John Baillieul

Information patterns and hedging brockett's theorem in controlling vehicle formations

Efforts to apply computer vision and various optical and acoustic proximity sensors for distribut... more Efforts to apply computer vision and various optical and acoustic proximity sensors for distributed/ coordinated motion control of a small group of autonomous vehicles has led us to consider a number of natural feedback control laws which utilize realtime measurements of relative distances between the vehicles. Unfortunately, none of the feedback laws satisfies Brockett's necessary conditions for asymptotic stabilization. They do appear to provide a basis for practical solutions to a number of interesting vehicle control problems, however. Part of the rationale for proposing feedback laws which are not asymptotically stabilizing is that in a number of cases of practical interest, one may show that the set of initial conditions which are not driven to the prescribed rest point is either small (in some sense) or uninteresting (in the problem context) or both. In some cases, one can also show that by choosing feedback gains in terms of the problem's initial conditionsusing say a table look-up-it is possible to steer from any given initial state into an arbitrarily small neighborhood of the desired goal state. The aim of the research here is to develop a large catalogue of simple controlled motions which in appropriate sequential combinations permit autonomous nonholonomic vehicles to assemble themselves and execute coordinated motions in highly structured formations.

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Perceptual Control with Large Feature and Actuator Networks

arXiv (Cornell University), Mar 25, 2019

This paper discusses elements of a control theory of systems comprised of networks of simple agen... more This paper discusses elements of a control theory of systems comprised of networks of simple agents that collectively achieve sensing and actuation goals despite having strictly limited capability when acting alone. The goal is to understand sensorimotor feedback control in which streams of data come from large arrays of sensors (e.g. photo-receptors in the eye) and actuation requires coordination of large numbers of actuators (e.g. motor neurons). The context for this work is set by consideration of a stylized problem of robot navigation that uses optical flow as sensed by two idealized and precise photoreceptors. A robust steering law in this setting establishes a foundation for exploiting optical flow based on averaged noisy inputs from large numbers of imprecise sensing elements. Taking inspiration from neurobiology, the challenges of actuator and sensor intermittency are discussed as are learning actuator coordination strategies. It is shown that there are advantages in having large numbers of control inputs and outputs. The results will be shown to make contact with ideas from control communication complexity and the standard parts problem.

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Sensor Based Control of Robotic Mechanisms

Approved for public release; distribution .t~U1 ~9Q 33 unlimited. UMEII5. MONiTQ N!r,.FGAP IZATIO... more Approved for public release; distribution .t~U1 ~9Q 33 unlimited. UMEII5. MONiTQ N!r,.FGAP IZATIONIEPCO~ JLmaeptsI A D-Pr226 784 OL 76. NAM7 OF MONITORING ORGANIZATION Collge f E gine rin, tIf' cap cable) Collgo ni neri ng \L/\E Air Force Office of Scientific Research 6c. ADDRESS fCi t ate and ZIP Coda, 7o ADOB ity.Saewd ZIP coal. I V C tDire'ciorate of Mathematical & Information -K ~kI Sciences, Boiling AFB DC 20332-6448 Be -4A ME OF rUNOING,SPONSORING b. OFFICE SYMBOL 9. PROCuRPEMENT INSTRUMENT I0ENT7PCAT.CN NLMBE Q ORGANIZATION 11f apphtesbil AFOSR INM AFOSR -89-0135 Be ADOOSS C~ty. Slate and ZIP Code) 10 SOURCE OP FUNDING NOS3 ~7L-~ ~PROGRAM PROJECT TASK WORK '..NT )~(X '~~'ELIEMINT NO. NO. NO.

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Visual Navigation Using Sparse Optical Flow and Time-to-Transit

2022 International Conference on Robotics and Automation (ICRA), May 23, 2022

Drawing inspiration from biology, we describe the way in which visual sensing with a monocular ca... more Drawing inspiration from biology, we describe the way in which visual sensing with a monocular camera can provide a reliable signal for navigation of mobile robots. The work takes inspiration from a classic paper by Lee and Reddish (Nature, 1981, ) in which they outline a behavioral strategy pursued by diving sea birds based on a visual cue called time-to-contact. A closely related concept of time-to-transit, τ , is defined below, and it is shown that idealized steering laws based on monocular camera perceptions of τ can reliably and robustly steer a mobile vehicle within a wide variety of spaces in which features perceived to lie on walls and other objects in the environment provide adequate visual cues. The contribution of the paper is two-fold. It provides a simple theory of robust vision-based steering control. It goes on to show how the theory guides the implementation of robust visual navigation using ROS-Gazebo simulations as well as deployment and experiments with a camera-equipped Jackal robot. As far as we know, the experiments described below are the first to demonstrate visual navigation based on τ .

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Data-rate requirements for nonlinear Feedback control

IFAC Proceedings Volumes, Sep 1, 2004

Abstract This paper and talk describe recent research on communication and information processing... more Abstract This paper and talk describe recent research on communication and information processing requirements for implementing nonlinear feedback control laws in applications such as the coordinated motion control of groups of mobile robots. The principal focus is on how the well-known data-rate theorem might be reformulated in the context of essentially nonlinear control problems.

The control theory of motion-based communication: Problems in teaching robots to dance

The paper describes results on two components of a research program focused on motion-based commu... more The paper describes results on two components of a research program focused on motion-based communication mediated by the dynamics of a control system. Specifically we are interested in how mobile agents engaged in a shared activity such as dance can use motion as a medium for transmitting certain types of messages. The first part of the paper adopts the terminology of motion description languages and deconstructs an elementary form of the well-known popular dance, Salsa, in terms of four motion primitives (dance steps). Several notions of dance complexity are introduced. We describe an experiment in which ten performances by an actual pair of dancers are evaluated by judges and then compared in terms of proposed complexity metrics. An energy metric is also defined. Values of this metric are obtained by summing the lengths of motion segments executed by wheeled robots replicating the movements of the human dancers in each of the ten dance performances. Of all the metrics that are considered in this experiment, energy is the most closely correlated with the human judges' assessments of performance quality. The second part of the paper poses a general class of dual objective motion control problems in which a primary objective (artistic execution of a dance step or efficient movement toward a specified terminal state) is combined with a communication objective. Solutions of varying degrees of explicitness can be given in several classes of problems of communicating through the dynamics of finite dimensional linear control systems. In this setting it is shown that the cost of adding a communication component to motions that steer a system between prescribed pairs of states is independent of those states. At the same time, the optimal encoding problem itself is shown to be a problem of packing geometric objects, and it remains open. Current research is aimed at solving such communication-through-action problems in the context of the motion control of mobile robots.

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1Optical Flow Sensing and the Inverse Perception Problem for Flying Bats

The movements of birds, bats, and other flying species are governed by complex sensorimotor syste... more The movements of birds, bats, and other flying species are governed by complex sensorimotor systems that allow the animals to react to stationary environmental features as well as to wind distur-bances, other animals in nearby airspace, and a wide variety of unexpected challenges. The paper and talk will describe research that analyzes the three-dimensional trajectories of bats flying in a habitat in Texas. The trajectories are computed with stereoscopic methods using data from synchronous thermal videos that were recorded with high temporal and spatial resolution from three viewpoints. Following our previously reported work, we examine the possibility that bat trajectories in this habitat are governed by optical flow sensing that interpolates periodic distance measurements from echolocation. Using an idealized geometry of bat eyes, we introduce the concept of time-to-transit, and recall some research that suggests that this quantity is computed by the animals ’ visual cortex. Sever...

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Perception and Steering Control in Paired

Abstract: Animals within groups need to coordinate their reactions to perceived environmental fea... more Abstract: Animals within groups need to coordinate their reactions to perceived environmental features and to each other in order to safely move from one point to another. This paper extends our previously published work on the flight patterns of Myotis velifer that have been observed in a habitat near Johnson City, Texas. Each evening, these bats emerge from a cave in sequences of small groups that typically contain no more than three or four individuals, and they thus provide ideal subjects for studying leader-follower behaviors. By analyzing the flight paths of a group of M. velifer, the data show that the flight behavior of a follower bat is influenced by the flight behavior of a leader bat in a way that is not well explained by existing pursuit laws, such as classical pursuit, constant bearing and motion camouflage. Thus we propose an alternative steering law based on virtual loom, a concept we introduce to capture the geometrical configuration of the leader-follower pair. It i...

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Perceptual Control with Large Feature and Actuator Networks

2019 IEEE 58th Conference on Decision and Control (CDC), 2019

This paper discusses elements of a control theory of systems comprised of networks of simple agen... more This paper discusses elements of a control theory of systems comprised of networks of simple agents that collectively achieve sensing and actuation goals despite having strictly limited capability when acting alone. The goal is to understand sensorimotor feedback control in which streams of data come from large arrays of sensors (e.g. photo-receptors in the eye) and actuation requires coordination of large numbers of actuators (e.g. motor neurons). The context for this work is set by consideration of a stylized problem of robot navigation that uses optical flow as sensed by two idealized and precise photoreceptors. A robust steering law in this setting establishes a foundation for exploiting optical flow based on averaged noisy inputs from large numbers of imprecise sensing elements. Taking inspiration from neurobiology, the challenges of actuator and sensor intermittency are discussed as are learning actuator coordination strategies. It is shown that there are advantages in having large numbers of control inputs and outputs. The results will be shown to make contact with ideas from control communication complexity and the standard parts problem.

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A control theorist's perspective on “Reactive control of autonomous drones

OpenBU BU Open Access Articles BU Open Access Articles A control theorist's perspective on "React... more OpenBU BU Open Access Articles BU Open Access Articles A control theorist's perspective on "Reactive control of autonomous drones" This work was made openly accessible by BU Faculty. Please share how this access benefits you. Your story matters. Version Citation (published version): JB Baillieul. "A Control Theorist's Perspective on "Reactive Control of Autonomous Drones"." Communications of the ACM

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Data-rate requirements for nonlinear Feedback control

IFAC Proceedings Volumes, 2004

Abstract This paper and talk describe recent research on communication and information processing... more Abstract This paper and talk describe recent research on communication and information processing requirements for implementing nonlinear feedback control laws in applications such as the coordinated motion control of groups of mobile robots. The principal focus is on how the well-known data-rate theorem might be reformulated in the context of essentially nonlinear control problems.

Sensor Based Control of Robotic Mechanisms

Approved for public release; distribution .t~U1 ~9Q 33 unlimited. UMEII5. MONiTQ N!r,.FGAP IZATIO... more Approved for public release; distribution .t~U1 ~9Q 33 unlimited. UMEII5. MONiTQ N!r,.FGAP IZATIONIEPCO~ JLmaeptsI A D-Pr226 784 OL 76. NAM7 OF MONITORING ORGANIZATION Collge f E gine rin, tIf' cap cable) Collgo ni neri ng \L/\E Air Force Office of Scientific Research 6c. ADDRESS fCi t ate and ZIP Coda, 7o ADOB ity.Saewd ZIP coal. I V C tDire'ciorate of Mathematical & Information -K ~kI Sciences, Boiling AFB DC 20332-6448 Be -4A ME OF rUNOING,SPONSORING b. OFFICE SYMBOL 9. PROCuRPEMENT INSTRUMENT I0ENT7PCAT.CN NLMBE Q ORGANIZATION 11f apphtesbil AFOSR INM AFOSR -89-0135 Be ADOOSS C~ty. Slate and ZIP Code) 10 SOURCE OP FUNDING NOS3 ~7L-~ ~PROGRAM PROJECT TASK WORK '..NT )~(X '~~'ELIEMINT NO. NO. NO.

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The Geometry of Sensor Information Utilization in Nonlinear Feedback Control of Vehicle Formations

Lecture Notes in Control and Information Sciences, 2004

... V. Kumar, N. Leonard, AS Morse (Eds.): Cooperative Control, LNCIS 309, pp. 1–24, 2004. ^ Page... more ... V. Kumar, N. Leonard, AS Morse (Eds.): Cooperative Control, LNCIS 309, pp. 1–24, 2004. ^ Page 2. 2 J. Baillieul structured motions. ... (See [13] and [14] for basic definitions regarding graph rigidity.) The theory of graph rigidity is constructive, and Henneberg&amp;amp;#x27;s Theorem states that ...

Information patterns and hedging brockett's theorem in controlling vehicle formations

42nd IEEE International Conference on Decision and Control (IEEE Cat. No.03CH37475)

Efforts to apply computer vision and various optical and acoustic proximity sensors for distribut... more Efforts to apply computer vision and various optical and acoustic proximity sensors for distributed/ coordinated motion control of a small group of autonomous vehicles has led us to consider a number of natural feedback control laws which utilize realtime measurements of relative distances between the vehicles. Unfortunately, none of the feedback laws satisfies Brockett's necessary conditions for asymptotic stabilization. They do appear to provide a basis for practical solutions to a number of interesting vehicle control problems, however. Part of the rationale for proposing feedback laws which are not asymptotically stabilizing is that in a number of cases of practical interest, one may show that the set of initial conditions which are not driven to the prescribed rest point is either small (in some sense) or uninteresting (in the problem context) or both. In some cases, one can also show that by choosing feedback gains in terms of the problem's initial conditionsusing say a table look-up-it is possible to steer from any given initial state into an arbitrarily small neighborhood of the desired goal state. The aim of the research here is to develop a large catalogue of simple controlled motions which in appropriate sequential combinations permit autonomous nonholonomic vehicles to assemble themselves and execute coordinated motions in highly structured formations.

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The control theory of motion-based communication: Problems in teaching robots to dance

2012 American Control Conference (ACC), 2012

The paper describes results on two components of a research program focused on motion-based commu... more The paper describes results on two components of a research program focused on motion-based communication mediated by the dynamics of a control system. Specifically we are interested in how mobile agents engaged in a shared activity such as dance can use motion as a medium for transmitting certain types of messages. The first part of the paper adopts the terminology of motion description languages and deconstructs an elementary form of the well-known popular dance, Salsa, in terms of four motion primitives (dance steps). Several notions of dance complexity are introduced. We describe an experiment in which ten performances by an actual pair of dancers are evaluated by judges and then compared in terms of proposed complexity metrics. An energy metric is also defined. Values of this metric are obtained by summing the lengths of motion segments executed by wheeled robots replicating the movements of the human dancers in each of the ten dance performances. Of all the metrics that are considered in this experiment, energy is the most closely correlated with the human judges' assessments of performance quality. The second part of the paper poses a general class of dual objective motion control problems in which a primary objective (artistic execution of a dance step or efficient movement toward a specified terminal state) is combined with a communication objective. Solutions of varying degrees of explicitness can be given in several classes of problems of communicating through the dynamics of finite dimensional linear control systems. In this setting it is shown that the cost of adding a communication component to motions that steer a system between prescribed pairs of states is independent of those states. At the same time, the optimal encoding problem itself is shown to be a problem of packing geometric objects, and it remains open. Current research is aimed at solving such communication-through-action problems in the context of the motion control of mobile robots.

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Feedback Designs in Information-Based Control

Stochastic Theory and Control

ABSTRACT This paper reports a tight bound on the data capacity a feedback channel must provide in... more ABSTRACT This paper reports a tight bound on the data capacity a feedback channel must provide in order to stabilize a right half-plane pole of a linear, time-invariant control system. The proof is constructive, and involves considering a general class of quantized control realizations of classical feedback designs. Even for the coarsest quantizations—with two-element control input sets, which we refer to as a binary realization—the bound is achievable in the scalar case. The open question of whether bounded trajectories in higher order systems could be produced by a binary realization is answered in the affirmative—again via an explicit construction for a system with two-dimensional state space. It is also shown how binary realizations of classical feedback designs organize the way in which the controller pays attention to different open-loop modes in the plant.

Motion based communication channels between mobile robots - A novel paradigm for low bandwidth information exchange

2009 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2009

A formal notion of gesturing defined as the modulation of relative separation between mobile robo... more A formal notion of gesturing defined as the modulation of relative separation between mobile robots has been explored in [1]. We extend this work by developing a peerto-peer communication channel and an associated distributed communication protocol based exclusively on the modulation of relative motion and its observation. Protocols that enable two unicycle vehicles modulating their relative separation in the plane to effectively exchange information, as well as nonlinear control laws that enable these protocols are presented. Only local information is assumed for the control action. We illustrate the contextual nature of such signaling by showing applications to secure communication as well as robot formation motion. Simulations are presented to validate the work.

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Information and Communication Requirements for Intelligent Control

Robotics:[lecture notes prepared for the American Mathematical Society Short Course Robotics; held in Louisville, Kentucky, January 16-17, 1990]

Real-Time Data Structures for Information-Based Feedback Control of Complex Systems

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