OCSM Sim (2dof + traction loss) project

Hey guys thanks again for the help!
In the while I've found those motors and gearboxes:
motor: http://www.ebay.it/itm/380957901363?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
gearbox: http://www.ebay.it/itm/110963461935?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

What's your idea? mine is that once coupled they should be similar to the powerful worm motors bsft suggested..am i right?

I have same 90ZYT-155 motors with same MCP4 25:1 gearbox that you linked, also bought from Motion Control Products.
The motors specs are as following:

Voltage: 12v
Current: 23a
Speed: 5000rpm
Diameter: 90mm
Length: 155mm

So with 25:1 you will have 200 RPM.

Unfortunately for me, I've never could make them work with JRK controllers. The specs, if they are true, are saying 23A, but I think they draw A LOT more under load and motion changes and that was trouble for JRK boards. @Avenga76 had similar problems with his motors drawing over 70 Amps at moments and JRK's choking up, and he has 60:1 gearboxes. He needed to slow down the motors and motion to make them work with JRKs with minimum errors.

But there are also other people who are using ZYT90 motors, they can share more thoughts on it. I think @Erwan960 ?

You can use them with a big sabertooth 2x60 and an Arduino. It's a good choice for this price!

@Pit is using a similar motor from motion control products for his traction loss with a moto monster
http://www.xsimulator.net/community...h-traction-loss-by-pit-finished-but-wip.5276/

the higher rpm motors may be causing an issue, but that doesnt mean toss the jrk away.
As Avenga has done, slow the motors down and work with motion, PID and things, (same thing I had to do) or find slower RPM motors.
see if you can chase up motors under 4000 rpm.
@Roadster2 , got any slower motors?

Sorry Dave, the motors I had were the same and I only have a couple of 50:1 ratio gearboxes now. The spec. sheet for the ZYT90 motors (attached) state 23 Amps but a spec. sheet for a "90ZYT155 12V" states 27.8 Amps. Either way, I assume that this is under "no load" conditions. If so then given the task that they're fulfilling on a motion platform then they would indeed draw a much higher current.

@noorbeast , how hard do you thrash your motors?
Whats your PID and motor settings?

As far as I'm concerned, I currently use :
P : 0.47
I : 0
D : 0.67
period : 10 ms
Integral limit : 5000

Max duty : 400
Max accel : 300
brake : 0
max current : 35.7
current : 140
max dc out of range : 400

During a 1h race, I find no error in the report of the JRK software.

Motors : ZYT-90 155 : 3200 rpm / 0.6 Nm
Gearboxes are : 60:1

Hi guys and thanks for your feedback!
It's really helpful to read your comments and go back to your projects (I've spent A LOT of time on them) finally understanding why some points were so important.
By the way, tomorrow I will weld the complete frame so various things about movements will be finally clear and measured.
Regarding motors, in my first attempt I will try to move the structure with my current motors driven at 16V (12V+3.3V from two pc power supplies) and an arm of about 15cm. Curious to see what will happen.
Next step will be to finally buy decent motors and in case, proper electronics.
And I have to say, most probably I'll go for the ZYT-90 with 25:1 gearbox and Sabertooth, using the current Motomonster in the future to drive the traction loss.

Stay connected!
Marco

150mm CTC lever, on what motors?
even on larger motors you are looking at issues with actually having too much travel and reduced torque.
Been there, done that. Shorten the levers right down, even with bigger motors.
It will not move the frame.

after a productive day the frame has been almost completely welded. Not big issues so far..
But from now the challenge will be harder! Can't wait to see the sim moving!

@bsft, thanks, definitely 150mm CTC is too much, i will look for another solution…

if you are going to use 25:1 boxes, and a full frame, go no more that 40mm CTC levers.

Here I am again.
Thanks for your kind interest bsft!
Unfortunately this week-end just a few improvements and some new questions:

Has anyone ever tried to use a long screw (like this http://www.bricoman.it/negozio/ferr...a-friulsider-m12x1m-acciaio-zincato/10009913/) and those joints (http://www.ebay.it/itm/221474536259?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649) to link structure and motor? Would it be weak in your opinion?

Second question relates to Hbridge. I'm thinking to build my own Hbridge capable of driving the ZYT90 motors with 25:1 gearbox. Does anyone have tried to do the same?

Thanks in advance
Marco

hello Marco

M12 rod should be fine! Is it a shoulder mounted setup? or feet mounted setup?
my 2DOF shoulder mouinted was Ø12 (but not threaded)

For the unijoint, you have to check if their angulation meets the angulation needed by your sim.
Ebay didn't specify the angulation...

Thanks a lot noorbeast and RacingMat!

Pit's idea is absolutely smart! I'll go with it to give power to those hungry ZYT90 motors!

Regarding unijoints, mine is a shoulder mounted setup. Sorry Mat I cannot understand which angulation you mean. Would you mind to indicate me which one is it?

At the moment my Sim hasn't any definitive solution to place and hold the motors.

Again thanks to everybody spending their time to give me help.
I hope to be able to share my acquired knowledge in the near future.
Well, long story short, during this week (and wainting for next week WRC!) I will be trying my actual setup.
Unfortunately I haven't bought new motors so I'm using that old and slow motors I already had.
Here's the point: sometimes (especially with more reactive cars in Assetto Corsa) during hard and fast changes of direction the (I suppose) motomonster cuts the current supply to motors. At about 0:55 of this video () you can see what I mean..a strange sound (like tack tack) and then a fan (from the PSU) increases its RPMs, like it is going to protection mode or so.
What seems strange to me is that I've stacked two MM for each motor and I'm just using a 5cm CTC lever.
Is this behaviour just related to my actual loved up motors?

What's your opinion?
Thanks in advance

Marco

Thanks noorbeast! yes I can confirm I've carefully checked the balance with me myself on board and the peripherals.
However, as far as my simulator is adjustable in lenght and it is thought to be used by many, the pivotal position couldn't be always that precise.
That said, this strange behavior has happened (more or less) in all the CTC positions, including the shortest, 3.5 cm.
At the moment and in the video, the CTC is 5cm.

Another strange condition that makes me think about faulty motors is that the left motor isn't capable of holding the weight as the right is.
I can manually move the left motor arm but I cannot absolutely do the same with the right one.
And the two motors are supposed to be identical.