Managing Uncertainty in Environmentally Benign Design and Manufacture

NSF Grant # 0522116. Presented at the National Science Foundation Proposal. Courtesy: National Science FoundationWhen making design decisions in environmentally benign design and manufacture, the decision maker is often faced with extreme uncertainty. Due to a lack of understanding of the complex dynamics of environmental and societal systems, it is very difficult to judge the impact different design alternatives have on the environment, the economy and the society, especially in the distant future. In this paper, two formalisms are illustrated for making design decisions under extreme uncertainty. The formalisms are probability bounds analysis and info-gap decision theory. We introduce the basic concepts for both formalisms, discuss the advantages and limitations, and identify under which circumstances they are useful in the context of design decision making. One can think of both decision methods as having a built-in sensitivity analysis allowing the decision maker to judge whether a decision can be made confidently based on the current information, or whether additional information needs to be gathered.National Science Foundation (Grant #DMI-0522382

Millibots: The Development of a Framework and Algorithms for a Distributed Heterogeneous Robot Team

The definitive article was published in IEEE Robotics and Automation Magazine, Volume 9, Issue 4, located at http://ieeexplore.ieee.org/ (DOI: 10.1109/MRA.2002.1160069) © Institute of Electrical and Electronics Engineers (IEEE)

RAVE: A Real and Virtual Environment for Multiple Mobile Robot Systems

This paper was presented at the 1999 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS'99), Kyongju, Korea, October 17-21. The definitive paper is located at http://ieeexplore.ieee.org (DOI: 10.1109/IROS.1999.811669). © IEEE.To focus on the research issues surrounding collaborative behavior in multiple mobile-robotic systems, a great amount of low-level infrastructure is required. To facilitate our on-going research into multi-robot systems, we have developed RAVE, a software framework that provides a Real And Virtual Environment for running and managing multiple heterogeneous mobile-robot systems. This framework simplifies the implementation and development of collaborative robotic systems by providing the following capabilities: the ability to run systems off-line in simulation, user-interfaces for observing and commanding simulated and real robots, transparent transference of simulated robot programs to real robots, the ability to have simulated robots interact with real robots, and the ability to place virtual sensors on real robots to augment or experiment with their performance

Heterogeneous Teams of Modular Robots for Mapping and Exploration

The definitive article is published in Autonomous Robots. It is available at http://www.springerlink.com (DOI: DOI: 10.1023/A:1008933826411). © Springer-VerlagIn this article, we present the design of a team of heterogeneous, centimeter-scale robots that collaborate to map and explore unknown environments. The robots, called Millibots, are configured from modular components that include sonar and IR sensors, camera, communication, computation, and mobility modules. Robots with different configurations use their special capabilities collaboratively to accomplish a given task. For mapping and exploration with multiple robots, it is critical to know the relative positions of each robot with respect to the others. We have developed a novel localization system that uses sonar-based distance measurements to determine the positions of all the robots in the group. With their positions known, we use an occupancy grid Bayesian mapping algorithm to combine the sensor data from multiple robots with different sensing modalities. Finally, we present the results of several mapping experiments conducted by a user-guided team of five robots operating in a room containing multiple obstacles

SRL Research Overview -- Paredis: Information Economics

Presentation for SRL meeting on Feb 16 200

An Agent-Based Approach to the Design of Rapidly Deployable Fault Tolerant Manipulators

This thesis was submitted in partial fulfillment of the requirements for author Chris Paredis' degree of Doctor of Philosophy in Electrical and Computer Engineering at Carnegie Mellon University.There exists a need for manipulators that are more flexible and reliable than the current fixed configuration manipulators. Indeed, robot manipulators can be easily reprogrammed to perform different tasks, yet the range of tasks that can be performed by a manipulator is limited by its mechanical structure. In remote and hazardous environments, such as a nuclear facility or a space station, the range of tasks that may need to be performed often exceeds the capabilities of a single manipulator. Moreover, it is essential that critical tasks be executed reliably in these environments. To address this need for a more flexible and reliable manipulator, we propose the concept of a rapidly deployable fault tolerant manipulator system. Such a system combines a Reconfigurable Modular Manipulator System (RMMS) with support software for rapid programming, trajectory planning, and control. This allows the user to rapidly configure a fault tolerant manipulator custom-tailored for a given task. This thesis investigates all aspects involved in such a system. It describes an RMMS prototype which consists of seven manipulator modules with a total of four degrees-of-freedom. The reconfigurability of the hardware is made transparent to the user by the supporting control software that automatically adapts itself to the current manipulator configuration. To achieve high reliability, a global fault tolerant trajectory planning algorithm is introduced. This algorithm guarantees that a manipulator can continue its task even when one of the manipulator joints fails and is immobilized. Finally, all these aspects are considered simultaneously in the task based design software, that determines the manipulator configuration, its base position, and the fault tolerant joint space trajectory that are optimally suited to perform a given task. The most important contribution of this thesis is a novel agent-based approach to solve the task based design problem. The approach is based on a genetic algorithm for which the modification and evaluation operations are implemented as autonomous asynchronous agents. Specific design knowledge about the task based design problem has been included in the agents, resulting in a significant reduction of the size of the design space and of the cost of evaluating a candidate design. Furthermore, thanks to their autonomous and asynchronous nature, these agents can be easily executed distributedly on a network of workstations. The flexibility and performance of the agent-based implementation, combined with the problem specific knowledge included in the modification and evaluation agents results in a powerful new approach to task based design of rapidly deployable fault tolerant manipulators. Finally, the thesis presents a performance analysis of the agent-based design framework by comparing its results with those of exhaustive search, random search, and multiple restart statistical hill-climbing. This analysis is performed for three examples, including a comprehensive example of a satellite docking operation with a fault tolerant modular manipulator mounted in the cargo bay of the space shuttle.Department of Energy (Grant #DE-F902- 89ER14042)Sandia National Laboratories (Contract #AL–3020)The Robotics Institute at Carnegie Mellon Universit

Agent-Based Design of Fault Tolerant Manipulators for Satellite Docking

This paper was presented at the 1997 IEEE International Conference on Robotics and Automation, Albuquerque, NM, April 20-25. It can be located at http://ieeexplore.ieee.org (DOI: 10.1109/ROBOT.1997.606873). © IEEEA rapidly deployable fault tolerant manipulator system consists of modular hardware and support software that allow the user to quickly configure and deploy a fault tolerant manipulator that is custom-tailored for a given task. The main focus of this paper is on the Task Based Design component of such a system; that is, the determination of the optimal manipulator configuration, its base position, and the corresponding joint space trajectory for a given task. We introduce a novel agent-based solution approach to task based design and illustrate it with a fault tolerant manipulator design for a satellite docking operation aboard the space shuttle.Department of Energy (Grant #DE-F902-89ER14042).Sandia National Laboratories(Contract AL-3020)The Robotics Institute at Mellon UniversityGeorgia Institute of Technolog

Fault Tolerant Task Execution through Global Trajectory Planning

This is the pre-print of an article to appear in the journal Reliability Engineering and Systems Safety. The published article is located at http://sciencedirect.com (DOI: 10.1016/S0951-8320(96)00050-6). © Elsevier.Whether a task can be completed after a failure of one of the degrees-of-freedom of a redundant manipulator depends on the joint angle at which the failure takes place. It is possible to achieve fault tolerance by globally planning a trajectory that avoids unfavorable joint positions before a failure occurs. In this article, we present a trajectory planning algorithm that guarantees fault tolerance while simultaneously satisfying joint limit and obstacle avoidance requirements.Department of Energy (Grant #DOE-F902- 89ER14042)Sandia (contract #AL–3020