Simulation of Hybrid Circuits in Constraint Logic Programming

This paper presents LOGISIM, a CAD tool to simulate the temporal behaviour of hybrid circuits containing electro-mechanical, electrohydraulic, hydro-mechanic, and digital control devices. LOGISIM combines the advantages of both qualitative and quantitative reasoning by producing a high-level description (discrete states) of the circuit behaviour while reasoning at the quantitative level (physical values). In addition, device models in LOGISIM follow a particular description methodology proposed to avoid introducing an artificial computational complexity in the simulation. LOGISIM is fully implemented in the constraint logic programming language CHIP. The constraint-solving techniques of CHIP used in LOGISIM, i.e. an incremental decision procedure for linear constraints over rational numbers, consistency techniques on domain-variables and conditional propagation, are all necessary to solve the problem efficiently. LOGISIM has been applied successfully to real-life industrial circuits from aerospace industry in the ELSA project and clearly demonstrates the potential of this kind of tool to support the design process for these circuits.