Linear actuator using ClearPath Integrated Servo System @ 72V DC

Ah, that explains why it looked so huge, travel is doubled!

Now that the travel is corrected I do gain a bit of heave by decreasing the length of the short sides of the bottom hex. I'll have to work the numbers again. LOL

Updated numbers. Note that I'm now back to the standard minimal dimensions on the short sides of the bottom hex.

It looks like the Heim joint angles are once again an issue for pitch and roll angles approaching 20 degrees. I don't expect I'll use that much but still I'll want to use joints that give me as much range as possible. Other than that, everything looks good!


Maximum travels shown here (mm and degrees) are the theoretical max so I'll have to take a bit out for a safety margin.

I would say that’s an optimistic statement although it’s very good as a starting point.
Depending on the design, actuation ability and the amount of HPF it can be that the heave full travel will need to be reduced by more than a half.

It’s a complex topic where the empirical approach will give you an answer.

He's just talking about the actuator stroke spec to be entered into the "range" field of his software...

Oh sorry, I thought the discussion was going on how big the heave can be ?

The standard heim joints will have to be customized with spacers in order to allow more bank angle otherwise you will hit the limit pretty quickly.

The good question is if it makes sense to go for expensive 360 rotative u joints with the actuator length and stroke you take as option.

I don’t know.

For range limitations:
- put 20 angular and 150 translational
- construct a profile for a vehicle and apply filtering according to your needs
- do all possible maneuvers except accident.

If you lock your platform increase first the HPF, if it doesn’t help increase the heave range limiter.

Otherwise you can search for bigger heave.

Since long time I was thinking about a safety feature based on joint angle of attack. I’ve abandoned it when I bend my legs to help to overcome the issue.

@pmvcda you could maybe imagine a setable starting point angle for heim joints (assuming the design starts with 0 degrees) and monitor the displacement of those.

It could maybe give a important info while you design the rig and prevent the collisions while driving it.

Best

Once I've got my G-seat built I'm expecting to use near 100% heave, 50% surge and sway, and keep the rotations pretty small based on past experiments probably about 10 degrees. I know, I know, I'm doing it wrong by letting cues clip but the platform only ever stays at those extreme heave positions for an instant.

I'm probably going to (stubbornly) use 330 mm on all translational DOF's, and 12-15 degrees max on all rotational DOF's. I still refuse to use software that stops the platform when clipping occurs. I'm also going to add a G-Seat.

This would be a fantastic feature, but I do also understand "feature creep" and that it's possible this could be more difficult to implement than I would guess. If it's not too much work I would love to have that in the software. I've been trying to eyeball that very thing based on the 3D simulator in Mover.

I ordered these:
https://de.aliexpress.com/item/32789668396.html?spm=a2g0s.9042311.0.0.7c2c4c4dlOIKck
...for a 25mm belt, 30 teeth, with 6 having 10mm bore and 6 having 19mm bore.
They fit onto the motors really well. Absolutely no gap.
I glued them on with a tiny drop of Loctite 243 and [hope that I]can remove them with a heatgun.








Cheers,... Dirty

I pretty much agree!

Here's my cautious claim:
- The rig is most stable in all directions when the actuator axises (is THAT even a word?) intersect at right angles.
- The load on the actuators due vertical acceleration is smaller when the actuator axises intersect at acute angles.
- The load on the actuators due lateral acceleration is smaller when the actuator axises intersect at obtuse angles.

Does that make sense?

I got the motors from China!


Those are the ones I ordered,...

https://de.aliexpress.com/item/32843516422.html?spm=a2g0s.9042311.0.0.9b984c4dYKpspH

...and I find them great! @Thanos' AMC AASD-15A works great with them and they are easy to hook up.


If you have ordinary European 240V, just put the Line (brown or black) on L1 and the Neutral (blue) on L2. Polarity shouldn't even make a difference here.

If you use six of them on a Stewart platform, make sure to utilize all three Lines of the 3-phase supply in your home as evenly as possible. I will use...
- Phase 1 for actuators 1 & 4
- Phase 2 for actuators 2 & 5
- Phase 3 for actuators 3 & 6
...so each line will supply two actuators that are diametrically opposed.

I will stay with these motors and abandon the ClearPaths, mostly because all six of those motors are less expensive than only the 75V DC power supplies required from Teknic.

Cheers,....

Oh, and probably also noteworthy:
These motors have a 19mm shaft with an inserted key. After spending an hour trying to find key'ed pulleys, I noticed that you can pull them out of the "trench" with a strong pair of pliers

The issue is that the EU standard for new electrical installations usually lay the 3 hot 230V only to the kitchen for induction cookers which needs such a power. Otherwise the max in other rooms is 230V 16 Amp everywhere else.

What are the limitations of this system if you don’t want to destroy the half of your appartement by creating new installation for simulator purpose ?

Could you calculate by how much the power of 6 motors has to be reduced in order to fit 16 Amp/230V on a single phase ? I am to stupid for that.

Please have that checked by a professional:

1. 16A * 230V = 3680 Watts (peak) coming out of a single outlet ("Steckdose")
2. In reality better stay below 3000W.
3. 500W per motor should work fine.

You're right, 380V/3-phase is mostly only available in kitchens and bathrooms. It is however certainly available in your circuit breaker closet ("Sicherungskasten"). Maybe you can have a 3Phase outlet installed next to or inside the circuit breaker closet.

Cheers,...

Yes, now actually my little finger tells me that you should be fine with 6 1KW motors on a single phase 16amp 230V

If the rated torque is 1/3 of the peak, that means that the maximum theoretical current draw for holding the load will be around 2 KW for the whole system. (333W per motor) In reality you have to take a good margin so you can take 1.5 KW as max.

It gives you room to accelerate over 1G with all 6 motors using a half of their peak power and leaves the full power for some motors while returning from unbalanced poses where the load is unequally split between the actuators. So I would say you don’t need 3 phases.

Without being an expert that’s what my simple logic tells me.

Cheers

This system seems really great. Bravo @Thanos for making this possible.

You don’t have to be afraid anymore about lack of torque and you can finally easily build and interface strong and steady rigs capable of holding and accelerating big loads.

I bet such a power could even handle a light dual cockpit platforms.

It will rock like hell. Don’t forget all safety precautions.

On the photo, where you have a label as encoder on the cable on the screw terminal, this cable is actually the 3phase AC power for the motor!!! Just saying

Which cable you may want to replace at some point. Its unshielded and produces lots of EMI
https://www.racedepartment.com/thre...controller-thread.168360/page-26#post-3070461

@Thanos, It’s a shame to reveal my ignorance but I just want to die less stupid.

This servo drive is designed to be powered by a single phase 230V than it sends 3 x 230V = 400V (L1 L2 L3 and Neutral) to the motor. Is this correct ?

OMG,... You're right. Of course! UVW are the three AC phases.

The encoder is the cable to the lower right. I will correct it when I get home.

Thanks for checking!