To support an Oak Ridge National Laboratory programs exoskeleton project, a unique multi-axis foot force/torque sensor was constructed and tested that has biomedical application such as clinical gait analysis. The challenging aspect of this multi-axis force sensor is that it had to conform to the bending of the human foot, withstand high impact loads, have high force sensitivity, feel comfortable to the human wearer, be integrated into a military style boot, measure the forces on the human foot when either the ball or the heel of the foot is in contact with the ground, respond to both positive and negative loading and have a low overall height and weight. This paper describes the design and testing of this unique sensor.

Needle insertion is pervasive in almost all medical activities. The development of compact, lightweight automated tools for needle insertion with the reliability of an expert needle-inserting nurse could significantly reduce the risk to both civilian and military patients. Such tools could open the door to many advanced concepts for future medicine by being an ¿enabler¿ of one of the first actions in almost all procedures. The purpose of this paper is to discuss two force-based devices that address the needle insertion problem: a compliance-sensing system that mimics the nurse palpation to determine the best needle insertion point across a vein, and a needle insertion device that uses force-based profiles during insertion to achieve successful catheterization without puncturing the vein back wall. The methodologies and implementation approaches for the two enabling systems are described. Experimental data obtained with training pads and phantom arms are presented and discussed.

The loss of fingers and hands severely limits career and lifestyle options for the amputee. Unfortunately, while there have been strides made in advancements of upper arm and leg prosthetics, the state of the art in prosthetic hands is lagging far behind. Options are generally limited to claw like devices that provide limited gripping capacity. The overall objective of this paper is to demonstrate a path towards a low-cost prosthetic hand with multiple articulated fingers and a thumb that rivals the human hand in terms of weight, size, dexterity, range of motion, force carrying capacity and speed. We begin with a description of the functional requirements for a human hand. When comparing requirements with actuation technologies, the fluid power approach has the potential to realize a prosthetic hand that rivals a human hand in size, strength and dexterity. We introduce a new actuation technology, mesofluidics, that focuses on miniaturization of fluid power to the meso-scale (mm to cm). As a novel demonstration of the potential for this technology, we describe a proof-of-principle mesofluidic finger that has intrinsic actuation and control (actuators and control valves within the volume of the finger). This finger weighs 63 grams, is sized to the 50thpercentile male finger, has a total of 25 mechanical parts and is capable of providing 10 kg (22 lbs) of pinch force.

In typical teleoperated surgeries, skilled staff are still necessary in the remote surgical room to change manipulator tooling and to manage surgical supply delivery and removal. This paper describes the development of a nurse robot to provide automated support to a teleoperated surgical manipulator system in environments where the presence of skilled surgical support staff may not be practical. The tools must be inserted precisely into a compliant manipulator in a timely manner, and the supplies are diverse in nature. To support experimental investigations and evaluations, a seven degrees-of-freedom commercially available manipulator was selected. The design of novel end-effectors, tool grasping and supply holding features, and tool auto-loading systems for optimum surgical tool changing and supply delivery in minimum time is presented. A novel approach for calibration of the nurse robot among compliant and rigid subsystems and for managing forces during subsystem interaction is described and experimental results using this force management approach are presented. Overall experimental performance data for the nurse robot system during tool changing and supply delivery tasks is also presented to illustrate the feasibility of performing these functions in a remote medical or trauma care-assist cell.

While there is a wide range of actuation technologies, none currently rivals the overall performance (power density, bandwidth, stress, stroke) of conventional hydraulic actuation [1]. It is well known in the actuation community that the power-to-weight ratios and the power-to-volume ratios of hydraulic actuators are, respectively, around 5 times and 10 to 20 times larger than comparable electric motors. Due to fundamental limitations in the magnetic flux density in the supporting structures and limitations in the heat transfer out of electric actuators, significant changes in these ratios are not likely in the near future [2]. Thermal limitations associated with electric motors do not apply to hydraulic actuators since the hydraulic fluid cools and lubricates the system. However, with all of these virtues, hydraulic actuators have serious practical implementation problems. Typically, servo-based hydraulic actuators are leaky and have generally poor energy efficiencies. This work addresses a new type of electric actuator that combines the best of both the electric and hydraulic mediums.

The decrease in manpower and increase in material handling needs on many naval vessels provides the motivation to explore the modeling and control of naval robotic and robotic assistive devices. This paper presents a simple methodology to symbolically compute the dynamic equations of motion of a serial link manipulation system operating on the moving deck of a ship. First we provide background information that quantifies the motion of the ship, both in terms of frequency and amplitude. We then formulate the motion of the ship in terms of homogeneous transforms. Likewise, the kinematics of a manipulator is considered as a serial extension of the ship motion. We then show how to use these transforms to formulate the kinetic and potential energy of the arm moving on a ship. As a demonstration, we consider two examples: a one degree-of-freedom system experiencing three sea states operating in a plane to verify the methodology and a 3 degree of freedom system experiencing all six degrees of ship motion to illustrate the ease of computation and complexity of the solution. We provide a preliminary comparison between conventional linear control and repetitive learning control (RLC) and show how fixed time delay RLC breaks down due to the varying wave disturbance frequency.

Experimentation and a survey of the literature clearly show that contact stability in a force reflecting teleoperation system requires high levels of damping on the master robot. However, excessive damping increases the energy required by an operator for commanding motion. The objective of this paper is to describe a new force reflecting teleoperation methodology that reduces operator energy requirements without sacrificing stability. We begin by describing a new approach to modeling and identifying the remote environment of the teleoperation system. We combine a conventional multi-input, multi-output recursive least squares (MIMO-RLS) system identification, identifying in real-time the remote environment impedance, with a discretized representation of the remote environment. This methodology generates a time-varying, position-dependent representation of the remote environment dynamics. Next, we adapt the target impedance of the master robot with respect to the dynamic model of the remote environment. The environment estimation and impedance adaptation are executed simultaneously and in real time. We demonstrate, through experimentation, that this approach significantly reduces the energy required by an operator to execute remote tasks while simultaneously providing sufficient damping to ensure contact stability.

The purpose of this paper is to describe the development of a telerobotic system focused on addressing the complex tasks found in real-world deactivation and decommissioning (D&D) activities for the Department of Energy. Because of the large gap between the conditions and constraints required to implement robotic systems and the conditions encountered in in situ D&D work, nearly all D&D activities that are too hazardous for direct human contact are presently executed using purely teleoperated remote systems. Advances in capability and efficiency can be achieved by developing new telerobotic control methodologies that integrate tasks ideally suited for robotic control with task definitions provided by more traditional teleoperated control. The objectives are to reduce task execution time, reduce the required operator skill level, and to enable the use of tools that are not suited for purely teleoperated control.

Waste tank cleanup is a current application area for robotics in the United States. As a result of tank access restrictions, designs for several current waste cleanup manipulator systems have long links with small cross-sections and variable lengths. In addition, as a result of anticipated payload capacity, these manipulator designs are hydraulically actuated. This paper takes two approaches to investigating the problem of the control of manipulators having variable-length flexible links and hydraulic actuators. First, a simulation of a hydraulically actuated, 2-DOF, polar (r-/spl Theta/), manipulator with one flexible link is used to illustrate the problem of applying controllers successfully developed for hydraulically actuated, fixed-length flexible manipulators to hydraulically-actuated, variable-length systems. Next, based upon the simulation results, simple controller modifications are proposed and are shown to work on a full-scale experimental test bed. Motion control of hydraulically actuated, variable-length flexible-link manipulators is the focus of this paper.

The primary mission of Oak Ridge National Laboratory (ORNL) during World War II was the processing of pure plutonium metal in support of the Manhattan Project. Between 1943 and 1951, the Gunite and Associated Tanks (GAAT) at ORNL were built to collect, neutralize, and store the radioactive by-products. Currently, twelve gunite tanks and four stainless steel tanks are located on the ORNL complex. These tanks hold approximately 75,000 gal of radioactive sludge and solids and over 350,000 gal of liquid. Characterization studies of these tanks in 1994 indicated that the structural integrity of some of the tanks is questionable. Subsequently, there is presently an aggressive program directed towards the remediation and relocation of waste stored in the ORNL tanks. A number of factors complicate the remediation process. The material stored in these tanks ranges from liquid to sludge and solid and is composed of organic materials heavy metals, and radionuclides. The tanks, which range from 12 to 50 ft in diameter, are located below ground and in the middle of the ORNL complex. The only access to these ranks is through one of three access ports that are either 12 or 24 in. in diameter. These characteristics provide a daunting challenge: How can material be safely removed from such a confined structure? This paper describes the existing strategy and hardware presently used in the remediation process. This is followed by a description of an integrated hardware system model. This investigation has isolated a few key areas where further work is needed.

Most of the research related to flexible link manipulators to date has focused on single link, fixed length, single plane of vibration test beds. In addition, actuation has been predominantly based upon electromagnetic motors. Ironically, these elements are rarely found in the existing industrial long reach systems. This paper describes a new hydraulically actuated, long reach manipulator with a flexible prismatic link at Oak Ridge National Laboratory (ORNL). Focus is directed towards both modeling and control of hydraulic actuators as well as flexible links that have variable natural frequencies.

During the 1995 DOE Robotics Forum at Albuquerque, New Mexico, Georgia Tech's Intelligent Machine Dynamics Laboratory demonstrated remote display capabilities of its telemanipulated long-reach manipulator testbed through the Internet. This paper describes the testbed and addresses the methods, limitations, and capabilities of remote operations.

We focus on the fusion of autonomous and teleoperated commands. This combination provides full use of the robot's workspace without requiring large motion amplification between a master and slave robot. Combining autonomous and teleoperated commands provides the potential for large variations in the commanded momentum of the flexible robot. These variations excite the lightly damped, low resonant frequencies associated with these manipulators. Two techniques are proposed to reduce the vibration during sudden stops in the commanded motion of a flexible manipulator. First a new command filtering approach that permits shorter delay times than standard input shaping methods is presented. Next, we propose dynamic alteration of the desired trajectory. Our investigation shows that filtering techniques exhibit an oscillatory response, more so than standard PD control algorithms, during hard stopping conditions. However the shorter time delay filtering algorithm has less vibration than standard input shaping techniques. Furthermore, any vibration may be eliminated by commanding the robot to decelerate instead of immediately stopping the motion.

Impedance control is a popular method of controlling the dynamic response a robot has to external forces. The advantage of such a control paradigm is the ability to manipulate in both unconstrained and constrained environments. Unlike hybrid control methods that attempt to control forces and motions in orthogonal directions, impedance control consists of a single control law that accommodates external forces. One problem associated with such a controller is the selection of the robot's target impedance. This paper illustrates, through analysis and experimentation, the shortcoming of improper target impedance selection. The integration of a real time estimate of the robot's environment with the impedance controller resolves this problem. Experimental results illustrate improved performance during the transition from unconstrained to constrained manipulation.