Active vibration control techniques for flexible space structures

Two proposed control system design techniques for active vibration control in flexible space structures are detailed. Control issues relevant only to flexible-body dynamics are addressed, whereas no attempt was made to integrate the flexible and rigid-body spacecraft dynamics. Both of the proposed approaches revealed encouraging results; however, further investigation of the interaction of the flexible and rigid-body dynamics is warranted

Attitude control/momentum management and payload pointing in advanced space vehicles

The design and evaluation of an attitude control/momentum management system for highly asymmetric spacecraft configurations are presented. The preliminary development and application of a nonlinear control system design methodology for tracking control of uncertain systems, such as spacecraft payload pointing systems are also presented. Control issues relevant to both linear and nonlinear rigid-body spacecraft dynamics are addressed, whereas any structural flexibilities are not taken into consideration. Results from the first task indicate that certain commonly used simplifications in the equations of motions result in unstable attitude control systems, when used for highly asymmetric spacecraft configurations. An approach is suggested circumventing this problem. Additionally, even though preliminary results from the second task are encouraging, the proposed nonlinear control system design method requires further investigation prior to its application and use as an effective payload pointing system design technique

IMECE2004-60039 IMPLEMENTATION OF HIGH BANDWIDTH SENSOR ARRAYS USING FEEDBACK MECHANISMS

ABSTRACT Proposed in this paper is a new method to implement the high operating bandwidth sensor arrays. In certain control applications, it is necessary that a high bandwidth sensor be used to improve the efficiency of feedback. The design of a single sensor with the desired high bandwidth may not be easy and economically feasible. It is shown that the idea of sensor arrays can be utilized to obtain a cost effective and efficient solution to the problem posed. It is discussed that an effective data fusion scheme is necessary in order to implement the proposed sensor array that consists of low bandwidth pass-band sensors with possible overlapping operating regions. Moreover, we point out that obtaining accurate sensor models may not be always easy in practice and this may make the proposed sensor arrays inapplicable for certain applications. To address this issue, a new implementation scheme that utilizes feedback mechanisms to combine multi-sensor data is developed. The proposed framework is validated using simulation examples

A Robust Synthesis Methodology For Neutrally Stable Uncertain Siso Plants Under Input Amplitude Saturation

In this article, a control system design methodology for neutrally stable, uncertain, single-input single-output plants under input amplitude saturation is presented. Based on Horowitz\u27s original three degree of freedom design and extensions developed afterwards, this approach concentrates on neutrally stable, higher type, uncertain plants. A three degree of freedom non-interfering loop structure is used for the synthesis, along with the structure of the additional, independent loop transmission around the saturating element proposed for designing the third degree of freedom H(s). Robust stability and performance are established. The circle criterion, the describing function and non-overshooting conditions are utilised to obtain design constraints. Finally, all these design constraints are expressed in frequency domain bounds and synthesis follows from loop shaping methods such as quantitative feedback theory. © 2013 Copyright Taylor and Francis Group, LLC

Guaranteed Consensus In Radar Deception With A Phantom Track

Radar deception problems serve as a motivation to address the key issue of feasibility in trajectory planning for constrained dynamics of multi-agent systems. In a recent paper, Jayasuriya et al. presents an algorithm which claims to produce a dynamically feasible reference trajectory in real time. However, there was no proof provided for the proposed control strategy. This paper work through that algorithm; and, with a slight modification, provides some conditions on configuration parameters and the desired trajectory such that the proposed control guarantees consensus. These conditions dictate certain conditions on the initial configuration of the agents, consistent with the limitations on their actuators. Simulations support the idea that if the initial configuration along the final team goal is in admissible regions, the agents would always reach a consensus and maintain the formation. Copyright © 2013 by ASME

Multi-Agent Deployment Based On Homogenous Maps And A Special Inter-Agent Communication Protocol

In this paper, presented is a methodology for formation control of an n-D multi agent system (MAS). The n-D motion of the MAS is treated as n one-D motions with the evolution of each coordinate of an agent representing the collective motion of a continuum of agents constrained to always stay on a straight line. The motion of the continuum is controlled by the two vertex agents, left most and the right most, by preserving certain distance ratios among the agents. First, it is shown how a specific homogenous map defining a desired agent topology may be achieved by local inter-agent communication. Second, a strategy for deploying agents to lie on a desired curve utilizing local inter-agent communication and starting from a randomly distributed initial topology is outlined. © 2013 IFAC

Preserving Stability Under Communication Delays In Multi Agent Systems

The effect of time delays on the stability of a recently proposed continuum approach for controlling a multi agent system (MAS) evolving in n-D under a special local inter-agent communication protocol is considered. There a homogenous map determined by n+1 leaders is learned by the follower agents each communicating with n+1 adjacent agents. In this work both position and velocity information of adjacent agents are used for local control of follower agents whereas in previous work [1, 2] only position information of adjacent agents was used. Stability of the proposed method under a time delay h is studied using the cluster treatment of characteristic roots (CTCR) [3]. It is shown that the stability of MAS evolution can be preserved when (i) the velocity of any follower agent is updated using both position and velocity of its adjacent agents at time (t-h); and (ii) the communication matrix has real eigenvalues. In addition, it is shown that when there is no communication delay, deviations from a selected homogenous map during transients may be minimized by updating only the position of a follower using both position and velocity of its adjacent agents. Copyright © 2013 by ASME