Interfacing III

Software interfacing via parameter extraction from flight simulator program

For the 3DoF platform I have still made use of the below setup.

An add-on program that  enables you to select the required parameters from the flightsim, and send these via a fast com port link to another PC. The update speed for the more dynamic movements to drive the platform, like landing gear bumps, buffering, turbulence, etc. needs to be in the order of 50msec to achieve  a signal bandwidth of around 10Hz or so.

For the initial tests I have made use of the Ian's new  Motion Drive Software that can be downloaded at This is a fantastic new utility that includes most motion cues and is user configurable for all three axis of a 3DoF Motion Platform. The output of the utility can be set at Hex, which includes 3 bytes of data: Pitch, Roll and Heave.   

I have used a GWbasic program on the 2nd PC to receive the three parameters. The big advantage of having a second (receiving) PC is that you can do manipulations like gain control, differentiation, mixing and limiting with the different parameters. Then the results can be send to the parallel port, where 2, 3 or 4 D/A converters translate the digital signals into varying DC voltage for the different motor drives.  GWbasic has the advantage that you can download it from the net for free, including the user manual. It will run on any old junk PC you have lying around. GWbasic will let you access any hardware I/O without special tricks and, on most junk PC's it's still fast enough to do most motion software actions.  

In the Motion software III chapter I have described the method on com port linking and parameter manipulation to make Ian's data suitable to drive my rig.

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