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Showing 3 results for Dynamic Inversion

Robust Control of Flexible Spacecraft Considering Actuator Dynamic

Maryam Malekzadeh,
Volume 14, Issue 15 (3-2015)

Abstract

In this paper, the effect of the reaction wheel dynamics as controller actuator in multi axis attitude maneuver of a 3D nonlinear flexible spacecraft is considered. In modeling of the actuator dynamic, friction, inertia and electrical subsystems are considered. The nonlinear robust control approach is composed of dynamic inversion and µ-synthesis schemes. To overcome the non-minimum phase characteristics, the controllers are designed by utilizing the modified output re-definition approach. In the design of controllers actuator saturation is considered. It is assumed that only three reaction wheels in three directions on the hub are used. To evaluate the performance of the proposed controllers, an extensive number of simulations on a nonlinear model of the spacecraft are performed. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, vibration suppression of panel, sensitivity to measurement noise, environment disturbance and nonlinearity in large maneuvers. In the disturbance modeling all terms such as constant, sinusoidal and impulse are considered. Simulation results show the effects of actuator dynamics and confirm the ability of the proposed controller in tracking the attitude trajectory while damping the panel vibration.

Controller Design for a Ducted Fan MAV Using Dynamic Inversion Method in Lateral Motion

F. Sharifzadeh, A. Naghash,
Volume 19, Issue 6 (6-2019)

Abstract

Today, Ducted Fan micro aerial vehicle much attention in the field of business and research due to the duct and, thus, the ability to be safe in enclosed environments. In order to identify and practical help to control and implement the vehicle in various maneuvers, the experimental example of this VTOL MAV was built by of Amirkabir University of Technology. In this research, in the first step, the modeling of the ducted fan is considered. In this way, after obtaining the dynamic model of the fan, the parameters in this model are calculated, using empirical methods. In this regard, the aerodynamic coefficients of the control levels and the inertia of the fan can be mentioned. In the second step, the controller design of the ducted fan is discussed. -Fan MAV control is one of the important issues in designing this fan due to inherent instability. The study of vehicle that reported shows that nonlinear dynamic inversion is an appropriate choice among control methods due to its successful empirical implementation on . Thus, by choosing this method, the control system was designed to follow the desired command of the vehicle in the Simulink simulation environment. In this process, the position command is first applied to the fan and converted by the controller to the command of state control actuators, after which these commands by changing the angles of the control levels of the fan lead to the change in the angles of the fan’s side, the pitch, and and, thus, achieved a desired position. The results indicated that the desired command was correctly followed; also, the stability of the closed loop system was successfully accomplished by using dynamic inversion method for the Ducted Fan MAV.

Nonlinear Dynamic Inversion Controller Design for a Satellite, Considering the Dynamics of Magnetorquers

H. Arefkhani, S.h. Sadati, M. Shahravi,
Volume 19, Issue 8 (8-2019)

Abstract

In this paper, a nonlinear inverse dynamic controller is designed for a magnetic actuated satellite. Since the stability of linear control laws in nonlinear dynamics is not guaranteed far from the equilibrium point, a global stabilizing nonlinear control law is necessary. In this method, by changing the system parameters, the nonlinear dynamics of the system is converted to linear dynamics and the input controller compensates the changes. The stability of the closed loop system was, then, investigated and proved by the Lyapunov method. Dynamic and kinematic equations of satellite are also developed in the presence of aerodynamic disturbance, gravity gradient, magnetic and radiation moments, and the linearization of the motion equations is done around the equilibrium point. In order to evaluate the performance of the dynamic inverse controller, the proportional-derivative linear control law and linear quadratic regulator optimal control law are designed and the results are compared. By modeling satellite orbit, the disturbance moments and the local magnetic field vector are calculated instantaneously according to the satellite's position in the orbit. Finally, the system response is presented by considering the saturation range of magnetic actuators. The results show a better performance of the nonlinear dynamic inversion controllers in both accuracy and convergence time.

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