Linear actuator using ClearPath Integrated Servo System @ 72V DC

Yes, single phase 110v/220v input, 3phase 220v output to the servo motor.

You can connect 3phase for input as well if available. It will provide more solid power source for the drive with less chopping when under load.

When you say "3phase", I guess you mean US (120V phase /208V line)? Or 3 phase in general? Like the European 3 phase power (230V phase/400V line)? I'd love to try that, but I think for Europe it requires the special 380V version of the servo drivers.

I am still a bit confused but please watch this diagram because I don’t see the neutral in the input

When using 3phase, you can connect the Neutral (equipment ground) to the ground screw of the driver.

The 3phase in US is 120v per phase. They use actually 2 of the 3 phases to create 220v for equipment that needs such voltage here.

The 3phase on Europe is usually still 220v for each line, except for cases where they combine the phases to create higher voltages like 380v or 400v...

Again an ignorant question...
Is the 3 phase voltage (230 vs 400) related to delta / star wiring ?

Yes, that's the difference. You can either use...
- one phase against neutral (star)
- one phase against another phase (delta)

The factor between the two methods is always square root of 3 (~1.73)

230V --> 400V (Germany)
120V --> 208V (US)

Hey

finally the first actuator is working. Properly driven by the sim. It performs as expected
Push and pull force way within design specs. So much so actually that it's possible to change the gear ratio to 1:2 for twice the speed (830mm/s) if needed.



Cheers, Dirty

Thath speed!
You can get killed in the rig

Yeh,.... 830mm/s is quite something! Even 415mm/s is a lot if the actuator reaches that speed within 100ms. I think I better dial down the filters a bit to give the platform less acceleration over a longer timespan.

I think I will build the other 5 early next year and then have a rig mock-up probably by April. That should make motion tuning easier, because so far I only have the virtual model to tune the motion.

Have done the same in my rig with Mover.
You will get to the conclusion that the 3d view small movements are huge in the rig, and it can get really violent.

I use a rigid seat with the idea of feeling the small details, but... It can be really hard!

Don't forget that in a roll, you have the left going down and right going up, and at those speeds, it looks a terror!

Congrats, looks great !!

There is nothing to do to make it a bit more silent ?

I agree! Your butt can feel motion a lot better than your eyes can see it. Especially when all there is to see is a tiny concept-model on the screen.

Ohhhhh,..... Thanks for asking! There is actually A LOT that can be done to make it quieter!!!

I have a couple of Ideas that I will test out soon:

1. Encapsulation by closing the frame on both sides.
   
2. Armaflex
3. Dynamat
4. Filling the hollow spaces of the aluminium extrusions with 2 component polyurethane foam.
5. or a a combination of the above

It won't do wonders, but it will make the actuators quite a bit less noisy, for sure. Especially when considering that there are six of those, every little bit of sound muffling/deadening will make an audible difference.

Wow! That is fantastic. There is certainly no fear they will be too slow now!

This also bodes well for me. With my current plan I'm hoping for three of these to be strong enough to move my heave elevator with it's own frame, floor, G-seat, pilot, and cockpit on it. I expect to have it running in two or three months so I'll find out soon!

Hi,

your design looks fantastic, I have some questions :

1. is the friction between aluminium and PETG a problem ? won't the PETG be "cutted" by aluminium ?
   
2. did you finally use 1610 ball screw and for what displacement/speed in final ?
3. what dimension for your rig base and final platform displacements expected ?
4. is your base joint strong enough in PETG ?
5. what carbon tube finally ?
6. do you think glue will be enough to fix pulley ?
7. why did you choose 25mm width pulley ? seem enormous !!

thanks a lot (once again)

Hey there

1. So far, there is no noticeable wear. The actuator only has a few hours worth of operating time, but I can see absolutely no traces of friction. Keep in mind that the aluminium slots are rounded and slide easily along the PETG. I have chosen this cube shaped slider to distribute the load from the torque over a larger surface.
2. Yes. SFU1610 and they work great. Initially I planned SFU1605 with 4000RPM motors, but now I use SFU1610 with 2500RPM motors. All in all, that is an increase in actuator speed with a decrease in RPM. Since noise depends on RPM to a great degree, I chose this combination. The belt drive is still a 1:1 ratio but it gives me the option to make gradual changes for tuning later on.
3. Not 100% sure yet. The most probable dimensions will be:
   Lower diameter: 1.6m
   Upper diameter: 1.4m - 1.6m
   Stroke: 560mm (Min: 1050mm, Max: 1610mm)
   Height: 0.8m - 1.5m
   
4. I guess so I hope so! So far, I see no bending or other deformations. I have printed the parts with a 3mm shell and 50% infill. There are two kinds of load on the part: Compression and extension. Compression does not seem to be a big factor here. Extension might be a more critical case. Especially considering that the parts are printed with the layer lines horizontal! I have put ~150Kg of extension load on the actuator for a few minutes. That went fine. But....
   ...I have a friend who works with thermoplastics as an engineer in a professional manner. He mentioned, that over longer periods (weeks/months) even PETG can flow like a Glacier. I will see how it holds up.
   I have tried to melt a steel wire into the plastic to transfer the load into the deeper layers of the part:
   
   At the end of the day, I think that the part will hold the load fine when dimensioned big enough even without steel reinforcement. Especially the shell thickness is important.
5. No, I use a 28mm aluminium tube. It's surface is anodized and quite hard. I use IGUS sliding bearings. They should hold 10+ years on normal use.
6. Yes, I am pretty sure. In fact, I got that tip from an engineer at Clearpath who recommended this method over anything else. And I can agree. Loctite 648 holds like mad and can be removed easily when heated up to ~250°C with a heatgun.
7. I like to over dimension stuff And I didn't find the right formulae to calculate the belt drive more precisely, so I went with 25mm as a precaution. It feels VERY rigid but 10mm probably would've done as good a job as 25mm.

Not sure, but maybe this download will work.

Cheers,... Dirty

@Dirty thanks for all your answers !

so the final dimension of your ballscrew is 560+180 mm ?

and did you think about 2010 screew ? maybe it's another way than putting 2 bearings ?

Thanks

Hey ,

The ballscrews are SFU1610 700mm. Of the 700mm total length about 140mm are unusable because the bearing blocks, the ball nut and some buffer zones occupy that space. There is still a little room for spatial optimization left, but I think 120mm unusable travel is the absolute minimum you can achieve.

I have indeed considered SFU2010 or even higher diameters/leads. And if we were all honest (and complied with the manufacturers dimensioning recommendations), we'd have to use at least 20mm diameters for a typical linear actuator. But since there are so many linear actuator designs out there that work just fine with 16mm, I figured: What the heck...

You mean the double upper bearing? Not sure, but I think that is independent of ballscrew diameter. The buckling load has to be carried by something. It gets bigger with the square of the length, so for an actuator with 560mm travel I definitely wanted it in there. Maybe I am paranoid, but for now I will keep ~100mm of overlap between the rod and the two upper bearings.

Bon nuit

@Dirty thanks for your answer

I really have no idea what is huge or not in a rig ? is 30° in pitch and roll fine ?

thanks