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NASA NTRS1990

Advancing automation and robotics technology for the Space Station Freedom and for the US economy: Submitted to the United States Congress

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 the 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. This report is the ninth in a series of progress updates and covers the period between February 24, 1989, and July 12, 1989. NASA has accepted the basic recommendation of ATAC for its Space Station Freedom efforts. ATAC and NASA agree that the thrust of Congress is to build an advanced automation and robotics technology base that will support an evolutionary Space Station program and serve as a highly visible stimulator, affecting the U.S. long-term economy. The work of NASA and the Freedom contractors, e.g., Work Packages, as well as the Flight Telerobotic Servicer is identified. Research in progress is also described and assessments of the advancement of automation and robotics technology on the Space Station Freedom are given.

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NASA NTRS1990

Passive navigation using image irradiance tracking

Rotorcraft operating at low altitudes require navigational schemes for detecting terrain and obstacles. Due to the nature of the missions to be accomplished and available power onboard, a passive navigation scheme is desirable in this situation. The development of a passive navigation scheme using optical image sequences and vehicle motion variables from an onboard inertial navigation scheme is described. This approach combines the geometric properties of perspective projection and a feedback irradiance tracking scheme at each pixel in the image to determine the range to various objects within the field-of-view. Derivation of the numerical algorithm and simulation results are given. Due to the feedback nature of the implementation, the computational scheme is robust. Other applications of the proposed approach include navigation for autonomous planetary rovers and telerobots.

Menon, P. K. A.↗

NASA NTRS1990

Instrumentation and robotic image processing using top-down model control

A top-down image processing scheme is described. A three-dimensional model of a robotic working environment, with robot manipulators, workpieces, cameras, and on-the-scene visual enhancements is employed to control and direct the image processing, so that rapid, robust algorithms act in an efficient manner to continually update the model. Only the model parameters are communicated, so that savings in bandwidth are achieved. This image compression by modeling is especially important for control of space telerobotics. The background for this scheme lies in an hypothesis of human vision put forward by the senior author and colleagues almost 20 years ago - the Scanpath Theory. Evidence was obtained that repetitive sequences of saccadic eye movements, the scanpath, acted as the checking phase of visual pattern recognition. Further evidence was obtained that the scanpaths were apparently generated by a cognitive model and not directly by the visual image. This top-down theory of human vision was generalized in some sense to the frame in artificial intelligence. Another source of the concept arose from bioengineering instrumentation for measuring the pupil and eye movements with infrared video cameras and special-purpose hardware.

Stark, Lawrence↗

NASA NTRS1989

A robot arm simulation with a shared memory multiprocessor machine

A parallel processing scheme for a single chain robot arm is presented for high speed computation on a shared memory multiprocessor. A recursive formulation that is derived from a virtual work form of the d'Alembert equations of motion is utilized for robot arm dynamics. A joint drive system that consists of a motor rotor and gears is included in the arm dynamics model, in order to take into account gyroscopic effects due to the spinning of the rotor. The fine grain parallelism of mechanical and control subsystem models is exploited, based on independent computation associated with bodies, joint drive systems, and controllers. Efficiency and effectiveness of the parallel scheme are demonstrated through simulations of a telerobotic manipulator arm. Two different mechanical subsystem models, i.e., with and without gyroscopic effects, are compared, to show the trade-off between efficiency and accuracy.

Kim, Sung-Soo↗

NASA NTRS1990

Advancing automation and robotics technology for the Space Station Freedom and for the US economy

In April 1985, 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). The progress made by Levels 1, 2, and 3 of the Office of Space Station in developing and applying advanced automation and robotics technology are described. Emphasis was placed upon the Space Station Freedom Program responses to specific recommendations made in ATAC Progress Report 9, the Flight Telerobotic Servicer, the Advanced Development Program, and the Data Management System. Assessments are presented for these and other areas as they apply to the advancement of automation and robotics technology for the Space Station Freedom.

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NASA NTRS1989

Hierarchy of on-orbit servicing interfaces

A series of equipment interfaces is involved in on-orbit servicing operations. The end-to-end hierarchy of servicing interfaces is presented. The interface concepts presented include structure and handling, and formats for transfer of resources (power, data, fluids, etc.). Consequences on cost, performance, and service ability of the use of standard designs or unique designs with interface adapters are discussed. Implications of the interface designs compatibility with remote servicing using telerobotic servicers are discussed.

Moe, Rud V.↗

NASA NTRS1989

An Earth Orbiting Satellite Service and Repair Facility

A conceptual design was produced for the Geosynchronous Satellite Servicing Platform (GSSP), an orbital facility capable of repairing and servicing satellites in geosynchronous orbit. The GSSP is a man-tended platform, which consists of a habitation module, operations module, service bay and truss assembly. This design review includes an analysis of life support systems, thermal and power requirements, robotic and automated systems, control methods and navigation, and communications systems. The GSSP will utilize existing technology available at the time of construction, focusing mainly on modifying and integrating existing systems. The entire facility, along with two satellite retrieval vehicles (SRV), will be placed in geosynchronous orbit by the Advanced Launch System. The SRV will be used to ferry satellites to and from the GSSP. Technicians will be transferred from Earth to the GSSP and back in an Apollo-derived Crew Transfer Capsule (CTC). These missions will use advanced telerobotic equipment to inspect and service satellites. Four of these missions are tentatively scheduled per year. At this rate, the GSSP will service over 650 satelites during the projected 25 year lifespan.

Berndt, Andrew↗

NASA NTRS1990

Space Station Based Microacceleration Experiment Platform

Normal Space Station Freedom activities, such as docking, astronauts' movement, equipment vibrations, and space station reboosts, exert forces on the structure, resulting in static or transient accelerations greater than many microgravity experiments can tolerate. A solution to this problem is to isolate experiments on a separate platform free from such disturbances. The Space Station Based Microacceleration Experiment Platform, a proposed solution to the Space Station microgravity experiment problem is described. It is modular in design and can be telerobotically assembled and operated. The Microacceleration Experiment Platform (MEP) consists of a minimum configuration platform to which power, propulsion, propellant, and experiment modules are added. The platform's layout is designed to take maximum advantage of the microgravity field structure in orbit.

Barber, Katy↗

NASA NTRS1990

SDIO robotics in space applications

Robotics in space supporting the Strategic Defense System (SDS) program is discussed. Ongoing initiatives which are intended to establish an initial Robotics in Space capability are addressed. This is specifically being referred to as the Satellite Servicing System (SSS). This system is based on the NASA Orbital Maneuvering Vehicle (OMV) with a Robotic Manipulator(s) based on the NASA Flight Telerobotic Servicer (FTS) and other SSS equipment required to do the satellite servicing work attached to the OMV. Specific Robotics in Space Requirements which have resulted from the completion of the Robotics Requirements Study Contract are addressed.

Iliff, Richard↗

NASA NTRS1990

Visualization of three dimensional data

The objective of research is to characterize patterns of errors observers make when relating the judged exocentric direction of a target presented on a perspective display to their egocentric sense of visual direction. This type of spatial task is commonly faced by operators of telerobotic systems when using a map-like display of their workspace to determine the visual location and orientation of objects seen by direct view. It is also essentially the same task as faced by an aircraft pilot using a cockpit perspective traffic display of his surrounding airspace to locate traffic out his windows. The results of the current study clearly show that the visual direction is a significantly biased metric of virtual space presented by flat panel perspective displays. Modeling and explanation of the causes of the observed biases will allow design of compensated perspective displays.

Ellis, Stephen R.↗

NASA NTRS1990

A laboratory breadboard system for dual-arm teleoperation

The computing architecture of a novel dual-arm teleoperation system is described. The novelty of this system is that: (1) the master arm is not a replica of the slave arm; it is unspecific to any manipulator and can be used for the control of various robot arms with software modifications; and (2) the force feedback to the general purpose master arm is derived from force-torque sensor data originating from the slave hand. The computing architecture of this breadboard system is a fully synchronized pipeline with unique methods for data handling, communication and mathematical transformations. The computing system is modular, thus inherently extendable. The local control loops at both sites operate at 100 Hz rate, and the end-to-end bilateral (force-reflecting) control loop operates at 200 Hz rate, each loop without interpolation. This provides high-fidelity control. This end-to-end system elevates teleoperation to a new level of capabilities via the use of sensors, microprocessors, novel electronics, and real-time graphics displays. A description is given of a graphic simulation system connected to the dual-arm teleoperation breadboard system. High-fidelity graphic simulation of a telerobot (called Phantom Robot) is used for preview and predictive displays for planning and for real-time control under several seconds communication time delay conditions. High fidelity graphic simulation is obtained by using appropriate calibration techniques.

Bejczy, A. K.↗

NASA NTRS1989

A 17 degree of freedom anthropomorphic manipulator

A 17 axis anthropomorphic manipulator, providing coordinated control of two seven degree of freedom arms mounted on a three degree of freedom torso-waist assembly, is presented. This massively redundant telerobot, designated the Robotics Research K/B-2017 Dexterous Manipulator, employs a modular mechanism design with joint-mounted actuators based on brushless motors and harmonic drive gear reducers. Direct joint torque control at the servo level causes these high-output joint drives to behave like direct-drive actuators, facilitating the implementation of an effective impedance control scheme. The redundant, but conservative motion control system models the manipulator as a spring-loaded linkage with viscous damping and rotary inertia at each joint. This approach allows for real time, sensor-driven control of manipulator pose using a hierarchy of competing rules, or objective functions, to avoid unplanned collisions with objects in the workplace, to produce energy-efficient, graceful motion, to increase leverage, to control effective impedance at the tool or to favor overloaded joints.

Vold, Havard I.↗

NASA NTRS1989

A complete analytical solution for the inverse instantaneous kinematics of a spherical-revolute-spherical (7R) redundant manipulator

Using a method based upon resolving joint velocities using reciprocal screw quantities, compact analytical expressions are generated for the inverse solution of the joint rates of a seven revolute (spherical-revolute-spherical) manipulator. The method uses a sequential decomposition of screw coordinates to identify reciprocal screw quantities used in the resolution of a particular joint rate solution, and also to identify a Jacobian null-space basis used for the direct solution of optimal joint rates. The results of the screw decomposition are used to study special configurations of the manipulator, generating expressions for the inverse velocity solution for all non-singular configurations of the manipulator, and identifying singular configurations and their characteristics. Two functions are therefore served: a new general method for the solution of the inverse velocity problem is presented; and complete analytical expressions are derived for the resolution of the joint rates of a seven degree of freedom manipulator useful for telerobotic and industrial robotic application.

Podhorodeski, R. P.↗

NASA NTRS1989

A system architecture for a planetary rover

Each planetary mission requires a complex space vehicle which integrates several functions to accomplish the mission and science objectives. A Mars Rover is one of these vehicles, and extends the normal spacecraft functionality with two additional functions: surface mobility and sample acquisition. All functions are assembled into a hierarchical and structured format to understand the complexities of interactions between functions during different mission times. It can graphically show data flow between functions, and most importantly, the necessary control flow to avoid unambiguous results. Diagrams are presented organizing the functions into a structured, block format where each block represents a major function at the system level. As such, there are six blocks representing telecomm, power, thermal, science, mobility and sampling under a supervisory block called Data Management/Executive. Each block is a simple collection of state machines arranged into a hierarchical order very close to the NASREM model for Telerobotics. Each layer within a block represents a level of control for a set of state machines that do the three primary interface functions: command, telemetry, and fault protection. This latter function is expanded to include automatic reactions to the environment as well as internal faults. Lastly, diagrams are presented that trace the system operations involved in moving from site to site after site selection. The diagrams clearly illustrate both the data and control flows. They also illustrate inter-block data transfers and a hierarchical approach to fault protection. This systems architecture can be used to determine functional requirements, interface specifications and be used as a mechanism for grouping subsystems (i.e., collecting groups of machines, or blocks consistent with good and testable implementations).

Smith, D. B.↗

NASA NTRS1989

A neural network for controlling the configuration of frame structure with elastic members

A neural network for controlling the configuration of frame structure with elastic members is proposed. In the present network, the structure is modeled not by using the relative angles of the members but by using the distances between the joint locations alone. The relationship between the environment and the joints is also defined by their mutual distances. The analog neural network attains the reaching motion of the manipulator as a minimization problem of the energy constructed by the distances between the joints, the target, and the obstacles. The network can generate not only the final but also the transient configurations and the trajectory. This framework with flexibility and parallelism is very suitable for controlling the Space Telerobotic systems with many degrees of freedom.

Tsutsumi, Kazuyoshi↗

NASA NTRS1989

Reflexive obstacle avoidance for kinematically-redundant manipulators

Dexterous telerobots incorporating 17 or more degrees of freedom operating under coordinated, sensor-driven computer control will play important roles in future space operations. They will also be used on Earth in assignments like fire fighting, construction and battlefield support. A real time, reflexive obstacle avoidance system, seen as a functional requirement for such massively redundant manipulators, was developed using arm-mounted proximity sensors to control manipulator pose. The project involved a review and analysis of alternative proximity sensor technologies for space applications, the development of a general-purpose algorithm for synthesizing sensor inputs, and the implementation of a prototypical system for demonstration and testing. A 7 degree of freedom Robotics Research K-2107HR manipulator was outfitted with ultrasonic proximity sensors as a testbed, and Robotics Research's standard redundant motion control algorithm was modified such that an object detected by sensor arrays located at the elbow effectively applies a force to the manipulator elbow, normal to the axis. The arm is repelled by objects detected by the sensors, causing the robot to steer around objects in the workspace automatically while continuing to move its tool along the commanded path without interruption. The mathematical approach formulated for synthesizing sensor inputs can be employed for redundant robots of any kinematic configuration.

Karlen, James P.↗

NASA NTRS1989

The KALI multi-arm robot programming and control environment

The KALI distributed robot programming and control environment is described within the context of its use in the Jet Propulsion Laboratory (JPL) telerobot project. The purpose of KALI is to provide a flexible robot programming and control environment for coordinated multi-arm robots. Flexibility, both in hardware configuration and software, is desired so that it can be easily modified to test various concepts in robot programming and control, e.g., multi-arm control, force control, sensor integration, teleoperation, and shared control. In the programming environment, user programs written in the C programming language describe trajectories for multiple coordinated manipulators with the aid of KALI function libraries. A system of multiple coordinated manipulators is considered within the programming environment as one motion system. The user plans the trajectory of one controlled Cartesian frame associated with a motion system and describes the positions of the manipulators with respect to that frame. Smooth Cartesian trajectories are achieved through a blending of successive path segments. The manipulator and load dynamics are considered during trajectory generation so that given interface force limits are not exceeded.

Backes, Paul↗

NASA NTRS1989

Building an environment model using depth information

Modeling the environment is one of the most crucial issues for the development and research of autonomous robot and tele-perception. Though the physical robot operates (navigates and performs various tasks) in the real world, any type of reasoning, such as situation assessment, planning or reasoning about action, is performed based on information in its internal world. Hence, the robot's intentional actions are inherently constrained by the models it has. These models may serve as interfaces between sensing modules and reasoning modules, or in the case of telerobots serve as interface between the human operator and the distant robot. A robot operating in a known restricted environment may have a priori knowledge of its whole possible work domain, which will be assimilated in its World Model. As the information in the World Model is relatively fixed, an Environment Model must be introduced to cope with the changes in the environment and to allow exploring entirely new domains. Introduced here is an algorithm that uses dense range data collected at various positions in the environment to refine and update or generate a 3-D volumetric model of an environment. The model, which is intended for autonomous robot navigation and tele-perception, consists of cubic voxels with the possible attributes: Void, Full, and Unknown. Experimental results from simulations of range data in synthetic environments are given. The quality of the results show great promise for dealing with noisy input data. The performance measures for the algorithm are defined, and quantitative results for noisy data and positional uncertainty are presented.

Roth-Tabak, Y.↗