Showing papers by "Abdelkader Abdessameud published in 2009"
TL;DR: This work considers the coordinated attitude control problem for a group of spacecraft, without velocity measurements, and designs a velocity-free attitude tracking and synchronization control scheme, that allows the team members to align their attitudes and track a time-varying reference trajectory (simultaneously).
Abstract: We consider the coordinated attitude control problem for a group of spacecraft, without velocity measurements. Our approach is based on the introduction of auxiliary dynamical systems (playing the role of velocity observers in a certain sense) to generate the individual and relative damping terms in the absence of the actual angular velocities and relative angular velocities. Our main focus, in this technical note, is to address the following two problems: 1) Design a velocity-free attitude tracking and synchronization control scheme, that allows the team members to align their attitudes and track a time-varying reference trajectory (simultaneously). 2) Design a velocity-free synchronization control scheme, in the case where no reference attitude is specified, and all spacecraft are required to reach a consensus by aligning their attitudes with the same final time-varying attitude. In this work, one important and novel feature (besides the non-requirement of the angular velocity measurements), consists in the fact that the control torques are naturally bounded and the designer can arbitrarily assign the desired bounds on the control torques, a priori, through the control gains, regardless of the angular velocities. Throughout this technical note, the communication flow between spacecraft is assumed to be undirected. Simulation results of a scenario of four spacecraft are provided to show the effectiveness of the proposed control schemes.
294 citations
01 Dec 2009
TL;DR: In this article, a design methodology based on the separation of the translational and the rotational dynamics, using the desired orientation, in terms of the unit-quaternion, as an intermediate variable to achieve the position tracking objective is proposed.
Abstract: This paper considers the formation control problem of a group of Vertical Take-Off and Landing (VTOL) Unmanned Aerial Vehicles (UAV) in SE(3). The vehicles among the team are required to track a reference velocity signal and maintain a desired formation. For each vehicle in the formation, we propose a design methodology based on the separation of the translational and the rotational dynamics, using the desired orientation, in terms of the unit-quaternion, as an intermediate variable to achieve our position tracking objective. Global asymptotic stability result of the closed loop system is established using the Lyapunov method. The communication topology between formation team members is assumed to be fixed and bidirectional. Our control scheme can also be applied to the position control of a single VTOL-UAV and constitute, in its own right, an interesting contribution since global results are seldom achieved in the available literature. Finally, simulation results of a scenario of four VTOL-UAVs in a formation are provided to show the effectiveness of the proposed control scheme.
21 citations
01 Dec 2009
TL;DR: The main interest is to provide new design methodologies to minimize the order of the controllers as well as the information flow requirement between spacecraft in the team to address the coordinated attitude control problem for a group of spacecraft without velocity measurements.
Abstract: We consider the coordinated attitude control problem for a group of spacecraft without velocity measurements. Our approach is based on the introduction of an auxiliary dynamical system for each spacecraft (playing the role of velocity observers in a certain sense) to generate the individual and relative damping terms in the absence of the actual angular velocities and relative angular velocities. Our main interest is to provide new design methodologies to minimize the order of the controllers as well as the information flow requirement between spacecraft in the team. We will address the following two problems: 1) Design a velocity-free attitude tracking and synchronization control scheme, that allows the team members to align their attitudes and track a time-varying reference trajectory (simultaneously). 2) Design a velocity-free synchronization control scheme, in the case where no reference attitude is specified, and all spacecraft are required to synchronize their attitudes to the same final time-varying attitude. Throughout this paper, the communication flow between spacecraft is assumed to be fixed and undirected. Simulation results are provided to show the effectiveness of the proposed control schemes.
11 citations