# Publications

# A few recent publications of J. Baillieul and colleagues

1. “Feedback Designs for Controlling Device Arrays with Communication Channel Bandwidth Constraints,” appearing in *ARO Workshop on Smart Structures, Penn State University, August 16-18, 1999.*

**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.

*2. “Self-organizing Behavior in a Simple Controlled Dynamical System,” J. Baillieul, appearing in Stochastic Theory and Adaptive Control, T.E. Duncan and B. Pasik-Duncan, Eds., Springer-Verlag Lecture Notes in Control and Information Sciences, Vol. 184, 1992.*

**Abstract:** A standard paradigm in control theory involves the use of feedback to change

the dynamics of a system in some significant way. In the language of Willems ([9]), this paradigm

prescribes the use of feedback to create desirable “behavior” in the system. There is growing interest

(see e.g. [8]) in exploring an alternative paradigm applied to the control of systems in which there is

a set of various behaviors pre-existing within the natural (uncontrolled) dynamics of the system, and

wherein control acts in a minimalistic way to entrain a mode of behavior chosen from this set. We

shall explore the latter in the context of some mechanical systems in which the control is only allowed

to act intermittently. The systems we look at involve the controlled one dimensional scattering of a

certain number of particles. In the absence of control, the systems are similar to the Toda lattices

that have been considered by Moser ([7]) and others. We introduce boundary controls and confine

our analysis to two classes of open loop controls – roughly corresponding to constant and periodic

forcing. For the constant controls, the set of possible behaviors is easily described using fixed point

analysis. For periodic forcing, on the other hand, the behavior set is very rich, and is modeled as

the dynamics of an iterated 2-d mapping. Results on the stability and bifurcations of periodic orbits

are given.

*3. “Robust and efficient quantization and coding for control of multidimensional linear systems under data rate constraints,” K. Li and J. Baillieul in International J. of Robust and Nonlinear Control, advance posting: J. Wiley Interscience, DOI: 10.1002/rnc.1142.*

*4. “Control and Communication Challenges in Networked Real-Time Systems,” J. Baillieul and P.J. Antsaklis, in Proceedings of the IEEE, January, 2007, 95:1, pp. 9-28.*

*5. “Control Communication Complexity of Nonlinear Systems,” W.-S. Wong and J. Baillieul, in Communications in Information and Systems, 2009, 9:1, pp. 103-140.*

*6. “The Standard Parts Problem and the Complexity of Control Communication,”* J. Baillieul and W.-S. Wong, Preliminary version submitted to CDC 2009.

*7. “Control Communication Complexity of Distributed Actions,”* W.-S. Wong and J. Baillieul, To appear in the *IEEE Transactions on Automatic Control*, 2012.

8. “Decision Making for Rapid Information Acquisition in the Reconnaissance of Random Fields,” D. Baronov and J. Baillieul, To appear in *PROCEEDINGS of the IEEE*, 2012.

**Abstract: **Research into several aspects of robot-enabled reconnaissance of random fields is reported. The

work has two major components: the underlying theory of information acquisition in the exploration of

unknown fields and the results of experiments on how humans use sensor-equipped robots to perform

a simulated reconnaissance exercise.

The theoretical framework reported herein extends work on robotic exploration that has been

reported by ourselves and others. Several new figures of merit for evaluating exploration strategies are

proposed and compared. Using concepts from differential topology and information theory, we develop

the theoretical foundation of search strategies aimed at rapid discovery of topological features (locations

of critical points and critical level sets) of a priori unknown differentiable random fields. The theory

enables study of efficient reconnaissance strategies in which the tradeoff between speed and accuracy

can be understood. The proposed approach to rapid discovery of topological features has led in a natural

way to to the creation of parsimonious reconnaissance routines that do not rely on any prior knowledge

of the environment. The design of topology-guided search protocols uses a mathematical framework

that quantifies the relationship between what is discovered and what remains to be discovered. The

quantification rests on an information theory inspired model whose properties allow us to treat search

as a problem in optimal information acquisition. A central theme in this approach is that “conservative”

and “aggressive” search strategies can be precisely defined, and search decisions regarding “exploration”

vs. “exploitation” choices are informed by the rate at which the information metric is changing.

The paper goes on to describe a computer game that has been designed to simulate reconnaissance of

unknown fields. Players carry out reconnaissance missions by choosing sequences of motion primitives

from two families of control laws that enable mobile robots to either ascend/descend in gradient

directions of the field or to map contours of constant field value. The strategies that emerge from

the choices of motion sequences are classified in terms of the speed with which information is acquired,

the fidelity with which the acquired information represents the entire field, and the extent to which

all critical level sets have been approximated. The game thus records each player’s performance in

acquiring information about both the topology and geometry of the unknown fields that have been

randomly generated.

9. “A Motion Description Language for Robotic Reconnaissance of Unknown Fields,” D. Baronov and J. Baillieul, To appear in the *European Journal of Control*, 2011.

* *

* *

* *