■ FIGURE 13. New
PenAeroBot design.
implementation with one motor works relatively fast and it
can be used to introduce students of all levels to the theory
behind automatic controls. The implementation with two
motors still needs to be refined.
As shown in Figure 12, it takes the system more time
to reach a steady state with two motors than with a single
motor. We think this is because the first prototype was not
thoroughly built. Asymmetries in the structure introduce
undesired oscillations. Also, the fact that we are using the
same PID controller for two different motors could be a
cause for poor performance.
We are currently working on a new design, shown in
Figure 13. In the future, we'll use modern control theory,
including state space design and/or gravity feed forward
controllers. We are confident that by
using these techniques, we'll be able
to achieve better results compared to
PenAeroBot with one motor. SV
References
Astroflight
www.astroflight.com
Static Thrust Calculator
www.mmaa-modelairplanes.org/
staticthrustcalculator.htm
Motor-Propeller Damped
Compound Pendulum
http://prism2.mem.drexel.edu/
~
paul/thrustTester/ thrustTester.html
Digital Control of Dynamic Systems
by G. F. Franklin, J. D. Powell,
and M. Workman
58 SERVO 02.2009
