David F. Knutti

The UTAH/M.I.T. Dextrous hand: work in progress

The Center for Biomedical Design at the University of Utah and the Artificial Intelligence Laboratory at the Massachu setts Institute of Technology are developing a tendon-oper ated multiple-degree-of-freedom dextrous hand (DH) with multichannel touch-sensing capability. Our goal is the design and fabrication of a high-performance yet well-behaved sys tem that is fast and stable and that includes considerable operational flexibility as a research tool. The paper reviews progress to date on project subtasks and discusses design issues important to hardware and control systems develop ment in terms of (1) structures that contain tendons, actua tors, joints, and sensors; (2) both pneumatic and electric tendon actuation systems; (3) optically based sensors that detect touch; (4) subcontrol systems that provide internal management of the DH; and (5) preliminary higher control systems that supervise general operation of the hand during execution of tasks and that provide integration of vision and tactile information.

Development of the Utah Artificial Arm

The development of a practical multifunction, electronically controlled artificial arm is an extremely complex undertaking. Various technical factors such as the limited capability of man-made components, together with problems in the development of adequate control systems, impair the ultimate performance of any prosthesis. Also, nontechnical problems in clinical, marketing, and economic areas strongly influence the potential success of any system. Consequently, the realization of a practical system with the possibility of near-term application requires simultaneous and coordinated work by personnel in a number of normally unrelated areas of medicine and engineering. The opinions of engineers, physicians, amputees, industrial entities, and institutions responsible for funding the fitting of artificial limnbs must be understood and must influence the design process. This paper begins with a discussion of the natural limb and those design objectives and compromises which govern the development of its artificial counterpart Specific details of the Utah Arm are then reviewed, along with general comments regarding the area of prosthetic limb research and application.

Research Robots for Applications in Artificial Intelligence, Teleoperation and Entertainment

Sarcos Research Corporation, and the Center for Engineering Design at the University of Utah, have long been interested in both the fundamental and the applied aspects of robots and other computationally driven machines. We have produced substantial numbers of systems that function as products for commercial applications, and as advanced research tools specifically designed for experimental use. This paper reviews various aspects of the design and control of a number of robot-like machines ranging from our first projects, the Utah Arm and the Utah/MIT Dextrous Hand, to present work on humanoid robots and the Wearable Energetically Autonomous Robot (WEAR). Our systems have been used in: entertainment, operator remotization from hazardous environments, R&D, and medicine. In addition to the robots and their subsystems, extensive work has been devoted to command systems that drive the robots. Command systems have been: playback supervisors, teleoperation masters, and various higher level approaches based on work from the AI community. Playback interfaces have included motion capture mechanisms that provide movement-stream information to storage systems configured for later, repeated and coordinated, operation of many robots and associated mechanisms. Play-back command systems use human commands, from an “earlier” time, to command motions that are played out, over and over, mindlessly. Teleoperation “masters”, that operate in real-time with the robot, have ranged from simple motion capture devices, to more complex force reflective exoskeletal masters. Teleoperation interfaces have been composed of complex kinematic structures designed to perform motions compatible with operator movements and are attached via appropriate soft tissue interfaces. The masters emit lower level commands (joint angles) in real-time using the natural intelligence and sensory systems of the operator. AI-based command sources, blend higher level (simple) commands, with system and existing environmental states, to make decisions for the management of the robot. As with the playback systems, AI-based systems are programmed earlier to perform later operations. In the AI case, however, adaptive intelligence and sensory capabilities reside in the robot. Our general design approach has been to begin with the definition of desired objective behaviors, rather than the use of available components with their predefined technical specifications. With the technical specifications of the components necessary to achieve the desired behaviors defined, the components are either acquired, or in most cases, developed and built. The control system, which includes the operation of feedback approaches, acting in collaboration with physical machinery, is then defined and implemented. Control is considered a function of both feedback, and the designed-in performance of the robot’s physical machinery. It has not been true that bad performance from physical machine elements can be simply compensated out via innovative control methods and faster computers. After the completion of many projects we believe that the final frontier(s) of robotics reside at both ends of the brain and brawn spectrum. Both frontiers (barriers) are related to autonomy—intelligence/computation and energy/power. Recently, energetic autonomy has become a major interest at Sarcos and projects are underway to develop appropriate fuel-based servo-actuators to satisfy that need. Our objective is to develop power systems that are capable producing high performance servo-quality actuation for extended operating times without reenergizing the system. At the other end of the spectrum, we are working in collaboration with various groups to supply physical robots capable of operation under the control of advanced AI-based systems.

Performance characteristics of improved antiscatter grids

The performance characteristics of prototype grids constructed with 0.1-mm-thick Ta strips were investigated. Significant improvement in scatter cleanup was noted in comparison to commercially manufactured grids, which are constructed with 0.04-0.05-mm-thick Pb strips. Highly efficient scatter rejection, approaching that of slit radiography techniques, may be possible using crossed grids constructed with 0.1-mm Ta strips. By constructing a grid from a crossed pair of linear grids and moving these grids at right angles to each other, grid lines can be eliminated from crossed grid images.

An Electropneumatic Actuation System for the Utah/MIT Dextrous Hand

The Center for Biomedical Design at the University of Utah and the Artificial Intelligence Laboratory at the Massachusetts Institute of Technology are developing a tendon-operated multiple-degree-of-freedom (MDOF) robotic hand with multichannel touch-sensing capability (see Figures 1 and 2).

Research Robots for Applications in AI, Teleoperation and Entertainment

Sarcos Research Corporation, and the Center for Engineering Design at the University of Utah, have long been interested in both the fundamental and the applied aspects of robots and other computationally driven machines. We have produced substantial numbers of systems that function as products for commercial applications, and as advanced research tools specifically designed for experimental use.