Benefit of a 4 channel control setup

While day-dreaming today at work (tedium, tedium, tedium...) I was thinking about the influence satellites low on the horizon have when calculating altitude in the z axis. When the aircraft is in a level flight attitude the GPS antennae will be pointed straight up. However when banking even at shallow angles, satellites low to the horizon can have a greater influence in the altitude calculating owing to the fact that the antennae is now pointed more toward the horizon and is more likely to lock on to one of these low satellites.

It occurred to me that a "simple way" to reduce or perhaps eliminate this problem in a 4 channel setup i.e. aileron, elevator, throttle and rudder, would be to enable a 4th channel to add aileron control. This way roll control could maintain "wings level" attitude while rudder provides yaw control for course correction. In this way the GPS antennae would always be pointed straight up.

This is simple in theory, however I anticipate it might be anything but simple to rewrite the code.

Anyone tried implementing this before? I'm sure it's not an original idea.

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3D Robotics

Chris Anderson April 7, 2010 at 5:18pm

Yes, we used to do that back in the ArduPilot 1.0 days, when we were using the FMA Co-Pilot to keep the wings level and navigating with the rudder, just "skidding" around turns. It works, but the turning radius is really wide. Also, with our current GPS module, the uBlox with the helical antenna, it works as well in turns as when it's level.
Michael Zaffuto April 7, 2010 at 5:12pm

It might be cool to use the two potential PWM servo outputs on ArduIMU to control a stabilized platform for the gps antenna/module, keeping the antenna pointing up as the plane banks and rolls and pitches, similar to, as is done on stabilized cameras.

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Benefit of a 4 channel control setup

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