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In this paper, we proposed several disturbance observer‐based matrix‐weighted consensus algorithms. A new disturbance observer is firstly designed for linear systems with unknown matched or mismatched disturbances representable as the multiplication of a known time‐varying matrix with a unknown constant vector. Under some assumptions on the boundedness and persistent excitation of the regression matrix, the disturbances can be estimated at an exponential rate. Then, a suitable compensation input is provided to compensate the unknown disturbances. Second, disturbance‐observer based consensus algorithms are proposed for matrix‐weighted networks of single‐ and double‐integrators with matched or mismatched disturbances. We show that both matched and mismatched disturbances can be estimated and actively compensated, and the consensus system uniformly globally asymptotically converges to a fixed point in the kernel of the matrix‐weighted Laplacian. Depending on the network connectivity, the system can asymptotically achieve a consensus or a cluster configuration. The disturbance‐observer based consensus design is further extended for a network of higher‐order integrators subjected to disturbances. Finally, simulation results are provided to support the mathematical analysis. [ABSTRACT FROM AUTHOR]

Vehicle energy usage has become a favorite topic for many global scientists. This paper presents calculations for almost all current cars operating under a particular driving cycle, whose method is to average the main technical parameters of the research objects. Nowadays, the calculation methods of vehicle energy consumption require many no-published technical parameters for modeling or many measurement devices for testing. The advantages of the proposed calculation method lie in the simplicity of using only the typical vehicle and driving cycle parameters. Experiments were carried out for different driving cycles with various speed ranges inside and outside urban areas to verify the proposed method. The experiments show an acceptable deviation from the results calculated by the presented method, which indicates that the proposed method in this paper is feasible for further studies on vehicles' energy forecasting during the operation in a given driving cycle. [ABSTRACT FROM AUTHOR]

In this article, free‐will arbitrary time consensus protocols are proposed for multi‐agent systems with single‐ and double‐ (possibly higher‐order) integrator dynamics, respectively, and with (possibly switching) connected interaction graphs and bounded matched disturbances. Under the proposed consensus laws, an average consensus is achieved in a free‐will arbitrary prespecified time regardless of the initial conditions or any other design parameters. Further, the proposed consensus laws for the case with no disturbances are smooth, and they are distributed in the sense that information is only communicated locally between neighboring agents. Finally, simulation results are also provided to illustrate the theoretical results and, an application to arbitrary prespecified time formation control of mobile agents is also presented. [ABSTRACT FROM AUTHOR]

This paper proposes fixed‐time solutions to several problems in multi‐agent systems. First, a fixed‐time consensus protocol is investigated and under the assumption that the lower bound of smallest positive eigenvalue of the Laplacian matrix is known in advance, the consensus time of the protocol can be arbitrarily selected. Second, the consensus law to attenuate bounded disturbances acting on the system is modified. Third, the fixed‐time design method is applied to the orientation alignment and network localization problems. Finally, several simulations are provided to support the mathematical analysis. [ABSTRACT FROM AUTHOR]

The authors propose fully distributed strategies for multi‐agent formation control of the two‐dimensional special Euclidean group. To control the rotated local reference frames, they firstly estimate the orientation angle of each agent with regard to a global reference frame. By using only local measurements, the orientation angle is estimated in a distributed way. The estimated orientation is, then, exploited to control each agent's orientation. Each agent's orientation converges to the prescribed desired orientation. Finally, a distributed formation control strategy based on displacement measurement is proposed to achieve the desired formation shape of the two‐dimensional special Euclidean group. Under the proposed strategy, the authors ensure that the formation shape including position and orientation exponentially converges to the desired formation shape. Moreover, the formation shape is invariant to a translation and a rotation compared with the desired formation shape. [ABSTRACT FROM AUTHOR]

This paper studies a distance-based formation control problem of multiagent systems, in which each agent uses only relative positions of its neighbors with respect to its own coordinate system. First,we provide an analysis for the properties of the undesired equilibria-corresponding 2 specific formations, ie, a triangle group in 2-dimensional space and a tetrahedron group in 3-dimensional space. Then, we consider the formation of multiagent systems whose interaction graph consists of a rigid group and an extra node. Although the extra node may have an additional control input, the desired formation where all interagent distance constraints are satisfied is asymptotically stable. If the rigid group is a triangle in 2-dimensional space or a tetrahedron in 3-dimensional space, any undesired equilibrium is unstable. In these cases, the desired formations are almost globally asymptotically stable. Finally, we extend these results to a more general formation, which is a series of rigid groups connecting via flex edges. [ABSTRACT FROM AUTHOR]

Summary: This paper studies a bearing‐only–based formation control problem for a group of single‐integrator agents with directed cycle sensing topology. In a 2‐dimensional space, a necessary and sufficient condition for the set of desired bearing vectors to be feasible is derived. Then, we propose a bearing‐only control law for every agent and prove that the formation asymptotically converges to a formation specified by a set of feasible desired bearing vectors. Analysis of the equilibrium formations in the plane for a 3‐agent system and subsequent extension to an n‐agent system is provided. We further extend the analysis on directed triangular formation into a 3‐dimensional space. Finally, simulations validate the theoretical results. [ABSTRACT FROM AUTHOR]

In the transmission systems of vehicles, unforced vibrations can be observed during the sliding phase of clutch engagement. These vibrations are due to frictional forces and may generate noise. Several studies have shown that the stability of such friction systems is highly sensitive to parameters (friction law, damping) which lead to significant dispersions. Therefore, uncertain parameters must be considered in the stability analysis of a clutch system. This paper investigates the ability of the multi-element generalized polynomial chaos to take an increasing number of uncertain parameters into account in the stability analysis of a clutch system: it focuses on accuracy, on the criterion for the choice of the order of truncation, on the criterion for the choice of the number of elements and on computation time. The objective is to propose a low-cost model of high accuracy, compared with the Monte Carlo method. [ABSTRACT FROM AUTHOR]

This article studies the problem of stabilizing a leader-follower formation specified by a set of bearing constraints while disturbed by some unknown uniformly bounded disturbances. A set of leaders are positioned at their desired positions while each follower is modeled by a single integrator with an additive time-varying disturbance. Adaptive variable-structure control laws using displacements or only bearing vectors are applied to stabilize the desired formation. Thanks to the adaptive mechanisms, the proposed control laws require neither information on the bearing Laplacian nor the directions and upper bounds of the disturbances. It is further proved that when the leaders are moving with the same bounded uniformly continuous velocity, the moving target formation can be achieved under the proposed control laws. Simulation results are provided to support the stability analysis.