Interfacing I

Hardware Interfacing directly form the cockpit controls:

For the DIY motion platform I,  interfacing directly from Yoke movements and signals derived from the Force Feedback stick were used.
When planning the interfacing, it is important to realize what kind of motion you want to achieve. The article in Motion systems clearly states that you would want to achieve the initial forces that act on your body when starting a certain aircraft maneuver. This would imply that one should take the  derivative of the aircraft movement in order to simulate the initial accelerations. Although this is probably a rather simplistic approach, I have based my hardware interfacing experiments on this principle.

The above circuits show some possibilities for deriving motion platform drive signals from the cockpit controls movement. For isolation purposes, I used dual potmeters or dual contact switches. For isolating the FF stick signals I fed the PWM signal of the FF circuit through a fast opto-coupler (having push-pull output).
The circuit in between the control and the buffer is a differentiating  network, that will slowly return to center. A resistor can be connected parallel to the differentiating capacitor, in order to keep the platform tilted with a constant yoke deflection (for simulating the back pressure during a climb)

The bread-board with several filters

The list above shows what cockpit controls can be used for generating platform drive signals.

I found that the interfacing of all these controls takes lots of tweaking: Sensitivity, time-constants, polarity, the results are not always what you expected. Sometimes a certain motion feels right only with certain maneuvers, but totally fake with other flight conditions. 
The motions I actually liked best were the pitch  rotation and small bumps and vibration signals that I got from the FF yoke signals.

In the new DIY motion platform II and III, I have used motion cues derived from the flight parameters in Flight Simulator. 


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