Reconfiguration strategies for hybrid systems

Abstract

In this work we propose several algorithms to solve the reconfiguration problem for linear and hybrid particular, we consider the decision about the usage of redundant hardware in order to compensate for faults. While this problem can be translated into a constrained model predictive control framework, the computation' grows very fast, as the number of possible decisions increases. In this work we prohave components that need not to be used in order to meet nominal control specifications, but can be used in extraordinary situations. The redundancy is Often given by subsystems with similar functions, different parameters or alternative locations within the system toPoloW*The main contribution of this work is to propose several solutions for the decision problem about the choice of redundant hardware using mathematical pose schemes, that require low computational effort. We discuss the applicability of the methods considering the reconfiguration of the three tank benchmark system.Keywords: Hybrid Systems, Fault Tolerant Control, tools. We will refer to this decision simply as reconfiguration of the control scheme. T~ this purpose we are using the modeling formalism of Mixed Logic Dynamical (MLD) systems introduced in [5,4]. The equations describing an MLD system are - Reconfiguration, Model Predictive ControlMany control systems are subject to faults or malfunctions. The failure of components, like sensors or actuators can partially or fully disable the action of the controller. This results in an unsatisfactory performance of the system, decreased availability, emergency shutdowns or even significant damages to the plant and to its environment. For this reason, several research activities recently focused on the safety aspects of control systems [B, 61. One way to classify the different approaches is the distinction between passive and active fault accommodation [16]. In passive fault accommodation the closed loop system is designed, such that it is robust, within some performance range, to fault occurrences. On the other hand, active fault accommodation aims at changing the control operation when a fault is detected. These changes can comprise reconfiguration of the controller scheme, modifications of controller parameters or alternative setpoint trajectories. In this work we will focus on active fault accommodation. The key issue we are considering is the usage of redundant hardware for reconfiguration when some faults occur. The term hardware redundancy is used for systems where a replication of hardware components is present [16]. In other words, such systems leave from: NKK Corporation, Sensing & Control Research Department, Applied Technology Research Center 1-1; Minamiwatarida-cho; Kawasaki-ku Kawasaki-shi, 210-0855 JAPAN; Email: tsudamlab. keihin.nkk. C o . j pl}nc are the continuous and binary-states, U E Etmc x {O,l}mc are the inputs, 9 E RPc x {O,l}pc the outputs, and 6 E {O,l}Q, t E RrC represent auxiliary binary and continuous variables, respectively, 4 E { O , l } f t denote the occurrence of faults....

Semantically Enhanced Online Configuration of Feedback Control Schemes

“…The switching between control structures is either based on deterministic criteria or even follows a stochastic process [18]. This type of systems are a special case of "hybrid dynamical systems" that have been studied extensively in the literature [19], also in terms of their reconfiguration strategies for active fault accommodation [20].…”

“…The switching between control structures is either based on deterministic criteria or even follows a stochastic process [18]. This type of systems are a special case of "hybrid dynamical systems" that have been studied extensively in the literature [19], also in terms of their reconfiguration strategies for active fault accommodation [20].An essentially complementary approach from a different perspective, is the design of modular architectures. An early effort towards introducing the need for a modular architecture for the control system design and the concept of structuring the data exchanged based on their basic semantic description, has been discussed in [21].…”

Reconfigurable control of PWA systems with actuator and sensor faults: Stability

“…For switched systems, adaptive schemes [5] and output feedback controller redesign have been developed (see for example [6]). For PWA systems, model-predictive control has been used for fault-tolerant control [7]. This approach is based on the idea of keeping the nominal controller in the loop by inserting a reconfiguration block between the faulty plant and the nominal controller when a fault occurs.…”

Estimation of hybrid systems using discrete sensors

“…A TANK SYSTEM EXAMPLE A tank system example is used to demonstrate the state estimation approach. This example has been proposed as a benchmark for control reconfiguration in [4] and has been used for illustrating estimation, fault detection, and control reconfiguration methods for hybrid systems in [2], [13]. The system consists of two identical cylindrical tanks that are connected by a pipe at level h, as shown in figure 1.…”

“…For every mode, we have a set of ordinary differential equations and the system transitions between modes based on x as described by (13). Clearly, these transitions are autonomous since they depend on the continuous behavior of the system as described by the guard conditions.…”