DC actuator design

Hi everybody, as you may have read on my simulator project thread here

http://www.xsimulator.net/community/threads/my-project-guide-me.5682/page-1

i'm building my own actuator, so i decided to open this to follow my work.

i have a list of all items that i am going to use, which is not finished yet. I'm starting with basics and then i will go with electronics.

The system will work just the same like other simulators, but, in this case, there will be a 10turn potentiometer instead of a 1turn detecting angle. This potentiometer will feedback the position of the piston, a 40mm solid steel bar. in a 500-600mm travel.

This is the pot

http://es.rs-online.com/web/p/potenciometros/4867093/

To power this i'm using a 350W 12V 30A motor, with a customised lockable worm gearbox.
The output of the gearbox is 100rpm 25-30N/m.

I suposse it lifts about 3kg with an 1meter arm. My first pulley has a radius of 6 cm (or 3 on next try)so i suposse about 50kg of force in the first pulley. I will increase the torque a bit more because i have to convert the 100 rpm out the gearbox to 80 rpm on the shafts inside, to achieve 500mm/sec.

This is what i have today, just bearings, i'm waiting for the 10t pot, 2 15mmx330mm solid steel shafts, 4 pulleys and 2 20mm M8 belts.



These are the 15mm bushings, the best i could find


they are factory oil filled and almost lifetime warranty, interchangable bushings 5euros /each

Shafts are made of a kind a steel, in spanish its something like Silver Steel, it has Cr, V, Mn, and of course C. This king of steel comes rectified, polished and it is used on precission drilling tools. So i hope with a Hardness of 65-70 HRC will be ok and it wont bend.

The motor will be about 30A max constant at 12v so now i'll look for a proper JRK-motomonster-pololu or whatever you recommend me.

I will order the ZYT-90 199mm which is 4700 rpm plus a mcp4 50:1 gearbox with customised steel or bronze gears ( pending budget from them) and 15mm output shaft.

Each actuator will own 1 arduino, its own PSU, and will be completly independent. It will be PWM guided, and just 1 more arduino controlling 6 independient PWM will be able to move a 6dof plattform ( lets hope so) ultra easy. It will also be possible to be controlled with a monochannel radio-control receiver. This is my goal.

right now dont think using wood makes this weak or something. Actually it holds me(im 72kg) with no flexion, and still need to add 3 more panels and about 60 screws. The lack of hardness/stiffness will appear in belts, for now, and i still have not received them.

Belts are OPTIBELT OMEGA "red series" M8 20mm

I will update as i go on.

I hear options on H-bridges/JRK/motomonster/polulu . 1 chip 1 motor, so singlemotor.

Greets

Great work!
(although linear actuators are to complicated for me

Will you be using server PSU to power the motors?

Can you send a link to your motors (350W 12V 30A motor) and have you done any load testing?
Looking forward to your updates!

Thanks, Tino.

Hi I did not make any load test because i did not buy them yet. i'm just waiting for a customized budget to buy them.

ZYT-90 is 23A, i want to have a range in nominal power.

http://www.motioncontrolproducts.com/pdfs/pmdc_2.pdf

Here you are. There you can find all solutions for motors and gearboxes.

ZYT-120 is 50A and has almost 4x torq

Thanks Miguel.
Looking forward to your build updates

Did you manage to get in contact with them?

Only reply I got was few months ago when I asked for torque figures for 25:1 MCP 4 Gearbox,
Apparently it's 9Nm...
Do you know how much Nm 50:1 MCP 4 gearbox can handle?

It would be great (if you don't mid) to post parts list and approximate price for your build.
I think your motors should make a great choice for a light 6dof platform.

I wish we had a page on the site with the list of parts and prices for different simulator types...
Something like: http://www.tonymacx86.com/441-building-customac-buyer-s-guide-august-2014.html

Yes, I can send a part list, when it is finished. but if this works, i'm patenting this.<--[[[EDIT This does not mean that i'm going to have a profit of this, i would like to patent something in my life, as my grandfather did, he won 2 gold medals on the 74' geneve inventions convention, with this just my name will remain with my work, it is valid for spain only i think and its quite expensive. Everyone will be able to build this same actuator, but for these people that want it ready and plug&play i have plans to create an online shop, at where i want, of course simtools to participate. I will try to live from this in my country, things are hard here but people still spend 2500 euros in a graphic card for the computer. the succes of this project is going to be very positive for this community because its going to open new posibilities for simulators. Please if some of you think this is not apropiate or i am in the wrong site, please make me know it. I just need some help, i want to learn how to, and i will work for it

With this exlpained i want to come back to work, please PM me i will kindly answer everything
EDITED]]]
I've talked to Zach Mckay, he answered me in a few days (send message on friday)
The problem with this motors is that they use to sell 1 model, the 65 rpm on ebay, and people dont investigate it too much and find they make custom orders.

About the gearboxes.... hmm its a 25:1 wich has about 9N/m, 50:1 with same motor should have about 18N/m. but we cant raise this proportionally, because gears are made of delrin material, so it has a max force on last gear. I think using bronze gears o even steel ( available) would raise torque on high reduction gears >40:1 because the shaft could not backwards and gears are harder.

About the motor, ZYT-90 has 2 lengths, the 199mm case has way more torque than the shorter model. the sheet shows 4700 rpm for ZYT-90.

The price for 1 actuator is about 600-650 euros, but think 3 things:

-They are build with max quality of materials, best quality, most expensive, you know.

-For a full platform, 6 DOF, the price of the moving working structure will be under 4.000 euros. Find a cheaper one on market. available to raise about 250-300kg

-Find a cheaper actuator, with similar specs. ( 50kg push pull, and most important, 500mm/sec speed) plus PWM controlled. I've found some at 2000 euros/unit.

Greets

@Tino talking about PSU, this is what i ve found.

http://www.pccomponentes.com/tacens_radix_eco_500w.html

Check specs

At home under 30euros

27 amps at the +12v rail,( motor is 23A) 5 volts 20Amps output to power all ards and stuff. Please more experienced guys would suggest how apropiate is this for the ZYT-90 motor shown in the above catalogue????. ( 23A nominalpower)

If not,
http://www.pccomponentes.com/nox_nx_650w.html
50Amps at the single +12v rail, more than 2x the motor nominal amps. at home for 46 euros

i've received the 10t pot and the steel shafts, will show you in a few hours, i've got some dubts about which conector is +, gnd and signal.

Thanks

Hi Miguel,
Thank you for your detailed reply!

Good luck with your patent application, I hope you have experience with legal claims.
Although I have to add that this is a community driven site so I'm not sure how much help you will get from other members if the result of their help will be your private patent claim.

I'll try calling or emailing Zach again, but I might have to go China route if I don't get any reply.
I think it should be possible to build 6dof motion platform for <2000$ using chain sprockets to increase torque.
Mercan-e did 6dof prototype (to prove a point) for about 300 euros!


http://www.pccomponentes.com/tacens_radix_eco_500w.html
This looks like a cheap PC power supply, I wouldn't recommend it.

Get something like this:
147A @12V for $25 \0/
http://www.ebay.co.uk/itm/IBM-Blade...=US_Disk_Array_Components&hash=item5afdd59381

I think i wouldnt be the first that makes a commercial product that uses this comunity software, anyway, i keep in mind what you tell me and they would of course be a part of my future projects, for that i have to talk to them but thats a far future. This actuator is going to be posted here, everyone can follow it and is going to be able to build it. And if someone helps me i would make a list, as Tino suggested, but i dont understant html code. I can give all photos of items and factory codes plus prices, but first i need to finish 1 unit. because my brain is a chaos of websites and items.

That PSU is ok, but i dont want to have an used product on my rig, and i cant ensure a constant supply of that. Remember 1 actuator is completly independient and needs 1x everything. i've found +80bronze certified PSU's, at 1euro/Amp at 12v, I xplain:

PSU +80bronze certified with 60A on 12v rail - 60 euros
same 70Amps - 70 euros.
and so.

Has anyone used this kind of PSUs to power their DC motors?

I want max quality and reliability. PSU is about 50euros for my budget

merchant-e uses the arm style sim. and i dont think they support 3x 32"TV's plus everything.
and using chains will create some sound that pulleys and belts dont.

Hi Miguel,

Yes, 3x32" TV's might be a bit too much for cheap 6dof.
I'll be using Oculus DK2 so no need for heavy monitors

If you want max reliability then Server PSU are way to go, used or unused.
Server PSU are made to work 24h year after year after year, and I presume these units have been replaced because of server room procedures, not because they don't work any more.
I'd rather have used Server PSU than new PC PSU (even good brand like Seasonic) anytime.

I plan to power all six of my motors from one (or maybe two) server PSU.

PC PSU vs Server PSU difference is similar to difference between Renault Twingo and M939 Truck.
Have a look what bitcoin and litecoin community is using for their farms:
https://litecointalk.org/index.php?topic=5854.0

I'm happy to help with creating the table, although even word doc with prices links and images would be fine.

the tracens radix 500 has Rendimiento total 24/7 wich means total performance 24/7,

As you say, I prefer to power the rig with the M939 truck, more reliable at long drives. I'll look for some new server PSU. Thanks a lot.

Hi Miguel, recommend building just one actuator and then exhaustively test it. You may save yourself lots of effort and dollars. I look forward to your updates.
In regard to gaining a patent for a new type of actuator - Good luck.

Lets see.... Thanks!!

I wont start building a second until first one has been 8 hours in a loop with 40kg of load. if something breaks, better thing and try the test again, until so.

If it lifts enough power, i will build a rodend-chair and see what it can do

Thanks for advice !!

Update of what i get, its nothing special but there are a lot a things comming.



15mm steel plated shafts. Cr,V,Mn needs to be cut, depends on the motor position which is being shipped.



This is the 10turn pot. Its vishera, it seems to be good. has a metric shaft 6mmx17mm it will turn about 7 times in a 50cm travel.



This is a main view of the thing, thats the aprox position of the potentiometer. sensed via belt, 9mm 3M pitch.

More soon.
Greetings

Hey guys!!! got more things!

This is the PSU, 54A @12v modular. Check specs.



This is the pulley.



This is the fan for the small heatsinks for pololu



And finally, the motor!!!



Specting to receive the pololu&arduino soon, so I can start trying to program it. Only mechanical addons until that.

Hope you are liking this.

Greetings!

Nice job!
How will you link motor and pulley? Thanks for the details

Hi RacingMat

The motor has a 20mm shaft, and i have 15mm shafts.



This connects the motor to the shaft. its a 20mm x 15mm solid coupler. The coupler is on the way.

For pulleys, im going to drill the hub, with the shaft, and insert a retention pin, made of sweet steel. ( 3-4mm ) finished with a key-ring to pull it out, and fixed with thermal glue.



Something like this, but this is not the exact model i need.

For that i need to buy a new tool because my drill and my hand is not enough to make this properly. I'm waiting for it.

Greetings

Yes a metal lathe is handy , I would have turned a shaft to connect it all but do recommend a flexi coupler in between.

Do you think a flexible coupler is better? I was thinking on a flexible but this seemed to be stronger and cheaper.

I Will point it as a weak point so i'm opened to other posibilities. That piece is easy to change.

Best to have a flexi shaft between the motor and coupling as any small misalignment will stress one or the other bearings etc. Which can lead to a premature failure. Also just my opinion, I have never seen a removable pin used to secure a pulley. Normally a key-way or grub screw is used - depends on application. I actually used both on my heave seat module motor connection. The Key-way to stop it moving on the axial plane and the screw to stop it moving on the shaft. If you haven't already have a look at this video.

@CalSim : you can have a look in the FAQ
http://www.xsimulator.net/community/faq/how-to-connect-potentiometer.13/