Carl's 2DOF Wiper motor 12v12 platform

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Re: Carl's 2DOF Wiper motor 12v12 platform

Postby Carl » Tue 23. Jul 2013, 23:54

1886
I inverted my pedals and mounted them on a rexroth goal post frame. I showed this view to illustrate the reinforcement flat bar I formed out of stainless steel. They are rock solid and give great feedback. I had to remove the spacer blocks to get them to the right height.
1885
I mounted my steering column on a linear track to make it adjustable between me and the boy. Spreading the mount across two bearing slides gives it great ridgidity.
1884
I fitted some gas struts to give the motors a little boost and provide damping. I chose to anchor them at the motor linkage point but this might change.
Last edited by Carl on Tue 27. Aug 2013, 21:09, edited 1 time in total.
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Re: Carl's 2DOF Wiper motor 12v12 platform

Postby Carl » Wed 24. Jul 2013, 00:00

I need to sort out a PSU or 2 PSU's to drive my 12v12's. Question is do I buy one psu or two? I have seen some very cheap psu's on fleabay designed for driving led lights. Has anybody ever tried one of these? http://www.ebay.com/itm/High-Quality-12V-30A-360W-Switch-Power-Supply-Driver-For-LED-Lights-Strips-/150790646680?pt=LH_DefaultDomain_0&hash=item231bd2ab98 Advice would be very welcome. Thanks
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Re: Carl's 2DOF Wiper motor 12v12 platform

Postby Carl » Wed 24. Jul 2013, 00:38

1889
I have fitted a bottomed out rod which is too long purely to give lockout on the platform whilst Im developing the build. What you may notice in this pic is that I had fixed a rotary magnet onto the shaft of my pots. I had tried to use a magnetic clutch directly driven from the other side of the wiper motor which I drilled and affixed a new positioning shaft but the shaft extension kept failing under test. I decided to scrap that idea and make a linkage as Floriske did.
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Re: Carl's 2DOF Wiper motor 12v12 platform

Postby crs2012 » Wed 24. Jul 2013, 09:29

Greetings Carl,

Great project so far! Just wanted to throw you my 2 cents from personal experience with my setup...

Carl wrote:I need to sort out a PSU or 2 PSU's to drive my 12v12's. Question is do I buy one psu or two? I have seen some very cheap psu's on fleabay designed for driving led lights. Has anybody ever tried one of these? http://www.ebay.com/itm/High-Quality-12V-30A-360W-Switch-Power-Supply-Driver-For-LED-Lights-Strips-/150790646680?pt=LH_DefaultDomain_0&hash=item231bd2ab98 Advice would be very welcome. Thanks


That PSU may not be adequate for a single PSU setup to run 2 jrk boards at once. 12v x 30A = 360 W, Not knowing what your motors will
draw under load, it's hard to really answer your query with a definite answer. But this math can be used as a guide.

I run 2 boards with 1 power supply myself, but I'm only moving a seat and H-shifter attached , and it's mounted with a U-Joint directly underneath. So,
there is very little load added to the motors from anyone sitting, and not much more added during motion.
It took me a good while to get the PID set correctly before it would be stable enough to handle various size/weight people on it without having the
PSU cut off due to AMP spikes out of range. Mainly from the fast direction changes.

So the amp spike draw for both motors are no where near what your setup will experience having to move the entire platform under load. The only
sure way to know what kind of PSU setup you require would be to test your motors under load with a car battery and AMP meter. I believe
the amp draw is doubled during immediate change of motor direction giving the massive spikes under load. Quick and easy to
test. Once you know what AMP draw you have for how much weight, just double it up for 2 motors, and get a PSU with 20% more power than what your
total MAX would be. Which I think would be cheaper than 2 separate power supplies. Unless your power requirement is something outrages due to spikes,
in which case, an inline car battery may be an alternate option. I've seen that solution used by many different wiper mover projects as well.

This is my simplified version of the math. Anyone with more technical expertise is welcome to explain it with more detail.
Hope this bit of info is of some use to you...
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Re: Carl's 2DOF Wiper motor 12v12 platform

Postby Carl » Wed 24. Jul 2013, 22:52

Thanks CRS.

I measured my motors at around 11a peak under no additional load but working hard in the changes of direction. If I double this and add 20% Im still way below what I had in mind. I was planning on running them at about 30a each. If I buy 2 separate psu's Im thinking at least 30a each, if its one supply Im thinking 60a plus. I have the weight balanced neutral on the gas springs from pivot to pedal but the inertial forces will need the beans current wise when shifting the platform from side to side. Think Im just gonna have to take a chance with the 30a psu's... the Mrs would kill me if I attempted to bring a car battery into the living room. Also, my 12v12's wouldn't like any more than 30a even with the heatsink and cooler enclosure.

Did you fit any caps or diodes into your card dc supply wiring circuit to manage back emf or is it nothing to be worried about?

How much did them scn5's cost... hope to upgrade to them at some point.
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Re: Carl's 2DOF Wiper motor 12v12 platform

Postby crs2012 » Thu 25. Jul 2013, 05:35

Did you fit any caps or diodes into your card dc supply wiring circuit to manage back emf or is it nothing to be worried about?


I guess it depends who you ask on this one, the answer will always be different. I guess it depends on how careful someone
wants to be. Some believe using every precaution necessary is the way to go. Others may opt for whatever works.

I'm somewhere in the middle. As long as enough measures are already in place 'somewhere' in the system, then it should
be ok. In my particular situation, since you asked what I did with my setup, I did not require any extra caps or diodes. The
PSU and boards I used were perfectly capable of handling everything. So adding anything else was just overkill for my setup.

I'll add some pictures of my control box to my project page in the next few days. It's actually a very simple wiring setup.

the Mrs would kill me if I attempted to bring a car battery into the living room


HAHA, well at least she's cool with the simulator being there!

How much did them scn5's cost...


I think each actuator was $575'ish at the time + tax + shipping. I think the prices came down a little bit on those actuators
since the time I bought them.
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Re: Carl's 2DOF Wiper motor 12v12 platform

Postby Carl » Sun 25. Aug 2013, 13:01

Well things have moved on quite a bit since my last post. I bought 3 cheap 12vdc 30a psu's of ebay for £25 each. Power wise I think they are great but I must say 1 of the 3 I bought died within 20 minutes of powering up. Glad I bought a spare. The other 2 have been running fine now for over a week without issue.

I could not help myself being so close to motion and cut a few corners just to get it rocking. I have to tidy up the electrics this week, put some fuses in to protect the jrk's 'n motors + I need to wire in a kill switch and do some supplementary bonding but thats for later. I AM ROCKING! :mrgreen:

What a BLAST!!! The platform was a bit jumpy at first so I did a lot of playing with the motor and PID settings. I found that although my motors were pretty closely matched the setting I have found that work best are miles away from what I have read as good starting points for wiper motors. I am currently running 4:2, 0:3, 20:7 and 4:2, 0:3, 15:2 on my wiper motors. Motor settings wise I have duty cycle and max.acceleration max'd out and brake duration down to 5ms. Heres where things get confusing, I have my Max. current set at 0.255 and my current calibration set to 1. This does not make much sense to me but it works. Maybe one of you guys could shed some light on this setting in the jrk config utility and what the current calibration number has to do with the price of fish. It works well as it stands but I would like to know why. :?:

I am still learning and getting to know how to work with the x-sim software (need to read some more about math plugin setup) but were operational so no panic. Can somebody point me in the direction of a good tutorial on math setup please. I need to understand the range parameter... min and max values? splitting neg and pos and why? Auto adjustment? Thanks for your help in advance peeeps. Also the third step is all a bit confusing for me... add, multiply or overwrite result? I currently have longitudinal and lateral force set up with "add result value"... again this works but it would be nice to kn0w why. I played about with the smoothness setting and can see what that does and same with intensity. Also when would you use the log, mean, smoothness and spike filters? When would you use a scaler? HMMMM.... so many questions. Im goona try and upload some videos now... my boy loves it... so do I.
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Re: Carl's 2DOF Wiper motor 12v12 platform

Postby Carl » Sun 25. Aug 2013, 13:04

Almost forgot to mention, mechanically I had to fit two trampoline springs on line with the pivot point to assist the motors in righting the platform and counteract the gas struts. An unfortunate necessity but needed given the entire platform is made from aluminium and rather heavy.
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Re: Carl's 2DOF Wiper motor 12v12 platform

Postby Carl » Sun 25. Aug 2013, 14:49

first attempt at uploading a vid... epic fail!
Last edited by Carl on Tue 27. Aug 2013, 21:13, edited 2 times in total.
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Re: Carl's 2DOF Wiper motor 12v12 platform

Postby Carl » Sun 25. Aug 2013, 15:14

Last edited by Carl on Tue 8. Apr 2014, 21:08, edited 1 time in total.
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