Showroom 6DOF rally simulator by Grizus :)

@OZHEAT
I also considered the capacitor idea so I emailed Dimension Engineering and this is what they said:
My email:
Rather using 2 x 12V @ 30Ah lead acid batteries for each Sabertooth 2x60 driving 2 x 24v 450W DC motors (max current 25A fully loaded), could I use 10 x 2.7V 500 Farad super capacitors connected in series for a total capacity of 50 Farads and a rating of 27V? I have attached an example from eBay. These capacitors can start cars and so are capable of 100A+ but would they be suitable for the motor regenerative current? If they are then I wouldn't have to buy 6 x 12V @ 30Ah lead acid batteries saving weight, cost and safety.

DE reply:
You can try it, but I would be surprised if it worked.
If your max current per motor does not exceed 25A, then you may be able to use a smaller battery than 30Ah. Something like 12Ah might work.

I should have been more specific and said electrolytic capacitors.
I will reply in your thread 6dof.

@OZHEAT , @SixDegreesOfFlight, @SilentChill thanks for the replies in my thread.

Can you tell me what the power supply to my installation really needs to be?
2x Mean well rsp-3000-24 - 3000W 24VDC 125A is probably a little too much ?? what do you think ?

@Grizus
The 24V 450W motors you will use are similar to my build. So you will need around 30A per motor. If you use server psu they tend to shutdown as they are sensitive to the regenerative current. Hence @SilentChill went for LED power supplies. These are cheap and robust and more tolerant in this application. You have to make a decision about whether you want them all in parallel. Read through @SilentChill thread from the famous page 25 (my favourite ) where he almost started his build again.

I am a newcomer so my ideas need to be read with caution

Hi SIX DOF,
Concerning your advise on the two MeanWell PSUs in parallel; PSUs of this size often have a load sharing connection which enables up to 5 PSUs in parallel and when the load sharing line is connected will shed the load across the PSUs. If the PSUs have no loadsharing option then the suggested diodes are a good option. To ensure that the diodes are not dissipating too much heat the best types are with a low internal resistance. Most likely Skotty diodes for their low internal resistance which results in a lower heat dissipation. It is still a bit tricky in respect to tolerances of these diodes and the voltage drop across them as if there is a slight difference tolerance then the PSU with the lowest voltage drop will take all the load with all sorts of issues such as current limiter being activated and most likely, due to the strain of maximum performance on this PSU, an early exit to the eternal fields of PSUs. If there is no loadsharing option on the PSUs then the voltage must be adjusted for each PSU. This you can do by connecting the PSU NEGs together and measure between the common NEG and individual POS of each PSU. With the voltage adjust on the PSU you can adjust till the voltages are equal. Another way is to read the manual or contact MeanWell before you parallel them together "cold".

Hi OZHEAT, for a rig I am presently designing I was thinking of electrolytic capacitors too but we must be cautious about the charge of these cap's and what could happen during maintenance on the electrical side and the discharge of these large charges. I was looking at car audio cap's with voltage indication so it would be easy to recognize if there was any charge left. Although these low voltages will not kill you the surge of the current will cause serious burns and could cause fires too.

Ok it's time for a small update

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The first actuator is pre-assembled, all in accordance with the plan made lower construction and the upper one is in a workshop where they weld it for me using aluminum profiles.

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I got the motors but unfortunately not this what I ordered (only 3600rpm no load :/ ) I have to wait another month to replacemnet : / in this time will try to connect everything and make the actuator start moving only on the batteries (bought 2x 95Ah 12v 820A) because I still do not know how to connect the power supply to them

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As I wrote the top and bottom mount it will be the car's ball joint with the extra thick rubber pad cut with waterjet

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Inside the pipe I used a teflon wheel as well as in the vertical profiles are teflon rails to reduce noise and improve the slip.

I am thinking about using only one MEAN WELL RSP-3000-24 24V 125A 3000W and see maybe that's enough ????

@SilentChill changing to LED power supplies and rebuilding his rig - I wonder if I had anything to do with that .

Sorry, that ball joint at the bottom of your actuators will allow twisting, which is something you do not want to happen - use a Uni joint .

Don't feel bad , you were possibly copying something that you may have seen on a 'commercial' simulator . Quick look on Youtube and I knew I would find one (there are plenty more).



A bit sad really...

Looks good, hope it works

Thanks, I was thinking about it and when it was needed to make the protection against rotation it will not be too difficult. This ball joints have a big advantage over the Uni joint

?

Ah..OK message understood - It's your sim .

But I don't understand, you have a very interesting form of help, thank you for a valuable and constructive conversation...

You're the sole reason any of us are building actuators matey

The whole actuator will want to twist with those joints is what he is saying. You will not be able to stop them twisting ???

How will you stop them twisting ?

See here, I have attached the actuator freely on flexible links, so he has the best conditions to twist.

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The voltage gives it directly from the battery so it has full speed right away



As you can see he does not want to twist. I think ball joint loaded by construction and me will be even less prone to twist.

Of course, we will see after assembling everything, but for this moment after the test I do not see such a problem

Hi @Grizus , Like I said it's your sim - and I don't have the time to argue, I would although not want other members to think that this was how you mount a actuator. I don't know what you educational background is, but you cannot fight physics and every other properly built actuator driven Stewart Platform that you will see uses uni joints - so it is not my invention/design . That same youtube videos comes to my help again: love that guy for showing how it is not done . (watch the actuator near center of screen - and this is not as bad as it can get)

see near the end of the video for best effect.

Now as you can see from the video the Stewart Platform is working and that company was selling a product with that design, but it is a poor design and will lead to a loss of tracking (fidelity) and unwanted noise (and possibly even damaged to equipment). The effect on each actuator will be dependent on the friction of your ball joints and inertia built up in the whole actuator itself due to load and speed. I'm sure a good mechanical engineer could write the math for it . There is although nothing wrong with finding out these facts by yourself - I could have easily just not have commented - but did you not come to this site to leverage off what has been proven to work? Anyway just trying to help and all the best in your project

@SeatTime I perfectly understand and agree with this, but wrong that you compare my ball joint to those used on the movie you pasted

nice, that I forced you to a deeper expression

Please tell me does that mean, you agree with the assertion that if the ball joint have proper friction, it themselves are able to effectively counteract this force ??

He should have used universal joints on the bottom of the actuators, to prevent them from rotation. Otherwise this is expensive platform, the linear actuators are MOOG servomotors, with extra external linear potentiometer attached on their side to measure the position so it can be driven by AMC1280USB...

"little" progress in my simulator

All actuators ready - tested, connected, work well

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The whole installation is almost done - I am waiting for the power supplies, will be in a few days

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Despite the positive tests on the mounts of the actuators I decided not to expose them to twist and change the top mount, but not on the U joints because I do not like them, maybe someday also change the bottom

At the weekend I plan all put together and make the first move with the whole simulator !!