go along the lines of VEX BBs, RobotEqs and the like though I've known Cytrons to be used as well with a bit of modification.
I do advocate reading the build diaries here, they are a wealth of information of what works and, perhaps more importantly, what doesn't.
However, it is worth bearing in mind that to get a system that works and works well (that includes the motors, the gearing and the speed controllers and the batteries), it can get quite expensive and if you've never built a fighting robot of any description before, it's worth starting in a lighter weight class like Featherweights or Beetleweights simply because they are far cheaper to build and maintain plus, in my experience, they are easier to learn the basics with.
For example, my Beetleweight I put together for about £75 I want to say (albeit with some components reused from other projects) but the axe motor and speed controller in my Middleweight easily cost will in excess of twice that alone. One of my Featherweight robots cost me ~£300, my first Middleweight was in the £700 region all told and that is before the cost of keeping them running.
Cool. Atm I have made an ant weight and working on a featherweight. Wanted to start doing the research early for something heavier.
I have had a read on some of the stuff but I'm semi worried as something like ampflow one motor with gearbox people have said isn't powerful enough yet another is. Is there like a specific go to for roboteers?
Without knowing which combination of motor and gearbox they are talking about, I can't say. I tend to make my own gear reductions for my Middleweights drive (and will have to for my next big project as I talked about in my build diary). Each motor has its own characteristics and quirks.
For example, the CIM motors I use seem to be fine being overvolted to quite a height with a 6.35:1 single stage reduction drive to the wheels using MOD 1.25 gears. That's fine for the weight it has to shift and for the application it is being used for but I wouldn't dream of using that same combination in a Heavyweight because of the extra weight. I am envisaging having double that reduction in my next project with A28-400 Ampflow motors though that does rather depend on which weight class it ends up being. ^^;
The off the shelf gearbox on Ampflows is 8.3:1 I think, which is relatively high and possibly where that comment comes from if it was paired up with something like a E30-150, which is the "smallest" motor Ampflow make as of writing I think. With the right gearing, that can be used I feel though I must confess, I can't think of any examples right at this moment.
I've managed to grab myself some Ampflow A28-150-F48-G motor and gearbox for a cheap ish price (https://www.rapidonline.com/ampflow-...earbox-37-0318).
They are 48v and I can't seem to find 12s lipos online, at least not a sensible price. I thought that I could run two 6s in series?
Also I was thinking about maybe looking at the cytron dual channel 60A ESC (https://www.robotshop.com/uk/cytron-...or-driver.html) for these but not sure itl be suitable.
Any thoughts are welcome.
So long as your wiring is of good gauge then sure, I use a pair of 4S LiFes in my Middleweight in series without issue.Quote:
They are 48v and I can't seem to find 12s lipos online, at least not a sensible price. I thought that I could run two 6s in series?
I've used these in my MWs before and whilst it is very plug and play, the exposed capacitors in that can easily be knocked out. The low amperage (comparatively) is also a problem. It'll drive the motors with no load without issue but its not a regularly used ESC in the MW and HW scenes so it is a bit of an unknown as to how robust they are with 12S LiPo. That being said, my MW was easily in a pulling match with another MW the last time it was used and didn't die on me then. The other issue as well is that it is actively cooled which whilst can be worked around, is yet another failure point.Quote:
Also I was thinking about maybe looking at the cytron dual channel 60A ESC (https://www.robotshop.com/uk/cytron-...or-driver.html) for these but not sure itl be suitable.
Ok. So what you're saying is that the cytron would run it but may fail depending on circumstance?
I've read some of the other forums and saw some people suggesting the 4QD range.
4QDs are tried and tested definitely. RobotEQs are more modern and I am sure robots like Thor use that exact motor and ESC combo.
I am saying that the draw from the motors in terms of overall amperage could cause the ESC to cut out. With a bit of preventative modifications (such as putting a vented box around the ESC for example), it should hold up but it is still a relatively untested piece of kit. That being said, I think Tango (HW pusher) uses a Cytron but with scooter motors.Quote:
Ok. So what you're saying is that the cytron would run it but may fail depending on circumstance?
I take it both the 4QDs and RobotEQs are not just plug and play?
I can't speak about 4QDs as I've no hands on experience with them but I've heard that they require interface boards and such. RobotEQs you do need to read the documentation to get working.
jason uses a40 300 amp flow motors the same as me. i use a megawotty i believe jason uses a robotek , i used to use 4qd controllers and yes needs an interface i would stay away from them now im not sure anyone knows how to fix them at events.
i also run them on on 7cell lipo
Megawotty? I have never heard of them. Do you have a link?
wotty or watty no links they're made by a roboteer call ian watts runs bigger brother , if you're using smaller motors like bosch 750 or equivalent then a normal watty would do. when ive ever had problems you just send to him and he fixes it simple.
probably someone will post a second hand one on here now !
Ok. I'd rather buy something new. Don't want to buy something and it not last.
I take it no one uses the 4QD pro 360 then?
https://www.4qd.co.uk/product/pro-36...-programmable/
Not to my knowledge, no. I use a HW controller in my MW for its axe, a VEX Victor BB (ref: https://www.ampflow.com/controllers/vex/) which is a little fiddly but works for my needs.
Regarding the 4QD, i have used them in the past but they are bulky and in the case of the PRO 360, expensive. As for the Vex BB controllers, they are again expensive ($499 each) and are not easily bought in the UK anymore.
Your best bet would be to look at the Roboteq controllers, there are plenty of builders who use them so plenty of people who can help with them, they are also available as dual channel and single channel controllers so you can choose if you want 1 controller or have 1 per motor.
Another option would be the Robot Power Vyper: https://www.robotshop.com/uk/vyper-1...ontroller.html
you would need 2 for drive and you would be limited to 36V but then you would need 2 4QD controllers as well or 2 Vex BBs.
lol.... just because something is new will not guarantee it lasts longer in this sport !
The robotek ones on robot shop are quite expensive too. Like £500+ minimum
HW components are expensive across the board usually. They don't have to be, the Vex BB controller I mentioned was a second hand affair (as Chris mentioned, they aren't readily available in the UK and are expensive new) and the pair of Ampflow A28-400 motors for my upcoming HW were definitely second hand as well.
I like to think of buying second hand as them having been tested in the sport in some capacity, even if it was only for testing purposes by the seller. As Terry mentions, buying brand new doesn't ensure they'll last any longer than used and as you might imagine, this sport is unforgiving. I've blown up at least one Cytron dual controller which I bought new.
I get that. What I was saying is they are the same price of not mroe expensive than the pro360s.
One silly question. The motors Ive got have an upper limit for current of about 290 amps. Is it then wose to get a esc which has a limit continuous current of 300 amps? Or could I get by with something lower?
The amperage rating is the peak that the motor can draw at any one time (usually when stalled). If the motors can pull 290 and the ESC handle 300, then in theory you are OK. The other way around is a bit more complicated.
For example, the ESC I use in my Middleweight now (a RageBridge v2) can handle 40 amps a side continuously with a peak of 75A for 30 seconds. The CIM motors I use (from RobotShop) states a peak of 133 amps. However, this is at 12v, I run these motors at 26.4v (8S LiFe). Therefore, to get the same wattage from the motor, you need, in very rough terms, half the amperage. 133 / 2 = 66.5amps at peak. It is entirely possible that the motor could still draw 133 amps but at that point, my 80A fuse would blow and prevent the motor from exploding.
It is also worth noting that the gearing on your drive will make a difference to how much amperage is needed at any one point since all of the above is based on a 1:1 gearing as I understand it (i.e. direct drive). The Middleweight uses a quite high 6:1 (ish) single stage gearbox.
So in answer to your question, you could theoretically get by with something lower, yes but it needs to be calculated.
Has anyone tried the roboclaw solo 300?
Not the Solo 300 but I know a MW (Audacious) that I think used a Roboclaw in their drive for a while. It ended up randomly cutting out on them a lot.