Supervisor Synthesis for Networked Discrete Event Systems With Communication Delays and Lossy Channels

Online State Estimation for Supervisor Synthesis in Discrete-Event Systems with Communication Delays and Losses

“…As in [17], [21], [23], this paper assumes that i) both the control channel and the observation channel satisfy first-infirst-out (FIFO); ii) the observation delays and the control delays are upper bounded by N o and N c event occurrences (observable or not), respectively; iii) the numbers of consecutive observation losses and consecutive control losses are no larger than N l,o and N l,c , respectively. This paper answers the following two questions.…”

“…Besides, since the communication losses are usual small, we also assume that both the consecutive observation losses and the consecutive control losses are with upper bounds. The same assumption can be found in [21]. Meanwhile, the delays are measured by the number of event occurrences (observable or not).…”

Supervisor Synthesis for Networked Discrete Event Systems with Delays against Non-FIFO Communication Channels

“…For each σ ∈ Σ o , each 0 ≤ i ≤ num o and each k ≥ 0, let ((m σ , i), k) denote the multi-set that consists of k copies of (m σ , i). We define |((m σ , i), k)| = k, obs ∪Σ out obs ∪{tick})×Q obs can be defined, in a way that is similar to the partial transition function of [16] for FIFO observation channels. The observation channel automaton is then given by G obs = (Q obs , Σ in obs ∪ Σ out obs ∪ {tick}, δ obs , q {} ), where q {} ∈ Q obs is the initial state that corresponds to the empty observation channel.…”

“…be formulated and fit into the generalized framework for networked systems. The synthesis problem under FIFO assumption of the communication channels has been discussed in [16]; Finally, it can be extended to other control architectures naturally, e.g., distributed, hierarchical and decentralized networked supervisory control.…”

“…Consequently, the definitions of networked controllability and networked observability are reduced to standard definitions of controllability and observability [15]. Compared with [16], in this paper we assume non-FIFO communication channels instead of FIFO communication channels and will only consider network delays while ignoring communication losses. In reality, many communication networks allow messages to overtake each other, making it possible that events are not necessarily observed in the same order as they take place in the plant.…”