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NASA's Autonomous Landing and Hazard Avoidance Technologies (ALHAT) project is currently developing the critical technologies to safely and precisely navigate and land crew, cargo and robotic spacecraft vehicles on and around planetary bodies. One key element of this project is a high-fidelity Flash Lidar sensor that can generate three-dimensional (3-D) images of the planetary surface. These images are processed with hazard detection and avoidance and hazard relative navigation algorithms, and then are subsequently used by the Guidance, Navigation and Control subsystem to generate an optimal navigation solution. A complex, high-fidelity model of the Flash Lidar was developed in order to evaluate the performance of the sensor and its interaction with the interfacing ALHAT components on vehicles with different configurations and under different flight trajectories. The model contains a parameterized, general approach to Flash Lidar detection and reflects physical attributes such as range and electronic noise sources, and laser pulse temporal and spatial profiles. It also provides the realistic interaction of the laser pulse with terrain features that include varying albedo, boulders, craters slopes and shadows. This paper gives a description of the Flash Lidar model and presents results from the Lidar operating under different scenarios.

The use of a space manipulator (robot) for capturing a tumbling object is a risky and challenging task, mainly because when the manipulator onboard a servicing satellite (base satellite) intercepts with an external object for capture, the resulting impulse will be transferred along the mechanical arm down to the servicing satellite causing disturbance to the attitude of the satellite. Such disturbance may destabilize the servicing satellite if the captured object is tumbling and the physical contact between the robot end-effector and the object is not controlled properly. Certainly, the risk may be mitigated with a force or impedance control capability of the manipulator. However, the implementation of force or impedance control usually requires the robot to have a joint torque sensing and control capability which is a very expensive requirement for a space manipulator. To date, there has never been a really flown space manipulator having a joint torque control capability. Further, even a force or impedance control capability becomes available, much development is still needed before safe capture of a tumbling object can be confidently tried in a real mission. This paper presents an optimal control strategy for a space manipulator to have minimal impact to the base satellite during a capturing operation. The idea is to first predict an optimal future time and motion state for capturing and then control the manipulator to reach the determined motion state such that, when the tip of the robot maneuvers to and intercepts with the tumbling object, a minimal attitude disturbance to the servicing satellite will occur. The proposed control strategy can be implemented regardless whether the manipulator has a joint torque control capability or not. Since the control acts before a physical contact happens, it will not affect but actually augment any existing force or impedance control capability of the manipulator. The proposed method is demonstrated using a simulation example.

An adaptive PID control method based on RBF neural network for the free-floating dual-arm space robot's uncertain system model is proposed in this paper. Bring about the precise control of joints and carrier by the design of the control algorithm for space robot. Compared to traditional control method, its adaptive ability is stronger and requirement for the linearization of dynamic equation's inertial parameters is weak. We put it compared to the adaptive PID control method which is a traditional control methods .Having simulation in the case of luffing, frequency conversion and posture intrusive. The results of experimental demonstrate the feasibility and practicability of this method.

Space robot is a special robotic system which is expected to perform important tasks in space, like servicing satellites. But any motion of robotic manipulator will disturb its supporting vehicle in space due to the dynamic coupling. Moreover, the evaluating method of manipulability used on ground can not be directly applied to the space robot. A volume element concept is developed to evaluate the manipulability and disturbance of a space robot system. This paper shows the application of volume element method in two-link planar space robot. The volume element method is a new theoretical approach for the research and analysis of space robot system.

For realizing omni-directional movement and operating task of spherical space robot system, this paper describes an innovated prototype and analyzes dynamic characteristics of a spherical rolling robot with telescopic manipulator. Based on the Newton-Euler equations, the kinematics and dynamic equations of the spherical robot's motion are instructed detailedly. Then the motion simulations of the robot in different environments are developed with ADAMS. The simulation results validate the mathematics model of the system. And the dynamic model establishes theoretical basis for the latter job.

Effective scientific exploration of remote targets such as solar system objects increasingly calls for autonomous data analysis and decision making on-board. Today, robots in space missions are programmed to traverse from one location to another without regard to what they might be passing by. By not processing data as they travel, they can miss important discoveries, or will need to travel back if scientists on Earth find the data warrant backtracking. This is a suboptimal use of resources even on relatively close targets such as the Moon or Mars. The farther mankind ventures into space, the longer the delay in communication, due to which interesting findings from data sent back to Earth are made too late to command a (roving, floating, or orbiting) robot to further examine a given location. However, autonomous commanding of robots in scientific exploration can only be as reliable as the scientific information extracted from the data that is collected and provided for decision making. In this paper, we focus on the discovery scenario, where information extraction is accomplished with unsupervised clustering. For high-dimensional data with complicated structure, detailed segmentation that identifies all significant groups and discovers the small, surprising anomalies in the data, is a challenging task at which conventional algorithms often fail. We approach the problem with precision manifold learning using self-organizing neural maps with non-standard features developed in the course of our research. We demonstrate the effectiveness and robustness of this approach on multi-spectral imagery from the Mars Exploration Rovers Pancam, and on synthetic hyperspectral imagery.

Virtual reality is an effective method to solve the time-delay problem in force-reflecting teleoperation, but it depends on the accuracy of the virtual model. So we consider the online error compensate of the predictive virtual model, for acquiring accurate interaction information. Firstly, the sliding average least square (SALS) method is adopted to identify the mass, damp and stiffness of the remote environment, in order to build and amend the virtual environment dynamic model in real time. Secondly, we consider the predictive virtual model as a time forward observer, and design our error compensate observer. Through constructing the dynamics equation of the system, we also analyzed the condition of stability and transparency. Experimental results are shown that these methods can reduce the influence of time delay with guarantee of stability, and promote the operability of the system.

Fault tolerance of robot was highly demanded in hazard working circumstances. And, actuator fault is a common type of system failure. This paper researches some basic issues of 2-DOF planar redundant actuation parallel system and faulting robot. At the beginning, the Jacobian matrix resolving problem of redundant actuation parallel robot is introduced, and the Jacobian matrix actuator fails is deduced. Furthermore, the forward and inverse position solution methods for both redundant actuation parallel manipulator and system with faulting actuator are presented. With detailed example, the validation of position solution method is proved. Moreover, the workspace analysis method of the redundant parallel manipulator pre and post faulting is addressed. Also, the resolving diagram is included. Finally, based on virtual work principle, a new way to reallocate actuation force and faulting compensation is introduced.

The robot vision measure system based on stereovision is a very meaningful research realm within the engineering application. In this system, the industry robot is the movable carrier of the stereovision sensor, not only extending the work space of the sensor, but also reserving the characteristics of vision measure technology such as non-contact, quickness, etc. Controlling the pose of the robot in space, the stereovision sensor can arrive at the given point to collect the image signal of the given point one by one, and then obtain the 3D coordinate data after computing the image data. The method based on the technique of binocular stereovision sensor, which uses two transit instruments and one precision drone to carry out the whole calibration, is presented. At the same time, the measurement program of the robot and the computer was written in different program language. In the end, the system was tested carefully, and the feasibility was proved simultaneously.

Present paper is aimed to work out efficient algorithm of multi-chain manipulator path planning in 3D space with static polygonal obstacles. The resulting solution is based on navigational maps approach. Using this approach, manipulator features are considered as intellectual agent, and reachability information is stored in compact form. This enables fast adaptation to arbitrary parameters of manipulator and workspace. The paper describes two algorithms: (i) a local walkthrough with obstacle avoidance, and (ii) incremental navigational map building, performed at running stage. Both algorithms take an extensive use of the specific features of the task. Working simultaneously, they allow real-time manipulator path planning, as well as self-learning in idle mode. Algorithms are implemented as a demonstration program.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A mobile robot can identify its own position relative to landmarks, the locations of which are known in advance. The main contribution of this research is that it gives various ways of making the self-localizing error smaller by referring to a sensitivity which is defined as the ratio of the localizing error to sensor error. In this paper, the authors propose the index to evaluate the accuracy of the self-localizing methods. And then, a rational way to minimize the localizing error is proposed. Finally, we discuss a method to reduce the computational cost of selecting the best self-localizing method.

On Earth orbit, astronomical observation is in very good condition that is free from any absorptions or disturbances by the Earth's atmosphere. Therefore, some large space telescopes and large space radio telescopes are planned. Diameter of payload bay of launch vehicle might be restriction for the size of such telescopes. That is the reason why structures larger than the payload bay have to be deployed or assembled onboard. Onboard assembling structure is better in surface accuracy and rigidity than deployable structure. We present a constitution of on-board assembling telescope reflector structure and its connecting mechanisms suitable for robot tasks. For assembling of such large structure, space robot has to move around on the structure. Power/signal lines, its connectors and grapple fixtures are needed on the structure for providing power/signal and foot restraints to the mobile robot arm. Compliant motions of robot are needed for constrained motion tasks such as grasping, attaching and mobile inchworm motion of onboard structure assembling. A new control method, active limp control of the robot arm joints, has high response and high stability because of their sensor/actuator collocation. So they are adequate to space robots for onboard assembling tasks. Constitutions of on-board assembling structure, a scenario of its assembling and control methods of the space robot are described in this paper. Characteristics of the new control methods and its suitability for onboard assembling tasks were confirmed by testing with using a prototype joint mechanism and its control system. The testing results and evaluation are also described in this paper.

Robonaut, NASA's latest anthropomorphic robot, is designed to work in the hazards of the space environment as both an astronaut assistant and, in certain situations, an astronaut surrogate. This highly dexterous robot is now performing complex tasks under telepresence control in the Dexterous Robotics Laboratory at the Johnson Space Center that could previously only be carried out directly by humans. With 43 degrees of freedom (DOF), Robonaut is a state-of-the-art human size telemanipulator system. It has a three-DOF articulated waist and two seven-DOF arms, giving it an impressive work space for interacting with its environment. Its two five-fingered hands allow manipulation of a wide range of common tools. A pan/tilt head with multiple stereo camera systems provides data for both teleoperators and computer vision systems. Telepresence control is the main mode of operation for Robonaut. The teleoperator dons a variety of sensors to map hand, head, arm and body motions to control the robot. A distributed object-oriented network architecture links the various computers used to gather posture and joint angle data from the human operator, to control the robot, to generate video displays for the human operator and to recognize and generate human voice inputs and outputs. Distributed object-oriented software allows the same telepresence gear to be used on different robots and allows interchangable telepresence gear in the laboratory environment. New telepresence gear and new robots only need to implement a standard software interface. The Robonaut implementation is a two-tiered system using Java/Jini for distributed commands and a commercial-off-the-shelf data sharing protocol for high-speed data transmission. Experimental telepresence gear is being developed and evaluated. Force feedback devices and techniques are a focus, and their efforts on teleoperator performance of typical space operations tasks is being measured. Particularly, the augmentation of baseline Robonaut teleoperation control techniques with force feedback information is shown to significantly reduce potentially damaging contact forces and improve operator consistency.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper, a PUMA562 robot, a micro CCD camera and an image acquisition card, along with IBM/PC 586 host computer, formed eye-in-hand visual servoing experimental system of an intelligent space robot. A novel robot visual servo control method is adopted, based on FMF neural network. Computer simulation and many experiments of object tracking with the capture of floating object were carried out in this eye-in- hand visual servoing system. It is an important reference to further research in the future.

This paper is concerned with the difficult and interesting problem of real-time planning and efficient motion control of rigid multi-robot systems to dynamically avoid moving obstacles and/or robots as these move. Most techniques described so far in the literature deal with the simpler problem of generating (generally off-line) a path among stationary obstacles. For practical purposes, however, obstacles are not always static and most interesting environments are in general not known precisely and/or time varying. Motivated by the fact that robots capable of maneuvering among moving obstalces will be capable of accomplishing a much larger and more versatile class of tasks, and as a result of our current and past research investigations over the years, we present an innovative approach and tackle the problem from a different angle. The proposed method follows upon our previous work which employs a notion of complex potential fields representation, and involves the use of state variables which preserve the Newman Boundary condition of such complex potential fields while allowing mobile robots to autonomously and dynamically avoid each other as well as other moving obstacles. In the heart of the technique is the exploitation of the powerful and fundamental tool of conformal mapping to derive the path solution for obstacles of arbitrary shapes. The advantage this novel approach offers over traditional formulations is its handling of both static and arbitrary moving obstacles/multi-robots. To the author's best knowledge, the proposed technique is the only proposed approach in the literature for real-time mobile robots motion control and obstacles avoidance which not only guarantees the reaching of the robot's goal under some conditions but also focuses on the means by which both the obstacles positions and orientations can elegantly and efficiently be dealt with when these latter continuously change with time.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

There is increasing realization that some tasks can be performed significantly better by humans than robots but, due to associated hazards, distance, etc., only a robot can be employed. Telemedicine is one area where remotely controlled robots can have a major impact by providing urgent care at remote sites. In recent years, remotely controlled robotics has been greatly advanced and the NASA Johnson Space Center’s robotic astronaut, “Robonaut,” is one such exa mple. Unfortunately, due to the unavailability of force and tactile feedback the operator must determine the required action by visually examining the remote site and therefore limiting the tasks that Robonaut can perform. There is a great need for dexterous, fast, accurate teleoperated robots with the operator's ability to "feel" the environment at the robot's field. The authors conceived a haptic mechanism called MEMICA (Remote MEchanical MIrroring using Controlled stiffness and Actuators) that can enable the design of high dexterity, rapid response, and large workspace haptic system. The development of a novel MEMICA gloves and virtual reality models are being explored to allow simulation of telesurgery and other applications. The MEMICA gloves are being designed to provide intuitive mirroring of the conditions at a virtual site where a robot simulates the presence of a human operator. The key components of MEMICA are miniature electrically controlled stiffness (ECS) elements and Electrically Controlled Force and Stiffness (ECFS) actuators that are based on the use of Electro-Rheological Fluids (ERF). In this paper the design of the MEMICA system and initial experimental results are presented.

Sensor fusion is an important technology, which is growing exponentially due to its tremendous application potential. Appropriate fusion technology is needed to be developed specially when a system requires redundant sensors to be used. The more the redundancy in sensors, the more the computational complexity for controlling the system and the more is its intelligence level. This research presents a strategy developed for multiple sensor fusion, based on geometric optimization. Each sensor's uncertainty model has been developed. Using Lagrangian optimization techniques the individual sensor's uncertainty has been fused to reduce the overall uncertainty to generate a consensus among the sensors regarding their acceptable values. Using fission-fusion architecture, the precision level has further been improved. Subsequently, using feed back from the fused sensory information, the net error has further been minimized to any pre assigned value by developing a fusion technique in the differential domain (FDD). The techniques have been illustrated using synthesized data from two types of sensors (optical encoder and a single camera vision sensor). The application experience of the same fusion strategy in improving the precision of correctness of stereo matching using multiple baselines has also been discussed.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Remote teleoperation allows humans to extend their capabilities to environments too dangerous for biological organisms. The communication between the operator and the robot needs to be fast in order to accommodate quick interaction with the environment. However, certain remote environments, such as deep-sea and space operations, impose restrictions on the communication link which limits the available bandwidth. In addition, as the distance increases, the communication between the operator and robot is further handicapped by significant time delays. The difficulties of controlling a robotic system remotely with long time delays and limited communication bandwidth are investigated. Four subjects performed a manipulator positioning task, controlling a simulated seven-joint manipulator under various time delay and communication rates. Results confirm performance degradation for 1.5, 3, and 6-second round trip delays. Compared to no delay, the time to complete the task increased between 160% and 480%. Limiting the communication bandwidth from 20 Hz also degraded performance, but not as severely as time delay. Only a 36% increase in completion time occurred when the bandwidth was reduced by a factor of eight to 2.5 Hz. A novel predictive display was introduced which dramatically decreased completion times to levels similar to no delay being present.

It is the most important that we perform safe and reliable teleoperation of space robots in the experiment/operation using real satellite. Therefore we have developed and used Audio Feedback System (AFS) that use some auditory information such as motorized sound and prerecorded voice converted from a part of telemetry information to reduce loads to operators of space robots of the Engineering Test Satellite VII(ETS-VII). We applied AFS to the experiment ofAntenna Assembling Mechanism (AAM) which is experiment module of the Communications Research Laboratory (CRL) on the ETS-Vil for testing the mechanism of assembling structures in space. Our purpose of this study is to assess effectiveness of AFS by using the Eye Mark Recorder (EMR) which records eye movements for the astronaut and two operators as telemetry monitor who observe telemetry data. In results of macro shape of 0-500 (deg/sec) velocity distribution graph, average fixation time, and average velocity of eye movement, we have got important points as followings: ( 1) the spectrum patterns of velocity of eye movement of specialist operator of controlling space robots like an astronaut are significantly differed from other two operators, (2) the spectrum patterns of velocity of eye movement of specialist operator and nonexpert operator are not affected ofAFS, (3) the spectrum patterns of velocity of eye movement of well-trained expert operator was similar to specialist operator with AFS and similar to nonexpert operators without AFS, (4) average fixation time of specialist operator was not effected by AFS, average fixation time of well-trained expert operator, nonexpert operator became long without AFS support.

The symbiosis between computer graphics and modern planning and control methodologies is the basis for the development of projective virtual reality based telepresence techniques at the IRF. Virtual world appear close-to-reality for the user because of the interaction modeling technique borrowed from the field of robotic research. These techniques provide an intuitively operable user~environment for a greater range of application.The underlying idea of projective virtual reality is to first let the user work in a virtual world modeled after the physical plant to control and supervice. A projective virtual reality system then automatically deduce the impact of the user”saction on the state of the virtual plant and in turn employs action planning method to generate the equivalent impact on the physical plant using robots or other means of automation.Thus the robots are projecting the user “s action from the virtual into the physical world. The the German /Japanese project GETEX (German ETS-VII Experiment),the IRF realized the telerobotic ground station for the free flying robot ERA on board the japanese satellite ETS-VII. During the mission in April 1999the Virtual Reality based command interface out to be an ideally suited platform for the intuitive commanding and supervision of the robotic in space.

At the Institute of Robotics Research in Germany (IRF), an excavator- and construction machine simulator based on latest virtual reality technology has been developed. The main issues of the realization so far have been the real-time capability, the close-to-reality presentation of the environment and the physically correct simulation of the process, i.e. the simulation of the flow of the material handled with e.g. the simulated excavator. In the next step, it is being envisaged to enhance the system in a way that it cannot only be used for training, but also to command and supervise large construction machines in real world applications by means of virtual reality and automatic action planning components. Experiences gained from the control of space robots being controlled by methods of “projective virtual reality” will be introduced into this application to allow one driver to remotely control several excavators e.g. in a mining environment. In the paper, we describe how the simulation of the excavator and its interaction with the handled material can be handled mathematically and we will explain the basic ideas of how to “project” action that were carried in the virtual word onto physical excavators by employing the methods of projective virtual reality.

Intelligent autonomous robotic systems require efficient safety components to assure system reliability during the entire operation. Especially if commanded over long distances, the robotic system must be able to guarantee the planning of safe and collision free movements independently. Therefore the IRF developed a new collision avoidance methodology satisfying the needs of autonomous safety systems considering the dynamics of the robots to protect. To do this, the collision avoidance system cyclically calculates the actual collision danger of the robots with respect to all static and dynamic obstacles in the environment. If a robot gets in collision danger the methodology immediately starts an evasive action to avoid the collision and guides the robot around the obstacle to its target position. This evasive action is calculated in real-time in a mathematically exact way by solving a quadratic convex optimization problem. The secondary conditions of this optimization problem include the potential collision danger of the robots kinematic chain including all temporarily attached grippers and objects and the dynamic constraints of the robots. The result of the optimization procedure are joint accelerations to apply to prevent the robot from colliding and to guide it to its target position. This methodology has been tested very successfully during the Japanese/German space robot project GETEX in April 1999. During the mission, the collision avoidance system successfully protected the free flying Japanese robot ERA on board the satellite ETS-VII at all times. The experiments showed, that the developed system is fully capable of ensuring the safety of such autonomous robotic systems by actively preventing collisions and generating evasive actions in cases of collision danger.

Commanding complex robotic systems over long distances in an intuitive manner requires new techniques of man-machine- interaction. A first disadvantage of conventional approaches is that the user has to be a robotic expert because he directly has to command the robots. He often is part of the real-time control loop while moving the robot and thus has to cope with long delays. Experience with space robot missions showed that it is very difficult to control a robot just by camera images. At the IRF, a new approach to overcome such problems was developed. By means of Projective Virtual Reality, we introduce a new, intuitive way of man-machine communication based on a combination of action planning and Virtual Reality methods. Using data-helmet and data-glove the user can immerse into the virtual world and interact with the virtual objects as he would do in reality. The Virtual Reality System derives the user's intention from his actions and then projects the tasks in to the physical world by means of robots. The robots carry out the action physically that is equivalent to the user's action in the virtual world. The developed Projective Virtual Reality System is of especially great use for space applications. During the joint project GETEX (German ETS-VII Experiment), the IRF realized the telerobotic ground station for the free flying robot ERA on board the Japanese satellite ETS-VII. During the mission in April 1999 the Virtual Reality based command interface turned out to be an ideally suited platform for the intuitive commanding and supervision of the robot in space. During the mission, it first had to be verified that the system is fully operational, but then out Japanese colleagues allowed to take the full control over the real robot by the Projective Virtual Reality System. The final paper will describe key issues of this approach and the results and experiences gained during the GETEX mission.

The Communications Research Laboratory has been studying the inspection technology needed for the first step of an Orbital Maintenance System (OMS) for maintaining space systems by inspecting satellites, re-orbiting useless satellites, and simply repairing satellites in orbit. OMS will use a modular manipulator for remote inspection. One of the most important issues concerning control of the modular manipulator is a determination process that utilizes its decentralized control architecture. In this paper, we introduce a decentralized kinematics control algorithm that automatically adapts to partial faults and reconfigures itself.

Through the study of 3D information acquisition technique, this paper proposed an experiment system for robot eye-in-hand vision 3D information acquisition. The system adopts to a singer camera, and realizes object space 3D information through the detection to object for PUMA562 robot system. This system has been successfully implied in space robot system and intelligent grippers.

A set of tolls addressing the problems specific to the control and monitoring of remote robotic systems from extreme distances has been developed. The tools include the capability to model and visualize the remote environment, to generate and edit complex task scripts, to execute the scripts to supervisory control mode and to monitor and diagnostic equipment from multiple remote locations. Two prototype systems are implemented for demonstration. The first demonstration, using a prototype joint design called Dexter, shows the applicability of the approach to space robotic operation in low Earth orbit. The second demonstration uses a remotely controlled excavator in an operational open-pit tar sand mine. This demonstrates that the tools developed can also be used for planetary exploration operations as well as for terrestrial mining applications.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Communications Research Laboratory has been studying the inspection technology needed for the first step of 'Orbital Maintenance System' (OMS) that maintains space system by inspecting of satellites, re-orbiting useless satellites, and simply repairing satellites in orbit. In this paper, we introduce a re-configurable modular-type manipulator for space utilization, and its control algorithm for the inspection of satellites in orbit. The manipulator system is interconnected by a joint mechanism which can be connected and disconnected by simple robotic motion and also resist inertia during space operation. The modules are also specially designed for thermal, vacuum, and radiation conditions. The control processors are qualified in a piggyback flight on 2000. We have adopted a decentralized control algorithm for the redundant manipulator, which automatically adapts to the manipulator reconfigurations.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper reports research in compensating for position inaccuracy and flexibility problems in a loosely coupled robot arm by means of machine learning methods. Error sources in the system are studied and problems are described. A number of methods for eliminating problems due to inaccuracy in 2D-space have been previously reported. These methods have been extended to address the problem in 3 dimensions. Utilizing a real time monitoring system, the end-effector position is sensed. The collected data is converted into appropriate error maps. Using a novel machine learning method, the error maps are used to predict system errors and compensate for them. The machine learning engine generalizes the data for the points between the sampled points. The experimental results are presented.

The 3D shape measurement and recognition of surroundings are expected for advanced space robot missions, such as on-orbit inspections, autonomous navigation of robots, and so on. We have been studying small size scanning laser range finders for space applications for years, and have just developed a new compact model for small on-orbit robots and small rovers. In this paper, its design and test results are described, comparing them with our previous model, which have been used for research test of autonomous rover navigation these years.

Experiments have confirmed the feasibility of an innovative, new class of very simple, reliable, low mass, low packaging volume, and low-cost self-deployable structures for space and commercial applications. The concept called 'cold hibernated elastic memory' (CHEM) utilizes shape memory polymers (SMP) in open cellular (foam) structures. The SMP foam materials are under development by the Jet Propulsion Laboratory (JPL) and Mitsubishi Heavy Industries (MHI). The CHEM structures are described here and their major advantages are identified over other expandable/deployable structures. In preliminary proof- of-concept investigation conducted on SMP foams, all evaluation/test results were very encouraging and confirmed the basic characteristics of CHEM structures. The main objective of this program is to develop and validate the CHEM structure technology for most promising space applications. However, possible terrestrial commercial applications are also anticipated and described in this paper as well.

This paper presents an update on the Ranger Telerobotic Shuttle Experiment (RTSX) and associated key robotics technologies within the Ranger program. Ranger TSX will operate from a Spacelab logistics pallet inside the cargo bay of the shuttle and will demonstrate space station and on-orbit servicing operations including extravehicular (EVA) worksite setup, an orbital replacement unit (ORU) exchange, and various task board experiments. The flight system will be teleoperated from the middeck inside the shuttle as well as from a ground control station at NASA Johnson Space Center. This paper addresses the technical and programmatic status of the flight experiment and describes progress on the engineering test unit, Ranger Neutral Buoyancy Vehicle II (RNBVII), currently in fabrication. Also described are associated technologies, which support this effort. These include a flight robot mockup built to practice EVA stowage and Ranger NBV I, a free-flight prototype vehicle.

Antenna assembly by space robots is an effective method for producing large antennas in space and it offers several advantages over using inflatable antennas and deployable antennas. The Communications Research Laboratory has developed such assembled antennas as a means to produce large space antennas, and the first on-board experiments were performed on Engineering Test Satellite VII, which was launched in 1997. In this paper, we outline the antenna- assembly experiments on ETS-VII and present initial experiments results.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The body of work called `Camera Space Manipulation' is an effective and proven method of robotic control. Essentially, this technique identifies and refines the input-output relationship of the plant using estimation methods and drives the plant open-loop to its target state. 3D `success' of the desired motion, i.e., the end effector of the manipulator engages a target at a particular location with a particular orientation, is guaranteed when there is camera space success in two cameras which are adequately separated. Very accurate, sub-pixel positioning of a robotic end effector is possible using this method. To date, however, most efforts in this area have primarily considered holonomic systems. This work addresses the problem of nonholonomic camera space manipulation by considering the problem of a nonholonomic robot with two cameras and a holonomic manipulator on board the nonholonomic platform. While perhaps not as common in robotics, such a combination of holonomic and nonholonomic degrees of freedom are ubiquitous in industry: fork lifts and earth moving equipment are common examples of a nonholonomic system with an on-board holonomic actuator. The nonholonomic nature of the system makes the automation problem more difficult due to a variety of reasons; in particular, the target location is not fixed in the image planes, as it is for holonomic systems (since the cameras are attached to a moving platform), and there is a fundamental `path dependent' nature of nonholonomic kinematics. This work focuses on the sensor space or camera-space-based control laws necessary for effectively implementing an autonomous system of this type.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Animals have been considered to develop ability for interpreting images captured on their retina by themselves gradually from their birth. For this they do not need external supervisor. We think that the visual function is obtained together with the development of hand reaching and grasping operations which are executed by active interaction with environment. On the viewpoint of hand teaches eye, this paper shows how visual space perception is developed in a simulated robot. The robot has simplified human-like structure used for hand-eye coordination. From the experimental results it may be possible to validate the method to describe how visual space perception of biological systems is developed. In addition the description gives a way to self-calibrate the vision of intelligent robot based on learn by doing manner without external supervision.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper we propose a system for studying emergence of motion patterns in autonomous mobile robotic systems. The system implements an instance-based reinforcement learning control. Three spaces are of importance in formulation of the control scheme. They are the work space, the sensor space, and the action space. Important feature of our system is that all these spaces are assumed to be continuous. The core part of the system is a classifier system. Based on the sensory state space analysis, the control is decentralized and is specified at the lowest level of the control system. However, the local controllers are implicitly connected through the perceived environment information. Therefore, they constitute a dynamic environment with respect to each other. The proposed control scheme is tested under simulation for a mobile robot in a navigation task. It is shown that some patterns of global behavior--such as collision avoidance, wall-following, light-seeking--can emerge from the local controllers.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Robots operating in an unstructured environment need high level of modeling of their operational space in order to plan a suitable path from an initial position to a desired goal. From this perspective, operational space modeling seems to be crucial to ensure a sufficient level of autonomy. In order to compile the information from various sources, we propose a fuzzy approach to evaluate each unit region on a grid map by a certain value of transition cost. This value expresses the cost of movement over the unit region: the higher the value, the more expensive the movement through the region in terms of energy, time, danger, etc. The approach for modeling, proposed in this paper, employs fuzzy granulation of information on various terrain features and their combination based on a fuzzy neural network. In order to adapt to the changing environmental conditions, and to improve the validity of constructed cost maps on-line, the system can be endowed with learning abilities. The learning subsystem would change parameters of the fuzzy neural network based decision system by reinforcements derived from comparisons of the actual cost of transition with the cost obtained from the model.

Collision freeness is an essential feature in off-line programming of robots. It relates to safe and efficient operation, and becomes even more critical, when two or more robots are sharing the same work space, which is typical for so called holonic robot systems. Here we are reporting a simple and fast path planning algorithm based on configuration space method, suitable for holonic robot applications. The basic version of the algorithm can be found from the literature, and we have extended and modified it to improve its feasibility. Simulation and experimental tests have been carried out successfully.

For planetary surface operations, the European Space Agency initiated a development for teleoperated mini-rovers. Remote control functions related to autonomous reaction capabilities and sensor data processing on-board the vehicle exhibit interesting transfer potential to industrial and educational teleoperation tasks. Similar requirements to the space application arise in particular, when low cost communication links are used for teleservicing. This paper reviews the operational concept for the Mars rover and its operations test environment. The technology transfer to terrestrial teleservicing applications is analyzed, regarding remotely controlled equipment or robots. This is illustrated at the example of pipe inspection robots, industrial transport robots and virtual laboratories for educational purposes.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper presents an automated parking strategy for a car- like mobile robot. The study considers general parking manoeuvre cases for a rectangular robot, including parallel parking. The robot is constructed simulating a conventional car, which is subject to non-holonomic constraints and thus only has two degrees of freedom. The parking space is considered as rectangular, and detected by ultrasonic sensors mounted on the robot. A motion planning algorithm develops a collision-free path for parking, taking into account the non- holonomic constraints acting on the car-like robot. A research into general car maneuvers has been conducted and useful results have been achieved. The motion planning algorithm uses these results, combined with configuration space method, to produce a collision-free path for parallel parking, depending on the parking space detected. A control program in the form of a graphical user interface has been developed for users to operate the system with ease. The strategy is implemented on a modified B12 mobile robot. The strategy presented has the potential for application in automobiles.

This work prescribes the procedures that are required to implement, on a conventional mobile robot, a sensor based motion planning algorithm based on the generalized Voronoi graph (GVG). The GVG is a roadmap of a static environment; recall that a roadmap is a 1D representation of an environment which the robot can use to plan a path between any two points in that environment. Once the robot has constructed the roadmap, it has in essence explored the environment. This work describes some issues in incrementally constructing the GVG with a mobile robot wit a ring of sonar sensors. Specifically, we consider some issues in specularity and dead-reckoning error reduction.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper, behavior-based cognitive control for special shape mobile robots is studied thoroughly by using reinforcement learning idea. The study case considered is that a cross mobile robot with the shape of a Greek cross '+', which is equipped with a perception system for sensing environment, passes through a crack whose width is less than the width and length of robot body. This means that the robot can never pass through the narrow crack unless it knows how to take advantage of its self special shape intelligently. The objective of our work is to investigate how to automatically generate a trajectory for the mobile robot based on its own behavior. In the paper we first briefly introduce a behavior-based cognitive control system developed in Windows platforms, by which we can design and study various behavior-based cognitive control schemes for different shape mobile robots. Secondly, we discus the definitions of state and action space for the behavior-based cognitive control, and then investigate a learning algorithm using reinforcement learning idea. Thirdly, we propose a behavior-based cognitive control architecture. Finally, in order to prove the validity and efficiency of the developed behavior-based control strategy, we present some simulation results for the cross mobile robot.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper discusses a new testbed developed at the Stanford Aerospace Robotics Laboratory (ARL) to address some of the key issues associated with semi-autonomous construction in a hazardous environment like space. The new testbed consists of a large two-link manipulator carrying two smaller two-link arms. This macro/mini combination was developed to be representative of actual space manipulators, such as the SSRMS/SPDM planned for the Space Station. This new testbed will allow us to investigate several key issues associated with space construction, including teleoperation versus supervised autonomy, dexterous control of a robot with flexibility, and construction with multiple robots. A supervised autonomy approach has several advantages over the traditional teleoperation mode, including operation with time delay, smart control of a redundant manipulator, and improved contact control. To mimic the dynamics found in space manipulators, the main arm was designed to include joint flexibility. The arm operates in 2-D, with the end-point floating on air-bearing. This setup allows cooperation with existing free-flying robots in the ARL. This paper reports the first experiments with the arm which explore the advantages of moving from teleoperation or human-in-the-loop control to the human supervisory or task-level control. A simple task, such as capturing a satellite-like object floating on the table, is attempted first with the human directly driving the end-point and second with the human directing the robot at a task-level. Initial experimental results of these two control approaches are presented and compared.

We propose the use of cubic quadratic cubic squared (CQCS) spline for the trajectory generation in Cartesian space. Use of CQCS spline gives simple analytical solution to minimum time trajectory generation with velocity and acceleration constraints. The expressions for wandering time and wandering acceleration are also calculated. A straight line path with constant maximum allowed speed in minimum time can be generated with this method. This property leads to interpolate two position points by constant speed straight line motion with smooth transition. The advantage of this method is that the trajectory thus obtained is traversed in minimum time while passing through the given intermediate points. The simplicity of this method makes its on-line computation possible.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This article presents a method to combine data from two sensorial modalities, a stereoscopic vision based sensor and a ring of ultrasonic sensors, in a grid based framework for obstacle detection and avoidance with mobile robots. The sensors' data is combined using Dempster-Shafer theory. This theory allows the combination of multiple sensorial data sources in a way that they are mutually enhanced and validated. A connectionist grid is used to support these operations and the environment modeling. Each grid node maps a configuration in a discrete subset of the robot's configuration space. The process used to obtain obstacle presence information from the stereoscopic setup and ultrasonic sensors is explained in detail. Detected obstacles result in sets of restricted configurations. The grid dynamic behavior allows the iterative computation of a repulsive potential field, which rises in the vicinity of the restricted configurations. As new information is collected by the sensors during the robot's motion so new configurations are marked as restrict and the potential field changes accordingly. Since this process occurs in real time, the computed potential field can be used to navigate the robot avoiding the detected obstacles. Experimental results are presented to support the used sensor models, the integration procedure and the control strategy.

The assembly of the International Space Station will require the robotic manipulation of elements with a degree of complexity and restricted visibility which will be unprecedented in the history of manned space operations. Space-based robotic operators will maneuver multi-ton space station elements into tight capture envelopes with limited, non-orthogonal camera views and little to no direct viewing through windows. A camera-based system known as the Canadian Space Vision System will provide astronauts with the necessary precise positioning cues to perform these element berthings. An experimental version of this vision system was utilized on the space shuttle Columbia flight in November, 1996 to demonstrate element berthings and to evaluate several space station assembly operations.

The International Space Station (ISSP) currently under development is equipped with robotic workstations to perform and provide information on the mobile servicing system robotic functions in use. The workstations include conventional and special developed hardware, software displays, and control software configurations. The robotic activities are critical to the ISSP during assembly and maintenance activities resulting in detailed crew interface requirements. Operational scenarios were used to develop the requirements of the ISSP Robotic activities resulting in the specification and configuration of the Mobile Servicing System Robotic Workstation.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We report a significant advance in space robotics design based on innovation of 3D composite structures and piezoelectronic actuation.

Human visual system is well suited for reliable and adequate volumic perception of natural environment. Volumic data flows coming from outer physical space are easily acquired in real time. Current modes of imitating physical spaces or creating of hypothetical virtual spaces have a lot of drawbacks. The quality and the speed of volumic data presentation are severely limited. Moreover most of current devices destined to operate with artificially generated volumic data flows seem poorly compatible with eye/brian data processing procedures. It can be illustrated for example by multiple failures in introduction of public stereoscopic TV in spite of numerous lengthy efforts made for years since the appearance of TV. Thus quite novel approaches must be formulated and novel principles introduced. Unified concept of volumic imaging of artificially generated data is introduced here. This concept gives way to creation of principally novel prospective devices which might drastically enhance authenticity of perceived artificially generated data. Quite novel principle of 'one-eyed' volumic imaging system for robotics is proposed.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Ranger Telerobotic Flight Experiment is planned for launch into low Earth orbit in the Space Shuttle in 1998. During its mission, the Ranger space telerobot will demonstrate a wide variety of spacecraft servicing capabilities, and will set the stage for future telerobotic spacecraft servicing missions in Earth orbit. With for highly advanced robot manipulators and the capability for free flight in the space environment, the Ranger spacecraft will be able to perform on-orbit servicing tasks previously accomplishable only by astronauts. An underwater analog to the Ranger spacecraft has already been developed and is collecting data for comparison against the flight experiment data. It is anticipated that the results of the Ranger mission will lead to a new class of dexterous extravehicular telerobots for use in on-orbit spacecraft servicing operations.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper, we studied the trajectory generation problem for a two-degrees-of-freedom robot in a workspace with obstacles. To generate the robot's trajectories, we developed a genetic algorithm to search for valid solutions in the configuration space. Our results present a novel perspective on the problem not seen in the conventional robot trajectory planners. The genetic algorithm approach is beneficial because it may be extended to plan trajectories for robots with more degrees of freedom. The evolutionary search process may allow the user to solve the trajectory problem in an n-dimensional space where the 'curse of dimensionality' inevitably stalls conventional methods. We demonstrate the algorithm with some examples and discuss the possible extension to higher order problems.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.