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We investigate the trajectory tracking problem of vertical take-off and landing (VTOL) unmanned aerial vehicles (UAV), and propose a practical disturbance rejection control strategy. Firstly, the nonlinear error model is established completely by the modified Rodrigues parameters, while considering dynamics of the servo actuators. Then, a hierarchical control scheme is applied to design the translational...
In this paper, a sliding mode attitude controller with a two-cascaded loop structure is designed for the attitude control of a quadrotor micro unmanned aircraft vehicle. Considering that the quadrotor systems usually suffer external disturbances in the practical flight, a nonlinear disturbance observer is introduced to improve the robustness of the attitude controller. Extensive simulations show that...
In this paper, the distributed attitude coordinated tracking controller is presented for multi-group spacecrafts based on input normalized adaptive neural network. In contrast to the existing works about spacecraft formation flying(SFF), where all spacecrafts reach the same reference attitude asymptotically, we require that all spacecrafts track several leaders and each spacecraft only synchronize...
In this paper, we propose a new control strategy for flexible spacecraft attitude maneuvers in the presence of an uncertainty inertia matrix, actuator constraints and external disturbances. The Vibration of flexible appendages, inertia matrix uncertainty and external disturbances (coming from space environmental, sensors and actuators error, etc.) are considered as the total disturbance to be estimated...
This paper studies the three-axis attitude stabilization problem for a nadir-pointing spacecraft using only magnetic torquers as actuators. Since magnetic control systems are relatively lightweight, require low power and are inexpensive, they are attractive for small, inexpensive satellites in low Earth orbits. In this paper we present three-axis attitude control algorithms for small satellites using...
We propose a new position control scheme for vertical take-off and landing (VTOL) unmanned airborne vehicles (UAVs). Traditionally, the control schemes for this type of vehicle assume that the system attitude is accurately known (or measured). Unfortunately, there does not exist any sensor that directly measures the orientation of a rigid body. Instead, to obtain the orientation of the aircraft, separately...
Control of trajectile and other systems requires reliable real-time estimates of the system state. The design procedure is the mathematical formulation of the state observer by vector calculus possible by different variants of the observer, the determination of its rectro position, attitude and the dynamic system behavior. State Estimation takes all the telemetry seen so far and uses it to determine...
In this paper, equivalent tilt error models are derived which are applicable to the alignment of the small AUV attitude and heading reference system (AHRS), using quaternions in the body frame approach. And they are compared with the error models which use quaternions directly from the view of computational burdens. Based on the equivalent tilt error models, an alignment algorithm is developed for...
This paper presents a robust and efficient approach for relative navigation and parameter estimation of spacecraft flying in formation. This approach uses measurements from the optical data that provides a line of sight vector from the master spacecraft to the secondary satellite. State estimation for formation flying is achieved through an optimal observer design. Also, because the rotational and...
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