Nonlinear modeling of a miniature fixed-pitch coaxial UAV

Abstract

Abstract-This paper presents the work that has been done to derive an accurate nonlinear model for a miniature fixedpitch coaxial helicopter. Starting from the Newton-Euler rigid body dynamic equations, forces and torques generated at various parts of the UAV have been identified and formulated. The physical meanings behind the model are clearly explained, and the methods of identifying all the important model parameters are also provided. The full model is verified by comparing simulation results and actual flight tests with the NUS FeiLion coaxial UAV. The agreement between the two is promising.Index Terms-Nonlinear model, coaxial helicopter, micro unmanned aerial vehicle.

Design and Control of Autonomous Rover for Foliage Navigation

“…As the local frame of the rover, xb and yb will translate and rotate together with respect to the global frame, therefore the relationship between global frame and local frame can be formulated as shown in Equation ( 4). R as shown in Equation ( 5) is defined as the 2D rotational matrix which represent the translation and rotation of the rover [16].…”

“…By manipulating Equation (15) and relates it to Equation ( 14), (10) and (11), the angular acceleration of the rover with respect to the torque of the wheels can be formulated as shown in Equation (16).…”

The modeling and cascade sliding mode control of a moving mass-actuated coaxial dual-rotor UAV

“…6 Moreover, for a system in which only the lower rotor can pitch periodically, the lower rotor becomes susceptible to interference from the wash flow of the upper rotor. 7 This results in a lower forward thrust, poorer performance, and shorter flight duration.…”

“…Complicated variable pitch mechanisms and rotors with opposite rotation directions cause more severe mechanical wear, which results in lower service life, more frequent maintenance, and consequently higher maintenance costs [6]. Meanwhile, for a system where only the lower rotor can periodically pitch, the lower rotor becomes susceptible to interference by the upper one's wash flow [7]. This results in a lower forward thrust, poorer performance, and a shorter flight duration.…”