Hi-Fidelity Motion Simulation Development Kit

[smacdon2112]

Greetings to the mycockpit.org community. I am a first time poster.

Full disclosure: I am a professional in motion simulation and want to solicit feedback from this community on a hi-fidelity motion simulation development kit my company recently launched called STAR (http://www.simcraft.com/star.html) (which stands for Some Time and Assembly Required.) It essentially takes most of the engineering out of motion simulation for cockpit and sim builders. The idea for this kit is born from a labor of love for my late father who founded SimCraft (http://www.simcraft.com) in 1998 and also pioneered the SimCraft architecture for motion simulation. Thank you in advance for any and all feedback.

Sean

[Badge]

What is the maximum weight that your product can support? The vast majority of us have plans for a full size 2 place cockpit with enclosure can with a weight approaching 800kg.

[smacdon2112]

The max payload is 500 pounds for occupant, monitors, controls + seat.

[Roland]

Hi Sean,

I see that you are using good grade actuators and fast software. That will help a lot in getting good motion response.
For the 2DoF: For a flightsim I'd advice more pitch angle than roll angle. It maybe different for car sims, but you'll want lots of pitch for take-off acceleration and braking decelleration.
Why not add heave as a third DoF? with your actuators and software speed, lots of nice heave effects could be generated. (but it may be a bit complicated for the ready-to-fly kit kind of setup due to weightbalancing)

I had also thought about preparing a 3DoF kit of my system a while back. Unfortunately I don't live in the Far East anymore (material prices in Europe are just terrible, the kit would be 7 ~ 10x more expensive than when sourcing from Taiwan or China)
Then I thought about all the things that need to be taken care of: all mechanical and electrical tolerance calculations, safety issues, guarantees & aftercare, marketing, logistics, taxes, ect. I decided to keep it hobby and share info for free.

[autocadplease]

Sean,
I would buy something like that, but would like to see more pitch and an increased weight load. Heave would be great too. I would pay up to $5,000 for something that had those features. I like the DIY element of this product too - I am sure it keeps the costs down. Thank you for sharing.

[smacdon2112]

Roland: Thank you for all of your comments. We can add more pitch motion by increasing the stroke length of the actuator but heave will be a bit more difficult to add in. We have some ideas about how to add heave but safety and performance factors are currently very tough to overcome. Lifting and supporting hundreds of pounds of weight is a major factor in latency unless you have a lopsided ratio of force to weight - which is where the safety issues come in.


Grant: Thank you as well for your comments. How much pitch would you want to see? What would your payload requirements be?

[autocadplease]

Grant: Thank you as well for your comments. How much pitch would you want to see? What would your payload requirements be?

I would like to see at least +\- 20 degrees pitch and payload somewhere around 1000lbs.

Grant

[Jackpilot]

On the weight issue, do not forget that the whole visual system has to be included...but you know that I'm sure !!
Jack

[smacdon2112]

40 degrees of pitch is not a big challenge with a longer stroke actuator. (Which we have.)

The 1000 pound payload is doable with the system, the bearings are not the issue however, it is the moment of inertia created from rotating 1000 pounds. No doubt, the way the system is designed, the control system could actuate this amount of weight quickly but upon stopping and going the opposite direction, from a performance standpoint, that I would emphasize as the challenge.

Something to analyze and test - and we will - thanks again for the feedback!

[Doon1]

Hi Sean,
Then I thought about all the things that need to be taken care of: all mechanical and electrical tolerance calculations, safety issues, guarantees & aftercare, marketing, logistics, taxes, ect. I decided to keep it hobby and share info for free.

And God love ya for it brother :mrgreen:

[Terry214]

I would like to see at least +\- 20 degrees pitch and payload somewhere around 1000lbs.

Grant

Another request for the increased payload of around 1000lbs to 1500lbs if possible. I am working on building a 2 seater cockpit. I weigh 235lbs and I estimate that my cockpit weighs 500+lbs. Factor in the second person(co pilot) then the total weight of the sim cockpit is getting close to 1000+lbs.

Your DIY kit is exactly what I am looking for... thanks for posting your information. Hopefully the increased payload requests can be met.

Terry

[Roland]

40 degrees of pitch is not a big challenge with a longer stroke actuator. (Which we have.)

The 1000 pound payload is doable with the system, the bearings are not the issue however, it is the moment of inertia created from rotating 1000 pounds. No doubt, the way the system is designed, the control system could actuate this amount of weight quickly but upon stopping and going the opposite direction, from a performance standpoint, that I would emphasize as the challenge.

Something to analyze and test - and we will - thanks again for the feedback!

Sean,

Up to now I have not found any need for very fast pitch movements. Take-off acceleration and braking de-celleration all need some low-pass to minimize the false cue due to the rotation needed to achieve the desired tilt angle. So pitch should be relatively easy on the actuators.

Roll is slightly different: Similar to pitch, the lateral accelerations on during turns on ground need some low pass to avoid false cues.
In the air, the small lateral turbulence acceleration can be ported into the roll angle unfiltered: since most of your body sits higher than the rotation piont, fast roll pulses actually feel like lateral movement, quite convincing. These are small excursions though, so again not too much of a burden to the actuators. Touchdown is another fast movement that can be ported directly to roll angle. I found that platform pitch is not required for touchdown effects.

So only 2DoF power platform requirements are not that bad for most airplanes in normal flying conditions. Ofcourse weight unbalance may add to the steady state power consumption. I think the weight distribution is easily the most important factor in the whole design, and should be pointed out clearly to the user. Bigger payload should be possible, as long as they are properly balanced.

Heave is an entirely different matter, where my balanced 160kg system @ 0.5G heave easily consumes 2kW peak power during turbulence.

[smacdon2112]

Up to now I have not found any need for very fast pitch movements. Take-off acceleration and braking de-celleration all need some low-pass to minimize the false cue due to the rotation needed to achieve the desired tilt angle. So pitch should be relatively easy on the actuators.

First off, thanks Roland for all of the inputs - very helpful insight. I concur with your assessment here and might caveat with the type of aircraft. Anything in the combat arena probably requires a little more consideration for speed and direction changes in pitch rotations.


Roll is slightly different: Similar to pitch, the lateral accelerations on during turns on ground need some low pass to avoid false cues.
In the air, the small lateral turbulence acceleration can be ported into the roll angle unfiltered: since most of your body sits higher than the rotation piont, fast roll pulses actually feel like lateral movement, quite convincing. These are small excursions though, so again not too much of a burden to the actuators. Touchdown is another fast movement that can be ported directly to roll angle. I found that platform pitch is not required for touchdown effects.

Interesting take. We will experiment.


So only 2DoF power platform requirements are not that bad for most airplanes in normal flying conditions. Ofcourse weight unbalance may add to the steady state power consumption. I think the weight distribution is easily the most important factor in the whole design, and should be pointed out clearly to the user. Bigger payload should be possible, as long as they are properly balanced.

Couldn't agree more Roland. The challenges of multi-occupant systems though will require much more analysis for balancing on the part of the sim user.


Heave is an entirely different matter, where my balanced 160kg system @ 0.5G heave easily consumes 2kW peak power during turbulence.

Power requirements to physically move a mass is a big drawback, no doubt. There are safety and performance concerns here as well from our perspective: Lots of force required.

[IanH1960]

Roll is slightly different: Similar to pitch, the lateral accelerations on during turns on ground need some low pass to avoid false cues.
In the air, the small lateral turbulence acceleration can be ported into the roll angle unfiltered: since most of your body sits higher than the rotation piont, fast roll pulses actually feel like lateral movement, quite convincing.

Hi Roland,

I started playing with a version of the driver that combined both a low pass slow roll component to cue sustained lateral accels and high pass fast roll impulse to cue lateral impulses at the same time... Didn't finish it though. I wasn't sure about the physical movement "interface" between the two and how it would feel and was distracted by some other work - might be worth digging it back out again as it might be tunable to squeeze a bit more out of a 3DOF machine. Might be worth investigating Sean, would add a new take to the conventional cue algorithms.

Agree with your comments on pitch rate Roland - very easy when cueing fwd accel to introduce a feeling of pitch rotation when it just shouldn't be there - basic problem with gravity alignment cueing.

As a further take on heave cue I think I'm coming to the opinion that because trying to cue sustained heave G's is quite difficult (reduces to a rather unconvincing onset/offset impulse) that a platform with a fairly short heave travel to cue the higher frequency heave effects might not loose much in the end - ie good enough to engender an ongoing sense of vertical motion, and sufficient to deal with bumps and rumbles and general turbulence related bobbing about..

... shorter heave stroke would be easier to build than longer, but I'm not sure by how much. Perhaps an "enhanced" stroke seat tactile transducer might in the end be a good and cheaper compromise to get acceptable vertical motion effects without the expense and difficulty of a full heave DOF.

Ian