6dof Motion Platform - 1st Test of Full-Scale Hardware...

[sagrada737]

Hi Guys,

Yesterday, I started testing one segment of the VFD/Motor/Gearbox under the control of the AMC1280usb controller, BFF 6dof motion software, and FSX, with the Sim-Avionics 737 flight model.  Everything seems to function as it should, with the 6dof motion cues being processed correctly.  It is very helpful to see the 6" Lever (gearbox output shaft) move in "real-time" according to what FSX is feeding the BFF 6dof motion software.  The speed of rotation and response seems adequate for the 737 flight model I will be using. 

I should also point out that the BFF motion cue parameters that I have set for scaling and acceleration are purposefully "subdued" in this particular motion cue parameter configuration.  More testing and "tweaking" of these motion cue parameters will be necessary as I continue testing in order to determine "system limitations" and best motion cue settings for synchronizing motion sensations with the 737 flight model I am using.  These adjustments will require ongoing refinements as this project moves forward.

An interesting aspect of the Nord Gearbox is the fact that they use a Nylon spline coupler to mechanically interface the Motor's output shaft to the input side of the Gearbox.  This is a somewhat loose fit, and it tends to make a slight "clicking sound" as the Motor is commanded to start/stop - fwd/rev.  Not a big deal, as it is not a loud noise, and the Engineering at Nord claims that it is capable of handling the full output torque of the Gearbox, which is 11,000 lb.in of torque.

Another noticeable thing is the noise that the WJ200 VFD's fan makes.  I expect that this can be reduced somewhat when the six  WJ200 units are placed in their proper location in a shielded electrical box with external fans helping to cool components.  Of course, nothing is getting hot at this point in this initial testing due to the fact that there is no load on the system.

In any case, this initial testing of the electrical/hardware/software interconnect confirms that things are interfaced and working correctly with FSX and Sim-Avionics.  This phase of hardware testing helps to establish electrical configuration and packaging considerations.  It's also very helpful to work with the "real" full-scale hardware.  At this time, I am also considering foundation/mounting requirements within my Sim Room for such a full-scale 6dof Motion Platform.

As a side note, each Motor/Gearbox weighs 240 lbs.  I have decided to mount the Gearbox to a 1" thick steel plate 12" x 24", which will sit on top of a 1/2" rubber damper pad.  This will be sandwiched between four corner upper dampers, with 1" bolts mounted directly into its own concrete footing 12" x 24" x 36" deep.   Six of these mounting systems will need to be build in the existing Sim Room concrete floor/foundation.  This will be necessary to ensure safely dealing with the Moment of Inertia associated with the roughly 2,000 lbs. of Sim mass dynamically moving 7 feet above the Sim Room floor.

The more critical phase of testing will come next, as I place this single Motor/Gearbox in a fixture that will allow testing this system under full load.  I plan to build a fixture in the coming weeks that will emulate mechanically the motion platform layout, with full-scale Push-Rods connected to the steel Lever on the Gearbox.  This test fixture will allow dead weight to be placed directly on top of the Motor/Gearbox actuator, which will provide the "load" for this system - essentially moving the load Up/Down as it would as part of a full-motion platform system with six actuators.  I will add weight 50 lbs. at a time, up to 700 lbs. to determine system capability.  In actual practice, I expect that a single Motor/Gearbox should be able to manage 500 lbs. given the dynamics of the 6dof motion platform in actual use given the total nominal mass of the Sim being 1800 lbs.

Below is a video, which has descriptions along the way, which shows the Motor/Gearbox/Lever/actuator movements under various weather/flight conditions to show Lever rotation speed and response time.  This of course is initial testing of the full-scale hardware, as I get a step closer to determining the viability of moving forward with this 6dof Motion Platform system for my 737 Sim Project.

Regards,
Mike

https://www.youtube.com/watch?v=HwojZ793z9U&feature=youtu.be

[jfuenmayor]

Quite impressive Mike. The movements seem well measured .
Just how large is the "real estate" you have available for this.

Your set up is an experimental lab.
Keep up the good work.

JF.

[sagrada737]

Hello Joaquin,

Thanks for your encouragement.  I too agree that the general movements are getting closer to what might be acceptable to "trigger" the sense of movement for a 737 flight deck.  In the final analysis, this will be born out in a completed 6dof Motion Platform, as the various motion cues are fine-tuned to help create the "motion environment".

You're right about the experimental lab setup.  I have more fun playing around with this Sim Project.  My goal is to have it finally completed and packaged by the end of the year - motion platform or not.  I'll be making the decision to proceed with the 6dof motion platform project as soon as the "load testing" is completed - in a few weeks or so.

Let's see...   "Sim Real Estate" available for this project...   This directly in proportion to the health of one's marriage   
Right now, I have a small, dedicated space, which I call my Sim Room (certainly not a hangar size).  It will accommodate a full-scale motion platform, with no "crush zones" around the Sim and Platform - allowing for minimum of 4 feet clearance around the Sim/Platform, with more space available in two zones.  This means that I have to design the systems such that they can be build in my machine shop, then dismantled and reassembled in the Sim Room.  Not a problem, as I have done this successfully with other large scale systems, such as my larger telescopes and robotic observatories (another hobby of mine - CCD Imaging).

I am also keeping in mind that I may want to change display systems in the future - to a HD projection display if these type of short-throw systems become more viable at a decent price point.  Right now, I find the large LCD monitors to offer exceptional display performance.  Time will tell how well these consumer type of displays will hold up in a motion platform environment.  But as you can see from the motion cue movements, the acceleration/deceleration is not violent, so I believe they will survive.

Best Regards,
Mike

[meatbomber]

Hi Mike,

we`ve ordered the Thanos motion driver so the 6DOF project is definitely on GO here now too i`ve been experimenting a bit with the fly-elise motion platform designer, where you can have a model of the platform moving and recording data while flying in the sim, and i was quite surprised to see how little power was actually predicted to be required to move a 1000kg payload.

one thing that has me thinking tho now is placemetn of teh computers, i`m not sure i want to subject my computers to teh rigors of motion but on teh other hand that will require a major rethinking of how to drive monitors / inputs etc.

did you think about that yet ? are you gonna have your pc along for the ride or outside the platform?

cheers
Phillip

[sagrada737]

Hello Phillip,

Good to hear that you are working with Thanos' motion controller hardware.  Thus far, I have found the AMC1280usb motion controller hardware to be very stable in use with FSX and the BFF 6dof Motion Software.

As far as the torque required to move your 1000 Kg mass...   You will also need to consider the Moments of Inertia loading that will have an effect on moving such a mass within the motion cue parameters set, which will yield at times significant start/stop - acceleration/deceleration - forward/reverse events.  This is not a small consideration for the selected drive components and especially the mounting/anchoring of the Motion Platform to your floor/foundation.  I have found that motion resonance can induced high amplitudes of force vectors into the motion platform systems.  Since the energy has to go somewhere, you will need to account for it and control as necessary for the mass to be moved about.

Regarding mounting the computer gear on the Motion Platform...   If you are using military duty computer hardware that is designed to take the vibrations that will be present in the motion platform, then you will probably be OK.   But, with standard fair PC gear, I would definitely place the PCs on the floor - isolated from the Motion Platform.  That is what I plan to do.   Keep also in mind that cooling of the PCs and Motion Driver hardware is also a concern - especially if your flight Sim computers are overclocked.

The Motion Driver hardware (VFDs, Braking Resistors, etc.) will need to be placed in their own electrical cabinet that has proper cooling.  The shielded cabinet will help with radiated emissions.  Also consider electrically shielding all your control cables.  Don't forget to seriously plan for your electrical grounding of the entire Motion Platform/Sim systems.

In addition, clearly think out provisions for "killing" the system from within the cockpit, as well as other strategic areas near the Sim.  Basically...   Carefully plan out all safety issues, with human safety of main concern.

It is good that you are experimenting with the Motion Platform Designer simulation software.  Be sure to test parts of the real hardware to ensure critical links in the system can withstand the requirement.  Plan for safety margins in all your calculations - especially mechanical links that serve to support the Platform and Sim under dynamic loads.

Please keep me posted on your progress.

Best Regards,
Mike

[meatbomber]

Thanks for your thoughts Mike! it´s good to hear the voice of reason regarding a project like this and we`ll take all your inputs into careful consideration.
can`t wait to hear from your next update (i guess that will be with 6 actuators ? )