Design and Verification of a Distributed Communication Protocol

The safety of remotely operated vehicles depends on the correctness of the distributed protocol that facilitates the communication between the vehicle and the operator. A failure in this communication can result in catastrophic loss of the vehicle. To complicate matters, the communication system may be required to satisfy several, possibly conflicting, requirements. The design of protocols is typically an informal process based on successive iterations of a prototype implementation. Yet distributed protocols are notoriously difficult to get correct using such informal techniques. We present a formal specification of the design of a distributed protocol intended for use in a remotely operated vehicle, which is built from the composition of several simpler protocols. We demonstrate proof strategies that allow us to prove properties of each component protocol individually while ensuring that the property is preserved in the composition forming the entire system. Given that designs are likely to evolve as additional requirements emerge, we show how we have automated most of the repetitive proof steps to enable verification of rapidly changing designs

Formal verification of bond graph modelled analogue circuits

Analogue circuits are an increasingly critical component in embedded system designs. Traditionally, simulation is used for verification, but owing to the infinite state space of analogue components, the 100% correctness of a design cannot be guaranteed. Formal methods, based around applying mathematical expressions and reasoning to prove correctness, have been developed to increase the verification confidence level. This study introduces and demonstrates a methodology for formally verifying safety properties of analogue circuits. In the proposed approach, system equations are automatically extracted from a SPICE netlist by means of energy-conservative bond graph models. Verification based on abstract model checking and constraint solving is then applied on the extracted equation models. The authors methodology avoids an exhaustive and time demanding simulation that is normally encountered during analogue circuit verification. To this end, the authors have used a set of tools to implement the proposed verification flow and applied it on tunnel diode, Chua and Colpitts oscillators as case studies

Full-Scale Wind-Tunnel Investigation of Wing-Cooling Ducts Effects of Propeller Slipstream, Special Report

The safety of remotely operated vehicles depends on the correctness of the distributed protocol that facilitates the communication between the vehicle and the operator. A failure in this communication can result in catastrophic loss of the vehicle. To complicate matters, the communication system may be required to satisfy several, possibly conflicting, requirements. The design of protocols is typically an informal process based on successive iterations of a prototype implementation. Yet distributed protocols are notoriously difficult to get correct using such informal techniques. We present a formal specification of the design of a distributed protocol intended for use in a remotely operated vehicle, which is built from the composition of several simpler protocols. We demonstrate proof strategies that allow us to prove properties of each component protocol individually while ensuring that the property is preserved in the composition forming the entire system. Given that designs are likely to evolve as additional requirements emerge, we show how we have automated most of the repetitive proof steps to enable verification of rapidly changing designs

Using formal models to design user interfaces a case study

The use of formal models for user interface design can provide a number of benefits. It can help to ensure consistency across designs for multiple platforms, prove properties such as reachability and completeness and, perhaps most importantly, can help incorporate the user interface design process into a larger, formally-based, software development process. Often, descriptions of such models and examples are presented in isolation from real-world practice in order to focus on particular benefits, small focused examples or the general methodology. This paper presents a case study of developing the user interface to a new software application using a particular pair of formal models, presentation models and presentation interaction models. The aim of this study was to practically apply the use of formal models to the design process of a UI for a new software application. We wanted to determine how easy it would be to integrate such models into our usual development process and to find out what the benefits, and difficulties, of using such models were. We will show how we used the formal models within a user-centred design process, discuss what effect they had on this process and explain what benefits we perceived from their use

Verification of the FtCayuga fault-tolerant microprocessor system. Volume 1: A case study in theorem prover-based verification

The design and formal verification of a hardware system for a task that is an important component of a fault tolerant computer architecture for flight control systems is presented. The hardware system implements an algorithm for obtaining interactive consistancy (byzantine agreement) among four microprocessors as a special instruction on the processors. The property verified insures that an execution of the special instruction by the processors correctly accomplishes interactive consistency, provided certain preconditions hold. An assumption is made that the processors execute synchronously. For verification, the authors used a computer aided design hardware design verification tool, Spectool, and the theorem prover, Clio. A major contribution of the work is the demonstration of a significant fault tolerant hardware design that is mechanically verified by a theorem prover