Marina Waldén | Searcharxiv

arXiv2018

Online Fault Identification of Digital Hydraulic Valves Using a Combined Model-Based and Data-Driven Approach

Robustness and fault-tolerance are desirable properties for hydraulic working machines and field robots. In applications where service personnel do not have easy access to the machine, it is important that the machine can continue its operation despite single machinery faults. Digital hydraulics enables a design which is inherently fault-tolerant by having each hydraulic actuator controlled by a number of parallel on/off valves. The exact state operation of a digital hydraulic system enables model based diagnostics of the hydraulic components and the possibility to compensate for identified faults. This paper presents an approach for identifying faulty valves based on combination of pressure measurements made during the normal operation of the machine and a mathematical model describing the flow balance of the hydraulic system.

eess.SY↗

arXiv2011

Concurrent Scheduling of Event-B Models

Event-B is a refinement-based formal method that has been shown to be useful in developing concurrent and distributed programs. Large models can be decomposed into sub-models that can be refined semi-independently and executed in parallel. In this paper, we show how to introduce explicit control flow for the concurrent sub-models in the form of event schedules. We explore how schedules can be designed so that their application results in a correctness-preserving refinement step. For practical application, two patterns for schedule introduction are provided, together with their associated proof obligations. We demonstrate our method by applying it on the dining philosophers problem.

cs.LO↗