First off, you can always linearize the turning of the valve to engine thrust via a look up table. We do this in disk drives because the position error signal from the disk drives is often-times non-linear in nature. Ideally it would be linear, such that the amount off track is directly proportional to some position error measurement, but this is rarely the case these days due to the nature of disk drive read/write heads, etc.
Also, you can take into account any time delays in building up thrust for a given change of valve opening via the overall servo loop. This is pretty common stuff in the servo world, so I wouldn't be too worried about that. We get this all the time when dealing with electronics and physical systems that don't always respond right away, due to large amounts of inductance or what have you. Lastly, slop in the valve mechanics themselves can be compensated for, if not taken out immediately, by the overall effects of the servo loop. I would think that in a vectored thrust stearing configuration you would also want to make sure that the thrust vector for each engine DOES NOT pass through the CG of the vehicle, but is off of the CG such that the change in thrust really does cause the rocket to change where it is pointing. Otherwise, there is no point to vectoring your thrust. Lastly, you are going to have to solve for the effects of gravity by increasing the overall thrust in proportion to the cosine or sine of the angle you have now oriented your rocket (I leave it up to the readers to do the trig) and for the change in the total thrust you have caused across all of the engines due to reducing the thrust on one rocket. NOTE: The easiest way to compensate for changing the thrust on one rocket is to increase the thrust of the opposite engine by the same amount. If this does not cover your rocket configuration, then the overall math is only slightly more difficult. _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
