Adaptive Delta Modulation in Networked Controlled Systems With bounded Disturbances (original) (raw)
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Adaptive Delta-modulation Coding for Networked Controlled Systems
2007 American Control Conference, 2007
This paper investigates the closed-loop properties of the differential coding scheme known as Delta-Modulation (∆-M ) when used in feedback loops within the context of linear systems controlled through some communication network. We propose a new modified scheme of the original form of the ∆-M algorithm which improves the closed-loop properties. Semiglobal stability with convergence to a finite ball is proved in this framework, where the domain of attraction may be arbitrarily enlarged by tuning a quantization factor ∆, in tradeoff with the precision at steady state. In a further step, parameter ∆ is made adaptive, by defining an adaptation law exclusively in terms of information available at both the transmitter and receiver. With this approach, global asymptotic Stability of the Networked Controlled System is achieved for a class of unstable plants.
Differential coding in networked controlled linear systems
2006 American Control Conference, 2006
This paper investigates the closed-loop properties of the differential coding scheme known as Delta-Modulation (Δ-M ) when used in feedback loops within the context of linear systems controlled through some communication network. We propose a new modified scheme of the original form of the Δ-M algorithm which improves the closed-loop properties. The new coding structure explicitly uses information from the system model. Stability properties for both: the continuoustime and the discrete-time version of this new algorithm are assessed. The results shows that the stability domain and the resulting precision of the Δ-M is limited by the position of the unstable poles of the system. Index Terms-Differential coding, delta modulation, stabilization of linear systems in Networked controlled systems.
Delta-Modulator-Based Quantised Output Feedback Controller for Linear Networked Control Systems
IEEE Access
This article proposes a-Modulator (-M) based quantised output feedback controller for linear networked systems. The proposed-M is essentially a 2-level quantiser, in contrast to some of the existing quantisers such as 2 p level (p ≥ 1) uniform-interval-nearest-neighbour quantiser, and offers various advantages which include lower design complexity, less noisy and lower cost. The three key components of the control system: the controller, the filter and the quantiser are designed to achieve the desired performance. The stability conditions of theM are derived and conditions for the existence of zigzag behaviour in steady-state are determined. The performance of the proposed controller is illustrated through simulations considering practical communication network based on ZigBee protocol. The results of the simulation demonstrate that the proposed controller could effectively achieve desired performance under various imperfections of the practical communication network. INDEX TERMS-modulation, quantised control, networked control systems (NCSs), output feedback control.
Delta modulation for multivariable centralized linear networked controlled systems
This paper investigates the closed-loop properties of multivariable (MIMO 1) linear systems where the sensed information is centralized and coded on the basis of a ∆-modulation algorithm often used for minimizing the numbers of transmitted bits. In particular we propose a new centralized vector coding algorithm that allows us to extend our previous results in [4] to any type of linear multivariable systems. In addition, we provide an estimation of the stability attraction domain, and we give some simulation results validating the proposed approach.
Gain-scheduling multi-bit Delta-Modulator for Networked Controlled System
2007 European Control Conference, 2007
We analyze in this paper stabilization issues for a Networked Control System that uses a Delta-Modulator Scheme within the encoder/decoder structures. We also analyze the packet-loss issue, and determine a maximum allowable number of consecutive bits lost while keeping closed-loop stability. We then design a compensation scheme for re-synchronizing the encoder and decoder, after a bit is lost in a network without acknowledgment signals. We finally present a compensation scheme that ensures stability after a pre-determined number of bits is lost. Examples and simulations are provided to demonstrate the results.
Quantized output feedback control for networked control systems
Information Sciences, 2008
The problem of the quantized dynamic output feedback controller design for networked control systems is mainly discussed. By using the quantized information of the system measurement output and the control input, a novel networked control system model is described. This model includes many networkinduced features, such as multi-rate sampled-data, quantized signal, time-varying delay and packet dropout. By constructing suitable Lyapunov-Krasovskii functional, a less conservative stabilization criterion is established in terms of linear matrix inequalities. The quantized control strategy involves the updating values of the quantizer parameters µ i (i = 1, 2)(µ i take on countable sets of values which dependent on the information of the system measurement outputs and the control inputs). Furthermore, a numerical example is given to illustrate the effectiveness of the proposed method.
Corresponding Author: Adaptive Control of Networked Systems in the Presence of Bounded Disturbances
Journal of Computer Science, 2007
The insertion of data network in the feedback adaptive control loops makes the analysis and design of networked control systems more complex than traditional control systems. This paper addresses the adaptive stabilization problem of linear time-invariant networked control systems when the measurements of the plant states are corrupted by bounded disturbances. The case of state feedback is treated in which only an upper bound on the norm of matrix A is needed. The problem is to find an upper bound on the transmission period h that guarantees the stability of the overall adaptive networked control system under an ideal transmission process, i.e. no transmission delay or packet dropout. Rigorous mathematical proofs are established, that relies heavily on Lyapunov's stability criterion and dead-zone Technique. Simulation results are given to illustrate the efficacy of our design approach.
Robust H∞output feedback control of networked control systems with dynamic quantizers
2011
Quantization effects are inevitable in networked control systems (NCSs). These quantization effects can be reduced by increasing the number of quantization levels. However, increasing the number of quantization levels may lead to network congestion, (i.e., the network needs to transfer more information than its capacity). In this paper, we investigate the problem of designing a robust H∞output feedback controller for discrete-time networked systems with an adaptive quantization density or limited information. More precisely, the quantization density is designed to be a function of the network load condition which is modeled by a Markov process. A stability criterion is developed by using Lyapunov-Krasovskii functional and sufficient conditions for the existence of a dynamic quantized output feedback controller are given in terms of Bilinear Matrix Inequalities(BMIs). An iterative algorithm is suggested to obtain quasi-convex Linear Matrix Inequalities (LMIs) from BMIs. An example is presented to illustrate the effectiveness of the proposed design.
Robust H∞ output feedback control of networked control systems with multiple quantizers
Journal of the Franklin Institute, 2012
This paper studies the robust H ∞ control problem of networked linear time-delay systems with discrete distributed delays, involving random packet dropout and quantization. Assume that the measured output of the networked time-delay system can be quantized by the logarithmic quantizer before being transmitted through the communication network. In addition, an appropriate compensation strategy is proposed to reduce the effect of the data packet dropout satisfying a Bernoulli distribution. To deal with the quantization issue, the sector bound method can be used to convert the quantized control problem of the networked system into the robust control problem with uncertainty. Then, a novel observer-based H ∞ output feedback controller is designed to ensure that the networked system is exponentially mean-square stable and an expected H ∞ performance constraint is achieved. Finally, a simulation example is given to prove the effectiveness of the proposed design method. INDEX TERMS Networked control systems, discrete distributed delays, packet dropout, quantization. The associate editor coordinating the review of this manuscript and approving it for publication was Rongni Yang.
Journal of Systems Science and Complexity, 2011
This paper addresses a robust stabilization problem of a class of uncertain nonlinear systems using output measurements via a finite data-rate communication channel. The authors assumes that there exist an observer and a control law for the systems in the absence of any finite data-rate communication channel. Based on the observer and the control law, the authors constructs an encoder/decoder pair and provides a sufficient condition, including suitable sampling period and data rate, which will guarantee the stability of the closed-loop systems when a finite data-rate communication channel is introduced.