David L. Brock

Haptic rendering: programming touch interaction with virtual objects

Haptic rendering is the process of computing and generating forces in response to user interactions with virtual objects. Recent efforts by our team at MITs AI laboratory have resulted in the development of haptic interface devices and algorithms for generating the forces of interaction with virtual objects. This paper focuses on the software techniques needed to generate sensations of contact interaction and material properties. In particular, the techniques we describe are appropriate for use with the Phantom haptic interface, a force generating display device developed in our laboratory. We also briefly describe a technique for representing and rendering the feel of arbitrary polyhedral shapes and address issues related to rendering the feel of non-homogeneous materials. A number of demonstrations of simple haptic tasks which combine our rendering techniques are also described.

Radio frequency identification and the electronic product code

Remotely scannable IC chips that can access vast amounts of constantly updated information and cost only pennies could be close to reality. New technological developments and a decline in chip cost hold the promise of an automatic data and identification system that uses the Internet.

Enhancing the dexterity of a robot hand using controlled slip

An analysis was performed of controlled slipping of an object within a robot hand. The possible ways an object can move within a grasp were enumerated. The set of permissible motions was found as a function of the constraint state, that is, the number, location, and types of contact on an object. The constraint state was found as a function of a number of controllable variables, such as grasping force and externally applied forces.<<ETX>>

A Dynamic Model of a Linear Actuator Based on Polymer Hydrogel

The design and analysis of a series of linear actuators based on polymer hydrogel is presented. The actuators use arrays of pH sensitive gel fibers together with a fluid irrigation system to locally and rapidly regulate the composition of the solution. A dynamic model is constructed for one of the linear actuators, which includes the polymer gel, fluidic system, and transmission mechanics. Emphasis in the design and mechanical modeling of the actuators is placed on the com plete system including not only the polymer gel, but also on the containment system, irrigation scheme, and servo valving system.

The networked physical world: an automated identification architecture

We have developed an open and scalable network-oriented architecture that integrates the physical world with the virtual world and admits the efficient storage and retrieval of data and information. The architecture works with existing and future network and Automated Identification (Auto-ID) technologies and requires the use of Globally Unique IDentifiers (GUIDes). An Auto-ID tag affixed to a physical object stores the GUIDe for that object. Networked tag readers wirelessly communicate with the Auto-ID tags, thereby connecting the physical objects to the network. An objects GUIDe acts as a pointer to storage locations for data and information about that object, operating in a similar manner to pointers in programming languages. Given a GUIDe, the Object Name Service (ONS), a facility similar to the Domain Name Service (DNS), is queried to identify these storage locations on the local network and over the Internet. Storing an objects data and information in a standardized XML-based language such as PML allows the use of Internet friendly query languages such as XQL and Quilt and enables the automated storage and retrieval of data and information at remote locations. Our architecture efficiently networks the physical world, allowing effective and truly automated information search, information retrieval, and functionality.

Coordination and control of multiple autonomous vehicles

The DARPA SIMNET project allows hundreds of soldiers to train together in a virtual air, land, and sea environment through a network of interactive simulators. In addition to the manned simulators, the virtual environment is also populated by a large number of autonomous vehicles called semi-automated forces, which are controlled by an operator at a single workstation. The authors address the issues of collision avoidance and formation keeping. The autonomous vehicles are responsible for the lower-level path planning, collision avoidance, and formation following. Routines are described for maneuvering among large obstacles, smaller objects, and moving vehicles.<<ETX>>

Experimental Evaluation of Friction Characteristics with an Articulated Robotic Hand

In this paper some applications of dexterous robotic hands to fine manipulation operations are discussed. Common to this kind of operations is the important role played by the frictional characteristics of the fingers and of manipulated objects. The paper discusses a procedure for measuring apparent coefficients of friction between the fingertips and manipulated objects. To take into account real contact phoenomena, the distinction is introduced between translational and rotational friction limits. Reported experiments rely on force-based (intrinsic) contact sensing devices, implemented in the phalanges of an articulated robot hand (Salisbury Hand). Data collected during these procedures can be subsequently used for tasks such as recognizing the superficial features of objects, controlling the internal grasp forces exerted by the hand on delicate objects, and following the contours of the surface of unknown objects.

Implementation of Behavorial Control on a Robot Hand/Arm System

Planning and behavior are two strategies which have characterized much of the recent research in robotic intelligent control. While planning algorithms provide provable convergence and analytic results, they are not generally robust and responsive in dynamic environments. Reactive behavior on the other hand, while designed for robust performance and rapid response, provide fewer analytic tools for design and evaluation. Our objective is to understand the mechanism of behavioral control and to develop analytic design tools, particularly in the area of robotic manipulation. In this paper we propose a general framework for reactive control and discuss some methods for analysis and design. We also analyze and implement a behavioral control scheme for the acquisition of a cylinder using a robot hand/arm system.

Experimental Evaluation of Friction Data with an Articulated Hand and Intrinsic Contact Sensors

In this paper some applications of dexterous robotic hands to fine manipulation operations are discussed. Common to this kind of operations is the important role played by the frictional characteristics of the fingers and of manipulated objects. The paper discusses a procedure for measuring apparent coefficients of friction between the fingertips and manipulated objects. To take into account real contact phoenomena, the distinction is introduced between translational and rotational friction limits. Reported experiments rely on force-based (intrinsic) contact sensing devices, implemented in the phalanges of an articulated robot hand (Salisbury Hand). Data collected during these procedures can be subsequently used for tasks such as recognizing the superficial features of objects, controlling the internal grasp forces exerted by the hand on delicate objects, and following the contours of the surface of unknown objects.

Lumped parameter modeling of polymer gel for real-time control

Lumped parameter models of non-electrolyte and electrolyte polymer gel based on the energy method are presented. Emphasis is placed on developing model that is simple enough for real time control implementation, yet able to capture essential inter-domain energy coupling effect. The dynamics of quasistatic polymer gel system are translated to bond graph representation.