Flexible, large area electronics - macroelectronics - using amorphous silicon, low-temperature polysilicon, or various organic and inorganic nanocrystalline semiconductor materials is beginning to show great promise. While much of the activity in macroelectronics has been display-centric, a number of applications where macroelectronics is needed to enable solutions that are otherwise not feasible are beginning to attract technical and/or commercial interest. In this paper, we discuss the application drivers and the technology needs and device performance requirements to enable high performance applications to include RF systems.

A full tactile sensing suite for the finger segments and palm of the Utah/MIT dextrous hand is presented. The rubber-based sensors employ capacitance sensing and floating electrodes in the top layer, and contain local electronics for excitation, filtering, analog-to-digital conversion, and serial communication. Experimental results on static, dynamic, and spatial properties are presented. Use of the tactile sensor in contact force control is demonstrated.

An antagonistic controller which is to be used in tendon-driven master/slave end-effectors is described. High stiffness was achieved by developing a control law which eliminates one local force loop in the flexion/extension control loops. One force loop maintains tendon cocontraction, while the other force loop is eliminated when the tendon tension is greater than cocontraction. In order to minimize the input impedance or slew drag caused by inertia and intrinsic damping of the system, force compensations were implemented according to the characteristics of the actuators. These techniques have been implemented experimentally on both electromechanical and electrohydraulic systems. A computer analysis of an electromechanical antagonistic control system is included. Servostiffness equations are derived from the transfer function of the electromechanical system.>

The effect of the variation of parameters of system elements on the overall performance of a generic model of a hydraulic actuation system for a robot is investigated. Specifically, an examination is made of the effects on actuator performance of two issues: intrinsic compliance i.e. the physical compliance within the actuator itself, and independent control of the actuator valve areas (e.g. supply and return areas for hydraulic fluid chamber) versus control of actuator valves with fixed area relationships. Increasing intrinsic compliance in the actuator degrades response to controller commands but improves the ability of the actuator to tolerate disturbances. Independent control of valve areas provides better response to commands and better rejection of disturbances than control with valves that have fixed area relationships. The performance information provided by the model permits behavior-based design of hydraulic actuation systems.>

Two antagonistic control algorithms are described. These algorithms are used to control manipulator links which are antagonistically driven by two actuators via tendons. They have been simulated and experimentally shown to produce better active and passive performance for an electric test system than control algorithms developed earlier. The algorithms use both positive and negative (push and pull) commands to be given to the actuators. Previous systems generated only pull commands, ensuring that tendons would not go slack and give rise to backlash and other problems. The proposed controllers allow push commands to the actuators but still do not allow tendons to go slack. Each actuator, in addition to being fed back its respective tendon force, is fed back both positive and negative manipulator joint torques. This feature allows both actuators to simultaneously respond to torque errors.>

The basic characteristics and advantages of microelectromechanical systems, machines constructed of small moving subelements which have characteristic dimensions in the range of about 0.5 to 500 mu m, are reviewed; design problems are considered; and particular attention is given to the wobble motor (WM) developed by S.C. Jacobsen et al. (1989) using electrodischarge machining (EDM). Fifteen EDM WMs have been constructed and utilized for experimental purposes. WM explorations have demonstrated that micro systems can be quite easily constructed by means other than etching silicon. Experiments aimed at generating simple preliminary data have been conducted, and results compare reasonably to analytical studies. Results reported include stall torque measurements, speed measurements, torque-speed measurements, and wear measurements.>

Research in robotics and automation is gradually revealing the importance of tactile information in the control of machine manipulation systems. Substantial research efforts have been devoted to the construction of compact, high resolution force sensing arrays which employ sophisticated transduction and processing techniques. A variety of systems have been experimentally investigated and a widespread optimism exists regarding the potential use of complex tactile sensing systems in robotic end effectors. Unfortunately, relatively few multi-detector systems have seen actual have seen actual use in real manipulation systems. Those designs that have been applied in automatic environments have almost invariably been used in static circumstances for simple contact imaging. As a consequence of these efforts, it is becoming clear that much work remains to be done before machine touch can be understood and then used to enhance the performance of a dynamic manipulation process. The slow progress in the development of comprehensive tactile sensing systems indicates that the fundamental problem is not simply one of transducer array design and fabrication. Advancements in this area will require: (1) understanding new concepts related to contact detection and image formation as well as the use of contact information to control grasp and to aid in task planning; and (2) the development of actual sensing systems which can be used first to experimentally explore important issues in machine manipulation, and later as a basis for the future design of practical and economic tactile sensing systems. The development of appropriate tactile sensors for research applications will require an exhaustive design effort aimed at understanding the architecture of these systems at all levels, including: (1) transducers and preprocessors which acquire data indicating the type of contact between end effector surfaces and an object and which prepare that data for transmission; (2) multiplexing and transmission systems which efficiently supply sensor data to the controller; and (3) tactile focus control systems which, in order to maximize system transmission efficiency, will dynamically select which sensors will be interrogated for information which will be integrated with other sensory input. This paper reviews preliminary work aimed at understanding the general issues and trade-offs governing the design of real tactile sensing systems. Also, specific designs emphasizing practical necessities such as simplicity, reliability, and economy will be discussed along with plans to integrate this system into the Utah/MIT Dextrous Hand.

The University of Utah Center for Engineering Design (CED) and the Massachusetts Institute of Technology Artificial Intelligence Laboratory (AI Lab) are developing a tendon operated multi-degree-of-freedom (MDOF) dextrous robotic hand for use as a research tool. The goal of the project is to design and fabricate a high performance hand which includes the operational flexibility to investigate issues related to machine based manipulation (MBM). This document will concentrate on issues related to the present implementation of the lowest level servos for the hand. The paper will first discuss the current configuration of the Utah/M.I.T. Hand including the actuation system and the internal sensor systems. It will then focus on the hardware used to implement the controller and the exact form of the control equations. Finally, future work and directions of the control aspects of the project will be discussed.

The Center for Engineering Design at the University of Utah, and the Artificial Intelligence Laboratory at the Massachusetts Institute of Technology have developed a robotic end effector intended to function as a general purpose research tool for the study of machine dexterity. The high performance, multifingered hand will provide two important capabilities. First, it will permit the experimental investigation of basic concepts in manipulation theory, control system design and tactile sensing. Second, it will expand understanding required for the future design of physical machinery and will serve as a "test bed" for the development of tactile sensing systems. The paper includes: 1) a discussion of issues important to the development of manipulation machines; 2) general comments regarding design of the Utah/M.I.T. Dextrous Hand; and, 3) a detailed discussion of specific subsystems of the hand.