Vasumathi Raman

• PhD
• California Institute of Technology

In this paper, we consider the problem of learning Boolean formulae from examples obtained by actively querying an oracle that can label these examples as either positive or negative. This problem has received attention in both machine learning as well as formal methods communities, and it has been shown to have exponential worst-case complexity in...

Robot control for tasks such as moving around obstacles or grasping objects has advanced significantly in the last few decades. However, controlling robots to perform complex tasks is still accomplished largely by highly trained programmers in a manual, time-consuming, and error-prone process that is typically validated only through extensive testi...

In the near future mobile robots, such as personal robots or mobile manipulators, will share the workspace with other robots and humans. We present a method for mission and motion planning that applies to small teams of robots performing a task in an environment with moving obstacles, such as humans. Given a mission specification written in linear...

Autonomous vehicles have found wide-ranging adoption in aerospace, terrestrial as well as marine use. These systems often operate in uncertain environments and in the presence of noisy sensors, and use machine learning and statistical sensor fusion algorithms to form an internal model of the world that is inherently probabilistic. Autonomous vehicl...

We consider the problem of privacy enforcement for dynamic systems using the technique of obfuscation. Our approach captures the trade-off between privacy and utility, in a formal reactive framework. Specifically, we model a dynamic system as an automaton or labeled transition system with predefined secret behaviors. The system generates event stri...

This paper describes a holistic method for automatically synthesizing controllers for a team of robots operating in an environment shared with other agents. The proposed approach builds on recent advances in Reactive Mission Planning using Linear Temporal Logic, and Local Motion Planning using convex optimization. A local planner enforces the dynam...

Motivated by the synthesis of controllers from high-level temporal specifications, we present two algorithms to compute dominant strategies for continuous two-player zero-sum games based on the Counter-Example Guided Inductive Synthesis (CEGIS) paradigm. In CEGIS, we iteratively propose candidate dominant strategies and find counterexamples. For sc...

As a city becomes smarter, the integrated networks of engineered cyber and physical elements provide the capability to greatly improve the quality of life of its citizens. In order to leverage these capabilities to benefit all classes of society, we propose a framework that balances the supply and demand of available resources while maximizing the...

This paper describes a holistic method for automatically synthesizing controllers for a team of robots operating in an environment shared with other agents. The proposed approach builds on recent advances in Reactive Mission Planning using Linear Temporal Logic, and Local Motion Planning using convex optimization. A local planner enforces the dynam...

We address the problem of synthesizing reactive controllers for cyber-physical systems subject to Signal Temporal Logic (STL) specifications in the presence of adversarial inputs. Given a finite horizon, we define a reactive hierarchy of control problems that differ in the degree of information available to the system about the adversary's actions...

In this paper, we consider the problem of learning Boolean formulae from examples obtained by actively querying an oracle that can label these examplesz as either positive or negative. This problem has received attention in both machine learning as well as formal methods communities, and it has been shown to have exponential worst-case complexity i...

We present a mathematical programming-based method for model predictive control of cyber-physical systems subject to signal temporal logic (STL) specifications. We describe the use of STL to specify a wide range of properties of these systems, including safety, response and bounded liveness. For synthesis, we encode STL specifications as mixed inte...

Cyber-physical systems are often hybrid consisting of both discrete and continuous subsystems. The continuous dynamics in cyber-physical systems could be noisy and the environment in which these stochastic hybrid systems operate can also be uncertain. We focus on multimodal hybrid systems in which the switching from one mode to another is determine...

Applying reactive synthesis in practice often requires modifications of the synthesis algorithm in order to obtain useful implementations. We present slugs, a generalized reactivity(1) synthesis tool that has a powerful plugin architecture for modifying any aspect of the synthesis process to fit the application. Slugs comes pre-equipped with a vari...

Autonomous vehicles have found wide-ranging adoption in aerospace, terrestrial as well as marine use. These systems often operate in uncertain environments and in the presence of noisy sensors, and use machine learning and statistical sensor fusion algorithms to form an internal model of the world that is inherently probabilistic. Autonomous vehicl...

We consider the problem of synthesizing an obfuscation policy that enforces privacy while preserving utility with formal guarantees. Specifically, we consider plants modeled as finite automata with pre-defined secret behaviors. A given plant generates event strings for some useful computation, but meanwhile wants to hide its secret behaviors from a...

We address the problem of diagnosing and repairing specifications for hybrid systems, formalized in signal temporal logic (STL). Our focus is on automatic synthesis of controllers from specifications using model predictive control. We build on recent approaches that reduce the controller synthesis problem to solving one or more mixed integer linear...

We address the problem of diagnosing and repairing specifications for hybrid systems formalized in signal temporal logic (STL). Our focus is on the setting of automatic synthesis of controllers in a model predictive control (MPC) framework. We build on recent approaches that reduce the controller synthesis problem to solving one or more mixed integ...

Most automated systems operate in uncertain or adversarial conditions, and have to be capable of reliably reacting to changes in the environment. The focus of this paper is on automatically synthesizing reactive controllers for cyber-physical systems subject to signal temporal logic (STL) specifications. We build on recent work that encodes STL spe...

This paper describes a holistic method for automatically synthesizing controllers for a team of robots operating in an environment shared with other agents. The proposed approach builds on recent advances in Reactive Mission Planning using Linear Temporal Logic, and Local Motion Planning using convex optimization. A local planner enforces the dynam...

Correct-by-construction synthesis of high-level reactive control relies on the use of formal methods to generate controllers with provable guarantees on their behavior. While this approach has been successfully applied to a wide range of systems and environments, it scales poorly. A receding horizon framework mitigates this computational blowup, by...

We present a new framework for reactive synthesis that considers the dynamics of the robot when synthesizing correct-by-construction controllers for nonlinear systems. Many high-level synthesis approaches employ discrete abstractions to reason about the dynamics of the continuous system in a simplified manner. Often, these abstractions are expensiv...

The use of formal methods for synthesis has recently enabled the automated construction of verifiable high-level robot control. Most approaches use a discrete abstraction of the underlying continuous domain, and make assumptions about the physical execution of actions given a discrete implementation; examples include when actions will complete rela...

We present a counterexample-guided inductive synthesis approach to controller synthesis for cyber-physical systems sub- ject to signal temporal logic (STL) specifications, operating in potentially adversarial nondeterministic environments. We encode STL specifications as mixed integer-linear constraints on the variables of a discrete-time model of...

Temporal logics have proven effective for correct-by-construction synthesis of controllers for a wide range of applications. Receding horizon frameworks mitigate the computational intractability of reactive synthesis for temporal logic, but have thus far been limited by pursuing a single sequence of short horizon problems to the current goal. We pr...

We present a mathematical programming-based method for model predictive control of discrete-time cyber-physical systems subject to signal temporal logic (STL) speci-fications. We describe the use of STL to specify a wide range of properties of these systems, including safety, response and bounded liveness. For synthesis, we encode STL specification...

Energy-efficient control mechanisms are necessary to manage the ever increasing energy demand. Recently several tools for building energy consumption control have been proposed for small (e.g. homes) [8] and large (e.g. offices) buildings [3][6][1]. The mechanism each tool uses is different, e.g. HVAC control [3] and appliance rescheduling [8], but...

With the increasing ubiquity of multi-capable, general-purpose robots arises the need for enabling non-expert users to command these robots to perform complex high-level tasks. To this end, high-level robot control has seen the application of formal methods to automatically synthesize correct-by-construction controllers from user-defined specificat...

Reactive synthesis deals with the automated construction of implementations of reactive systems from their specifications. To make the approach feasible in practice, systems engineers need effective and efficient means of debugging these specifications. In this paper, we provide techniques for report-based specification debugging, wherein salient p...

This paper addresses the problem of designing control schemes for teams of robots engaged in complex highlevel tasks. It presents a method for automatically creating hybrid controllers that ensure that a team of possibly heterogeneous robots satisfies a user-defined high-level task. The proposed approach relaxes constraints on the simultaneous and...

This paper describes current work on framing the model predictive control (MPC) of cyber-physical systems as synthesis from signal temporal logic (STL) specifications. We provide a case study using a simplified power grid model with uncertain demand and generation; the model-predictive control problem here is that of the ancillary service power flo...

This paper presents an integrated system for generating, troubleshooting, and executing correct-by-construction controllers for autonomous robots using natural language input, allowing non-expert users to command robots to perform high-level tasks. This system unites the power of formal methods with the accessibility of natural language, providing...

High-level robot control has recently seen the application of formal methods to the automatic synthesis of correct-by-construction controllers from user-defined specifications. When a specification fails to yield a corresponding controller, existing techniques provide feedback on portions of the specification that cause the failure, but at a coarse...

Formal methods have recently been successfully applied to construct verifiable high-level robot control. Most approaches use a discrete abstraction of the underlying continuous domain, and make simplifying assumptions about the physical execution of actions given a discrete implementation. Relaxing these assumptions unearths a number of challenges...

A key challenge in robotics is the generation of controllers for autonomous, high-level robot behaviors comprising nontrivial sequences of actions, including reactive and repeated tasks. When constructing controllers to fulfill such tasks, it is often not known a priori whether the intended behavior is even feasible; plans are modified on the fly t...

This paper addresses the challenge of creating correct-by-construction controllers for robots whose actions are of varying execution durations. Recently, Linear Temporal Logic synthesis has been used to construct robot controllers for performing high-level tasks. During continuous execution of these controllers by a physical robot, one or more low-...

This paper addresses the challenge of incorporating event memory into the automatic synthesis of hybrid controllers for high-level reactive robot behavior. The goal is to provide a natural, concise grammar for specifying high-level tasks that require remembering past events, and to ensure that the required memory is correctly updated during control...

One of the main challenges in robotics is the generation of controllers for autonomous, high-level robot behaviors comprising a non-trivial sequence of actions. Recently, formal methods have emerged as a powerful tool for automatically generating autonomous robot controllers that guarantee desired behaviors expressed by a class of temporal logic sp...

The Linear Temporal Logic MissiOn Planning (LTLMoP) toolkit is a software package designed to generate a controller that guarantees a robot satisfies a task specification written by the user in structured English. The controller can be implemented on either a simulated or physical robot. This video illustrates the use of LTLMoP to generate a correc...

This video shows a demonstration of a fully autonomous robot, an iRobot ATRV-JR, which can be given commands using natural language. Users type commands to the robot on a tablet computer, which are then parsed and processed using semantic analysis. This information is used to build a plan representing the high level autonomous behaviors the robot s...

While highly constrained language can be used for robot control, robots that can operate as fully au-tonomous subordinate agents communicating via rich language remain an open challenge. Toward this end, we developed an autonomous system that supports nat-ural, continuous interaction with the operator through language before, during, and after miss...

Recent work in robotics has applied formal verification tools to automatically generate correct-by-construction controllers for autonomous robots. However, when it is not possible to create such a controller, these approaches do not provide the user with feedback on the source of failure, making the experience of debugging a specification somewhat...

Halpern, Moses and Tuttle presented a definition of interactive proofs using a notion they called practical knowledge, but left open the question of finding an epistemic formula that completely characterizes zero knowledge; that is, a formula that holds iff a proof is zero knowledge. We present such a formula, and show that it does characterize zer...