The Accident Response Mobile Manipulator System (ARMMS) is a teleoperated emergency response vehicle that deploys two hydraulic manipulators, five cameras, and an array of sensors to the scene of an incident. It is operated from a remote base station that can be situated up to four kilometers away from the site. A modular telerobot control architecture called SMART (Sandia's Modular Architecture for Robotic and Teleoperation) was previously applied to ARMMS to improve the precision, safety, and operability of the manipulators on board. Using SMART, a prototype manipulator control system was developed in a couple of days, and an integrated working system was demonstrated within a couple of months. New capabilities such as camera-frame teleoperation, autonomous tool changeout and dual manipulator control have been incorporated. The final system incorporates twenty-two separate modules and implements seven different behavior modes. The paper describes the integration of SMART into the ARMMS system.

This paper describes a modular approach for computing redundant robot kinematics. First some conventional redundant control methods are presented and shown to be "passive control laws", i.e. they can be represented by a network consisting of passive elements. These networks are then put into modular form by applying scattering operator techniques. Additional subnetwork modules can then be added to further shape the motion. Modules for obstacle detection, joint limit avoidance, proximity sensing, and for imposing nonlinear velocity constraints are presented. The resulting redundant robot control system is modular, flexible and robust.

This paper analyses the problems and presents solutions for building a modular robot control system. The approach requires modeling the entire robot system using multi-dimensional passive networks, breaking the system into subnetwork "modules" and then discretizing the subnetworks, or n-ports, in a passivity preserving fashion. The main difficulty is the existence of "algebraic loops" in the discretized system. This problem is overcome by the use of scattering theory, whereby the inputs and outputs of the n-ports are mapped into wave variables before being discretized. By first segmenting the n-ports into nonlinear memoryless subnetworks and linear dynamic subnetworks and then discretizing using passivity preserving techniques such as Tustin's method, a complete modular robot control solution is obtained.

This paper illustrates how different modes of operation such as bilateral teleoperation, autonomous control, and shared control can be described and implemented using combinations of modules in the SMART robot control architecture. Telerobotics modes are characterized by different "grids" of SMART icons, where each icon represents a portion of run-time code that implements a passive control law. By placing strict requirements on the module's input-output behavior and using scattering theory to develop a passive sampling technique, a flexible, expansible telerobot architecture is achieved. An automatic code generation tool for generating SMART systems is also described.

This paper presents a modular control architecture for multi-arm telerobotic systems. It provides a platform for the implementation of various robot control and planning schemes, as well as a framework for quickly transferring academic research to real-world applications. The advantage is exemplified by the transfer of an intelligent planning and control scheme for telerobotic systems to Sandia National Laboratories. The intelligent planning and control scheme accepts the human supervisory control and autonomous control into one seamless unit. It combines the strength of both human and autonomous control to achieve a safe, robust, and reliable operation. More importantly, the results presented in this paper demonstrate the importance of developing an efficient mechanism for transferring research and technology developed in the academic environment to the national laboratories and eventually into practical applications. It could be a crucial step towards the cross-development of robotic technology in our university, industrial, and national laboratories. The modular controller presented in this paper surely is an important step in this direction.

Describes an algorithm by which obstructions and surface features in an underground storage tank can be modeled and used to generate virtual barrier functions for a real-time telerobotic system, which provides an aid to the operator for both real-time obstacle avoidance and for surface tracking. The algorithm requires that the slave's tool and every object in the waste storage tank be decomposed into convex polyhedral primitives, with the waste surface modeled by triangular prisms. Intrusion distance and extraction vectors are then derived at every time step by applying Gilbert's polyhedra distance algorithm, which has been adapted for the task. This information is then used to determine the compression and location of nonlinear virtual spring-dampers whose total force is summed and applied to the manipulator/teleoperator system. Experimental results using a PUMA 560 and a simulated waste surface validate the approach, showing that it is possible to compute the algorithm and generate smooth, realistic psuedo forces for the teleoperator system using standard VME bus hardware.>

For a number of reasons, systems designers have recently shown considerable interest in ethnography. For the most part, this has been used as a method for the specification of end-user requirements for systems. In this article, I argue that most of this interest is predicated in a misunderstanding of ethnography's role in social science. Instead of focusing on its analytic aspects, designers have defined it as a form of data collection. They have done this for very good, design-relevant reasons, but designers do not need ethnography to do what they wish to do. In the central part of this article, I introduce and illustrate an approach to analytic ethnography in human-computer interaction. In the latter sections I take this approach and show how it opens up the play of possibilities for design. These possibilities are illustrated by counterpoising a summary logic of organizational structure such as that associated with the calculus of efficiency and productivity with the local logics of daily organizational life.

Dynamic damping laws have been investigated. The approach is based on modulating the velocity feedback gain based on a model of the manipulator inertia and the desired stiffness. By using different stiffness gains, different dynamic damping laws can be obtained. In particular, joint space, gripper space, and constant bandwidth versions have been developed. Simulations have been used to illustrate the advantages and disadvantages of using dynamic damping control laws over conventional computed torque and proportional-derivative (PD) control laws. The disadvantages are greater computational requirements and greater coupling of joints. The advantages are guaranteed stability, greater bandwidth for small inertias, and more effective utilization of torque. It is shown that as the manipulator inertia decreases, the amount of torque commanded by the dynamic damping control law exceeds the torque commanded by computed torque and PD controllers, resulting in greater bandwidth.>

The authors validate their previously published (1988) algorithm for controlling a force-reflecting teleoperator with time delay. The time-delay compensation is shown to result in a control law which ensures asymptotic stability of manipulator velocities when contacting arbitrary passive environments. The results are based on the full n-DOF (degrees of freedom) nonlinear system and allow for the inclusion of power gain between the human operator and the environment.>

The inclusion of force information in the control of robots increases their adaptability to uncertain environments, such as are found in deburring, grinding, and assembly tasks. The authors present a foundation for force control strategies, in view of the fact that the type of control strategy that is employed depends fundamentally on the characteristics of the environment. A general control approach is introduced, called hybrid impedance control which in its simplest forms reduces the operational space control of O. Khatib and J. Burdick (1986), or to N. Hogan's (1985) impedance control. The control law is formulated in a general enough fashion, however, to allow for higher order controllers.>

This work presents a new algorithm for controlling the contact forces of a robotic manipulator. The algorithm, to be called hybrid impedance control (HIC), combines two fundamental force control strategies; hybrid position/force control, and impedance control. A duality condition is defined which specifically determines how the manipulator should respond for a given environment. A system-theoretic approach is utilized to motivate the algorithm, and specific examples are developed to illustrate it.