Special Access Project part 4

21 Sep 2014

I could possibly put the center of rotation axes behind the pilot, in order to make the sensation of lift when pitching up or down more real (requires a lot of torque for the pitch motor though, especially if not counter weighted).


I need to understand how the motion hardware will work with impossible angles, such as if I pitch straight down, roll 90 degrees, then I am unable to pitch up (this problem exists for all designs seemingly)?! Not sure how this is dealt with at the moment.

I’ve been looking through forums and youtube to try and find people who have made similar projects and until just now I was only able to find one example of a home built flight sim with full roll and pitch, the viper


I spoke to one of the makers of the Viper, Sam, who told me they were having trouble with torque requirements. So I’m weary of the weight of my design, I may need to lose my previous work of the electric seat adjuster, which alone weighs a few kg’s.

I found the x-sim forum, x-sim is software for flight simulator design (mostly motion platforms), so this is really useful, which lead me to another flight sim with full roll and pitch! (made by bsmotion)

If I can look further into this, it may make the challenge of meeting torque requirements much easier as well as possibly finding out about the computer interface.

Flight Sim Software:

  • Microsoft Flight Simulator X (no longer in production and sold to Lockheed Martin), this may be a good option! Alailable for $30 new.
  • Prepare3D (by Lockheed), works with Oculus DK2 with DCOC-Extension.
  • X-Plane (No support for Oculus DK2 Yet due to using OpenGL insted of Direct X).


Looking into Flight Sim Motion Software (which interfaces with the actual Simulator game software):

  • Microsoft Flight Simulator X (no longer in production and sold to Lockheed Martin), this may be a good option! Alailable for $30 new.X-Sim motion Sim Software supports Microsoft Flight Simulator X (I’m assuming Prepare3D aswell) using FSUIPC;
  •   I’ve just discovered FSUIPC, which ports data in and out of Microsoft Flight Simulator X and Prepare3D Flight SimThere’s also
  • BFF Simulation software, this seems to be specifically for motion platforms though

Not related to my design, but here are some interesting motion sim builds


For Motor Control, I’ve seen:
Thanos 6DOF (degrees of freedom) Motion controller AMC1280USB, which is the last part in the electronics control flow diagram:
Flight model/car model -> acceleration data in 6 dof -> cueing / washout -> kinematics calculation -> actuator position close loop control.

Although, I am only using 2 degrees of freedom, where I don’t need acceleration, but position (mathematically the second integral of acceleration).
The thanos hardware is compatable with VFD (Variable-frequency drive) motors, which is highly likely what I will be using. Also I will need to use a quadrature rotational encoder on each axis, so my motion hardware knows the location of the rotating seat.
If I want to get fancy I could put an accelerarometer on the seat as well, which could be used to reset the seat if Quadrature Encoder data is lost somehow. Also if I really really really get to know the motion control software, I could get the actual G force data for the sim pilot (although this varies with distance from center of rotation). Perhaps that could be used to prevent jerking or something… Luckily I have some experience with the infamous arduino :p Maybe if I get really crazy I could use one of the several TI launch pads I have laying around to control the VFDs.

I have found a build log of a motion platform type Flight Simulator, also using Oculus Rift DK2. This system uses fsx/prepar3d (obviously as X-Plane doesn’t have DK2 graphics support yet). For Motion Hardware, it uses dimension engineering kangaroo, which is a 2 channel self-tuning PID controller.

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