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At least 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Robot cable-compliant devices

A cable compliant robotic joint includes two U configuration cross section brackets with their U cross sections lying in different planes, one of their brackets being connected to a robot arm and the other to a tool. Additional angle brackets are displaced from the other brackets at corners of the robotic joint. All the brackets are connected by cable segments which lie in one or more planes which are perpendicular to the direction of tool travel as it approaches a work object. The compliance of the joint is determined by the cable segment characteristics, such as their length, material, angle, stranding, pretwisting, and prestressing.

Kerley, James J., Jr.↗
NASA NTRS1991

IVA the robot: Design guidelines and lessons learned from the first space station laboratory manipulation system

The first interactive Space Station Freedom (SSF) lab robot exhibit was installed at the Space and Rocket Center in Huntsville, AL, and has been running daily since. IntraVehicular Activity (IVA) the robot is mounted in a full scale U.S. Lab (USL) mockup to educate the public on possible automation and robotic applications aboard the SSF. Responding to audio and video instructions at the Command Console, exhibit patrons may prompt IVA to perform a housekeeping task or give a speaking tour of the module. Other exemplary space station tasks are simulated and the public can even challenge IVA to a game of tic tac toe. In anticipation of such a system being built for the Space Station, a discussion is provided of the approach taken, along with suggestions for applicability to the Space Station Environment.

Konkel, Carl R.↗
NASA NTRS1991

Forward and inverse kinematics of double universal joint robot wrists

A robot wrist consisting of two universal joints can eliminate the wrist singularity problem found on many individual robots. Forward and inverse position and velocity kinematics are presented for such a wrist having three degrees of freedom. Denavit-Hartenberg parameters are derived to find the transforms required for the kinematic equations. The Omni-Wrist, a commercial double universal joint robot wrist, is studied in detail. There are four levels of kinematic parameters identified for this wrist; three forward and three inverse maps are presented for both position and velocity. These equations relate the hand coordinate frame to the wrist base frame. They are sufficient for control of the wrist standing alone. When the wrist is attached to a manipulator arm; the offset between the two universal joints complicates the solution of the overall kinematics problem. All wrist coordinate frame origins are not coincident, which prevents decoupling of position and orientation for manipulator inverse kinematics.

Williams, Robert L., II↗
NASA NTRS1991

Adaptive control of space based robot manipulators

For space based robots in which the base is free to move, motion planning and control is complicated by uncertainties in the inertial properties of the manipulator and its load. A new adaptive control method is presented for space based robots which achieves globally stable trajectory tracking in the presence of uncertainties in the inertial parameters of the system. A partition is made of the fifteen degree of freedom system dynamics into two parts: a nine degree of freedom invertible portion and a six degree of freedom noninvertible portion. The controller is then designed to achieve trajectory tracking of the invertible portion of the system. This portion consist of the manipulator joint positions and the orientation of the base. The motion of the noninvertible portion is bounded, but unpredictable. This portion consist of the position of the robot's base and the position of the reaction wheel.

Walker, Michael W.↗
NASA NTRS1990

Method and apparatus for positioning a robotic end effector

A robotic end effector and operation protocol for a reliable grasp of a target object irrespective of the target's contours is disclosed. A robotic hand includes a plurality of jointed fingers, one of which, like a thumb, is in opposed relation to the other. Each finger is comprised of at least two jointed sections, and provided with reflective proximity sensors, one on the inner surface of each finger section. Each proximity sensor comprises a transmitter of a beam of radiant energy and means for receiving reflections of the transmitted energy when reflected by a target object and for generating electrical signals responsive thereto. On the fingers opposed to the thumb, the proximity sensors on the outermost finger sections are aligned in an outer sensor array and the sensors on the intermediate finger sections and sensors on the innermost finger sections are similarly arranged to form an intermediate sensor array and an inner sensor array, respectively. The invention includes a computer system with software and/or circuitry for a protocol comprising the steps in sequence of: (1) approach axis alignment to maximize the number of outer layer sensors which detect the target; (2) non-contact contour following the target by the robot fingers to minimize target escape potential; and (3) closing to rigidize the target including dynamically re-adjusting the end effector finger alignment to compensate for target motion. A signal conditioning circuit and gain adjustment means are included to maintain the dynamic range of low power reflection signals.

Hess, Clifford W.↗
NASA NTRS1991

A color-coded vision scheme for robotics

Most vision systems for robotic applications rely entirely on the extraction of information from gray-level images. Humans, however, regularly depend on color to discriminate between objects. Therefore, the inclusion of color in a robot vision system seems a natural extension of the existing gray-level capabilities. A method for robot object recognition using a color-coding classification scheme is discussed. The scheme is based on an algebraic system in which a two-dimensional color image is represented as a polynomial of two variables. The system is then used to find the color contour of objects. In a controlled environment, such as that of the in-orbit space station, a particular class of objects can thus be quickly recognized by its color.

Johnson, Kelley Tina↗
NASA NTRS1991

Robotics in space-age manufacturing

Robotics technologies are developed to improve manufacturing of space hardware. The following applications of robotics are covered: (1) welding for the space shuttle and space station Freedom programs; (2) manipulation of high-pressure water for shuttle solid rocket booster refurbishment; (3) automating the application of insulation materials; (4) precision application of sealants; and (5) automation of inspection procedures. Commercial robots are used for these development programs, but they are teamed with advanced sensors, process controls, and computer simulation to form highly productive manufacturing systems. Many of the technologies are also being actively pursued in private sector manufacturing operations.

Jones, Chip↗
NASA NTRS1991

Advanced mechanisms for robotics

An overview of applied research and development at the Goddard Space Flight Center (GSFC) on mechanisms and collision avoidance skin for robots is presented. The work on robot end effectors is outlined, followed by a brief discussion of robot-friendly payload latching mechanisms and compliant joints. This is followed by discussions of the collision avoidance/management skin and the GSFC research on magnetorestrictive direct drive motors. A new project, the artificial muscle, is introduced. Each of the devices is described sufficiently to permit a basic understanding of its purpose, capabilities, and operating fundamentals. The implications for commercialization are discussed.

Vranish, John M.↗
NASA NTRS1991

Advancing automation and robotics technology for the Space Station Freedom and for the U.S. economy. Submitted to the Congress of the U.S. May 1991

In April 1985, as required by Public Law 98-371, the NASA Advanced Technology Advisory Committee (ATAC) reported to Congress the results of its studies on advanced automation and robotics technology for use on Space Station Freedom. This material was documented in the initial report (NASA Technical Memorandum 87566). A further requirement of the law was that ATAC follow NASA's progress in this area and report to Congress semiannually. The report describes the progress made by Levels 1, 2 and 3 of the Office Space Station in developing and applying advanced automation and robotics technology. Emphasis has been placed upon the Space Station Freedom Program responses to specific recommendations made in ATAC Progress Report 11, the status of the Flight Telerobotic Servicer, and the status of the Advanced Development Program. In addition, an assessment is provided of the automation and robotics status of the Canadian Space Station Program.

Lum, Henry, Jr.↗
NASA NTRS1991

Robotic tool change mechanism

An assembly of three major components is disclosed which included a wrist interface plate which is secured to the wrist joint of a robotic arm, a tool interface plate which is secured to each tool intended for use by the robotic arm, and a tool holster for each tool attached to the interface plate. The wrist interface plate and a selected tool interface plate are mutually connectable together through an opening or recess in the upper face of the interface plate by means of a notched tongue protruding from the front face of the wrist interface plate which engages a pair of spring-biased rotatable notched wheels located within the body of the tool interface plate. The tool holster captures and locks onto the tool interface plate by means of a pair of actuation claws including a locking tab and an unlocking wedge which operate respective actuation bosses on each of the notched wheels in response to a forward and backward motion of the tool interface plate as a result of motion of the robotic arm to either park the tool or use the tool.

Voellmer, George M.↗
NASA NTRS1991

A magneto-sensitive skin for robots in space

The development of a robot arm proximity sensing skin that can sense intruding objects is described. The purpose of the sensor would be to prevent the robot from colliding with objects in space including human beings. Eventually a tri-mode system in envisioned including proximity, tactile, and thermal. To date the primary emphasis was on the proximity sensor which evolved from one based on magneto-inductive principles to the current design which is based on a capacitive-reflector system. The capacitive sensing element, backed by a reflector driven at the same voltage and in phase with the sensor, is used to reflect field lines away from the grounded robot toward the intruding object. This results in an increased sensing range of up to 12 in. with the reflector on compared with only 1 in. with it off. It is believed that this design advances the state-of-the-art in capacitive sensor performance.

Chauhan, D. S.↗
NASA NTRS1990

Insight to human and robotic parallels in spacecraft and space tool design

The parallels between human space activity and robotics and the role of their compatibility in the design of critical spacecraft elements are discussed with reference to current manned spacecraft programs, such as the Shuttle and Space Station Freedom. In particular, it is noted that the human variable may be the limiting factor with regards to repetition, fatigue, and possibly strength. This limiting factor serves as the natural constraint in the design of compatible interfaces. However, the mechanism or tool, not the capability of the robot, is constrained to human limits. Results of a limited test to study the robotic compatibility of the EVA-suitable connectors are reported.

Lewis, Ruthan↗
NASA NTRS1990

Robotic missions for the moon

In the course of the exploration and settlement of the moon, robotic missions will precede and accompany humans. These robotic missions are defined respectively as precursors and adjuncts. Their contribution is twofold: to generate information about the lunar environment (and system performance in that environment), and to emplace elements of infrastructure for subsequent use. This paper describes information that may be gathered by robotic missions and infrastructure elements that may be deployed by them during an early lunar program phase.

Bourke, R. D.↗
NASA NTRS1990

A testbed for a unified teleoperated-autonomous dual-arm robotic system

This paper describes a complete robot control facility built at the Jet Propulsion Laboratory as part of NASA a telerobotics program to develop a state-of-the-art robot control environment for laboratory based space-like experiments. This system, which is now fully operational, has the following features: separation of the computing facilities into local and remote sites, autonomous motion generation in joint or Cartesian coordinates, dual-arm force reflecting teleoperation with voice interaction between the operator and the robots, shared control between the autonomously generated motions and operator controlled teleoperation, and dual-arm coordinated trajectory generation. The system has been used to carry out realistic experiments such as the exchange of an Orbital Replacement Unit (ORU), bolt turning, and door opening, using a mixture of autonomous actions and teleoperation, with either a single arm or two cooperating arms.

Hayati, S.↗
NASA NTRS1989

Finite solid representation of robot manipulation in three-dimensional geometric reasoning

Intelligence robotic system design involves sensor allocation and sensor data fusion. In the field of geometric reasoning, a fast and effective representation method is needed to determine the physical dimensions of the manipulator as well as the motion environment in sufficient detail. Due to the capability of current sensor technology, the integrity of the sensor information is location dependent and point-wise, line-wise and plane-wise in nature. In order to maneuver the robot by reasoning the environment, there is a minimum requirement of prior information for integrating the allocated sensor feedback. Some new theoretical developments of how to associate the number and the locations of the sensors with three-dimensional geometry of the robot and the motion environment is presented. The related collision avoidance problem (CAP) will be addressed as well.

Chen, Alexander Y. K.↗
NASA NTRS1990

A teleoperated robotic field geologist

A robotic field geologist, called Teleprospector, is proposed that would be teleoperated from a base on the moon, or possibly from the earth. For field work on Mars, Teleprospector could also be operated from a base in Mars orbit or on the Martian surface. The design incorporates telepresence, so the operator-geologist, though actually located thousands of kilometers away from the telerobot, has the sensation of being inside the body of the robot. The system could be equipped with superhuman sensory capabilities, such as multispectral eyes. This concept combines human intelligence with robotic capabilities, without risk to a human operator, yet still provides the operator with the important sense of personal involvement in the field work.

Taylor, G. Jeffrey↗
NASA NTRS1991

A unified teleoperated-autonomous dual-arm robotic system

A description is given of complete robot control facility built as part of a NASA telerobotics program to develop a state-of-the-art robot control environment for performing experiments in the repair and assembly of spacelike hardware to gain practical knowledge of such work and to improve the associated technology. The basic architecture of the manipulator control subsystem is presented. The multiarm Robot Control C Library (RCCL), a key software component of the system, is described, along with its implementation on a Sun-4 computer. The system's simulation capability is also described, and the teleoperation and shared control features are explained.

Hayati, Samad↗
NASA NTRS1990

An adaptive inverse kinematics algorithm for robot manipulators

An adaptive algorithm for solving the inverse kinematics problem for robot manipulators is presented. The algorithm is derived using model reference adaptive control (MRAC) theory and is computationally efficient for online applications. The scheme requires no a priori knowledge of the kinematics of the robot if Cartesian end-effector sensing is available, and it requires knowledge of only the forward kinematics if joint position sensing is used. Computer simulation results are given for the redundant seven-DOF robotics research arm, demonstrating that the proposed algorithm yields accurate joint angle trajectories for a given end-effector position/orientation trajectory.

Colbaugh, R.↗