Showroom FlyPT - 6DOF Brushless DIY Actuators

Ok, changed the stiffness and friction values.
I think it works now.
Uploaded a new version:

Download here: https://3dwarehouse.sketchup.com/mo...6-8a40-6f58c6f11452/6DOF-Motion-Sim-Version-3

I have to say that you are wrong The lateral movement depends on the angle between the bottom platform and the actuator, the bigger the angle is, the smaller is the lateral movement. The size of the platfroms has nothing to do with the lateral movement

i tried to explain it here:
https://www.xsimulator.net/community/threads/basics-6-dof-stewart-platform.9396/#post-119948


@pmvcda
Great project! it's nice to see BLDC motors in use

OK, it's slow progress, but money is also slow (coming in, not out).

Some changes in the seat, instead of JKComposites seats, I changed to a Tillett for the Caterham, bought on ebay at jjcraceandrally.
Simple, no phone calls, no options, no bank transfers, but more expensive.
Just received it, looks good (around 4,5 kg):




Now I finally can design the rig around the seat and solve all my doubts about the seating position.

i love that seat, i have been stocking it since forever. nice pick

WOW!
I was thinking about building a 6DOF but I am absolutely new to DIY Motion Sims. Now i found your detailed build Log
What material did you use for the printed parts? I cant imagine PLA can withstand the forces. Or did you use a huge amount of infill?

They are solid PETG...
I'm on standby, because of some health problems, (not severe, but physically not helping) and lot's of professional work delayed.
The project is on stand by for some more days, but I will try to pick it up again in the next week.

Great project "pmvcda" please get well so we can enjoy the ride with you!

Regards Jerry.

Hey there,

first of all: Great build! Especially the fact that you are using PET-G for load carrying parts. A bit of a bold move though, but certainly one I will follow closely.

Please keep us posted as soon as you have a test under a realistic set of loads. It would make my own design quite a bit easier if I could swap all the 8-10mm aluminum plates for PET-G printed parts. That'd allow me a much sleeker and way more integrated design. So far I'm still staying with aluminum for load carrying parts.

A couple of questions on my mind for you @pmvcda , @SeatTime and @wannabeaflyer2:
1. Does the single upper bearing take all the bending moments when the actuator is in its fully extended position? I know, that there isn't all THAT much on there, but what IS there needs to go somewhere. I am tempted to use two upper bearings with ~150mm between them, just to be sure. Igus don't cost that much, so the only real consideration I'm giving this feature is the space requirements of it.
2. Does the loose end of the ballscrew simply dangle around inside the rod? I assume it does, so does it create any audible noise (klonk-klonk) during load changes. Or scraping?
3. I know, it's a bit of a delicate subject: Are there any features on your designs that you'd do differently if you were to make V2.0 of it? Come on,... you received praise and approval left and right, so show us the "dark" side of your designs

Thank you guys, you saved me months of work!

Dirty

1. Yes, for this Stewart platform design. I have been running them quite hard for around two years now and they are still working fine.
2. No, there is a nylon spacer on the end of the shaft.
3. No, I have made plenty of other changes over time with my 6DOF rig, but have never needed to touch the actuators. On reflection a encoder would be nice, but have not had any issues running with just pots.

Hi @Dirty cant speak for the other guys, but from the limited running I had on my system, I was of the opinion that the Distance and support of the IGUS bearing and the tube attachment to the Ball nut which was typically 100+ mm's, provided enough support to limit excessive flexing of the extended Tube / Carbon Fibre or metal Version ,

Point 2 :- Most of us I believe have added some sort of centralising insert at the top of the leascrew to minimise the rotational Whip, which may occur during rapid movements .. ( note this is fixed Axially but free to rotate if it does make contact with the tube wall ..

Point 3:- LOL this is a dodgy area . as were DIY by nature its always a learning and evolving curve with these project , I mean no sooner than you think you have sorted something out , a better option or alternate way crops up , just look at the variation on the theme regarding the basic design of our actuators .. £D printers have a lot to answer for LOL but also have allowed member to really push the design to another level ... were getting close to what commercial guys are selling for serious money ( yes I admit horses for courses but bang for bucks were doing ok ) so short answer to last point ...... Loads of lessons learnt form other member and ideas which can be incorporated in our base design ...it never stops evolving as each new member brings something new to the game ..

Yeah guys I know ...Never one to a few words when a book will do LOL but ya'll get the Jist

LOL @seatime your half the planet away and we still posted at the same time dam that's some serious Karma LOL

And yours was to the point LOL see I told you about deaf men and postings its a compensation thing

That's true! Even during the few months that I am working on my actuator, I have gone through a few design iterations. It's OK at an early stage where everything exists only in CAD, but if I come across a serious problem at a later stage it might become a costly lesson learnt. That's why I asked.

@pmvcda, I am really interested to hear, how the PET-G Parts hold up over time.

Me too...

Well, I'm back. Finally some time to pick this again.

I'm right now building the aluminium structure for the base and the seat.
Well, more or less, since I have no tools to weld, so I asked someone nearby to make me this:





In another front, I also ordered this:

It's a " VL53L0X Time-of-Flight ToF Ranging Sensor Laser Distance Measurement Module"
The idea is to replace the pot for something cheap with absolute positioning, but It needs a good white surface for reflection and needs a conic volume completely free.
This might take one or two weeks to arrive. If it doesn't work, it will be used in my son robotic projects.

Let's hope I get some news very soon.

Hi,

After some requests, I'm sharing the files of the 3D printed parts.
So I updated the post with the plans.
You can find it here: https://www.xsimulator.net/community/threads/flypt-6dof-brushless-diy-actuators.10799/#post-139681

If you want ti use them, please read the warning on that post!

What is this connector called? Link?

D SUB compound connectors.
I updated the post with the list of parts. It's the last item in the list: https://www.xsimulator.net/community/threads/flypt-6dof-brushless-diy-actuators.10799/#post-139680

After some tests, I'm going to ignore this solution.
It really needs a "big" conic volume.
It's fast and I could make it work, but I would need to point the sensor outside and have a big target on the slider, increasing the actuator section.
So it's a no.

I'm still looking at the hall sensors from the motors.
Made some tests and was able to count the signals, but I was also able to burn the Arduino... in a stupid way...

But I have a new Due and also an Espressif esp32 to try .
The ESP32 is way faster and with lot's of interrupt pins, good to count the signals from the hall sensor (and only 9€ !!!).

They are 3.3V but I got some logic level shifters for 3.3V <-> 5V.

Need some free time...

Slow slow slow...

Finally got the upper structure.
Not perfect... Asked a professional, but I'm not happy with the welding. But they are strong.
Needs some cleaning.
Also bought two articulated joints and an aluminium plate to hold the wheel (still have to drill and cut it).
Let's join parts to at least see some development:





Meanwhile, working with the ESP32 on a solution to count steps with the hall sensors of the brushless motors.
I have to deal with 3.3V logic in ESP32 and 5V on the controller, so more work than expected.
But it's also a way to protect the ESP32.
But it might work and maybe I Can scrap the pots and the belts.

This looks like a great actuator design. For one i can get my head around it without too much trouble. The 3d printed parts look great too. I'm looking forward to news on replacing the pots with a more durable solution. This could be a great reference design for an affordable actuator and if someone made a kit of all 3d printed parts i'm sure that would sell well. The only suggestion would be to boost the motor power a touch. Maybe it isn't needed - it will be interesting to see how it works in action as a 6dof. I've been reading up on PETG. Is it the best material for the job? Better than ABS? How about polycarbonate? I don't have a 3d printer... yet.

Well, for now it's working OK, but only moving the motor manually.

First tests with an extra motor I have. Just tested manually. I achieve 12 interrupts for one turn, so less than 0.5 mm precision, since 1 turn is 5mm.
(The Arduino was just to get 5V and test the logic level shifter 5V <->3.3V)



Started changing the code and wiring to test the actuator moving.
Remember, I have 5V for the motor controllers and 3.3V for the logic, so I have to separate more than I wanted.
Also, the minimum and maximum switches will be handled as a pot for initial test.
Minimum will be 0V, maximum 3.3V. For the test, the pot gives around half the value (+- 1.8V fixed).
If this works, I might use interrupts for the switches.
Big mess:



I think it will work.
I'm afraid of loosing the position with time. So I must keep the limit switches to handle a severe error.
Now let's change the code... Wiring is done for one actuator.