scispace - formally typeset
Search or ask a question
Author

Pei-Hsin Ho

Other affiliations: Cornell University, Intel
Bio: Pei-Hsin Ho is an academic researcher from Synopsys. The author has contributed to research in topics: Model checking & Hybrid system. The author has an hindex of 28, co-authored 48 publications receiving 6233 citations. Previous affiliations of Pei-Hsin Ho include Cornell University & Intel.

Papers
More filters
Book ChapterDOI
01 Jan 1993
TL;DR: This work presents two semidecision procedures for verifying safety properties of piecewiselinear hybrid automata, in which all variables change at constant rates, and demonstrates that for many of the typical workshop examples, the procedures do terminate and thus provide an automatic way for verifying their properties.
Abstract: We introduce the framework of hybrid automata as a model and specification language for hybrid systems. Hybrid automata can be viewed as a generalization of timed automata, in which the behavior of variables is governed in each state by a set of differential equations. We show that many of the examples considered in the workshop can be defined by hybrid automata. While the reachability problem is undecidable even for very restricted classes of hybrid automata, we present two semidecision procedures for verifying safety properties of piecewiselinear hybrid automata, in which all variables change at constant rates. The two procedures are based, respectively, on minimizing and computing fixpoints on generally infinite state spaces. We show that if the procedures terminate, then they give correct answers. We then demonstrate that for many of the typical workshop examples, the procedures do terminate and thus provide an automatic way for verifying their properties.

1,260 citations

Journal ArticleDOI
TL;DR: HyTech is a symbolic model checker for linear hybrid automata, a subclass of hybrids that can be analyzed automatically by computing with polyhedral state sets that combines automaton transitions for capturing discrete change with differential equations for capturing continuous change.
Abstract: A hybrid system consists of a collection of digital programs that interact with each other and with an analog environment. Examples of hybrid systems include medical equipment, manufacturing controllers, automotive controllers, and robots. The formal analysis of the mixed digital-analog nature of these systems requires a model that incorporates the discrete behavior of computer programs with the continuous behavior of environment variables, such as temperature and pressure. Hybrid automata capture both types of behavior by combining finite automata with differential inclusions (i.e. differential inequalities). HyTech is a symbolic model checker for linear hybrid automata, an expressive, yet automatically analyzable, subclass of hybrid automata. A key feature of HyTech is its ability to perform parametric analysis, i.e. to determine the values of design parameters for which a linear hybrid automaton satisfies a temporal requirement.

1,092 citations

Journal ArticleDOI
TL;DR: The model-checking procedure and the implementation of the verification procedure-implemented in the Cornell Hybrid Technology tool, HyTech-applies to hybrid automata whose continuous dynamics is governed by linear constraints on the variables and their derivatives.
Abstract: Presents a model-checking procedure and its implementation for the automatic verification of embedded systems. The system components are described as hybrid automata-communicating machines with finite control and real-valued variables that represent continuous environment parameters such as time, pressure and temperature. The system requirements are specified in a temporal logic with stop-watches, and verified by symbolic fixpoint computation. The verification procedure-implemented in the Cornell Hybrid Technology tool, HyTech-applies to hybrid automata whose continuous dynamics is governed by linear constraints on the variables and their derivatives. We illustrate the method and the tool by checking safety, liveness, time-bounded and duration requirements of digital controllers, schedulers and distributed algorithms.

483 citations

Proceedings ArticleDOI
01 Dec 1993
TL;DR: A model checking procedure and its implementation for the automatic verification of embedded systems, used to prove digital controllers and distributed algorithms correct in hybrid automata systems.
Abstract: We present a model checking procedure and its implementation for the automatic verification of embedded systems. Systems are represented by hybrid automata - machines with finite control and real-valued variables modeling continuous environment parameters such as time, pressure, and temperature. System properties are specified in a real-time temporal logic and verified by symbolic computation. The verification procedure, implemented in Mathematica, is used to prove digital controllers and distributed algorithms correct. The verifier checks safety, liveness, time-bounded, and duration properties of hybrid automata. >

441 citations

Book ChapterDOI
22 Jun 1997
TL;DR: HyTech is a symbolic model checker for linear hybrid automata, an expressive, yet automatically analyzable, subclass of hybrids, and a key feature of HyTech is its ability to perform parametric analysis, i.e. to determine the values of design parameters for which alinear hybrid automaton satisfies a temporal requirement.
Abstract: A hybrid system consists of a collection of digital programs that interact with each other and with an analog environment. Examples of hybrid systems include medical equipment, manufacturing controllers, automotive controllers, and robots. The formal analysis of the mixed digital-analog nature of these systems requires a model that incorporates the discrete behavior of computer programs with the continuous behavior of environment variables, such as temperature and pressure. Hybrid automata capture both types of behavior by combining finite automata with differential inclusions (i.e. differential inequalities). HyTech is a symbolic model checker for linear hybrid automata, an expressive, yet automatically analyzable, subclass of hybrid automata. A key feature of HyTech is its ability to perform parametric analysis, i.e. to determine the values of design parameters for which a linear hybrid automaton satisfies a temporal requirement.

407 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: A detailed user guide is given which describes how to use the various tools of Uppaal version 2.02 to construct abstract models of a real-time system, to simulate its dynamical behavior, to specify and verify its safety and bounded liveness properties in terms of its model.
Abstract: This paper presents the overal structure, the design criteria, and the main features of the tool box Uppaal. It gives a detailed user guide which describes how to use the various tools of Uppaal version 2.02 to construct abstract models of a real-time system, to simulate its dynamical behavior, to specify and verify its safety and bounded liveness properties in terms of its model. In addition, the paper also provides a short review on case-studies where Uppaal is applied, as well as references to its theoretical foundation.

2,358 citations

Journal ArticleDOI
TL;DR: A general framework for the formal specification and algorithmic analysis of hybrid systems is presented, which considers symbolic model-checking and minimization procedures that are based on the reachability analysis of an infinite state space.

2,091 citations

Proceedings ArticleDOI
27 Jul 1996
TL;DR: The goal is to demonstrate that concepts from the theory of discrete concurrent systems can give insights into partly continuous systems, and that methods for the verification of finite-state systems can be used to analyze certain systems with uncountable state spaces.
Abstract: We summarize several recent results about hybrid automata. Our goal is to demonstrate that concepts from the theory of discrete concurrent systems can give insights into partly continuous systems, and that methods for the verification of finite-state systems can be used to analyze certain systems with uncountable state spaces.

1,900 citations

Journal ArticleDOI
01 Jul 2000
TL;DR: In this paper, the authors introduce the concept of hybrid systems and some of the challenges associated with the stability of such systems, including the issues of guaranteeing stability of switched stable systems and finding conditions for the existence of switched controllers for stabilizing switched unstable systems.
Abstract: This paper introduces the concept of a hybrid system and some of the challenges associated with the stability of such systems, including the issues of guaranteeing stability of switched stable systems and finding conditions for the existence of switched controllers for stabilizing switched unstable systems. In this endeavour, this paper surveys the major results in the (Lyapunov) stability of finite-dimensional hybrid systems and then discusses the stronger, more specialized results of switched linear (stable and unstable) systems. A section detailing how some of the results can be formulated as linear matrix inequalities is given. Stability analyses on the regulation of the angle of attack of an aircraft and on the PI control of a vehicle with an automatic transmission are given. Other examples are included to illustrate various results in this paper.

1,647 citations

Book ChapterDOI
22 Jun 1997
TL;DR: This paper proposes a method for the automatic construction of an abstract state graph of an arbitrary system using the Pvs theorem prover.
Abstract: In this paper, we propose a method for the automatic construction of an abstract state graph of an arbitrary system using the Pvs theorem prover.

1,647 citations