Common configurations?

Hello All,

I am currently captaining a team of engineers intending on producing a robot, in the hope that robot wars gets renewiewed for a 2017 series.

A few of us were fortunate enough to travel to scotland for the filming of the current series and saw the filming of episode 2.
I have not managed to get in contact with menthorn since filming to ask for technical advice.
I also went to the robots live show in reading about a month ago where I met Kane (who was very helpful) and referred me here for some professional advice.
I approached my company, who have agreed to sponsor the hardware (within reason) and we have begun design on a two stage hydraulic piercing type (build thread to follow shortly)


My question is regarding commonly used electronic components and advice on the hydraulic system.

Is there a commonly used receiver unit/ motors (brushed vs brushless?)/ speed controllers/ batteries?
i am hearing good things about ampflow

We are also unfamiliar with hydraulics and unsure how to spec the pump?

Any advice would be greatly appreciated.
Thank you

Hi Tom
Others will fill you in with regard to hydraulics.
For drive though the tried and tested route is brushed and there are a number of reliable configurations. However...

A few people are now putting brushless drive systems into HWs. I believe two were running brushless drives in the current series(hopefully I will be corrected to say there were more) our entry ran out of time finishing the last couple of weapon bulkheads, but we did finish and test the brushless drive and whilst its not geared for a high top speed it gets there with featherweight levels of acceleration. This uses scorpion hk5020s and our own speed controllers now known as Mangle VESCs (see for sale section for techy details) after Rory from team Nuts who did most of the development. This gives us 7400 watts of drive as opposed to most brushed drive systems which typically deliver 2-3000 watts peak. The other plus is the weight saving which is a small fraction of a brushed setup. We are also fitting a brushless drive to our new HW intended for non spinner competitions, currently under construction. This uses two brushless scooter motors with the same Mangle VESCs.

We have had teething problems as there is quite a bit of fine tuning needed in software but the system is definitely viable and as cheap or cheaper than a brushed setup, depending on which brushless motors you use.

Pm me if you are tempted to go down the brushless route.

Good luck

Ian

Commonly used brushed motors,

- bosch 750w - like hens teeth to find these days but everyone used to use them
- iskra 800w - lighter than the bosch 750 and completely sealed. Still available in various voltages and configurations and can sometimes be found second hand on ebay as they are used as hydraulic motors. Expensive brand new.
- magmotors / ampflow motors - Different but essentially the same motors. Various variants available from the cheap and cheerful e series to the powerful neodymium series
- NPC T64 motors - nice all in one units from the USA that require no additional gearing and are nice and easy to attach wheels to. Downside being that they aren't cheap and need to be imported. Mind you once you take into account a gearbox they aren't all that more expensive.
- ebay cheapo scooter motors - I believe some are experimenting with these. Whether they will be of use remains to be seen

Brushless motors,

- Dozens of variants available. I believe pulsar used the 50cc ones from hobbyking to great effect. I've used scorpion motors in featherweights in the past and they have been great.

Speed controllers, brushed

- vantec - nice but expensive
- roboteq - some swear by them, others not a fan of the new versions
- wotty - Created by Ian of bigger brother fame. Need to contact him directly for pricing etc
- ragebridge - a US creation. Been used well over there. A few have made it over the pond

Speed controllers - brushless

- This be where dragons lie. Experimentation and blue smoke are the order of the day!

Batteries,

- SLA - tend not to be used nowadays. Heavy and not as much current
- nicad - not available for sale in the EU
- nimh - lower current capabilities than the lithium based tech and tend not to be used
- A123 - a lithium based chemisty with cells similar in shape to nicad / nimh. Tombstone in the US uses them along with a number of builders over there. Tend not to be used as much over here
- Life - Regarded as a safer lithium chemistry but with lower current discharge than lipo
- Lipo - the high current, give it all it's got until it sets itself on fire and then some battery tech. Although if you use high quality cells, a balancing charger and aren't an idiot about mounting them, they work just dandy.

Hopefully this is of use.

oh and as a starter for 10 with regards to hydraulics, your basic components being a pump, a reservoir, a ram, control solenoid and hydraulic lines. For a basic machine to get going you could start out with a pump / reservoir unit used on a tipping trailer (generally found on ebay used for £50 plus). If you want to go higher performance then you will need to start looking into companies that specialise in pumps and hooking them up to high powered motors.

Pulsar uses our Mangle VESCs to control his 5000 watt brushless motors . But yes there was an episode involving blue smoke. All part of the learning process.:kiss:

Hello,

Thank you all for your feedback.
Although brushless do sound tempting ( I have seen the 48v scooter motors on ebay for very cheap) they also sound pretty daunting, and the software side may be a bit too far out of our knowledge base.
Mechanically we can hold our own, as so far we are a team of mechanical design engineers and machinists, but we do not have mush of a clue regarding electronics! We deal with pneumatics on a day to day basis, and when we struggle so much getting to grips with hydraulics, we kick our selves for wanting a crusher rather than flipper/ axe bot.

The NPC T64's sound too good to be true! I will have to take a look.
How long do the US imports generally take?

I think our plan will be to assemble a test chassis for the drive train first, both to ensure the components work together adn so that we can get our hands on the components, as I expect CAD is hot or miss?
As I say I will start a build thread very shortly, when we have some more details decided and post some of our thinking so far.
In terms of the hydraulics we have looked at some all in one units, used mainly for power steering systems but so far they have not seemed all that suitable. We are aiming for 6 tons of pressure at the end of the tip based on some penetration tests we performed. If this becomes unfeasible or falls out of our budget then it can be amended, but I figure we may as well start with the best of intentions.
I will certainly take a look at some of the lifter kits. if nothing else they may be useful for a test rig.
I am also toying with the idea of using the same motor throughout the robot, to minimise the amount of spares needed, as we will need 2 for the drive, one for the pump (potentially if we cannot find a suitable all in one unit) and one for the electronic arm.
Thank you all again for your advice!

I ordered my T64s from Robotmarketplace. Took around 3 to 4 weeks to arrive. In the new series, carbide, nuts, sabretooth and my machine PP3D all run them. Nice all in one units and you can also get wheels that will bolt straight on in 10, 12 and 14 inch sizes.

Same motors all around is a nice idea but chances are the motors you need for drive will have different characteristics from those you need for the pump mechanism.

I have done a lot of research, and understood very little, but we thought we would start at teh drive motors and work backwards, with a view to place an order early next week.
I have taken your advice and am looking at either
ampflow A28-400-g or
NPC's...

Has anybody any advice on the NPC T64's VS the T74's? They look very similar in price and the T74's seem to have the edge in performance on paper?

I know there are a lot more factors, but will two of these be enough as a drive system? As were a crusher, we will have to be a little.. pushy.

I may still possibly run a 48v drive system if the motor characteristics on the A28-44-f48's can be used on the pump, as this will reduce the spares cost justifying the price increase and bringing it just within budget.


Looking at speed controllers, is there any advantage to single channel over double channel? (does it give redundancy in the event of failure, or just introduce a new part?)
Does channel mean what I think it does, that I will need one for each 'wheel' if single, or double can handle both?

We are probably looking at the Roboteq, though I have read some positive things about the ampflow VEX

Sorry for the massive amount of questions!

I'd stick with the T64s. The T74s are better on paper but are heavier. Weight always becomes an issue in robots and the T64s will be more than enough to drive up any other machine and keep going. I ran mine on 32v (8s lipo) and they were too powerful. Had to derate them on the transmitter.

Can't comment on the ampflow as I haven't used them.

Dual channel means it will run two different motors independently. Single channel means it will run a single motor. If you want to have drive you need a minimum of two motors for tank skid steer style control. There isn't really a huge advantage for one method over another.

Hi Gary
What sort of speed do you get from the T64s and do the require much modification to bolt wheels on?
thanks
Daniel

I forget the exact numbers but it's around 12mph give or take. If you watch PP3D in action both in the arena and on our test drive video via our youtube channel you will see what kind of speed they give us on 10 inch wheels running on 8s (around 32v).

As far as bolting wheels on, it's easy. When you buy them if you also buy the aluminium adapter plate that robotmarketplace have then this allows you to use standard sack truck style wheels as one of the outer bolt patterns lines up with the 4 bolts that most sack truck wheels have. Just remember that the threads on the motor are imperial but you can get bolts the right thread form on ebay.

We are moving away from the sack truck wheels as they can't take the abuse that our weapon throws back through the chassis but for a hydraulic crusher or similar they should be more than adequate.

That's great thank you We where looking for more speed, but looking at the short time limit we have I think this would be the easiest option, what speed controllers do you use with them as we tend to us 4qds.
Thanks
Daniel

I use an old vantec 47E as it's what I had lying around. I plan to look at the rage bridges as an upgrade.

As Gary said- we use T-64's and run them of a pair of vyper esc's.

The T-74's are not as reliable. More power through the small pinion- this is the weakness on the T-64's so putting more power through it makes the issue exponentially worse.

Also the added weight hanging off the back of the back of the gearbox can cause the casting to break (i asked the same question to a few teams while at Battlebots and that was the general opinion)

Thats great thanks I think we will be ordering them.