Altitude Control System Design of Bicopter Using Lyapunov Stability Approach

This paper presents a Lyapunov stability approach to design a controller for an altitude control system of a bicopter. The altitude control system enables the bicopter to fly at a desirable altitude. A representative nonlinear model of the bicopter required for designing the controller can be derived based on a first-principle modeling approach. Control law of the controller is derived by applying the Lyapunov stability theorem. The resulting controller gives rise to a global-asymptotically-stable closed-loop system when it is applied to the bicopter. Such a stability property is satisfied via the LaSalle's invariance principle. Performance of the bicopter equipped with the altitude control system is evaluated through numerical simulations. Simulation results show that the bicopter succeeds to achieve a designated altitude level with a relatively fast-and-less-overshoot transient response. For instance, the controlled bicopter is capable of reaching 10 meters from 6 meters of altitude within 1.35 seconds with only 3% overshoot. Thus, these results signify the merit and potential of applying the proposed control method to an actual bicopter.