We study the decentralized control of discrete-event systems withmultiplelocal specifications. Only a subset of events occur at a local site, and a local specification as well as control/observation capabilities of a local supervisor are defined with respect to such local events. The goal of control is to ensure that the executed behavior at each local site is as desired, i.e., there are multiple specifications, one for each site. We show that the control problem for multiple local specifications is different from that of a single global specification, and present a necessary and sufficient condition for the existence of decentralized supervisors for enforcing the given multiple local specifications. The synthesis of decentralized control for enforcing multiple local specifications is also presented. We also specialize our results to the case of concurrent plants (one which is composed of several local subplants), which offers certain computational savings. The results are illustrated through a simple manufacturing system example.

We introduce the notion ofsafe-codiagnosability, extending the notion of safe-diagnosability (Paoli and Lafortune, 2005) to the decentralized setting. For a system, a certain subbehavior is deemed safe (captured via a safety specification), and a further subbehavior is deemed nonfaulty (captured via a nonfault specification). Safe-codiagnosability requires that when the system executes a trace that is faulty, there exists at least one diagnoser that can detect this within bounded delay and also before the safety specification is violated. The above notion of safe-codiagnosability may also be viewed as an extension of the notion of codiagnosability (Qiu and Kumar, 2006), where the latter did not have any safety requirement. We show that safe-codiagnosability is equivalent to codiagnosability together with ldquozero-delay codiagnosabilityrdquo of ldquoboundary safe tracesrdquo. (A safe trace is a boundary safe trace if there exists a single-event extension that is unsafe.) We give an algorithm of polynomial complexity for verifying safe-codiagnosability. For a safe-codiagnosable system, the same methods as those proposed in (Qiu and Kumar, 2006) can be applied for offline synthesis of individual diagnosers, as well as for online diagnosis using them.

We study distributed failure diagnosis under a -bounded communication delay, where each local site transmits its observations to other sites immediately after each observation and the transmitted observation is received within at most more event executions of the plant. A notion of diagnosability is introduced so that any failure can be diagnosed within a bounded delay of its occurrence by one of the local sites using its own observations and the -bounded delayed observations received from other local sites. The local sites communicate among each other using an ldquoimmediate observation passing (iop)rdquo protocol, forwarding any observation immediately up on its occurrence. We construct models for the -bounded communication delay and use them to extend the system and nonfault specification models for capturing the effect of bounded-delay communication. By using the extended system and specification models, the distributed diagnosis problem under the immediate observation passing protocol is then converted to a decentralized diagnosis problem of our previous work, where the results are applied for verifying diagnosability and for synthesizing local diagnosers. Methods by which complexity of testing diagnosability and of online diagnosis can be reduced are presented. Finally, we compare the notions of diagnosability, codiagnosability, and diagnosability.

By decentralized diagnosis we mean diagnosis using multiple diagnosers, each possessing its own set of sensors, without involving any communication among diagnosers or to any coordinators. The notion of decentralized diagnosis is formalized by introducing the notion of codiagnosability that requires that a failure be detected by one of the diagnosers within a bounded delay. Algorithms of complexity polynomial in the size of the system and the nonfault specification are provided for: 1) testing codiagnosability, 2) computing the bound in delay of diagnosis, 3) offline synthesis of individual diagnosers, and 4) online diagnosis using them. The notion of codiagnosability and the above algorithms are initially presented in a setting of a specification language (violation of which represents a fault) and are later specialized to the case where faults are modeled as the occurrences of certain events. The notion of strong codiagnosability is also introduced to capture the ability of being certain about both the failure as well as the nonfailure conditions in a system within a bounded delay.

This paper addresses the calibration-free robotic eye-hand coordination in a way other than the conventional image Jacobian matrix approach that has been studied extensively in literature. A nonlinear mapping rather than the linear mapping used in the image Jacobian matrix between the image space and the robotic control space is proposed. This mapping is regarded as the system's unmodeled dynamics expressed in system state equations. An extended state observer is designed first to estimate the unmodeled dynamics as well as the external disturbance of the system. With the estimation results as the compensation, a system controller is designed based on the nonlinear state-error feedback control strategy. Convergence of the extended state observer as well as the overall controller for a typical eye-hand coordination system is proved. Compared with the conventional calibration-free robotic eye-hand coordination with a Jacobian matrix, the proposed controller is independent of specific tasks and system configurations. Thus, a general design procedure is proposed for the calibration-free robotic eye-hand coordination. Simulation and experiment results demonstrate the satisfactory performance and effectiveness of the proposed approach.

This paper proposes a standard method to approach the uncalibrated robotic hand-eye coordination problem that is system configuration- and task-independent. The unknown hand-eye relationship is first modeled as the modeling errors of a dynamic system. An extended state observer is then implemented to estimate summation of the system's modeling error and the system's external disturbances. With the estimation results as the compensation, the system control is accomplished from a nonlinear combination of the system state errors. A universal framework of controller design is provided for decoupled and coupled hand-eye systems of different configurations to execute dynamic tracking task.