Generally, there are multiple sensor suites on existing rover platforms such as NASA's Sample Return Rover (SRR) and the Field Integrated Design and Operations (FIDO) rover at JPL. Traditionally, these sensor suit...
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ISBN:
(纸本)0819434329
Generally, there are multiple sensor suites on existing rover platforms such as NASA's Sample Return Rover (SRR) and the Field Integrated Design and Operations (FIDO) rover at JPL. Traditionally, these sensor suites have been used in isolation for such tasks as planetary surface traversal. For example, although distant obstacle information is known from the narrow FOV navigation camera (NAVCAM) suite on SRR or FIDO, it is not explicitly used at this time for augmentation of the wide FOV hazard camera (HAZCAM) information for obstacle avoidance. This paper describes the development of advanced rover navigation techniques. These techniques include an algorithm for the generation of range maps using the fusion of information from the NAVCAMs and HAZCAMs, and an algorithm for registering range maps to an a priori model-based range map for relative rover position and orientation determination. Experimental results for each of these techniques are documented in this paper.
Fusing information of multiple sensors is particularly difficult if the sensorsystems which provide the information have very different characteristics such as different data formats, reliabilities, signal to noise r...
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ISBN:
(纸本)0819434329
Fusing information of multiple sensors is particularly difficult if the sensorsystems which provide the information have very different characteristics such as different data formats, reliabilities, signal to noise ratios, sampling rates and so on. Furthermore, the information is often provided on different levels of abstraction such as the direct sensor output in contrast to expert knowledge or a priori information. We propose a new approach to sensorfusion which accounts for these problems. The basic idea is to represent the quantity to estimate as the state variable of a nonlinear dynamical system. The sensor signals act on this dynamics by specifying attractors with limited range of influence. The dynamics relaxes into a stable state which results from the superposition of the attractors. By means of the limited attractor ranges, the dynamics automatically averages nonlinearly over corresponding sensor signals while outliers stemming from temporarily de-calibrated or erroneous sensors are discarded. Self-calibration is achieved by representing also the sensor signals as dynamical states and specifying an attractor at the position of the fused estimate. By using the unified attractor representation, abstract information can be treated in the same way as direct sensor input. Furthermore a mathematically well defined and algebraically analyzable format for dynamic sensor information on various levels of abstraction is available. We verify our concept for the example of man-machine interaction: fusing visual and odometric sensor information for the autonomous position estimation with acoustic guidance information for the target acquisition of a mobile robot.
Emergence of stable gaits in locomotion robots is studied in this paper. A classifier system, implementing an instance-based reinforcement learning scheme, is used for sensory-motor control of an eight-legged mobile r...
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ISBN:
(纸本)0819434329
Emergence of stable gaits in locomotion robots is studied in this paper. A classifier system, implementing an instance-based reinforcement learning scheme, is used for sensory-motor control of an eight-legged mobile robot. Important feature of the classifier system is its ability to work with the continuous sensor space. The robot does not have a priori knowledge of the environment, its own internal model, and the goal coordinates. It is only assumed that the robot can acquire stable gaits by learning how to reach a light source. During the learning process the control system is self-organized by reinforcement signals. Reaching the light source defines a global reward. Forward motion gets a local reward, while stepping back and falling down get a local punishment. Feasibility of the proposed self-organized system is tested under simulation and experiment. The control actions are specified at the leg level. It is shown that, as learning progresses, the number of the action rules in the classifier systems is stabilized to a certain level, corresponding to the acquired gait patterns.
We investigate teams of complete autonomous agents that can collaborate towards achieving precise objectives in an adversarial dynamic environment. We have pursued this work in the context of robotic soccer both in si...
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ISBN:
(纸本)0819434329
We investigate teams of complete autonomous agents that can collaborate towards achieving precise objectives in an adversarial dynamic environment. We have pursued this work in the context of robotic soccer both in simulation and with real physical robots. We briefly present these two frameworks emphasizing their different technical challenges. Creating effective members of a team is a challenging research problem. We first address this issue by introducing a team architecture organization which allows for a rich task decomposition between team members. The main contribution of this paper is our introduction of an action-selection algorithm that allows for a teammate to anticipate the needs of other teammates. Anticipation is critical for maximizing the probability of successful collaboration in teams of agents. We show how our contribution applies to the two concrete robotic soccer frameworks and present controlled empirical results run in simulation. Anticipation was successfully used by both our CMUnited-98 simulator and CMUnited-98 small-robot teams in the RoboCup98 competition. The two teams are RoboCup-98 world champions each in its own league.
In the framework of our biologically inspired robotics approach, we describe a visually-guided demonstration model aircraft, the attitude of which is stabilized in yaw by means of a novel, non emissive optical sensor ...
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ISBN:
(纸本)0819434329
In the framework of our biologically inspired robotics approach, we describe a visually-guided demonstration model aircraft, the attitude of which is stabilized in yaw by means of a novel, non emissive optical sensor having a small visual field. This aircraft incorporates a miniature scanning sensor consisting of two photoreceptors with adjacent visual axes, driving a Local Motion Detector (LMD), which are made to perform a low-amplitude scanning at a varying angular speed. Under these conditions, the signal output from the motion detector varies gradually with the angular position of a contrasting object placed in its visual field, actually making the complete system a non-emissive optical "position sensor". Its output, remarkably, (i) varies quasi-linearly with the angular position of the contrasting object, and (ii) remains largely invariant with respect to the distance to the object and its degree of contrast. We built a miniature, twin-engine, twin-propeller aircraft (weight 100 grammes) equipped with this visual position sensor. After incorporating the sensor into a visuomotor feedback loop enhanced by an inertial sensor, we established that the "sighted aircraft" can fixate and track a dark edge placed in its visual field, thus opening the way for the development of visually-guided systems for controlling the attitude of micro-air vehicles, of the kind observed in insects such as hover-flies.
As part of a project for the Defense Advanced Research Projects Agency, Sandia National Laboratories' Intelligent systems & robotics Center is developing and testing the feasibility of a cooperative team of ro...
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ISBN:
(纸本)0819434329
As part of a project for the Defense Advanced Research Projects Agency, Sandia National Laboratories' Intelligent systems & robotics Center is developing and testing the feasibility of a cooperative team of robotic sentry vehicles to guard a perimeter and to perform a surround task. This paper describes on-going activities in the development of these robotic sentry vehicles. To date, we have developed a robotic perimeter detection system which consists of eight "Roving All Terrain Lunar Explorer Rovers" (RATLER(TM)), a laptop-based base-station, and several Miniature Intrusion Detection sensors (MIDS). A radio frequency receiver on each of the RATLER vehicles alerts the sentry vehicles of alarms from the hidden MIDS. When an alarm is received, each vehicle decides whether it should investigate the alarm based on the proximity of itself and the other vehicles to the alarm As one vehicle attends an alarm, the other vehicles adjust their position around the perimeter to better prepare for another alarm For the surround task both potential field and A* search path planners have been added to the base-station and vehicles. At the base-station, the operator specifies goal and exclusion regions on a GIS map. The path planner generates vehicle paths that are previewed by the operator. Once the operator has validated the path, the appropriate information is downloaded to the vehicles. For the potential field path planner, the polygons and line segments that represent the obstacles and goals are downloaded to the vehicles, instead of the simulated paths. On board the vehicles, the same potential field path planner generates the path except that it uses the true location of itself and the nearest neighboring vehicle. For the A* path planner, the actual path is downloaded to the vehicles because of limited on-board computational power.
New generations of modular and reconfigurable roboticsystems with many degrees of freedom can be transformed to achieve different functions, modes of manipulation, and means of mobility resulting in efficient multifu...
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New generations of modular and reconfigurable roboticsystems with many degrees of freedom can be transformed to achieve different functions, modes of manipulation, and means of mobility resulting in efficient multifunctional systems which adapt to complex environments. The design of modular distributed algorithms and architectures for control of these systems is particularly challenging since kinematic and dynamic performance must be maintained throughout a range of alternative physical reconfigurations. The `Tetrobot' is a prototype modular system using parallel, variable geometry truss-like mechanisms which can be reconfigured to create moving platforms, walking machines, manipulator arms, a pipe crawler and other devices. Modular algorithms for distributed control and dynamic redundancy resolution of these systems will be discussed, and the principles of distributed control for modular systems generalize beyond these specific mechanisms. The resulting Tetrobot system has a range of interesting applications including space robotics, construction, mining, medical, undersea, and flexible manufacturing.
The Accident Response Mobile Manipulator System (ARMMS) is a teleoperated emergency response vehicle that deploys two hydraulic manipulators, five cameras, and an array of sensors to the scene of an incident. It is op...
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The Accident Response Mobile Manipulator System (ARMMS) is a teleoperated emergency response vehicle that deploys two hydraulic manipulators, five cameras, and an array of sensors to the scene of an incident. It is operated from a remote base station that can be situated up to four kilometers away from the site. Recently, a modular telerobot control architecture called SMART (Sandia's Modular Architecture for robotic and Teleoperation) was applied to ARMMS to improve the precision, safety, and operability of the manipulators on board. Using SMART, a prototype manipulator control system was developed in a couple of days, and an integrated working system was demonstrated within a couple of months. New capabilities such as camera-frame teleoperation, autonomous tool changeout and dual manipulator control have been incorporated. The final system incorporates twenty-two seperate modules and implements seven different behavior modes. This paper describes the integration of SMART into the ARMMS system.
This paper presents the usage of Hall-Effect sensors for the creation of a low cost, zero friction, minimally invasive precise positional (linear/angular) sensor. Hall Effect sensors are generally been used for reveal...
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This paper presents the usage of Hall-Effect sensors for the creation of a low cost, zero friction, minimally invasive precise positional (linear/angular) sensor. Hall Effect sensors are generally been used for revealing the speed of geared-wheels as well as the angular position of wheels having an array of magnets mounted on. In most cases the Hall-Effect sensors have only been used as threshold sensing devices for revealing the presence of magnetic field. In this article we will experiment the use of the Hall-Effect sensors as continuous non-linear analog input devices. Moreover the article will exploit the condition of achieving data from an array of sensors spatially displaced. The article will show how to introduce the mathematical model of the magnetic field in order to design a correct acquisition system. The article proceeds to introduce the case of a linear transducer made up of a set of sensors. In this transducer the sensors have been linearly arranged along the path swept by a magnetic trolley. The model of data acquisition is presented. The performances and the numerical reliability of the transducer have been evaluated both analytically and experimentally. The achieved results are shown. Finally the transducer generalization for combining an arbitrarily great number of Hall-Effect sensors is discussed.
The Modular Manipulator System (MMS) is a general purpose user configurable modular robotic system that provides rapid and inexpensive implementation of standard or customized manipulator geometries of arbitrary compl...
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The Modular Manipulator System (MMS) is a general purpose user configurable modular robotic system that provides rapid and inexpensive implementation of standard or customized manipulator geometries of arbitrary complexity, tailored to the needs of individual researchers or application engineers. Structures are configured from serf contained 1-DOF rotary or linear JOINT modules, which include an on-board control processor, power amplifier, DC servomotor, high precision position sensor and a fast, rigid connect/disconnect latch. The joints are connected together by passive rigid LINK tubes (straight or 90 degree elbow), that define the manipulator geometry. These components are all offered in 5, 7, 10, 14 and 20 cm diameters, with power density and positional accuracy competitive with other commercial manipulators. A Fuzz Associative Memory (FAM) system is used to capture the arm solution equations for the user defined arm geometry with minimal user input. Task motion commands define trajectories for the end effector in 6-D cartesian workspace coordinates, broadcast to all joints concurrently. The control processor in each joint solves for its component of the movement (a distributed real-time arm equation solution), which is input to a PID control loop that drives the joint servomotor. Central to the system is the Model Manager control program, a model based data-flow architecture, which integrates a dynamic workspace model, off-line application program development, real-time task execution or simulation. The program supports easy teaching of workspace locations, hierarchical programming of complex tasks, sophisticated tool trajectory control integrated workspace I/O, manual manipulator operation and an intuitive user control interface. Additional components under development support automated planning for subtasks, line-model based vision capability to guide workspace interaction and cooperative operation of multiple arms. Various technical and economic advantages
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