Arancha Casal

Coordination and decentralized cooperation of multiple mobile manipulators

Mobile manipulation capabilities are key to many new applications of robotics in space, underwater, construction, and service environments. This article discusses the ongoing effort at Stanford University for the development of multiple mobile manipulation systems and presents the basic models and methodologies for their analysis and control. This work builds on four methodologies we have previously developed for fixed-base manipulation: the Operational Space Formulation for task-oriented robot motion and force control; the Dextrous Dynamic Coordination of Macro/Mini structures for increased mechanical bandwidth of robot systems; the Augmented Object Model for the manipulation of objects in a robot system with multiple arms; and the Virtual Linkage Model for the characterization and control of internal forces in a multi-arm system. We present the extension of these methodologies to mobile manipulation systems and propose a new decentralized control structure for cooperative tasks. The article also discusses experimental results obtained with two holonomic mobile manipulation platforms we have designed and constructed at Stanford University.

Vehicle/arm coordination and multiple mobile manipulator decentralized cooperation

Mobile manipulation capabilities are key to many new applications of robotics in space, underwater construction, and service environments. This article discusses the ongoing effort at Stanford University for the development of multiple mobile manipulation systems and presents the basic models and methodologies for their analysis and control. This work builds on four methodologies we have previously developed for fixed-base manipulation: the operational space formulation for task-oriented robot motion and force control; the dextrous dynamic coordination of macro/mini structures for increased mechanical bandwidth of robot systems; the augmented object model for the manipulation of objects in a robot system with multiple arms; and the virtual linkage model for the characterization and control of internal forces in a multi-arm system. We present the extension of these methodologies to mobile manipulation systems and propose a new decentralized control structure for cooperative tasks. The article also discusses experimental results obtained with two holonomic mobile manipulation platforms we have designed and constructed at Stanford University.

Robots in Human Environments: Basic Autonomous Capabilities

This article discusses the basic capabilities needed to enable robots to operate in human-populated environments for accomplishing both autonomous tasks and human-guided tasks. These capabilities are key to many new emerging robotic applications in service, construction, field, underwater, and space. An important characteristic of these robots is the “assistance” ability they can bring to humans in performing various physical tasks. To interact with humans and operate in their environments, these robots must be provided with the functionality of mobility and manipulation. The article presents developments of models, strategies, and algorithms concerned with a number of autonomous capabilities that are essential for robot operations in human environments. These capabilities include: integrated mobility and manipulation, cooperative skills between multiple robots, interaction ability with humans, and efficient techniques for real-time modification of collision-free path. These capabilities are demonstrated on two holonomic mobile platforms designed and built at Stanford University in collaboration with Oak Ridge National Laboratories and Nomadic Technologies.

Force Strategies for Cooperative Tasks in Multiple Mobile Manipulation Systems

Mobile manipulation capabilities are key to many new applications of robotics in space, underwater, construction, and service environments. This article discusses the ongoing effort at Stanford University for the development of multiple mobile manipulation systems and presents the basic models and methodologies for their analysis and control. This work builds on four methodologies we have previously developed for fixed-base manipulation: the Operational Space Formulation for task-oriented robot motion and force control; the Dextrous Dynamic Coordination of Macro/Mini structures for increased mechanical bandwidth of robot systems; the Augmented Object Model for the manipulation of objects in a robot system with multiple arms; and the Virtual Linkage Model for the characterization and control of internal forces in a multi-arm system. We present the extension of these methodologies to mobile manipulation systems and propose a new decentralized control structure for cooperative tasks. The article also discusses experimental results obtained with two holonomic mobile manipulation platforms we have designed and constructed at Stanford University.

Complex behaviors from local rules in modular self-reconfigurable robots

We demonstrate how simple local rules, inspired by social insects, produce complex dynamic behaviors required for locomotion and navigation in modular self-reconfigurable robots. We show how systems made up of many modules respond dynamically to their environment, such as obstacles during navigation. We present control algorithms tested on simulation experiments of TeleCube, a new modular robot developed at Xerox PARC.

Multiagent control of self-reconfigurable robots

Abstract We demonstrate how multiagent systems provide useful control techniques for modular self-reconfigurable (metamorphic) robots. Such robots consist of many modules that can move relative to each other, thereby changing the overall shape of the robot to suit different tasks. Multiagent control is particularly well-suited for tasks involving uncertain and changing environments. We illustrate this approach through simulation experiments of Proteo, a metamorphic robot system currently under development.

Decentralized cooperation between multiple manipulators

Mobile manipulation capabilities are key to many new applications of robotics in space, underwater, construction, and service environments. This article discusses the ongoing effort at Stanford University for the development of multiple mobile manipulation systems and presents the basic models and methodologies for their analysis and control. We present the extension of these methodologies to mobile manipulation systems and propose a new decentralized control structure for cooperative tasks. The article also discusses experimental results obtained with two holonomic mobile manipulation platforms we have designed and constructed at Stanford University.

Connectivity planning for closed-chain reconfiguration

Modular reconfigurable robots can change their connectivity from one arrangement to another. Performing this change involves a difficult planning problem. We study this problem by representing robot configurations as graphs, and giving an algorithm that can transform any configuration of a robot into any other in O (log n) steps. Here n is the number of modules which can attach to more than two other modules. We also show that O(log n) is best possible.

A Cellular Automata Model of Early T Cell Recognition

T cells are key components of the immune system, recognizing the presence of foreign antigens by coming in direct contact with specialized antigen-presenting cells (APCs) and scanning the array of surface molecules presented by the APC. During the first 60 seconds of contact, thousands of molecules on both cell surfaces interact. Based on these interactions the T cell makes a first crucial decision to either sustain contact, eventually leading to activation, or to disengage and move on. This paper presents a Cellular Automata model to study how a T cell integrates a varied array of positive and negative signals into its first activation decision. Our simulations use available biological data and support the notion that complex behaviors, such as the signal processing function of a cell, can emerge from the varied local interactions of many cellular receptors.

Cooperative Tasks in Mobile Manipulation Systems 1

Abstract Cooperative mobile manipulation capabilities are key to new applications of robotics in space, underwater, construction, and the service environments. This article discusses the ongoing effort at Stanford University for the development of mobile manipulation capabilities to aid humans in a variety of material handling tasks. The work presented in this paper focuses on the extension of the Augmented Object and the Virtual Linkage models for fixed base manipulation, to mobile cooperative manipulation systems. We propose a new decentralized control structure for cooperative tasks which is suitable to the more autonomous nature of mobile systems and prove its efficacy in simulation