World Academy of Science, Engineering and Technology 77 2013.
Abstract—Unmanned Aerial Vehicles (UAVs) have gained
tremendous importance, in both Military and Civil, during first
decade of this century. In a UAV, onboard computer (autopilot)
autonomously controls the flight and navigation of the aircraft. Based
on the aircraft role and flight envelope, basic to complex and
sophisticated controllers are used to stabilize the aircraft flight
parameters. These controllers constitute the autopilot system for
UAVs. The autopilot systems, most commonly, provide lateral and
longitudinal control through Proportional-Integral-Derivative (PID)
controllers or Phase-lead or Lag Compensators. Various techniques
are commonly used to ‘tune’ gains of these controllers. Some
techniques used are, in-flight step-by-step tuning, software-in-loop or
hardware-in-loop tuning methods. Subsequently, numerous in-flight
tests are required to actually ‘fine-tune’ these gains. However, an
optimization-based tuning of these PID controllers or compensators,
as presented in this paper, can greatly minimize the requirement of
in-flight ‘tuning’ and substantially reduce the risks and cost involved
in flight-testing.
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