TY - CONF AB - Hybrid systems model discrete programs that are embedded in continuous environments. Model-checking tools are available for the analysis of linear hybrid systems, whose continuous variables are bounded by piecewise-linear trajectories. Most embedded programs, however, operate in nonlinear environments. We present, analyze, and apply two algorithms for translating nonlinear hybrid systems into linear hybrid systems. The clock translation replaces nonlinear variables by clock variables; the rate translation approximates nonlinear variables by piecewise-linear envelopes. Both translations are sound for reachability; that is, if we establish a safety property of the translated linear system, we may conclude that the original nonlinear system satisfies the property. The clock translation is also complete for reachability; that is, the original system and the translated system satisfy the same safety properties. The two translations apply to incomparable classes of nonlinear hybrid systems. From the clock translation we obtain a new decidability result for hybrid systems. With the help of Hytech, a symbolic model checker for linear hybrid systems, we automatically verify a nonlinear railroad gate control program using the clock translation, and a nonlinear temperature control program using the rate translation. AU - Henzinger, Thomas A AU - Ho, Pei ID - 4450 SN - 9783540494133 T2 - 7th International Conference on Computer Aided Verification TI - Algorithmic analysis of nonlinear hybrid systems VL - 939 ER - TY - CONF AB - We report on several abstract interpretation strategies that are designed to improve the performance of HyTech, a symbolic model checker for linear hybrid systems. We (1) simultaneously compute the target region from different directions, (2) conservatively approximate the target region by dropping constraints, and (3) iteratively refine the approximation until sufficient precision is obtained. We consider the standard abstract convex-hull operator and a novel abstract extrapolation operator. AU - Henzinger, Thomas A AU - Ho, Pei ED - Panos, Antsaklis ED - Kohn, Wolf ED - Nerode, Anil ED - Sastry, Shankar ID - 4448 SN - 9783540604723 T2 - 3rd International Hybrid Systems Workshop TI - A note on abstract-interpretation strategies for hybrid automata VL - 999 ER - TY - CONF AB - This paper is addressed to potential users of HyTech, the Cornell Hybrid Technology Tool, an automatic tool for analyzing hybrid systems. We review the formal technologies that have been incorporated into HyTech, and we illustrate the use of HyTech with three nontrivial case studies. AU - Henzinger, Thomas A AU - Ho, Pei ED - Panos, Antsaklis ED - Kohn, Wolf ED - Nerode, Anil ED - Sastry, Shankar ID - 4447 SN - 9783540683346 T2 - 4th International Hybrid Systems Workshop TI - HyTech: The Cornell Hybrid Technology Tool VL - 999 ER - TY - CONF AB - HyTech is a tool for the automated analysis of embedded systems. This document, designed for the first-time user of HyTech, guides the reader through the underlying system model, and through the input language for describing and analyzing systems. The guide gives several examples of usage, and some hints for gaining maximal computational efficiency from the tool. The version of HyTech described in this guide was released in August 1995, and is available through anonymous ftp from ftp.cs.cornell.edu in the directory pub/tah/HyTech, and through the World-Wide Web via HyTech's home page http:/www.cs.cornell.edu/Info/People/tah/hytech.html. AU - Henzinger, Thomas A AU - Ho, Pei AU - Wong Toi, Howard ID - 4497 SN - 9783540606307 T2 - 1st International Workshop on Tools and Algorithms for the Construction and Analysis of Systems TI - A user guide to HyTech VL - 1019 ER - TY - CONF AB - We describe a new implementation of HYTECH, a symbolic model checker for hybrid systems. Given a parametric description of an embedded system as a collection of communicating automata, HYTECH automatically computes the conditions on the parameters under which the system satisfies its safety and timing requirements. While the original HYTECH prototype was based on the symbolic algebra tool Mathematica, the new implementation is written in C++ and builds on geometric algorithms instead of formula manipulation. The new HYTECH offers a cleaner and more expressive input language, greater portability, superior performance (typically two to three orders of magnitude), and new features such as diagnostic error-trace generation. We illustrate the effectiveness of the new implementation by applying HYTECH to the automatic parametric analysis of the generic railroad crossing benchmark problem and to an active structure control algorithm AU - Henzinger, Thomas A AU - Ho, Pei AU - Wong Toi, Howard ID - 4499 SN - 0818673370 T2 - Proceedings 16th IEEE Real-Time Systems Symposium TI - HyTech: The next generation ER -