Showing papers on "Obstacle published in 1996"

Compact vehicle based rear and side obstacle detection system including multiple antennae

Abstract: A rear and side object detection system for a vehicle (10) based on monolithic millimeter wave integrated circuit technology. A multiple antenna configuration is employed that defines six sensing regions (130,132,134,136,138,140) to the right, left and the rear of the vehicle. A first sensing region (140) is defined at the right side (20) of the vehicle (10), a second sensing region (132) is defined at the right side (20) and rear (22) of the vehicle (10) and overlaps the first sensing region, a third sensing region (136) and a fourth sensing region (130) extend from the rear (22) on both sides (18,20) of the vehicle (10) in the adjacent lanes, a fifth sensing region (134) is defined at the left side (18) of the vehicle and a sixth sensing region (138) is defined at the left side (18) and rear (22) of the vehicle (10) and overlaps the second (132) and fifth (134) sensing regions. A right side warning signal is issued if an object is detected in a right side detection zone defined by the first sensing region or a portion of the second sensing region that does not overlap the third or sixth sensing regions. Likewise, a left side warning signal is issued if an object is detected in a left side detection zone defined by the fifth region and a portion of the sixth sensing region that does not overlap the second or fourth sensing regions. A back-up warning signal is issued if an object is detected in an overlap region (146) between the second (132) and sixth (138) sensing regions.

Obstacle detection system for vehicles moving in reverse

Abstract: An electronic obstacle detection system (12) for guiding and warning a motorist of obstacles in the detection area while backing up. The main components of the system include a pair of sensor clusters (14 and 16) to be affixed to the rear of the vehicle (10), a pair of exterior visual indicators (18 and 20), and an audio-visual indicator (22) located in the vehicle (10). Each of the sensor clusters (14 and 16) are encased in a housing (30) having angled, stepped portions (44, 46 and 48) configured to provide complete area coverage of transmitted and received signals.

The Chinese Family and Economic Development: Obstacle or Engine?

Abstract: Perhaps the central problem in the social sciences is the riddle of economic development: Why do some countries, groups, and individuals prosper economically while others do not? One of the founding figures of sociology, Max Weber, spent much of his intellectual life attempting to explain why the Industrial Revolution had occurred first in England rather than in, say, China or India. The quest by scholars and policymakers toward an understanding of the sources of economic development remains no less pressing today. Over the years a variety of answers have been offered to explain the riddle of economic development. Weber, as is well known, focused on the role of the Protestant ethic in England in explaining why a small and not very rich country was able to leap ahead of more advanced countries in other parts of the world and into the industrial age. Others have focused on the role played by key inventions and by governments. I want to focus attention here on a variety of arguments that have been offered in regard to another factor-the role of the family in economic development, and the role of the Chinese family in particular. The claim that family patterns may have an impact on development represents a reversal of the more usual causal argument. We have abundant research on the ways in which economic development produces changes in dominant family patterns in societies around the world.1 Often, the family is seen as a relatively passive institution, buffeted and altered by powerful economic and political forces. The view that family patterns can affect whether and how rapidly economic

Uncalibrated obstacle detection using normal flow

Abstract: This paper addresses the problem of obstacle detection for mobile robots. The visual information provided by a single on-board camera is used as input. We assume that the robot is moving on a planar pavement, and any point lying outside this plane is treated as an obstacle. We address the problem of obstacle detection by exploiting the geometric arrangement between the robot, the camera, and the scene. During an initialization stage, we estimate an inverse perspective transformation that maps the image plane onto the horizontal plane. During normal operation, the normal flow is computed and inversely projected onto the horizontal plane. This simplifies the resultant flow pattern, and fast tests can be used to detect obstacles. A salient feature of our method is that only the normal flow information, or first order time-and-space image derivatives, is used, and thus we cope with the aperture problem. Another important issue is that, contrasting with other methods, the vehicle motion and intrinsic and extrinsic parameters of the camera need not be known or calibrated. Both translational and rotational motion can be dealt with. We present motion estimation results on synthetic and real-image data. A real-time version implemented on a mobile robot, is described.

Real-time robot motion control with circulatory fields

Abstract: This paper introduces a new feedback algorithm for steering a point robot through an obstacle field. The key innovation is the use of a circulatory field to rotate the robot path around the obstacles instead of the common potential field which repels the robot. This idea is motivated by a charged particle in a magnetic field generated by a current flowing around the obstacle. In constrast, the potential field approach is associated with a repulsive static electric field generated by charges of the same polarity as the robot, on the obstacle. The circulatory field does not generate any spurious local minimum as it does not change the total energy of the system. By combining with an attractive potential field associated with the desired destination, this method achieves global convergence while avoiding collisions with obstacles.

User-driven active guidance system

Abstract: A user-driven, active guidance system for guiding visually impaired users through obstacle filled routes of travel. The system includes an obstacle detection system, having an array of ultrasonic sensors, which detects the distance to and location of obstacles and a controller for receiving obstacle data and determining an optimal path around the obstacle so as to return the user back to the original path of travel without losing orientation or direction. The system provides active guidance by exerting physical force upon the user to intuitively direct the user around the obstacle. The system is driven by the user's motion and comprises a cane, as well as the my of ultrasonic sensors and controller supported on a pair of guide wheels.

The obstacle course: a tool for the assessment of functional balance and mobility in the elderly.

Abstract: Many conventional methods employed in the assessment of balance and mobility in the elderly are expensive, difficult to administer, rely heavily on complex technology, or provide limited functional information so essential to the planning and implementation of rehabilitation interventions. The author has developed a functionally oriented obstacle course for use in the rehabilitation setting, to aid in the evaluation of elderly subjects with balance and mobility dysfunction. The obstacle course consists of 12 simulated functional tasks. Qualitative and quantitative individual task and overall scores are given for each obstacle course performance. A description of the design and rationale for the obstacle course is presented. For demonstration purposes, nonexperimental obstacle course performance data from a small group of elderly volunteers is included. With further validation studies, the obstacle course has potential to become a useful tool in the evaluation and rehabilitation of balance and mobility disorders, in order to aid in the prevention of falls and fall-related injuries in the elderly.

Towards optimal Steiner tree routing in the presence of rectilinear obstacles

Abstract: An apparatus and method for locating a good approximation of optimal Steiner tree routing in the presence of rectilinear obstacles, including finding a Steiner tree on an escape graph The escape graph is constructed by forming lines from given points (pins) and obstacles Obstacles and the segments of obstacles are provided with lines parallel to that segment at a given minimum distance smin from the The lines are constructed until they reaches either a boundary of an obstacle or a boundary of the core For pins which do belong to a boundary of an obstacle, a ray, perpendicular to the segment of the boundary on which the pin is located is constructed from the pin and out from the obstacle until it reaches another obstacle or a boundary of the core For pins which do not belong to an obstacle, vertical and horizontal lines are constructed A Steiner tree may then be found on the escape graph by using any number of algorithms such as algorithm S and algorithm M The solution to the problem of finding a Steiner tree for the escape graph also provides a suitable approximation of a Steiner tree for the original problem This apparatus or method may be used to optimize the routing of conductive paths on integrated circuits

Device and method for detection of moving obstacles

Abstract: A moving obstacle detecting device detects moving objects, may be applied in the field of autonomous vehicles, intelligent robots, video monitoring system and similar systems. The device includes an optical flow extracting unit 1 for extracting optical flows for the respective local regions in the measured images, an focus of expansion (F.O.E.) calculating unit for calculating an F.O.E. of a straight line extended by the extracted optical flows, and a moving obstacle detecting unit for analyzing a temporal change of the calculated F.O.E. to judge the presence of the moving obstacle when the temporal positional change is larger than a predetermined variation quantity.

Avoidability measure in moving obstacle avoidance problem and its use for robot motion planning

Abstract: This paper presents a new solution approach to moving obstacle avoidance problem of a robot. A new concept avoidability measure (AVM) is defined to describe the state of a pair of a robot and an obstacle regarding the collision between them. As an AVM, virtual distance function (VDF) is derived as a function of the distance from the obstacle to the robot and outward speed of the obstacle relative to the robot. By keeping the virtual distance above some positive limit value, the robot avoids the obstacle. In terms of the VDF, an artificial potential field is constructed to repel the robot away from the obstacle and to attract the robot toward a goal location. At every sampling time, the artificial potential field is updated and the force driving the robot is derived from the gradient of the artificial potential field. The suggested algorithm drives the robot to avoid moving obstacles in real time. Since the algorithm considers the mobility of the obstacle as well as the distance, it is effective for moving obstacle avoidance. Some simulation studies show the effectiveness of the proposed approach.

Traditional Sharing Norms as an Obstacle to Economic Growth in Tribal Societies

Abstract: This first objective of the paper is to achieve a better understanding of the values and the worldview that lead traditional tribal societies to distribute wealth and incomes in manners that are hostile to economic change. The second objective can be persued namely that of identifying ways of getting out of the vicious "traditional" equilibrium in which all change would be blocked owning to the interplay of self-erinforcing forces.

Obstacle count independent real-time collision avoidance

Abstract: Robotic manipulator real-time collision avoidance is a safety critical mode of teleoperation where motion commands which would result in a collision are disallowed. To achieve real-time performance, it is necessary to efficiently detect impending collisions between the manipulator and the workspace obstacles. A collision detection method is presented which is based upon two representations. The dynamic elements, such as the manipulator links, are modelled as sets of spheres. The static elements, such as the workspace obstacles, are represented as a weighted voxel map, in which the value of any voxel is indicative of its distance to the nearest obstacle. Combining these two representations results in a collision detection method which is obstacle count independent, i.e. independent of the number of obstacles in the workspace. This property is desirable for operation in cluttered environments with many obstacles, where the total number of calculations in the alternative collision detection paradigm of pairwise comparison will prohibit real-time performance. The method is efficient enough to satisfy a hard real-time constraint Novel algorithms are described to generate the voxel map and spherical model representations, and an implementation is described which uses the collision detection method for real-time teleoperated collision avoidance and online path planning of a Puma 560 manipulator.

Boundary-layer analysis of waves propagating in an excitable medium: Medium conditions for wave-front-obstacle separation.

Abstract: In an excitable medium, wave breaks are essential for spiral wave formation. Although wave breaks can result from collisions between a wave and an obstacle, it is only when the resultant wave fragments separate from the obstacle ~wave-front‐obstacle separation! that a spiral wave will begin to develop. We explored collisions between a piecewise linear obstacle and an incident wave front while varying the excitability of the media and the angle between the linear obstacle segments. Wave-front‐obstacle separation was observed to occur within the small boundary layer of the order of the wave-front thickness. Conditions for wave-front‐ obstacle separation were determined by the relationship between reaction-diffusion flows within this boundarylayer region. We developed a theoretical characterization of the boundary-layer region that permits estimation of the critical values of medium parameters and obstacle geometry that define the transition from wave-front‐ obstacle attachment to wave-front‐obstacle separation. Theoretical predictions revealed good agreement with results of the numerical simulations. @S1063-651X~96!00707-6#

Cooperative sweeping by multiple mobile robots with relocating portable obstacles

Abstract: In this paper, we propose an off-line planning algorithm for cooperative tasks of multiple mobile robots. Sweeping means a motion that a robot covers a 2-dimensional area by its effector. Sweeping of a whole work area is fundamental and essential task of mobile robots. It is more effective if a robot can move an obstacle during a sweeping task as if we clean our room with relocating chairs. We can also consider that this is the simplest task which includes both point-to-point motion and sweeping. We model sweeping and relocation, and propose an algorithm to find appropriate path for robot and way of relocation of each obstacle. We apply the LT graph to solve the problem, which describes both motions of robots and blockades by obstacles in path-time space. We verify the efficiency of the algorithm through simulations and experiments.

A system for obstacle detection during rotorcraft low altitude flight

Abstract: An airborne vehicle such as a rotorcraft must avoid obstacles like antennas, towers, poles, fences, tree branches, and wires strung across the flight path. Automatic detection of the obstacles and generation of appropriate guidance and control actions for the vehicle to avoid these obstacles would facilitate autonomous navigation. The requirements of an obstacle detection system for rotorcraft in low-altitude Nap-of-the-Earth (NOE) flight based on various rotorcraft motion constraints is analyzed here in detail. It is argued that an automated obstacle detection system for the rotorcraft scenario should include both passive and active sensors to be effective. Consequently, it introduces a maximally passive system which involves the use of passive sensors (TV, FLIR) as well as the selective use of an active (laser) sensor. The passive component is concerned with estimating range using optical flow-based motion analysis and binocular stereo. The optical flow-based motion analysis that is combined with on-board inertial navigation system (INS) to compute ranges to visible scene points is described. Experimental results obtained using land vehicle data illustrate the particular approach to motion analysis.

Tiered obstacle course system for remotely controlled vehicles

Abstract: An obstacle course for remotely controlled toy vehicles. A plurality of track circuits are arranged in tiered fashion upon a core support structure. Each track circuit has obstacles such as pits, rocks, and traps which must be negotiated to complete a challenge level. Upon successful completion of a particular challenge on one of these track circuits, the vehicle may advance to the next higher track circuit through an up ramp. There a new challenge in the form of different obstacles are presented. The obstacle course ends on a top face of the support structure which allows direct head-to-head confrontations to determine a winner should all vehicles in a competition successfully complete the obstacle portion of the course. Optional clock timers may set a time limit for completion of the course as a whole or any given level.

View-time based moving obstacle avoidance using stochastic prediction of obstacle motion

Abstract: This paper proposes a new motion planning method of a mobile robot avoiding moving obstacles. To avoid moving obstacles, the trajectories of the obstacles are predicted using a stochastic model of obstacle motion. The obstacle motion is modeled as a random walk process. The method plans robot motion by the unit of view-time and view-period. View-time is defined as the time instant at which the robot senses the obstacle position and velocity. View-period is defined as the time interval during which the robot performs sensing, predicting and planning for collision-free motion. From the position and velocity at a view-time, we predict the future position of the obstacle. The random walk process model of obstacle motion is used to calculate the probability density that the predicted position is reached during the view-period. From the probability density function of the predicted position, the probability that a position can be swept by the obstacle during the view-period is calculated. Then artificial potential is assigned at every position by considering the probability. The force induced by the artificial potential field repels the robot away from the probable obstacle trajectory. This method is a look ahead scheme, and effective for moving obstacle avoidance. This method is applied to collision-free motion planning for a mobile robot in a dynamic and unknown environment with several moving and stationary obstacles.

Adaptive path planning and obstacle avoidance for a robot with a large degree of redundancy

Abstract: A new algorithm for path planning and obstacle avoidance for redundant planar robots is proposed. The task of path planning is formulated as a sequence of nonlinear programming problems. For each problem, the objective is to minimize the distance between the current location of the end-effector and a desired location. Two penalties are added to each objective function to ensure that the robot is not colliding with any obstacle and that its links are not crossed over. The effects of mechanical stops and limits for maximum joint movements are also incorporated as inequality constraints. The algorithm uses an adaptive scheme to activate the fewest number of the outboardmost joints, and none of the inboard ones if possible, to reach a desired location. The algorithm is especially useful when the number of joints is large. © 1996 John Wiley & Sons, Inc.

Obstacle collision preventing device for mobile object

Abstract: PROBLEM TO BE SOLVED: To exactly perform collision avoiding operation by exactly dealing with respective obstacle successively moving and exactly operating the relative speed of respective obstacles even when there are many obstacles, the relative speed is high, and a mobile object considerably swings in case of traveling. SOLUTION: Since relative positions P1-2, P1-1, P10...P2-2, P2-1, P20... of respective obstacles 31 and 32 existent outside a mobile object 1 are successively measured at intervals (t-2, t-1, t0...) shorter than fixed time by a position measuring means, sequential relative position data are successively made correspondent to the data of respective obstacles. Based on the relation between these respective correspondent obstacles and sequential relative position data, the relative speed of respective obstacles is successively calculated. Then, proximate time T to the most approach to the mobile object and proximate distance L in the case of most proximity are successively operated and operation and processing for preventing the mobile object 1 from colliding with the obstacles 31 and 32 are performed. COPYRIGHT: (C)1998,JPO

Planning and Navigation by a Mobile Robot in the Presence of Multiple Moving Obstacles and Their Velocities

Abstract: This paper presents a navigation scheme for a mobile robot which works even in an environment with multiple moving obstacles. An “iterated forecast and planning” approach is proposed by the authors. It is assumed that each obstacle moves at a constant velocity in the approach. The most feasible path for a robot is planned in (x, y, t) space. The planning and motion according to the plan are iterated frequently to cope with changes of motion of the moving obstacles. The behavior of proposed navigation algorithm is also presented by means of computer simulations.

A vision based online motion planning of robot manipulators

Abstract: This article presents a vision based online system for the robust trajectory planning of robot manipulators. It uses a 3D vision system to determine the relative position of the objects to be engaged and the obstacle to avoid, and a novel obstacle avoidance procedure for manipulator motion planning. From intensity images acquired by a CCD camera mounted on the robot arm, the salient features are first accurately and robustly detected and then grouped. Through the correspondences between the feature groupings and the model features, the 3D poses of the objects and the obstacles are determined and confirmed by back-projection. Once these poses are determined, an online procedure, based on redundancy resolution, is used to achieve obstacle avoidance. The approach utilizes a null space vector to set properly the robot configuration, and a potential field method to guide the end-effector. By pseudoinverse perturbation it also prevents singular configurations and local minima. The feasibility and effectiveness of the system is demonstrated by an experiment with online engagement and transportation of objects posed inside an aluminium frame.

Obstacle detector for vehicle

Abstract: PURPOSE: To obtain a detector having simple structure at low cost by providing a first searching unit directing sideways, a second searching unit directing obliquely rearward, an obstacle detection signal outputting means, etc. CONSTITUTION: First and second searching units are fixed to the right and left corner parts at the rear end of a vehicle 1 and connected with a controller 4 in the vehicle 1. Each unit 2 transmits a first searching signal A having outer sideward directivity intermittently while each unit 3 transmits a second searching signal B having obliquely rearward directivity intermittently and both units 2, 3 receive reflection signals from an obstacle. The controller 4 detects an obstacle within a predetermined sideward range based on a signal received from the unit 2 and sequentially operates the distance to the obstacle based on the time elapsed after transmission of the signal B from the unit 3 before reception of a reflection signal thus judging approach of the vehicle to an obstacle based on the variation of the distance. The controller 4 also determines the presence of any one of an obstacle detected based on the signal A and an obstacle detected based on the signal B and approaching to the vehicle 1 and delivers a detection signal to an alarm 5 and lights an alarm lamp.

Control method for cleaning robot

Abstract: PROBLEM TO BE SOLVED: To perform an avoiding operation according to an obstacle, when the obstacle is detected by a first obstacle detecting sensor, by extending the distance to a wall detected by a wall distance detection sensor, and then detecting the obstacle by a second obstacle detecting sensor, and stopping the traveling of a cleaning robot so as to perform a spin turn. SOLUTION: Detection signals from right front obstacle sensors 17a1, 17a2, central front obstacle sensors 17b1, 17b2, left front obstacle sensors 17c1, 17c2, right/left wall detecting sensors 23a, 23b, etc., are inputted in a controller 16 of a cleaning robot. When the left/right front and central front obstacle detection sensors 17a1, 17c1, 17b1 detect an obstacle, the left/right wall detecting sensors 23a, 23b make the robot to perform a primary avoidance operation which extends the distance to a wall. When the second left/right front and central front obstacle detecting sensors 17c2, 17a2, 17b2 detect the obstacle, the traveling of the cleaning robot is made to stop so as to perform a secondary avoidance operation of performing spin turning at a prescribed angle.

Pseudo radar type obstacle detecting device

Abstract: PROBLEM TO BE SOLVED: To provide a pseudo radar type obstacle detecting device accurately detecting an obstacle. SOLUTION: In an obstacle detecting device laying a leakage transmission path along a road or line in both sides thereof emitting a radio wave from one leakage transmission path 1 to the other leakage transmission path 2 to detect an obstacle, to one end of one leakage transmissions path 1, a transmitter 3 generating a pulse-state signal is connected, also to one end of the same side of the other leakage transmission path 2, a receiver 4 receiving a signal delayed in accordance with a position of the pulse-state signal is connected, and in this receiver 4, a filter 7 taking out an envelope from a signal waveform is connected, a memory device 5 storing an envelope of a signal waveform previously without an obstacle is provided, an arithmetic device 6 is provided, which detects a position of the obstacle from a differential waveform between the envelope without this obstacle and the envelope taking out the filter 7.

Device for preventing collision

Abstract: PROBLEM TO BE SOLVED: To notify beforehand the position of its own vehicle to another mobile object or a carrier by transmitting the position of its own vehicle to another mobile object or the carrier SOLUTION: Each vehicle position detecting means 1B and 2B detects the position of its own vehicle when each obstacle detecting means 1A and 2A detects an obstacle, and generates a detection signal Each communicating means 1C and 2C transmits obstacle information constituted of the information of the distance or position of the obstacle detected by its own vehicle and the information of the position of is own vehicle when the obstacle is detected to a vehicle traveling in the neighborhood, and receives the obstacle information from the vehicle traveling in the neighborhood Then, each driver warning mean 1D and 2D receives the obstacle information from its own vehicle, judges whether or not the driver should be warned of the presence of the obstacle according to the content of the obstacle information, and calls the driver's attention by warning the driver by, for example, an alarming demand with a voice or the turning-on of an alarming display lamp when the warning is necessary

Detector for obstacle

Abstract: PROBLEM TO BE SOLVED: To obtain a detector by which the height of an obstacle above a head in front is detected automatically and which automatically judges whether an own vehicle can be passed or not. SOLUTION: In a detector for an obstacle, a scene in front is photographed by two cameras 2a, 2b, an image which is photographed by the camera 2b on one side is analyzed, and, when an obstacle detecting part 4 detects a part at the lower end edge of an obstacle above a head in front, a region corresponding to a region in which the part at the lower end edge of the obstacle is photographed is searched by a matching processing part 5 on the basis of an image which is photographed by the camera 2a on the other side. Then, a distance computing part 6 computes a distance up to the obstacle on the basis of respective coordinate values of two corresponding image regions, on the basis of focal distances of the two cameras and on the basis of the positional relationship between the cameras, a height computing part 7 computes the height from the ground face of the object. Then, a height comparison part 8 compares the height of the obstacle with the height of an own vehicle, and it outputs a judged result regarding whether the own vehicle can be passed or not.

Vehicle periphery monitoring device, alarm display method to be used for device and medium-storing display method

Abstract: PROBLEM TO BE SOLVED: To obtain a device enabling caution by displaying information showing which object can become an obstacle dangerous for the travel of a present vehicle to a driver by displaying the image of the arbitrary designated obstacle, while intensifying it when the existence of plural obstacle is estimated based on a picked-up image. SOLUTION: This device has an image-reading means 12, feature point extracting means 14, marking operating means 22 and superimpose operating means 24 or the like. The image-reading means 12 is installed on the vehicle and by picking up the stereoscopic image of a monitoring area around the vehicle, raw image information 12a having three-dimensional coordinate information is generated. Then, this device has a function for performing intensified image display through superimposed display using superimposed image information 24a, concerning the image of the obstacle estimated existent by a position close to a traveling direction among obstacles inside an estimated present vehicle traveling track range, when the existence of plural obstacles inside the estimated present vehicle traveling track range is estimated based on the picked-up image.

An Obstacle-Based Probabilistic Roadmap Method For Path Planning

Abstract: This thesis presents a new obstacle-based probabilistic roadmap method for motion planning for many degree of freedom robots that can be used to obtain high quality roadmaps even when the robot''s configuration space is crowded. The main novelty in this approach is that roadmap candidate points are chosen on the constraint surfaces corresponding to obstacles in the workspace. As a consequence, the roadmap is likely to contain difficult paths, such as those traversing long, narrow passages in the robot''s configuration space. The approach can be used for both collision-free path planning and for planning contact tasks. A path planner based on this approach is implemented for planar articulated robots in a two-dimensional workspace with polygonal obstacles. Experimental results with various types of robots and a range of environments show that well connected roadmaps are generated for most environments, even when the number of nodes in the roadmap is small. After the roadmap is built during preprocessing, many difficult path planning operations are carried out in less than a second.

An Intelligent Navigator for Mobile Vehicles

Abstract: This paper presents an intelligent navigation method for navigation of a mobile vehicle in unknown environments. The proposed navigator consists of three modules: Obstacle Avoidor, Environment Evaluator and Navigation Supervisor. The Obstacle Avoidor is a fuzzy controller whose rule base is learnt through reinforcement learning. A new and powerful training method is proposed to construct the fuzzy rules automatically. The Navigation Supervisor determines the tactical requirement of avoiding obstacles or moving towards the goal location at each action step so that the vehicle can achieve its task without colliding with obstacles. The effectiveness of the learning method and the whole navigator are verified by simulation.