String Stability towards Leader thanks to Asymmetric Bidirectional Controller

This paper deals with the problem of string stability of interconnected systems with double-integrator open loop dynamics (e.g.~acceleration-controlled vehicles). We analyze an asymmetric bidirectional linear controller, where each vehicle is coupled solely to its immediate predecessor and to its immediate follower with different gains in these two directions. We show that in this setting, unlike with unidirectional or symmetric bidirectional controllers, string stability can be recovered when disturbances act only on a small ($N$-independent) set of leading vehicles. This improves existing results from the literature with this assumption. We also indicate that string stability with respect to arbitrarily distributed disturbances cannot be achieved with this controller.Comment: Version 2 corrects a typo in the proof, and adds the proof of stability before string stability. Slightly longer than published versio

Synchronising H∞ robust distributed controller for multi-robotic manipulators

In this paper the problem of synchronisation of multiple robotic manipulators using Hoo robust distributed control systems with respect to the parameter uncertainties and disturbance inputs acting on the manipulators is addressed. Robust synchronising controllers only use the information of outputs of the manipulators, and the corresponding parameters of these output-feedback controllers are designed by computing a series of linear matrix inequalities instead of solving the complex differential (e.g. Hamilton-Jacobi) (in)equalities. The proposed controller can guarantee H∞ robust performance with respect to the external disturbance inputs and parameters uncertainties, asymptotic stability and synchronisation in the networked manipulators. Using an illustrative example we compare the results extracted in this paper to other works existing in the literature

Delay-dependent criterion for exponential stability analysis of neural networks with time-varying delays

This note investigates the problem of exponential stability of neural networks with time-varying delays. To derive a less conservative stability condition, a novel augmented Lyapunov-Krasovskii functional (LKF) which includes triple and quadruple-integral terms is employed. In order to reduce the complexity of the stability test, the convex combination method is utilized to derive an improved delay dependent stability criterion in the form of linear matrix inequalities (LMIs). The superiority of the proposed approach is demonstrated by two comparative examples

Network-based robust H∞ stabilization of uncertain systems

This paper deals with the problem of the stability analysis and controller gain synthesis for networked control systems with the network-induced delay, data packet dropout, parameters' uncertainties and disturbance input. To achieve less conservative results compared with existing methods in the literature, a novel Lyapunov-Krasovskii functional is constructed and new free-weighting matrices are introduced to increase degrees of freedom in the sufficient robust stability conditions. The maximum allowable delay bound, minimum attenuation level and the gain of memoryless controller is obtained by solving a set of linear matrix inequalities (LMIs). Finally an illustrative example is given to reveal the effectiveness of the proposed approach

Delay dependent criteria for the consensus of second‐order multi‐agent systems subject to communication delay

In this paper, a distributed controller is designed for the consensus of multi-agent systems in which each agent has a general second-order linear dynamic and the information is exchanged over a data-delaying communication network. Using the sensitivity of system poles to the parameters of the control protocol, graphical delay-dependent synthesis conditions are derived to tune the controller gains. A systematic procedure is developed to attain maximum tolerable transmission delay in the system. Moreover, simpler condition is provided for the special case where the second-order model is reduced to a double integrator. Simulation results are presented to illustrate the merits of the proposed scheme compared to some recent rival ones in the literature

Tyre-road adherence conditions estimation for intelligent vehicle safety applications

It is well recognized in the automotive research community that knowledge of the real-time tyre-road friction conditions can be extremely valuable for intelligent safety applications, including design of braking, traction, and stability control systems. This paper presents a new development of an on-line tyre-road adherence estimation methodology and its implementation using both Burckhardt and LuGre tyre-road friction models. The proposed strategy first employs the recursive least squares to identify the linear parameterization (LP) form of Burckhardt model. The identified parameters provide through a Takagi-Sugeno (T-S) fuzzy system the initial values for the LuGre model. Then, it is presented a new large-scale optimization based estimation algorithm using the steady state solution of the partial differential equation (PDE) form of LuGre to obtain its parameters. Finally, real-time simulations in various conditions are provided to demonstrate the efficacy of the algorithm

An improved Η∞ approach for networked control systems with transmission delays and packet dropout

This paper is concerned with the H infinity controller design for robust stabilization of networked control systems with the network-induced delay, data packet dropout and norm-bounded parameter uncertainties. In order to obtain less conservative results, a new augmented Lyapunov-Krasovskii functional is used and novel free-weighting matrices are employed to make some extra degree of freedom in the H infinity design conditions. The feedback gain of a memoryless controller, maximum allowable delay bound and minimum disturbance attenuation level can be derived by solving a set of linear matrix inequalities (LMIs). The advantages of the proposed method are demonstrated by numerical example

A less conservative criterion for stability analysis of linear systems with time-varying delay

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A new approach to design switching strategy for the buck converters

In this paper, a novel method is developed to control switched DC-DC Buck converters. The circuit dynamic is described as an affine linear switched system. Utilizing switched systems theory, a switching state-feedback law is derived to asymptotically stabilize the desired equilibrium point and also minimize a guaranteed cost. The efficiency of the proposed method is illustrated by simulation which verifies the improvement of the obtained results compared with the literatures