Hong Wong

Brief Adaptive tracking control using synthesized velocity from attitude measurements

The attitude tracking control problem of uncertain rigid spacecraft without angular velocity measurements is addressed in this paper. The adaptive control law, which incorporates a velocity-generating filter from attitude measurements, is shown to ensure the asymptotic convergence of the attitude and angular velocity tracking errors despite unknown spacecraft inertia. Simulation results are presented to illustrate the theoretical results.

Output feedback control for spacecraft formation flying with coupled translation and attitude dynamics

In this paper, we address an output feedback tracking control problem for the coupled translation and attitude motion of a follower spacecraft relative to a loader spacecraft. It is assumed that the leader spacecraft is tracking a given desired translation and attitude motion trajectory and the translation and angular velocity measurements of the two spacecraft are not available for feedback. First, the mutually coupled translation and attitude motion dynamics of the follower spacecraft relative to a leader spacecraft are described. Next, a suitable high-pass filter is employed to estimate the follower spacecraft relative translation and angular velocities using measurements of its relative translational position and attitude orientation. Using a Lyapunov framework, a nonlinear output feedback control law is designed that ensures the semi-global asymptotic convergence of the follower spacecraft relative translation and attitude position tracking errors, despite the lack of translation and angular velocity measurements of the two spacecraft. Finally, an illustrative numerical simulation is presented to demonstrate the effectiveness of the proposed control design methodology.

Adaptive tracking control using synthesized velocity from attitude measurements

The attitude tracking problem of uncertain rigid spacecraft without angular velocity measurements is addressed in the paper. The adaptive control law, which incorporates a velocity-generating filter from attitude measurements, is shown to ensure the asymptotic convergence of the attitude and angular velocity tracking errors despite unknown spacecraft inertia. Simulation results are presented to illustrate the theoretical results.

Adaptive learning control for spacecraft formation flying

Considers the problem of spacecraft formation flying in the presence of periodic disturbances. In particular, the nonlinear position dynamics of a follower spacecraft relative to a leader spacecraft are utilized to develop a learning controller which accounts for the periodic disturbances entering the system model. Using a Lyapunov-based approach, a full state feedback control law, a parameter update algorithm, and a disturbance estimate rule are designed which facilitate the tracking of given reference trajectories in the presence of unknown spacecraft masses. Illustrative simulations are included to demonstrate the efficacy of the proposed controller.

UAV optimal path planning using C-C-C class paths for target touring

In this paper, 2-D optimal C-C-C class paths are determined for unmanned air vehicles performing target touring with kinematic and tactical constraints. Using vector calculus, a path-planning problem is decomposed to yield a parameter optimization problem. An efficient hybrid optimization algorithm is then used to solve the parameter optimization problem. Illustrative numerical simulations are given to demonstrate the efficacy of our approach.

Adaptive output feedback tracking control of multiple spacecraft

In this paper, an adaptive, output feedback control design methodology is presented for a multiple Spacecraft formation flying (MSFF) system. A Lagrangian derivation of the MSFF model is considered to produce position dynamics for follower spacecraft #n relative to follower spacecraft #(n-1), assuming that the leader spacecraft in the formation follows a no-thrust, natural, elliptical orbit. Next, a control law is designed to provide a filtered velocity measurement and a desired adaptive compensation with semi-global, asymptotic, relative position tracking. The proposed control law is simulated for the case of two and three spacecraft and is shown to yield semi-global, asymptotic tracking of the relative position errors.

Spacecraft formation flying near sun-earth L/sub 2/ Lagrange point: trajectory generation and adaptive output feedback control

In this paper, we present a trajectory generation and an adaptive, output feedback control design methodology to facilitate spacecraft formation flying near the Sun-Earth L/sub 2/ Lagrange point. Specifically, we create a spacecraft formation by placing a leader spacecraft on a desired Halo orbit and a follower spacecraft on a desired quasi-periodic orbit surrounding the Halo orbit. We develop the nonlinear dynamics of the follower spacecraft; relative to the leader spacecraft, wherein the leader spacecraft is assumed to be on a desired Halo orbit trajectory. In addition, we design a formation maintenance controller such that the follower spacecraft tracks a desired trajectory. Specifically, we design an adaptive, output feedback position tracking controller, which provides a filtered velocity measurement and an adaptive compensation for the unknown mass of the follower spacecraft. The proposed control law is simulated for the case of the leader and follower spacecraft pair and is shown to yield semi-global, asymptotic convergence of the relative position tracking errors.

Output feedback control for spacecraft with coupled translation and attitude dynamics

In this paper, we address a tracking control problem for a spacecraft with coupled translation and attitude motion, in, the absence of translation and angular velocity measurements. We begin by describing the mutually coupled translation and attitude dynamics of the spacecraft. Next, a suitable high-pass filter is employed to estimate the spacecraft translation and angular velocities using measurements of its translational position and attitude orientation. Using a Lyapunov framework, a nonlinear output feedback control law is designed that ensures the semi-global asymptotic convergence of the spacecraft translation and attitude position tracking errors, despite the lack of translation and angular velocity feedback.

Matlab Data Acquisition and Control Toolbox for Basic Stamp Microcontrollers

In this paper, we present a Matlab and Simulink based software platform that enables the use of inexpensive microcontrollers for data acquisition and control tasks. The proposed framework is well suited for data acquisition and control tasks that require graphical user interface (GUI) and/or advanced computational capabilities but do not require stringent hardware performance. We illustrate the efficacy of our data acquisition and control technique by performing position control of a DC motor using a Basic Stamp 2 (BS2) microcontroller and our Matlab data acquisition and control toolbox

Adaptive learning control-based periodic trajectory tracking for spacecraft formations

This paper addresses a periodic trajectory tracking problem arising in spacecraft formation flying. In particular, the nonlinear position dynamics of a follower spacecraft relative to a leader spacecraft are utilized to develop a learning controller which learns a periodic, unknown model reference control. Using a Lyapunov-based approach, a full state feedback control law, a parameter update algorithm, and a model reference control estimate are designed that facilitate the tracking of given periodic reference trajectories in the presence of unknown leader and follower spacecraft masses. Furthermore, using a discrete Lyapunov-type stability analysis, model reference control error is shown to converge to zero. Illustrative simulations are included to demonstrate the efficacy of the proposed controller.