Matthew T. Mason

The geometry of time-optimal trajectories for an omni-directional robot (2009)

Paritosh A. Kavathekar, Devin J. Balkcom, Matthew T. Mason

The optimal trajectories are known analytically for only a few ground vehicles: steered cars (Dubins 1957; Reeds & Shepp 1990), and wheel-chair-like differential-drive vehicles (Balkcom &...

1997 IEEE International Conference on Robotics and Automation Sensorless Parts Orienting with a One-Joint Manipulator (2008)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

parts off the middle of three conveyors. These three conveyors, along with an elevator bucket, circulate parts; an overhead camera looks down on the back-lit middle conveyor to determine the position...

of (2008)

Siddhartha S. Srinivasa, Michael A. Erdmann, Matthew T. Mason

time-scaling for control of task freedoms

Abstract Impulsive Manipulation (2008)

Wesley H. Huang, Eric P. Krotkov, Matthew T. Mason

In this paper, we examine a little-studied method of manipulation — manipulation by striking an object and letting it slide. There are two parts to this problem: The Inverse Sliding Problem,...

From Robotic Juggling to Robotic Parts Feeding (2008)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

This paper describes our recent work on robotic manipulation using a robot with just one motor. The drift field provided by gravity can serve as an uncontrolled motor to allow a single-motor robot to...

Algorithmica, to appear Parts Feeding on a Conveyor with a One Joint Robot (2008)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

This paper explores a method of manipulating a planar rigid part on a conveyor belt using a robot with just one joint. This approach has the potential of offering a simple and flexible method for...

Downloaded from (2008)

Matthew T. Mason, Matthew T. Mason

This paper reviews my recent research in robotic manipulation and speculates on potentially fruitful directions for future work. My recent work is focused on nonprehensile manipulation: manipulating...

Downloaded from (2008)

Wesley H. Huang, Matthew T. Mason, Wesley H. Huang, Matthew T. Mason

We present analysis and experimental demonstration of manipulation by tapping. Our problem domain is positioning planar parts on a support surface by a sequence of taps; each tap imparts some initial...

Downloaded from (2008)

Srinivas Akella, Matthew T. Mason, Srinivas Akella, Matthew T. Mason

Parts manufactured to tolerances have variations in shape. Most previous work in robotic manipulation assumes that parts do not have shape variations. Orienting devices such as bowl feeders often...

Downloaded from (2008)

Srinivas Akella, Matthew T. Mason, Srinivas Akella, Matthew T. Mason

Parts orienting, the process of bringing parts in initially unknown orientations to a goal orientation, is an important aspect of automated assembly. The most common industrial orienting systems are...

Downloaded from (2008)

Devin J Balkcom, Matthew T Mason, Devin J. Balkcom, Matthew T. Mason

This paper presents the time optimal trajectories for differential drive vehicles in the unobstructed plane. The wheel angular velocities are bounded, but may be discontinuous. The paper proves the...

Abstract Parts Orienting with Partial Sensor Information (2008)

Srinivas Akella, Matthew T. Mason

Parts orienting, the process of bringing parts in initially unknown orientations to a goal orientation, is an important aspect of automated assembly. Bowl feeders used in industry rely on a sequence...

Abstract Impulsive Manipulation (2008)

Wesley H. Huang, Eric P. Krotkov, Matthew T. Mason

In this paper, we examine a little-studied method of manipulation — manipulation by striking an object and letting it slide. There are two parts to this problem: The Inverse Sliding Problem,...

A Dynamic Single Actuator Vertical Climbing Robot (2008)

Amir Degani, Amir Shapiro, Howie Choset, Matthew T. Mason

Abstract — A climbing robot mechanism is introduced, which uses dynamic movements to climb between two parallel vertical walls. This robot relies on its own internal dynamic motions to gain height,...

Abstract Parts Orienting with Shape Uncertainty (2008)

Srinivas Akella, Matthew T. Mason

Parts manufactured to tolerances have shape variations. Most work in robotic manipulation assumes that part shape does not vary. Orienting devices such as bowl feeders frequently fail due to...

of (2008)

Siddhartha S. Srinivasa, Michael A. Erdmann, Matthew T. Mason

time-scaling for control of task freedoms

Srinivas Akella (2008)

Srinivas Akella, Matthew T. Mason

Parts manufactured to tolerances have variations in shape. Most previous work in robotic manipulation assumes that parts do not have shape variations. Orienting devices such as bowl feeders often...

Srinivas Akella (2008)

Srinivas Akella, Matthew T. Mason

Parts orienting, the process of bringing parts in initially unknown orientations to a goal orientation, is an important aspect of automated assembly. The most common industrial orienting systems are...

From Robotic Juggling to Robotic Parts Feeding (2007)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

This paper describes our recent work on robotic manipulation using a robot with just one motor. The drift field provided by gravity can serve as an uncontrolled motor to allow a single-motor robot to...

Matthew T. Mason Dinesh K. Pai Daniela Rus Lee R. Taylor Michael A. Erdmann (2007)

Carnegie Mellon, Matthew T. Mason, Dinesh K. Pai, Daniela Rus, Lee R. Taylor, Michael A. Erdmann

This paper describes a mobile manipulator that uses its wheels for manipulation as well as locomotion. This robot, named the mobipulator, looks like a small car with four independently powered...

constrained (2007)

Siddhartha S. Srinivasa, Michael A. Erdmann, Matthew T. Mason

time-scaling for control of task freedoms of a

, Elisha Sacks (2007)

Siddhartha S. Srinivasa, Christopher R. Baker, Grigoriy B. Reshko, Matthew T. Mason, Michael A. Erdmann

This paper summarizes ongoing work with a mobile manipulator (Mobipulator). We describe the system architecture of the latest version of the robot, a hierarchy of robot motion commands (the...

Carnegie-Mellon University (2007)

Tomas Lozano-prez, Matthew T. Mason, Russell H. Taylor

The use of active compliance enables robots to carry out tasks in the presence of significant sensing and control errors. Compliant motions are quite difficult for humans to specify, however....

Introducing Robotic Origami Folding (2007)

Devin J. Balkcom, Matthew T. Mason

Origami, the human art of paper sculpture, is a fresh challenge for the field of robotic manipulation, and provides a concrete example for many difficult and general manipulation problems. This paper...

Toward Legless Locomotion Control (2006)

Ravi Balasubramanian, Alfred A. Rizzi, Matthew T. Mason

Abstract — Motivated by an error-recovery locomotion problem, we propose a control technique for a complex mechanical system by decomposing the system dynamics into a collection of simplified...

Minimum wheel-rotation paths for differential-drive mobile robots (2006)

Hamidreza Chitsaz, Steven M. Lavalle, Devin J. Balkcom, Matthew T. Mason

The shortest paths for a mobile robot are a fundamental property of the mechanism, and may also be used as a family of primitives for motion planning in the presence of obstacles. This paper...

An explicit characterization of minimum wheel-rotation paths for differential-drives (2006)

Hamidreza Chitsaz, Steven M. Lavalle, Devin J. Balkcom, Matthew T. Mason

Abstract — This paper characterizes shortest paths for differential-drive mobile robots by classifying solutions in the spirit of Dubins curves and Reeds-Shepp curves for car-like robots. Not only...

Control synthesis for dynamic contact manipulation (2005)

Siddhartha S. Srinivasa, Michael A. Erdmann, Matthew T. Mason

Abstract — We explore the control synthesis problem for a robot dynamically manipulating an object in the presence of multiple frictional contacts. Contacts occur both between the object and the...

Legless Locomotion: Models and Experimental Demonstration (2004)

Ravi Balasubramanian, Alfred A. Rizzi, Matthew T. Mason

Abstract — We show through experiment and simulation that a high-centered round-bodied legged robot can locomote by generating out-of-phase motions of reaction masses attached to its legs. These...

Legless Locomotion for Legged Robots (2003)

Ravi Balasubramanian Alfred, Alfred A. Rizzi, Matthew T. Mason

this report, we use simple models to study how leg motions affect body attitude configuration for a highcentered robot

Legless Locomotion for Legged Robots (2003)

Ravi Balasubramanian Alfred, Alfred A. Rizzi, Matthew T. Mason

We propose a locomotion technique for a legged robot that is high-centered, i.e., a robot stuck on a block with its legs dangling in air. By using its legs as reaction masses, the robot might be able...

Experiments with Nonholonomic Manipulation (2002)

Siddhartha S. Srinivasa, Christopher R. Baker, Elisha Sacks, Grigoriy B. Reshko, Matthew T. Mason, Michael A. Erdmann

This paper summarizes ongoing work with a mobile manipulator (Mobipulator). We describe the system architecture of the latest version of the robot, a hierarchy of robot motion commands (the...

Extremal Trajectories for Bounded Velocity Mobile Robots (2002)

Devin J. Balkcom, Matthew T. Mason, Previous Work

Previous work [3, 6, 9, 8, 7, 1] has presented the time optimal trajectories for three classes of non-holonomic mobile robots: steered cars that can only go forwards, steered cars that go forwards or...

Rapid Prototyping of Small Robots (2002)

Greg Reshko, Matthew T. Mason, Illah R. Nourbakhsh

This paper describes our work on high quality rapid prototyping. The focus is on techniques that produce prototypes of desired quality and yet do not take long to build. We present necessary...

Experiments with Nonholonomic Manipulation (2002)

Siddhartha S. Srinivasa, Christopher R. Baker, Elisha Sacks, Grigoriy B. Reshko, Matthew T. Mason, Michael A. Erdmann

This paper summarizes ongoing work with a mobile manipulator (Mobipulator). We describe the system architecture of the latest version of the robot, a hierarchy of robot motion commands (the...

Time optimal trajectories for bounded velocity differential drive robots (2000)

Devin J. Balkcom, Matthew T. Mason

A differential drive robot is perhaps the simplest type of mobile robot, and the bounded velocity model is perhaps the simplest useful model of the admissible controls. This paper develops the...

Geometric Construction of Time Optimal Trajectories for Differential Drive Robots (2000)

Devin J. Balkcom, Matthew T. Mason

We assume a differential drive mobile robot: two unsteered coaxial wheels are independently actuated. Each wheel has bounded velocity, but no bound on torque or acceleration. Pontryagin's...

Extremal Trajectories for Bounded Velocity Differential Drive Robots (2000)

Devin J. Balkcom, Matthew T. Mason

This paper applies Pontryagin's Maximum Principle to the time optimal control of differential drive mobile robots with velocity bounds. The Maximum Principle gives necessary conditions for time...

Extremal Trajectories for Bounded Velocity Differential Drive Robots (2000)

Devin J. Balkcom, Matthew T. Mason

This paper applies Pontryagin's Maximum Principle to the time optimal control of differential drive mobile robots with velocity bounds. The Maximum Principle gives necessary conditions for time...

Time Optimal Trajectories for Bounded Velocity Differential Drive Robots (2000)

Devin J. Balkcom, Matthew T. Mason

A differential drive robot is perhaps the simplest type of mobile robot, and the bounded velocity model is perhaps the simplest useful model of the admissible controls. This paper develops the...

Extremal trajectories for bounded velocity differential drive robots (2000)

Devin J. Balkcom, Matthew T. Mason

This paper applies Pontryagin’s Maximum Principle to the time optimal control of differential drive mobile robots with velocity bounds. The Maximum Principle gives necessary conditions for time...

Time optimal trajectories for bounded velocity differential drive robots (2000)

Devin J. Balkcom, Matthew T. Mason

A differential drive robot is perhaps the simplest type of mobile robot, and the bounded velocity model is perhaps the simplest useful model of the admissible controls. This paper develops the...

Parts feeding on a conveyor with a one joint robot (2000)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

This paper explores a method of manipulating a planar rigid part on a conveyor belt using a robot with just one joint. This approach has the potential of offering a simple and flexible method for...

Abstract (2000)

Wesley H. Huang, Matthew T. Mason

We present analysis and experimental demonstration of manipulation by tapping. Our problem domain is positioning planar parts on a support surface by a sequence of taps; each tap imparts some initial...

Extremal trajectories for bounded velocity differential drive robots (2000)

Devin J. Balkcom, Matthew T. Mason

This paper applies Pontryagin’s Maximum Principle to the time optimal control of differential drive mobile robots with velocity bounds. The Maximum Principle gives necessary conditions for time...

Time optimal trajectories for bounded velocity differential drive robots (2000)

Devin J. Balkcom, Matthew T. Mason

A differential drive robot is perhaps the simplest type of mobile robot, and the bounded velocity model is perhaps the simplest useful model of the admissible controls. This paper develops the...

Dynamic manipulation (1999)

Matthew T. Mason, Kevin M. Lynch

This paper"'describes some preliminary work on dynamic manipulation--some ezamples, a definition, and analysis of throwing a club. I

Dynamic nonprehensile manipulation: Controllability, planning, and experiments (1999)

Kevin M. Lynch, Matthew T. Mason

We are interested in using low degree-of-freedom robots to perform complex tasks by nonprehensile manipulation (manipulation without a form- or force-closure grasp). By not grasping, the robot can...

Experiments with desktop mobile manipulators (1999)

Matthew T. Mason, Dinesh K. Pai, Daniela Rus, Jon Howell, Lee R. Taylor, Michael A. Erdmann

Abstract: This paper describes our work on Desktop Robotics. The main focus is two robots that locomote and manipulate paper on a desktop. One robot uses wheels for both manipulation and locomotion....

Experiments with Desktop Mobile Manipulators (1999)

Matthew Mason Carnegie, Matthew T. Mason, Dinesh K. Pai, Daniela Rus, Jon Howell, Lee R. Taylor, ...

: This paper describes our work on Desktop Robotics. The main focus is two robots that locomote and manipulate paper on a desktop. One robot uses wheels for both manipulation and locomotion. The...

A Mobile Manipulator (1999)

Matthew T. Mason, Dinesh Pai, Daniela Rus, Lee R. Taylor, Michael A. Erdmann

This paper describes a robot that challenges the usual distinction between locomotion and manipulation. This mobile manipulator, named the mobipulator, looks like a small car with four independently...

A Mobile Manipulator (1999)

Matthew T. Mason, Dinesh K. Pai, Daniela Rus, Lee R. Taylor, Michael A. Erdmann

This paper describes a mobile manipulator that uses its wheels for manipulation as well as locomotion. This robot, named the mobipulator, looks like a small car with four independently powered...

Experiments with Desktop Mobile Manipulators (1999)

Matthew T. Mason, Dinesh K. Pai, Daniela Rus, Jon Howell, Lee R. Taylor, Michael A. Erdmann

: This paper describes our work on Desktop Robotics. The main focus is two robots that locomote and manipulate paper on a desktop. One robot uses wheels for both manipulation and locomotion. The...

Progress in Nonprehensile Manipulation (1999)

Matthew T. Mason

This paper reviews my recent research in robotic manipulation, and speculates on potentially fruitful directions for future work. My recent work is focused on nonprehensile manipulation: manipulating...

Parts Feeding on a Conveyor with a One Joint Robot (1999)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

This paper explores a method of manipulating a planar rigid part on a conveyor belt using a robot with just one joint. This approach has the potential of offering a simple and flexible method for...

Parts Feeding on a Conveyor with a One Joint Robot (1999)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

This paper explores a method of manipulating a planar rigid part on a conveyor belt using a robot with just one joint. This approach has the potential of offering a simple and flexible method for...

Experiments with desktop mobile manipulators (1999)

Matthew T. Mason, Dinesh K. Pai, Daniela Rus, Jon Howell, Lee R. Taylor, Michael A. Erdmann

Abstract: This paper describes our work on Desktop Robotics. The main focus is two robots that locomote and manipulate paper on a desktop. One robot uses wheels for both manipulation and locomotion....

Abstract Progress in Nonprehensile Manipulation for Special Issue of IJRR (1999)

Matthew T. Mason

This paper reviews my recent research in robotic manipulation, and speculates on potentially fruitful directions for future work. My recent work is focused on nonprehensile manipulation: manipulating...

Parts Orienting with Partial Sensor Information (1998)

Srinivas Akella, Matthew T. Mason

Parts orienting, the process of bringing parts in initially unknown orientations to a goal orientation, is an important aspect of automated assembly. Bowl feeders used in industry rely on a sequence...

Mechanics, Planning, and Control for Tapping (1998)

Wesley H. Huang, Matthew T. Mason

this paper, we present analytical and experimental results in the mechanics, planning, and control of this system.

Experiments in Impulsive Manipulation (1998)

Wesley Huang, Matthew T. Mason

In this paper, we present the results of our experimental effort in one form of impulsive manipulation: tapping. Our previous work studied the mechanics of tapping a planar object which then slides...

Dynamic manipulation with a one joint robot (1997)

Kevin M. Lynch, Matthew T. Mason

We are interested in using low degree-of-freedom robots to perform complex manipulation tasks by not grasping. By not grasping, the robot can use rolling, slipping, and free flight to control more...

Sensorless parts orienting with a one-joint manipulator (1997)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

parts off the middle of three conveyors. These three conveyors, along with an elevator bucket, circulate parts; an overhead camera looks down on the back-lit middle conveyor to determine the position...

Dynamic Nonprehensile Manipulation: Controllability, Planning, and Experiments (1997)

Kevin M. Lynch, Matthew T. Mason

We are interested in using low degree-of-freedom robots to perform complex tasks by not grasping (nonprehensile manipulation). By not grasping, the robot can use gravitational, centrifugal, and...

Dynamic Manipulation With a One Joint Robot (1997)

Kevin Lynch Biorobotics, Kevin M. Lynch, Matthew T. Mason

We are interested in using low degree-of-freedom robots to perform complex manipulation tasks by not grasping. By not grasping, the robot can use rolling, slipping, and free flight to control more...

Dynamic Manipulation With a One Joint Robot (1997)

Kevin Lynch Biorobotics, Kevin M. Lynch, Matthew T. Mason

We are interested in using low degree-of-freedom robots to perform complex manipulation tasks by not grasping. By not grasping, the robot can use rolling, slipping, and free flight to control more...

Sensorless Parts Orienting with a One-Joint Manipulator (1997)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

This paper explores a sensorless technique for orienting planar parts. We follow an approach described in earlier papers [3, 4] called 1JOC for One Joint Over Conveyor, which can perform planar...

Mechanics for Vibratory Manipulation (1997)

Wesley H. Huang, Matthew T. Mason

Vibratory manipulation is any mode of manipulation involving repeated impacts due to a striker which follows some periodic motion. In this paper, we study vibratory manipulation in the context of...

Parts Orienting with Shape Uncertainty (1997)

Srinivas Akella, Matthew T. Mason

Parts manufactured to tolerances have shape variations. Most work in robotic manipulation assumes that part shape does not vary. Orienting devices such as bowl feeders frequently fail due to...

Sensorless parts orienting with a one-joint manipulator (1997)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

parts off the middle of three conveyors. These three conveyors, along with an elevator bucket, circulate parts; an overhead camera looks down on the back-lit middle conveyor to determine the position...

Dynamic underactuated nonprehensile manipulation (1996)

Kevin M. Lynch, Matthew T. Mason

By exploiting centrifugal and Coriolis forces, simple, lowdegree-of-freedom robots can control objects with more degrees-of-freedom. For example, by allowing the object to roll and slip, a...

A Mobile Manipulator (1996)

Proceedings Ieee Int, Matthew T. Mason, Dinesh K. Pai, Daniela Rus, Lee R. Taylor, Michael A. Erdmann

This paper describes a mobile manipulator that uses its wheels for manipulation as well as locomotion. This robot, named the mobipulator, looks like a small car with four independently powered...

Limiting Cases of Impulsive Manipulation (1996)

Wesley Huang, Matthew T. Mason

Impulsive manipulation is the use of impulsive forces to manipulate objects. In particular, we are studying how to manipulate a rigid planar slider by tapping. In this paper, we focus on the limiting...

Dynamic Underactuated Nonprehensile Manipulation (1996)

Kevin M. Lynch, Matthew T. Mason

By exploiting centrifugal and Coriolis forces, simple, lowdegree -of-freedom robots can control objects with more degrees-of-freedom. For example, by allowing the object to roll and slip, a...

Planar manipulation on a conveyor with a one joint robot (1995)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

This paper explores a method of manipulating a planar rigid body on a conveyor belt using a robot with just one joint. This approach has the potential of offering a simple and flexible method for...

Impulsive Manipulation (1995)

Wesley Huang, Eric P. Krotkov, Matthew T. Mason

In this paper, we examine a little-studied method of manipulation --- manipulation by striking an object and letting it slide. There are two parts to this problem: The Inverse Sliding Problem,...

Parts Orienting by Push-aligning (1995)

Srinivas Akella, Matthew T. Mason

Programmable parts orienting is an important capability for flexible automation systems. Here we study how a part grasped in an unknown orientation by a force-controlled robot can be oriented by a...

Pulling by Pushing, Slip with Infinite Friction, and Perfectly Rough Surfaces (1995)

Kevin Lynch, Matthew T. Mason

When one rigid object (the pusher) pushes another (the slider) across a horizontal support plane, Coulomb's law admits some surprising phenomena. First, it is possible to move the slider by...

Planar Manipulation on a Conveyor with a One Joint Robot (1995)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

This paper explores a method of manipulating a planar rigid body on a conveyor belt using a robot with just one joint. This approach has the potential of offering a simple and flexible method for...

Planar Manipulation on a Conveyor with a One Joint Robot (1995)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

This paper explores a method of manipulating a planar rigid body on a conveyor belt using a robot with just one joint. This approach has the potential of offering a simple and flexible method for...

Controllability of Pushing (1995)

Kevin Lynch, Matthew T. Mason

This paper addresses the question "Can the object be pushed from here to there?" We characterize the set of objects that are controllable (can be positioned arbitrarily), with and without...

Controllability of Pushing (1995)

Kevin Lynch, Matthew T. Mason

This paper addresses the question "Can the object be pushed from here to there?" We characterize the set of objects that are controllable (can be positioned arbitrarily), with and without...

Pulling by Pushing, Slip with Infinite Friction, and Perfectly Rough Surfaces (1995)

Kevin M. Lynch, Matthew T. Mason

When one rigid object (the pusher) pushes another (the slider) across a horizontal support plane, Coulomb's law admits some surprising phenomena. First, it is possible to move the slider by...

Planar manipulation on a conveyor with a one joint robot (1995)

Srinivas Akella, Wesley H. Huang, Kevin M. Lynch, Matthew T. Mason

This paper explores a method of manipulating a planar rigid body on a conveyor belt using a robot with just one joint. This approach has the potential of offering a simple and flexible method for...

Posing Polygonal Objects in the Plane by Pushing (1992)

Srinivas Akella, Matthew T. Mason

This paper studies the use of pushing actions with a fence to orient and translate objects in the plane. It describes a planner which is guaranteed to construct a sequence of pushing actions to move...

Bayesian grasping (1990)

Kenneth Y. Goldberg, Matthew T. Mason

This paper describes a Bayesian approach to the problem of autonomous manipulation in the presence of state uncertainty. We model uncertainty with a probability distribution on the state space. Each...

Automatic Synthesis of Fine-Motion Strategies for Robots (1983)

Lozano-Perez, Tomas, Mason, Matthew T., Taylor, Russell H.

The use of active compliance enables robots to carry out tasks in the presence of significant sensing and control errors. Compliant motions are quite difficult for humans to specify, however....

Automatic Synthesis of Fine-Motion Strategies for Robots (1983)

Lozano-Perez, Tomas, Mason, Matthew T., Taylor, Russell H.

The use of active compliance enables robots to carry out tasks in the presence of significant sensing and control errors. Compliant motions are quite difficult for humans to specify, however....

Manipulator grasping and pushing operations /--by Matthew Thomas Mason. (1982)

Mason, Matthew T.

Thesis (Ph. D.)--Massachusetts Institute of Technology, 1982.