PT-Actuators 3DOF system?

Wow, your RIG look awesome! Nice and clean. It's a good evolution.

Looking forward to seeing all this in motion ...

Totally agree, I would although like to see the actuator attachment points placed a bit higher (should be easy to do), so that the roll center is more realistic.

Quick video just showing everything all setup and working....

Your right - it is a solid box, but that means the roll center ends up very near the floor. That's unfortunate, luckily though in practice it does not roll much.

Is that with the extra cross member at the front to attach the front actuator?

Yes that's right, I added in an extra length of 40x160 at the front. Makes the frame into a completed rectangle shape.

hi guys just got the pt actuators , any guide for installing ?

Its pretty simple, PT-ACTUATOR can provide a wiring diagram for it. If you don't have the manual for the AMC controller email me.

Or, see the pictures of LukeBrown in the previous pages ...

hello how mutch cost this actuator?thanks

Best to just message PT actuator and ask them for a quote. It depends on your country for shipping and also there are some options in terms of which actuators and controllers you want.

Hi everyone . Yes that’s what I did . Contacted them through messenger via Facebook . Very helpful . I ordered the 4DOf set using the AMC - ASD15A. Just waiting for them to arrive . I’m sure I will have lots of questions

I agree that the 3 legged prevents the "high leg" but why does it happen? Now on 2.4 its more or less not doing that anymore?!? Problem with the 3 legged is that the one actuator in the back must take more load then the front and the rig is heavier in the back.

I would also want to know more about how to get the MDBOX vibration feature and GameVibe. I have tried it and could not get it to make any good vibrations. Who has done it successfully?

Thanks

Put the single actuator at the front and also bring the rear actuators forwards a little bit so that they are closer to the centre of gravity.

Another benefit I've realised of having only 3 actuators is that the front single actuator only has to handle 3 DOF (Heave / Pitch / Surge) and does not need to any assignment for Roll or sway. That means you can actually assign a higher percentage of the actuator stroke to those 3 DOF. If you are running a 4 actuator setup, then the two actuators at the front would need to cover all DOF so would be assigned something like 20% each for Heave/Pitch/Surge/Roll/Sway. However, with 3 actuators then for the one at the front you still assign 20% for Heave but then can increase it to 40% for pitch and 40% surge. So you actually get more more range of motion in Pitch/Surge with a 3 actuator setup vs. 4 actuators.

Why is a 4 leg system naturally unstable compared to a three leg?

- A three legged platform is naturally stable like a three legged stool. Even if you change the actuators or 'stools' length it will still remain stable and not allow any wobbling - or in this case lifting of one leg.

- what happens when you add a fourth actuator? Well, now there are multiple ways that the platform
'stool' can 'solve' the problem of which legs to use for support as the actuator lengths change.
Wobbling occurs when the Platform (stool) can't 'decide' which solution to use especially as the length of each leg changes.

In effect, during the time that the Rig is actually wobbling, it's
really a two-legged stool, with one degree of freedom - which is the
direction of the wobble.

As for a rear biased load, you could always have two actuators at the back and one in the front, although these types of actuators are quite powerful.

I asked the PT Actuators' support guy directly whether there's any problem weight-wise with running one actuator on the back and two on the front.

He said that there's no issue, and that you should be spacing your actuators so that they're evenly around the center of gravity anyway - meaning that if the actuators are properly configured, the rear actuator is not taking more weight than the others.

Yes that's right. If you have 2 at the front then they actually should actually be roughly in line with the steering column uprights and not at the very front corners.

I think it makes more sense to just have 2 at the back and 1 at the front though. With the 2 at the back they will be either side of the seat, you will feel more in the way of bumps etc.

Intuitively yes, but if the actual motions are the same, surely it shouldn't cause a difference unless you have vibration effects on those actuators...

I guess the big limiting factor here is that the further back you mount the front actuators, the higher you'll have to mount the body to ensure the rig doesn't hit the ground at full forward pitch, which in turn means the roll center will be higher.