September 30, 2019Benoit Barbot (LACL - UPEC)
This work is concerned with validation of cyber-physical systems (CPS) via simulation based on sampling of the input signal space. Such a space is infinite and in general too difficult to treat symbolically meaning that the only reasonable option is to sample a finite subset of it and simulate the corresponding system behaviours. It is thus of great interest to choose a finite sample so that it best “covers” the whole space of input signals. We use timed automata to model temporal constraints, in order to avoid spurious bugs coming from unrealistic inputs and this can also reduce the input space to explore. We propose a method for low discrepancy generation of signals with temporal constraints recognised by timed automata. The discrepancy notion reflects how uniform the input signal space is sampled and additionally allows deriving validation and performance guarantees. We also show how this notion can be used to measure the discrepancy of a given set of input signals. We describe a prototype tool chain and demonstrate the proposed methods on a Kinetic Battery Model (KiBaM) and a Sigma Delta modulator.