Remote Manipulator System Research Articles

Guidelines for the Use of Programmable Display Pushbuttons on the Space Station's Telerobot Control Panel

This investigation focused on the establishment of guidelines concerning the use of programmable display pushbuttons (PDPs) on a telerobot control panel. The method taken was to study two groups of subjects performing a simulated Remote Manipulator System (RMS)-like task on micro computer prototypes. Subjects were divided between those who had RMS-simulator experience and those who didn't. The computer prototypes contained simulations of two different control panels — one which used PDPs and one which used single-function pushbuttons. Data analysis revealed that there was a statistically significant ( p < 0.05) increase in the number of commands issued in the non-PDP control panel and that subjects rated the PDP control panel significantly higher on two of five scaled questionnaire items. Based on these findings, as well upon the results of responses to open-ended questionnaire items, a preliminary list of guidelines concerning the use of PDPs was developed.

On the expansion of ionospheric plasma into the near‐wake of the space shuttle orbiter

During the Spacelab 2 mission, while the Plasma Diagnostics Package was attached to the Remote Manipulator System, differential ion vector measurements were obtained in the near wake at a distance of 4‐5 Shuttle radii. The Orbiter's wake was found to fill in at a much faster rate than can be explained by simple thermal motion. The measurements strongly suggest that filling of the Orbiter's wake is produced by the process of "collisionless plasma expansion into a vacuum" and that, for oblique angles of the magnetic field and velocity vectors, the near wake plasma depletion a few radii downstream is not sensitive to the body scale size.

Control device effects on telerobotic manipulator operations

A series of simulation tests were performed to evaluate control input devices for the Remote Manipulator System ( rms). Six subjects operated the simulated rms in the manual end effector mode using two three-degrees-of-freedom ( dof) hand controllers and one six- dof hand controller. Two mission scenarios were used to vary operator workload. A task requiring docking to a stationary target from a six- dof offset was used to provide a low workload condition and a five- dof tracking task was used to provide a high-workload condition. Performance using the two types of controllers was compared in terms of task time, measures of position error, and operator ratings of workload. The results indicated few differences between the two controller types. Docking time was slightly longer with the six- dof controller, but the difference was not statistically significant. Differences in tracking errors were small, and no consistent pattern of differences was observed. Some differences in the operators' ratings of cognitive and manual control workload were found. The six- dof controller was rated slightly higher.

Orbiter environment at S- and Ku-band frequencies

Detailed measurements of the electric field strength associated with the Ku-band radar and S-band communication link were made by the Plasma Diagnostics Package (PDP) on STS 51F. These measurements were made while the PDP was attached to the Remote Manipulation System arm and again while the PDP was released as a subsatellite. The results indicate that cargo elements that remain inside of the scan limits of the radar should experience fields less than 2 V/m and that elements that may encounter the main beam can use 300 V/m as a design guideline with adequate safety margin. S-band fields tended to be several dB lower than worst-case predictions. Safe design practice indicates that an electric field E = 100/r (r in meters) should be used as a guideline for deployable systems. S-band electric fields within the cargo bay envelope should be less than 2 V/m even with edge diffraction effects and reflections from other payloads taken into account. The absolute accuracy of these measurements is about 2 dB.

All Resistojet Control of the NASA Dual Keel Space Station

This paper describes a control system that uses small (0.1 N) hydrogen fueled, high–expansion–ratio resistojets to control a space station’s position and attitude. The number and size of the resistojets is calculated based on requirements for stationkeeping, compensation for steady–state gravity–gradient and aerodynamic torques, momentum loading due to Mobile Remote Manipulator System motion, shuttle orbiter docking, and translational evasive maneuvering. The all resistojet control system performs continuous orbit maintenance while keeping the linear accelerations on the spacecraft lower than they would be without any control system operating. No momentum exchange devices are needed to augment the resistojets. Simulation results are given for nominal operations and rigid body response to shuttle orbiter docking.

Thermal ion perturbations observed in the vicinity of the Space Shuttle

During the Spacelab-2 Shuttle mission the University of Iowa Plasma Diagnostic Package (PDP) probed the plasma environment of the Space Shuttle by maneuvers at the end of the extended Remote Manipulator System (RMS) arm. Also the PDP was operated as a free flying satellite which remained in the vicinity of the Shuttle as the Shuttle was maneuvered about it. During this portion of the mission, the Bennett thermal ion mass spectrometer on the PDP measured some distinctive effects of the large and gaseous emitting Shuttle upon the ambient thermal plasma environment. Within the open cargo bay when thrusters were not firing there was typically an absence of measurable thermal ions when the bay was in the wake of the spacecraft. Just above the top of the bay when traces of ions are detected in the wake the dominant ion was the contaminant water. When the PDP was released in the wake of the Shuttle and moved away, the spin modulation of the ion flux into the spectrometer was initially different for the O + and H 2O + ions. The O + ions were streaming into the spectrometer from the spacecraft velocity direction whereas the water ions were flowing from a direction as much as 77° from this. The concentration of water ions in the near wake decreased with increasing distance, becoming less than the predominant ion O + at wake distances of the order of 30 m. However, traces of contaminant ions were present as far as the maximum distance of several hundred meters explored by the free-flying PDP. The neutral gases from the Shuttle extend in all directions as was shown by the presence of water ions, not only in the immediate vicinity of the Shuttle and in its wake but also even several hundred meters upstream. The presence of contaminant NO and O + 2 ions brings into question whether reliable ambient ion measurements can be made from the Shuttle.

Manned spacecraft automation and robotics

The Space Station holds promise of being a showcase user and driver of advanced automation and robotics technology. The author addresses the advances in automation and robotics from the Space Shuttle--with its high-reliability redundancy management and fault-tolerance design and its remote manipulator system--to the projected knowledge-based systems for monitoring, control, fault diagnosis, planning, and scheduling, and the telerobotic systems of the future Space Station.

Real-time simulation for space station

Real-time, man-in-the-loop simulation has served an important function in the NASA manned-space-flight program by providing the means to evaluate systems design and integrated systems performance on the ground in a simulated flight environment. The Space Shuttle Program has relied heavily on simulation throughout all phases of development and into Space Shuttle operations. The simulation facilities in the NASA Lyndon B. Johnson Space Center (JSC) Engineering Directorate used in support of Space Shuttle development and operations have been upgraded throughout the 16-year program and reflect near current technology in both computer systems and simulation software design. Operations of the JSC engineering simulation facility, the Systems Engineering Simulator, were expanded in 1985 to support Orbiter-related Space Station design activities such as Orbiter docking scenarios and the use of the Orbiter remote manipulator system in Space Station berthing scenarios. Development of a new Space Station simulation designed to provide long-term support to the Space Station Program is well under way. A description of the two Engineering Directorate simulation facilities, the Systems Engineering Simulator and the Shuttle Avionics Integration Laboratory, is presented. The function of each in support of the Space Shuttle Program is discussed, with emphasis on functions applicable to Space Station. The function of the Systems Engineering Simulator in Space Station development is described. Finally, a comprehensive and detailed description of the new Space Station simulation under development on the System Engineering Simulator is presented.

The Japanese Experiment Module

This paper describes Japanese Experiment Module (JEM) which is a Japanese contribution to International Space Station (SS) Program. First half of phase B study of JEM was completed last March successfully. JEM primary function and basic configuration has been established. JEM consists of a Pressurized Module (PM), an Exposed Facility (EF), a scientific/equipment airlock, a local remote manipulator, and an Experimental Logistic Module (ELM). With all those hardware elements, JEM will accommodate general scientific and technology development research (some of which are to utilize the advantage of microgravity environment), and also accommodate control panels for the Space Station Mobile Remote Manipulator System and attached payloads.

Measurements of plasma parameters in the vicinity of the space shuttle

A Langmuir probe flown as part of the Plasma Diagnostics Package aboard the third space shuttle flight was used to determine electron densities, temperatures and plasma potential in the vicinity of the shuttle orbiter. Measurements taken both in the cargo bay and 10 m above the cargo bay on the Remote Manipulator System arm are consistent with small satellite and laboratory results in that reduced densities and elevated temperatures are observed in the shuttle wake. The primary difference in the shuttle measurements is one of magnitude, i.e. orders of magnitude density decreases and factor of five temperature enhancements. Analysis of data taken in Δ N/ N mode (used to measure plasma density fluctuations) reveals large plasma fluctuations with a significant spectral component up through the lower-hybrid frequency. The peak amplitude of this Δ N/ N turbulence can be as high as a few percent, and the most intense turbulence seems to occur near regions with a steep gradient in plasma pressure.

Canadarm—a review of its flights

The Shuttle Remote Manipulator System (SRMS), or Canadarm, has been singularly successful in accomplishing both planned and unforeseen tasks in space. Following its first flight in November 1981, it has deployed payloads ranging in mass from 156 to 9765 kg. It has been flight tested for all its operating modes, its handling characteristics, and structural dynamics. It is now an operational subsystem of the Shuttle’s Orbiter. The SRMS was instrumental in the retrieval and repair of the Solar Maximum Mission Satellite (SMM) in 1984, and featured prominently in the salvage of the Palapa and Westar Satellites later that year. It has been used as an extension of the human arm in unforeseen duties such as removing ice from the orbiter’s waste management system and attempting to throw a switch on the malfunctioning Syncom Satellite. Most recently it has been part of an ingenious man/machine team in the in-orbit repair of the Syncom Satellite. A review of the highlights of the flight accomplishments of Canadarm is given.

Feasibility of Time Delay Compensation for a Space Teleoperation Task

Abstract When time delay is introduced in a remote manipulation system (RMS) due to long communication links the operator ability to perform complex tasks is decreased. A means to improve the manipulation performances is to compensate for time delay by displaying to the operator a predicted view of the system. The predictive technique is developed for a satellite grasping task that shows the two control problems time delay within the control loop inducing unstability time delay located on the reference input inducing a tracking error. In the first case a prediction algorithm is built using a dynamic model of the manipulator. in the second case the prediction of the reference input requires a model of the target movement that is real time identified. Digital simulations of the RMS where an automatic pilot is substituted to the operator have showed the efficiency of the method if the modelling is accurate enough. Then using a real teleoperator device, experiments have confirmed the previous results and have led to some basic considerations on the need to display the delayed view.

The Space Shuttle

Publisher Summary This chapter discusses the different aspects of Space Shuttle. The Space Shuttle orbiter Columbia flew for the first time on April 12, 1981. The Canadian-built Remote Manipulator System performance during the STS-7 mission was flawless as it achieved the first deployment and retrieval of a spacecraft, the West German Shuttle Pallet Satellite from the cargo bay. Additional scientific experimentation was accomplished on STS-7 with NASA's office of Space and Terrestrial Applications payload that remained fixed inside the payload bay to perform materials processing experiments. While the Shuttle flights have been demonstrating a large number of engineering accomplishments, the capabilities of the shuttle to provide outstanding scientific benefits have also been illustrated. The Multipurpose Experiment Support Structure was used on the OAST-1 mission, an experiment involving deployment of large structures in space and the Large Format Camera. The Shuttle revolution has also made it possible to offer space experimentation opportunities to new classes of investigators through small Self Contained Payload Program better known as Getaway Specials.

Human Operator Control of a Bilateral Teleoperator in Part-Simulation of Zero Gravity

An experimental investigation has been undertaken at the Jet Propulsion Laboratory to address issues associated with manual control of a teleoperated manipulator operated in an earth orbital environment (e.g., the Shuttle Remote Manipulator System (RMS)). Manual control of a teleoperator and the effect of microgravity on the operator's performance were examined using a force-reflecting hand controller (FRHC) and a gravity compensation system to simulate the effect of microgravity on the operator's arm. The kinematic and dynamic characteristics of the operator's arm and hand play a fundamental role in bilateral (backdriven) teleoperator control. Two control experiments were performed in this study: (a) verification of a linear damped harmonic oscillator model of human neuromotor control in trajectory formation and stability in standard one gravity (lg) operation, and (b) force tracking along simulated planes of resistance subject to unit pulse disturbance in simulated zero g operation. The results of the experiments verified the utility of the neuromotor model in teleoperator control performance and confirmed the existence of disturbance of human manual control performance associated with the micro-gravity condition. The results illustrate that compensatory techniques to return performance to a level commensurate with, or superior to, standard one gravity operation could be derived. These techniques are based on the human control model, and instituted through FRHC control parameter adjustment.

Radio frequency fields generated by the S-band communication link onOV102

The Space Shuttle STS-3 mission carried a Plasma Diagnostics Package (PDP) whose instrumentation included an S-band antenna and detector. The PDP was maneuvered by the Remote Manipulator System arm through a computer controlled sequence in the Orbiter's X-Z plane, above the quad and hemi S-band communications antennas. Antenna field strength measurements were conducted during transmitter high power modes, and the results were compared to ground full scale measurements and predictions. A field strength 4.8 + or - 3 dB higher than predicted is noted. This RF field is primarily due to the quad PM transmitter, whose power output of 115 W compares with 15 W for the hemi.

Wave emissions from dc and modulated electron beams on STS 3

The first active beam‐plasma experiments utilizing the space shuttle were carried out in March 1982 as part of the NASA Office of Space Science mission on the third space shuttle flight. A fast pulse electron generator emitted a 1‐keV, 100‐mA electron beam in either a continuous (dc) mode or an on/off modulated mode in the ELF to HF frequency range. Stimulated electrostatic and electromagnetic waves and associated plasma effects were measured with the plasma diagnostics package as it was maneuvered through and near the beam by the remote manipulator system. For the dc beam the wave spectrum was electrostatic, was peaked in the 300‐ to 500‐Hz range with a spectral density of 4 × 10−3 V2 m−2 Hz−1, and was unpolarized. Above the nominal lower hybrid resonance frequency the intensity decreased but was polarized. Strong emissions near the electron gyrofrequency and the plasma frequency were occasionally detected. The background spectrum was similar to the dc case for VLF and ELF modulations, but the emissions at the modulation frequency were more electromagnetic and more intense with field strengths of up to 1 Vm−1.

Subsatellite studies of wave, plasma, and chemical injections from Spacelab

Three classes of Orbiter subsatellites have been identified to support Spacelab active plasma investigations: 1) small, throw-away detectors which are not reusable; 2) medium-sized, recoverable subsatellites, and 3) large, maneuverable subsatellites with a significant orbit-adjust capability. A class 1 subsatellite—the Plasma Diagnostics Package (POP)—was utilized attached to the Remote Manipulator System on the STS-3 flight to diagnose effects of the fast pulse electron generator electron beam and of Orbiter-produced plasma wakes. On the Spacelab-2 mission, the PDP will be released as a subsatellite to examine Orbiter wakes out to 20 km and the ionospheric plasma depletion effects resulting from planned Orbiter engine-burns. Class 1 Magnetospheric Multiprobes and a class 2 Recoverable Plasma Diagnostics Package are under development for the follow-on Spacelab missions. In addition, a study has been completed on a class 3 Solar-Terrestrial Subsatellite. All of these planned subsatellites provide measurements of plasma composition, wave fields, particle spectra, and optical emissions.

Canadarm and the space shuttle

‘‘Canadarm’’ is the remote manipulator system (RMS) given by Canada to NASA for installation on the shuttle orbiter. The RMS is to be used for deployment, retrieval, and handling of payloads up to 65 000 lb mass, 15 ft in diameter and 60 ft in length. Controllability, operating constraints, flight environments, safety, reliability, volume, weight, and power allocations were factors which influenced the design. The system uses brushless dc servomotors to drive the six joints and the end effector of the 50 ft arm in a variety of control modes, which provide both manual and automatic control of arm functions. In describing the system, this paper concentrates on the various mechanical devices which are required to operate in the orbital environment and discusses some of the problems encountered during their development. SPAR Aerospace Ltd., under contract to the National Research Council of Canada, designed, developed, manufactured, tested, and delivered the system, which at the time of this writing has been successfully demonstrated on two flights of the orbiter ‘‘Columbia.’’

The Remote Manipulator System Second Generation Schemes

The Shuttle Remote Manipulator System is the payload handling system of the Space Shuttle Orbiter and will be used to deploy and retrieve satellites on-orbit. This paper gives an overview of future on-orbit manipulator tasks and discusses potential second generation RMS schemes. The paper concludes by identifying areas of research and development that will be required to ensure the appropriate level of technology development.

The Assembly of Large Structures in Space: An Evaluation of Hardware Configurations and Assembly Techniques through Neutral Buoyancy Simulation

The implementation of NASA's Space Transportation System (STS) presents the opportunity for the on-orbit assembly of structures which, before the advent of multi-launch missions, were not possible because of their physical size. This report presents the results of an eight-month effort in the investigation of assembly techniques and hardware configurations used in assembly of the basic tetrahedral cell by A7LB pressure-suited subjects in Marshall Space Flight Center's Neutral Bouyancy Simulator. Eleven subjects participated in assembly procedures which investigated two types of structural members and two configurations of attachment hardware. The assembly was accomplished through extra-vehicular activity (EVA) only, EVA with simulated manned maneuvering unit (MMU), and EVA with simulated MMU and simulated remote manipulator system (RMS). Assembly times as low as 10.20 minutes per tetrahedron were achieved.