Control system design for rotorcraft-based unmanned aerial vehicles using time-domain system identification

Abstract

This paper introduces the development of flight control system for rotorcraft-based unmanned aerial vehicle(RUAV). In this research, the linear time-invariant model valid for hover is sought. The system response data is acquired in carefully devised experiment procedure and then a linear time-invariant system model is obtained using time-domain analysis method. The acquired model is used to design feedback controller consisting of inner-loop attitude feedback control, mid-loop velocity feedback control and the outer-loop position control. The proposed controller is implemented on digital onboard computer and tested in a Berkeley RUAV and shows outstanding hovering performance.

Minimal Models to Capture the Dynamics of a Rotary Unmanned Aerial Vehicle

“…The constants 12 , are a correction factor to compensate for simplified flybar aerodynamics, ,  are the roll and pitch input command respectively, , are the roll rate and pitch rate of helicopter body frame respectively,  is the orientation angle of flybar and 5,6,7,8,9 L are the linkages in the rotor hub assembly.…”

“…where 1 2 3 ,, C C C are terms from the flybar flapping angle of Equation (8). The 1 C term augments the cyclic input of main rotor and 2 C term increases the damping moment in the helicopter attitude dynamics, which gives control booster to the actuator servo and stabilizing effect to the helicopter respectively.…”

“…System identification [7] can be combined with first principles modeling to identify the unknown or uncertain physical parameters. Typical approaches of system identification in time-domain are the prediction error method (PEM) [8], maximum likelihood method [9], equation error method and output error method [10]. However, these method are usually very time consuming, sensitive to starting point and with no guarantee of global optimality [11].…”

Centralized Robust Controllers Using Signal-based H_? and ?-Synthesis for an Unmanned Helicopter

“…Looking deeper into the system, the control of the directional velocities and the heading rate in the presence of internal and external disturbances would be the primary task to be solved. For that, various control techniques, such as classical PID, 5,6 Model Predictive Control, 7 H ∞ control, 8 H ∞ loop shaping method, 9 Composite Nonlinear Feedback (CNF) method 4 and Neutral Network method, 10 haven been presented in the literature. However, many of them are in a decentralized form, i.e., the control law is designed for partitioned subsystems separately and finally the entire control system has multi loops.…”

First Principle Approach to Modeling of Primitive Quad Rotor

“…Other modeling approaches to rotorcraft-based unmanned aerial vehicles (RUAVs) exist in the literature including the use of system identification [3], neural-networks [4] and linear parameter varying (LPV) identification [5]. The survey for the advances of modeling of RUAVs was reported in [6].…”