Attitude Consensus Problem Research Articles

Event-Triggered Attitude Consensus of Multiple Rigid Body Systems With Prescribed Performance.

The event-triggered almost global attitude consensus problem is considered in this article for multiple rigid body systems with prescribed performance. Two kinds of attitude consensus protocols using axis-angle vectors are proposed at the kinematic level with different prescribed performance constraints. The first protocol aims to achieve the event-triggered attitude consensus almost globally under jointly connected graphs. Based on a prescribed performance function with local states, the configuration space of parameterized attitude representations is shown to be positively invariant which almost globally covers [Formula: see text] . The second protocol is designed to reach attitude consensus with the prescribed transient behavior guaranteed in the event-triggered setting. By defining a prescribed performance function using the metric on axis-angle spaces, a dynamic event-triggered framework is designed to ensure both the attitude geometric topology constraint and prescribed convergence performance. Finally, numerical results are given to show the validness of the two control protocols.

Continuous Distributed Fixed-Time Attitude Controller Design for Multiple Spacecraft Systems With a Directed Graph

This brief addresses the fixed-time leader-following attitude consensus problem for multiple spacecraft systems on a directed graph. A distributed continuous observer is designed to estimate the angular velocity of the leader within a fixed time. Based on the fixed-time observer and adding a power integrator method, a continuous distributed adaptive controller is developed to achieve the consensus tracking control in a fixed time which is regardless of the initial conditions. The proposed continuous fixed-time scheme works well when the systems are subject to model uncertainties and external disturbances. The simulation results show the effectiveness of the proposed control scheme.

Leader-following consensus of multiple rigid body systems by a sampled-data distributed observer

In this paper, we study the leader-following attitude consensus problem of multiple rigid body systems by a sampled-data distributed observer. Comparing with the continuous-time distributed observer, the sampled-data distributed observer consumes fewer communication resources and is less vulnerable to such communication failures as network congestions and packet dropouts. The sampled-data distributed observer consists of two parts. The first part is a sampled-data distributed observer for the angular velocity leader subsystem and the second part is a sampled-data distributed observer for the attitude leader subsystem. It is noted that, since the attitude leader subsystem is nonlinear, a special effort has to be made to establish the sampled-data distributed observer for the attitude leader subsystem. Moreover, we give an explicit upper bound for the sampling intervals to guarantee the validity of the sampled-data distributed observer. On the basis of the sampled-data distributed observer, we further synthesize a distributed control law to solve the leader-following consensus problem. The effectiveness of our approach is illustrated by a numerical example.

Adaptive Fixed-Time Control for Attitude Consensus of Disturbed Multi-Spacecraft Systems With Directed Topologies

In this paper, the problem of leaderless fixed-time attitude consensus is studied for rigid spacecraft systems, where each spacecraft is subject to disturbance and the communication graph is directed. Based on the backstepping technique, a distributed control protocol is proposed to solve fixed-time attitude consensus problem. Then, to remove the dependence of control gains on the global information, an adaptive fixed-time control for attitude consensus is presented. Unlike the most existing consensus protocols, the parameters in the controllers for the spacecraft are chosen independently and can be different from each other. Finally, the performances of the proposed control protocol is illustrated through a numerical simulation.

Distributed Predefined-Time Attitude Consensus Control for Multiple Uncertain Spacecraft Formation Flying

This paper addresses the distributed predefined-time attitude consensus problem for multiple uncertain spacecraft systems in the presence of model uncertainties and external disturbances. Firstly, a new predefined-time terminal sliding surface (PTS) is proposed. Secondly, a distributed predefined-time consensus control (DPTC) based on the PTS is designed to solve the robust attitude consensus problem. It is proved that the proposed DPTC can ensure that the attitude consensus errors converge to an arbitrary small bound centered on equilibrium point within predefined time and then go to equilibrium point asymptotically. The appealing features of the proposed control are faster convergence, higher precision, stronger robustness and easy implementation. Simulations verify the effectiveness of the proposed approach.

Leader‐following consensus of multiple spacecraft systems with disturbance rejection over switching networks by adaptive learning control

AbstractIn this article, we study the leader‐following attitude consensus and disturbance rejection problem of multiple uncertain rigid spacecraft systems over jointly connected switching networks. In contrast with the previous work, which can only handle disturbances in the form of step functions and trigonometric functions via the internal model approach, we allow the disturbances to be any bounded unknown time functions. Moreover, instead of static and connected communication networks, we can handle jointly connected switching networks, which can be disconnected at all time. These improvements are due to the integration of two techniques, namely, the adaptive distributed observer technique and the adaptive learning control technique. The effectiveness of our approach is illustrated by two numerical examples.

Adaptive distributed observer for an uncertain leader over acyclic switching digraphs

AbstractThe existing results on the adaptive distributed observer for an uncertain leader system are restricted to connected static networks. In this article, we extend the existing results to acyclic every‐time connected switching networks. As an application of the adaptive distributed observer, we solve the leader‐following attitude consensus problem of multiple rigid body systems with an uncertain leader system over an acyclic every‐time connected switching network. A numerical example is provided to illustrate our design.

Retraction: Hybrid Attitude Coordination Controller for Multiple-Spacecraft Systems with Hyperbolic-Tangent Distributed Observer

This paper investigates the leader-following attitude consensus problem for a multiple-spacecraft system. Based on Lyapunov theory and homogeneous technique, quaternion-based hybrid globally finite...

Leader-Following Event-Triggered Adaptive Practical Consensus of Multiple Rigid Spacecraft Systems Over Jointly Connected Networks.

In this article, we study the leader-following practical attitude consensus problem of a group of multiple uncertain rigid spacecraft systems over jointly connected networks by a distributed event-triggered control law. We first establish a lemma that allows the problem to be converted to a distributed practical stabilization problem of a well-defined uncertain dynamical system. Then, we combine the adaptive distributed observer technique and the adaptive control technique to design an event-triggered adaptive control law and an event-triggered mechanism to solve our problem. The effectiveness of our design is illustrated by a numerical example.

Robust attitude alignment in multispacecraft systems with stochastic links failure

Attitude consensus problem in multispacecraft systems is addressed. Despite existing results devoted to attitude consensus control of spacecraft under deterministic communication, we propose a control strategy under which a team of spacecraft reaches almost sure consensus on an attitude, while communication links stochastically fail over time. Moreover, the robustness of the control strategy in the presence of parameter uncertainties is guaranteed. By quaternion formulation of the spacecraft attitudes dynamics, a nonlinear attitude consensus control strategy is developed such that by invoking the generalized invariance principle and the super-martingales convergence theorem, the mentioned objectives are achieved. Simulation results for a team of six spacecraft validate the obtained results.

Consensus of Multiple Spacecraft Systems Over Switching Networks by Attitude Feedback

In this paper, we further consider the leader-following attitude consensus problem of multiple rigid body systems subject to jointly connected switching networks by a distributed attitude feedback control law. Since the network is switching, the closed-loop system is discontinuous. We overcome this difficulty by a generalized Barbalat's lemma. Moreover, we remove two restrictive assumptions in the literature. As a result, our control law is fully distributed and the result is global.

Leader-Following Attitude Consensus of Multiple Rigid Spacecraft Systems Under Switching Networks

The leader-following attitude consensus problem of networked rigid spacecraft systems is addressed by a distributed control law. Compared with existing results, the salient characteristic of this work is that the communication network is allowed to be directed and switching. In particular, the switching network only needs to be jointly connected, which is a very mild condition on network connectivity. As a consequence, the robustness and reliability for consensus of networked rigid spacecraft systems can be greatly improved. By establishing a series of technical lemmas, it is shown that leader-following attitude consensus of switched networked rigid spacecraft systems can be achieved. The effectiveness of our main result is demonstrated by cooperative control of a group of rigid spacecraft.

Event-triggered fault tolerant control for spacecraft formation attitude synchronization with limited data communication

This paper investigates the leader-following attitude consensus problem of a group of n-th spacecrafts with actuator fault and limited data communication, where the event-triggered based sending mechanism is considered to decrease communication burthen. In this design, unknown actuator faults and external disturbances are considered, and an event-triggered based adaptive distributed cooperative attitude control law is developed to solve the multiple spacecrafts formation control problem. It is shown that leader-following attitude synchronization can be achieved under the designed event-triggered control law. Finally, a simulation example is provided to illustrate the effectiveness of the proposed attitude coordination control techniques.

Global finite-time attitude consensus of leader-following spacecraft systems based on distributed observers

This paper addresses the leader-following attitude consensus problem for a group of spacecraft when at least one follower can access the leader’s attitude and velocity relative to the inertial space. A nonlinear distributed observer is designed to estimate the leader’s states for each follower. The observer possesses one important and novel feature of keeping attitude and angular velocity estimation errors on second-order sliding modes, and thus provides finite-time convergent estimates for each follower. Further, quaternion-based hybrid homogeneous controllers recently developed for single spacecraft are extended and then applied, by establishing a separation principle with the proposed observer, to track the leader’s attitude motion. As a result, global finite-time attitude consensus is achieved on the entire attitude manifold, with either full-state measurements or attitude-only measurements, as long as the network topology among the followers is undirected and connected. Numerical simulations are presented to demonstrate the performance of the proposed methods.

Leader-following attitude consensus of multiple rigid body systems subject to jointly connected switching networks

The leader-following attitude consensus problem of multiple rigid body systems has been studied by the distributed observer approach. The key assumption in the existing results is that the communication network among the rigid body systems is static and connected. Nevertheless, this assumption is undesirable since, typically, the communication network is time-varying and disconnected from time to time due to changes of the environment or failures of some subsystems. In this paper, we will further study the leader-following attitude consensus problem of multiple rigid body systems subject to a jointly connected switching communication network. This new problem is more challenging than the existing one since a jointly connected switching communication network can be disconnected at every time instant. To overcome the difficulty, we first show that the distributed observer for a nonlinear target system subject to a jointly connected switching communication network exists. Then, we further synthesize a distributed control law utilizing this distributed observer for the multiple rigid body systems. Finally, we show that this distributed control law solves our problem through the argument of the certainty equivalence principle.

Distributed almost global finite-time attitude consensus of multiple spacecraft without velocity measurements

This paper addresses the attitude consensus problem of multiple rigid bodies in terms of the unit quaternion parameterization. By employing Lyapunov theory and homogeneous techniques, distributed finite-time attitude consensus laws are proposed for leader-following and leaderless multi-agent systems, with full-state (i.e., attitude plus angular velocity) or attitude-only measurements. Specifically, sliding mode observers are used to estimate the leader's information in finite time for followers without direct access to the leader. The so-called “separation principle” is then established between the observers and the consensus controllers. In addition, quaternion filtering systems are constructed to inject the necessary damping into the closed-loop system when angular velocity measurements are absent. In all scenarios, the proposed methods ensure almost global finite-time convergence, avoid the unwinding problem, and yield continuous control torques with a priori known bounds. Numerical examples demonstrate the effectiveness of the proposed methods.

Almost Sure Attitude Consensus in Multispacecraft Systems With Stochastic Communication Links

Leaderless attitude consensus problem over multispacecraft systems is studied. The base of convergence analysis of existing results devoted to attitude consensus control of multispacecraft systems is deterministic knowledge on networks communication links. The main contribution of the present study is to design a control strategy guaranteeing almost sure attitude consensus in a multispacecraft system when communication links stochastically fail over time. Moreover, it is assumed that there exist constraints on the spacecraft input torques. To achieve the mentioned objectives, we propose a magnitude-constrained consensus control law for the spacecraft; then, by invoking the generalized invariance principle and the super-martingales convergence theorem, almost sure convergence of quaternion-based consensus errors to zero is concluded. The results are verified via a simulation example.

Leader-following Attitude Consensus of Multiple Rigid Body Systems by an Adaptive Distributed Observer Approach

The leader-following attitude consensus problem of multiple rigid body systems has been studied by the distributed observer approach. The distributed observer is able to estimate the reference signals generated by a target system under the assumption that each rigid body system knows the two system matrices of the target system. In this paper, we propose an adaptive distributed observer approach which estimates not only the state of the target system, but also the two systems matrices of the target system. Utilizing this adaptive distributed observer, we are able to solve the leader-following attitude consensus problem without assuming that each rigid body system knows the two system matrices of the target system.

Leader-following attitude consensus of multiple uncertain spacecraft systems subject to external disturbance

Summary The attitude consensus problem of multiple rigid spacecraft systems is one of the key issues in spacecraft formation flying and has been extensively studied. In this paper, we further consider the leader-following attitude consensus problem of multiple rigid uncertain spacecraft systems subject to a class of multi-tone sinusoidal disturbances with arbitrarily unknown amplitudes, initial phases, frequencies, and constant biases. In contrast to the existing results, in order to achieve asymptotic reference tracking and disturbance rejection by smooth control, we have integrated the distributed observer approach with internal model and adaptive control techniques. Simulation results are shown to validate the effectiveness of the proposed control law. Copyright © 2016 John Wiley & Sons, Ltd.

Leader-following attitude consensus of multiple rigid body systems by attitude feedback control

In this paper, we study the leader-following attitude consensus problem for multiple rigid body systems by a distributed unit quaternion-based attitude feedback control law. The control law is based on the certainty equivalence principle and contains a distributed observer for estimating the state of the leader and an auxiliary system compensating for the unavailability of the angular velocity. It is shown that the problem is solvable under the standard assumption that each follower can access the information from the leader through a directed path.