Chaotic Dynamics Analysis Of The Attitude Of A Small Unmanned Helicopter

In the past twenty years,many numerical chaotic systems have emerged in the study of chaotic system generation,such as Chen system,Lii system,Lorenz system family,and Qi chaotic system.With the exception of the Lorenz system,these systems have no physical background and meaning.There are few studies on constructing chaotic models and analyzing chaotic phenomena from the actual engineering or physical processes.At present,there has been no literature to study the attitude dynamics of small unmanned helicopters from the perspective of chaos.This paper gives a model of small unmanned helicopters generating chaos,analyzes the chaotic characteristics of the model,and explores application of chaotic theory in the field of small unmanned helicopters.Under a reasonable simplification,a complete 5D attitude dynamics model of small unmanned helicopters is constructed.The attitude dynamics of small unmanned helicopters in hovering state are analyzed for different moment of inertia and structural parameters.By the means of equilibrium point,Lyapunov exponent and Poincare cross section,the chaotic phenomena of the system are analyzed.Through the analysis of maximum Lyapunov exponent of system with respect to the moment of inertia and structural parameters,the intervals and regions of generating chaotic,quasi-periodic or periodic and stable status of the system are given.The coexistence of two chaotic attractors,chaotic attractor and periodic attractor in the system are analyzed respectively when the moment of inertia and structural parameters are improper.The 4D highlt fixed attitude experimental platform is designed and built independently.Based on Pixhawk2 flight controller and Ardupilot flight control software,a complete hardware closed-loop experimental system is built.The moments of inertia of small unmanned helicopters are measured by the three-line pendulum under the same counterweight and different weight positions.It is verified that the random weight may cause the moment of inertia to be in an improper range.Based on the classical PID theory,the attitude controller is designed.The simulation results show that the attitude controller calms chaotic behaviors of system.The research in this paper provides a new perspective and method for the design and dynamic analysis of small unmanned helicopters.