33results about How to "Position coordinates are precise" patented technology

The imaging position of each of the frames in image data of a plurality of frames captured while a vehicle is traveling is accurately determined.An image data acquiring device (100) captures a front image by means of a video camera (120) while a vehicle is traveling. When in imaging, the device associates the vehicle speed pulse detected by a vehicle speed sensor (104) with the frame data and records them. An image data processing device (200) arranges data on each frame of the image along the initial path according to the correspondence with the vehicle speed pulse. The device determines the variation between the frames of a feature point such as a road lane marking included in the image, reflects the variation on the initial path, and corrects the errors in the direction perpendicular to the moving direction so as to determine the traveling path and imaging positions of the frames.With this, the accuracy in determining the imaging position of each frame is improved.

The invention relates to an underground space autonomous positioning multi-sensor intelligent detection robot. The detection robot includes a robot carrier platform, a cable rolling wheel, a main control box, a rear camera which is arranged on the carrier platform, a robot arm, an instrument cabin, a sampling basket, a battery pack, a front camera and the like; the robot carrier platform and the main control box are connected through a power supply and communication cable for realizing a power supply function and a communication function; the detection data of the instrument cabin are transmitted to the main control box through the power supply and communication cable; a main cable rolling wheel provides mileage information in real time; and a uniaxial fiber optic gyroscope, a biaxial inclinometer and a triaxial accelerometer which are mounted on the robot carrier platform, together with the mileage information provided by the main cable rolling wheel, realize the autonomous positioning of the robot. The detection robot can go to underground space to detect such properties as the location, spatial information and living environment of the underground space and can obtain the 3D model of underground space; and the robot is adaptive to complex road conditions and has a certain waterproof function.

The invention discloses a multi-rotor flight-path planning system and method orienting to inspection of power transmission lines. The multi-rotor flight-path planning system comprises a GPS-RTK (Global Positioning System-Real Time Kinematic) module, an obstacle detecting module, a multi-rotor unmanned aerial vehicle and a flight-path planning control module, wherein the GPS-RTK module comprises adifferential GPS positioning system and an RTK base station; the differential GPS positioning system adopts two GPS receivers which are respectively used as a reference station and a mobile station ofthe unmanned aerial vehicle; the reference station is arranged on a site, the mobile station is arranged on the unmanned aerial vehicle; the flight-path planning control module acquires the positionof the unmanned aerial vehicle of the GPS-RTK module and obstacle information detected by the obstacle detecting module and carries out offline flight-path planning and online flight-path planning onthe multi-rotor unmanned aerial vehicle by combination with geological information. The multi-rotor flight-path planning system and method disclosed by the invention has the beneficial effects that the preset flight-path flying and online real-time adjustment of the flight-path flying of the unmanned aerial vehicle can be realized; in the process of in-advance automatic generation of offline reference flight path and inspection, the coordinates of the aerial vehicles are positioned according to the high-accuracy RTK, and by combination with the obstacle detection module, the inspection flightpath can be adjusted online, so that the collision of the unmanned aerial vehicles can be avoided.

A method for positioning a portable communication device is provided. First, the signal intensities of a plurality of base stations near the portable communication device receiving radio waves from the base stations are detected, and coordinates of the base stations are found in order to calculate a position coordinate of the portable communication device through the coordinates and the signal intensities of the base stations. Then, the values of a plurality of environmental features between at least one of the base stations and the portable communication device are obtained from a geographic information system (GIS) according to at least one coordinate of the base stations and the position coordinate of the portable communication device. After that, the signal intensities of the base stations are modified by substituting the values of the environmental features into a path loss model. Finally, the position coordinate of the portable communication device is recalculated according to the modified signal intensities of the base stations thereby enhancing the positioning accuracy substantially.

The invention discloses an anisotropic characteristic descriptor based image stitching method which is applicable to stitching of multiple images having overlapping relation. The anisotropic characteristic descriptor based image stitching method comprises the following steps of (A) detecting characteristic points of a reference image and an image to be registered and obtaining the main directions of the characteristic points; (B) adopting an anisotropic point-to-point sampling model to form multiple groups of two-value testing and obtain characteristic descriptors; (C) adopting a nearest neighbor method to conducting matching on the characteristic descriptors and utilizing a PROSAC method to obtain a homographic matrix; (D) obtaining an illumination gain compensation matrix through an error solution function and utilizing multiband fusion to obtain a panorama natural in transition. The anisotropic characteristic descriptor based image stitching method can accurately register images shot at different viewing angles and from viewing points to obtain clear and natural wide-viewing-angle scene images, also has simple complexity and high operation speed and accordingly has good application value on a monitoring system or a remote sensing system.

The invention provides an aerial photograph image difference detection method based on a dual network, comprising four parts of image acquisition and processing, building a dual network model, training the dual network model and using the model. As the depth learning is not required to design feature manually, the problem that it is difficult to select an effective feature descriptor in image segmentation and difference detection can be avoided. The depth learning method can also overcome the shortcomings of low robustness to illumination in RGB image difference detection task. At the same time, the invention adopt the object detection instead of the traditional segmentation method, which can more distinguish the single object, and the position coordinate of the object is more accurate andeasier to express. By calculating the ROI of the prediction box after detection to determine the relevant objects of the two images, it can also reduce the requirements of registration accuracy. Importantly, the invention adds the semantic information of the object, has the object class information, has stronger anti-interference ability, and can better analyze the difference types.

The invention discloses a single-point calibration method for a multi-target automatic tracking and monitoring system. The method comprises the steps of installing a traditional camera and a pan / tilt / zoom (PTZ) camera on the same vertical line, and setting a certain height difference on the vertical line between the traditional camera and the PTZ camera; collecting pictures by using the traditional camera and the PTZ camera, and selecting a marker near the central point of the picture of the traditional camera as a reference point of the traditional camera; moving the PTZ camera so as to enable the central point of the picture of the PTZ camera to be aligned with the reference point of the traditional camera, and calculating the horizontal view angle and the vertical view angle of the PTZ camera; calculating the position coordinates of the PTZ camera according to the reference point of the traditional camera, the central point of the picture of the PTZ camera as well as the horizontal view angle and the vertical view angle of the PTZ camera; adjusting the horizontal view angle and the vertical view angle of the PTZ camera according to the actual situation, and reducing the positioning deviation of the position coordinates of the PTZ camera to complete single-point calibration. After the method is used, the calibration process can be completed by only setting a group of points, so that the problems that in the prior art, the calibration process is complicated, the flexibility is low, the calibration success rate can not be guaranteed, and the like are solved.

The present invention relates to a system and method to aid the placement of surgical devices under radiographic image guidance. More particularly, embodiments of the invention relate to a system utilizing radiopaque markers, an external light source projected onto the skin or surgical site in conjunction with a target guide holder. Using a radiographic image to identify landmarks for skin entry and bone entry points to facilitate the accurate placement of surgical devices. An exemplary system utilizes a radiopaque marker, target guide holder and external laser markers to determine intra-operative angles, trajectories and positioning coordinates to facilitate placement of needles, guide wires, surgical hardware, trocars and cannulae for the surgical placement of orthopedic implantation devices.

The present invention discloses a passive underwater sound positioning method based on moving a time window periodically. The method is composed of a strapdown inertial navigation system (SINS), a single hydrophone (receiver) at the bottom of an autonomous underwater vehicle (AUV) and a seafloor single hydrophone (band sound source), adopts a time window model which moves based on the cycle of an ultrasonic wave sent out by the seafloor hydrophone, and comprises the steps of carrying out the generalized cross correlation on the sound source signals received when the AUV is located at different positions in a time window to obtain the delay inequality, and then calculating a time window internal AUV multi-point model to obtain the latest position coordinate of the AUV. According to the present invention, by calculating the time window internal AUV multi-point model, the AUV does not need to navigate too far, so that a positioning error of an inertial navigation system which accumulates along with the time continuously is reduced effectively. According to the present invention, the AUV does not need to emerge from the water to update the position, does not need the digital communication, and receives an ultrasonic signal passively, so that the position of the AUV is difficult to expose, and the invisibility and the safety of the AUV are improved.

The invention discloses a slanted image positioning method and system of an unmanned aerial vehicle. The slanted image positioning method comprises the steps that POS information of a slanted image ofthe unmanned aerial vehicle is acquired; the POS information is utilized to position the slanted image of the unmanned aerial vehicle to obtain a first position coordinate; a stereo satellite image is utilized to extract second position coordinate of a ground control point; the second position coordinate is utilized to optimize the first position coordinate, and a third position coordinate of theslanted image of the unmanned aerial vehicle is obtained. It is visible that in the slanted image positioning method, the ground control point is calculated by utilizing the stereo satellite image and the ground control point obtaining process in the prior art is omitted, so that the measurement cost during positioning of the slanted image of the unmanned aerial vehicle is greatly decreased. Accordingly, the invention also discloses a slanted image positioning system and system of the unmanned aerial vehicle, a medium and a device. Similarly, the system had the above advantages.

The invention belongs to the technical field of communication and in particular relates to a node positioning method and a corresponding node positioning system. The node positioning method comprisesthe following steps: initializing a node and screening a node to be detected, which has at least four anchor nodes at the periphery; optimizing a weight factor of a positioning coordinate; calculatingan estimated coordinate value of the node to be detected according to the optimized weight factor of the positioning coordinate; selecting four nodes which have the closest distance from the node tobe detected as revised anchor nodes; calculating measured coordinate values of the revised anchor nodes according to the optimized weight factor of the positioning coordinate; calculating a positioning mean value error according to the measured coordinate values of the anchor nodes; correcting the estimated coordinate value of the node to be detected according to the positioning mean value error and calculating the position of the node to be detected. According to the node positioning method and system, provided by the invention, a more accurate position coordinate is obtained through a mannerof optimizing the weight factor of the positioning coordinate and carrying out positioning error compensation, so that the node positioning precision can be effectively improved and the node positioning precision can be improved to the greatest extent.

The embodiments of the present invention provide an indoor positioning method and device and a computing device. The indoor positioning method is applied to the computing device of an indoor positioning system. The indoor positioning system further comprises a to-be-tested terminal and N base stations, wherein N is an integer larger than 1; the method comprises the following steps: receiving strength indicator values RSSI of N received signals sent by the to-be-tested terminal, wherein the N RSSIs are strength indication values of signals sent by N base stations to the to-be-tested terminal; and selecting n RSSIs in a preset range in the N RSSIs, wherein n is an integer larger than 1 and not greater than N; according to the n selected RSSIs, determining n distance values between the n basestations corresponding to the n RSSIs and the to-be-tested terminal respectively; and determining the position coordinates of the to-be-tested terminal according to the n distance values and the n RSSIs. According to the technical scheme in the invention, the positioning precision for positioning the to-be-tested terminal can be improved.

The invention relates to a template file processing method and device, computer equipment and a storage medium. The method includes the steps that a first template and a second template correspondingto a scan file are acquired, and an operation on the first template is monitored; an extraction box addition instruction is received, and a corresponding extraction frame is added in the first template according to the addition instruction; the position coordinates of the extraction box are acquired; the dimensional change ratio of the first template relative to the second template is calculated;when the coordinates and the dimensional change ratio are monitored, a corresponding extraction box is added in the second template according to the coordinates and the dimensional change ratio; the second template with the extraction box added is used for extracting information in the scan file. By means of the method, the accuracy of the extraction box position on the template file can be improved, so that template file information extraction is more accurate.

The invention discloses a spraying robot dynamic supplementary spraying control system which comprises a spraying robot and a spraying target, the spraying robot comprises a spraying gun for spraying, a pressure sensor is arranged in a spraying gun pipeline, and the spraying robot dynamic supplementary spraying control system further comprises a data collecting module used for collecting real-time pressure data of the spraying gun pipeline; the calculation module is used for obtaining the real-time spraying sectional area of the spray gun nozzle; calculating the change relation of the thickness of the paint film on the spraying target along with time; the moving distance of the spraying robot in the clogging process of the spraying gun is calculated; the control module is used for controlling the spraying robot to stop spraying and controlling the spraying robot after blockage clearing to move to the initial position where clogging happens to conduct compensation spraying. And when the spray gun is blocked, the spray gun can be automatically closed, so that the phenomena of spraying pipeline damage and spraying leakage caused by overlarge pressure are avoided, and the overall spraying effect is improved. The target spraying thickness is obtained according to the pressure data of the spray gun pipeline, so that dynamic supplementary spraying is carried out, and the spraying quality of the clogged position of the spray gun is improved.

A Z-form position detector useful for ascertaining the position of Z-forms with respect to underlying composite structure. The device comprises an oscillating laser that generates a line projected onto the Z-form and composite structure at an angle. The line appears discontinuous due to the topography of the Z-form and composite structure. For example, the line is discontinuous at the edges of the Z-form. The device further comprises a sensor sensitive to the frequency of the laser. The sensor scans along the line until a discontinuity (i.e., a break in the line) is detected. Since the discontinuity corresponds to the edge of the Z-form, detection of the discontinuity allows the device to ascertain precise coordinates of a point on the edge of the Z-form. The device thus allows Z-pins to be driven into composite structure automatically for savings on time and cost.

The invention discloses a high-redundancy indoor coal yard navigation method and system, and relates to the high-redundancy indoor coal yard navigation method which comprises the following steps: S11,respectively acquiring navigation data of a UWB subsystem, an INS subsystem and an SLAM subsystem which are arranged in a coal yard; S12, judging whether the obtained navigation data of the SLAM subsystem is qualified or not, and if yes, selecting the navigation data of the SLAM subsystem and the navigation data of the UWB subsystem as to-be-fused data; if not, selecting the navigation data of the INS subsystem and the navigation data of the UWB subsystem as to-be-fused data; and S13, establishing a Kalman filtering model according to the to-be-fused data, and outputting an estimated value ofthe error amount of the SLAM subsystem or the INS subsystem according to the established Kalman filtering model to obtain positioning data of the coal yard. According to the invention, safe and accurate navigation data are provided for unmanned aerial vehicle flight in an indoor coal yard environment (with weak GNSS signals or without GNSS signals).

The invention relates to the technical field of exposure, in particular to a laser direct imaging device which comprises a workbench, a laser device, an image acquisition device and computer equipment. The table top of the workbench is provided with a through hole, and an anti-dazzling screen with a light transmitting hole is arranged in the through hole; the laser device is arranged under the table top of the workbench, a light outlet of the laser device is aligned with the through hole and used for emitting light to an exposure part through the through hole to form an alignment mark, the area of a light outlet light spot of the laser device is larger than the cross section area of the light transmitting hole, and the size of the alignment mark is consistent with that of the light transmitting hole; the image acquisition device is arranged over the workbench and is used for acquiring an alignment mark on the exposure part; and the computer equipment is connected with the image acquisition device and is used for calculating an alignment error of the exposure part according to the alignment mark acquired by the image acquisition device. The equipment solves the problem of incompleteexposure pattern caused by misalignment of the sleeve and the center of the through hole of the traditional laser imaging equipment, so that the double-sided exposure alignment of the exposure part is more accurate.

The embodiments of the present invention provide an indoor positioning method and device and a computing device. The indoor positioning method is applied to the computing device of an indoor positioning system. The indoor positioning system further comprises a to-be-tested terminal and N base stations, wherein N is an integer larger than 1; the method comprises the following steps: receiving strength indicator values RSSI of N received signals sent by the to-be-tested terminal, wherein the N RSSIs are strength indication values of signals sent by N base stations to the to-be-tested terminal; and selecting n RSSIs in a preset range in the N RSSIs, wherein n is an integer larger than 1 and not greater than N; according to the n selected RSSIs, determining n distance values between the n basestations corresponding to the n RSSIs and the to-be-tested terminal respectively; and determining the position coordinates of the to-be-tested terminal according to the n distance values and the n RSSIs. According to the technical scheme in the invention, the positioning precision for positioning the to-be-tested terminal can be improved.

The invention discloses a high-sensitivity obstacle avoidance system and method for an AGV robot. The operation safety width of the AGV robot and the nearest distance between a road base point and an obstacle model are obtained; when the nearest distance between the road base point and the obstacle model is smaller than the operation safety width, the (N+1)th road is selected to avoid the obstacle; when the nearest distance between the road base point and the obstacle model is greater than or equal to the operation safety width, the road base point is taken as a driving boundary point to avoid the obstacle, so that the AGV robot can accurately avoid the obstacle, and the problems that an existing obstacle avoidance system adopts dynamic obstacle avoidance, and the obstacle cannot be avoided when a sensor fails at one point. According to the method, the pre-established three-dimensional model map is loaded into the AGV robot, information delay caused by data transmission is avoided, and meanwhile, by positioning the road boundary of the three-dimensional model map, even if an obstacle avoidance sensor fails, obstacle avoidance can be performed through coordinate points in the three-dimensional model map.

The invention discloses a spatial omnibearing simulation system and method based on a virtual reality technology, and solves the problem that spatial free switching combination in the prior art cannotperform simulation preview, wherein the system comprises a virtual reality spatial data acquisition module, a spatial change network module, a server and a virtual reality demonstration module whichare connected in sequence; the virtual reality spatial data acquisition module acquires data of each virtual reality space, the spatial change network module performs modularization, distinguishable and dynamic processing on the virtual reality spatial data, the server transmits the processed virtual reality spatial data to the virtual reality demonstration module, and the virtual reality demonstration module demonstrates image information. According to the invention, the virtual reality demonstration module is used for demonstrating freely combined scene images of a virtual reality space in real time, generating a panoramic image according to coordinates and image information, displaying the effect of free combination of the space, and displaying different free combination results according to an instruction of a user so as to verify the feasibility of a space switching technology.

The invention relates to a calibration device for a sensor, the calibration device comprises a calibration plate (1), a slide rail (21), a translation driving mechanism, a first mounting bracket (4) and a position sensor (5), the calibration plate (1) is slidably connected to the slide rail (21) through a slide block (22), the translation driving mechanism is used for driving the calibration plate (1) to slide along the slide rail (21), the first mounting bracket (4) is arranged in the extension direction of the sliding rail (21) and is provided with a mounting seat (7) for mounting a sensor (10) to be calibrated, and the position sensor (5) is used for detecting the position coordinates of the sliding block (22) so as to calibrate the sensor (10) to be calibrated. The calibration device can improve the calibration efficiency and ensure the calibration precision while achieving the dynamic calibration of the sensor.

The invention provides an embedded part detection method and system, and belongs to the technical field of prefabricated buildings, and the method comprises the following steps: S0, obtaining the standard position coordinate and type of an embedded part; S1, photographing a prefabricated part and an embedded part to obtain an actual assembly image; s2, correcting the distortion of the actual assembled image to obtain a corrected assembled image; s3, inputting the corrected and assembled image into a deep learning classification network, and identifying position coordinates and types of the embedded parts; and S4, comparing the position coordinate and the type of the embedded part with the known standard position coordinate and the type of the embedded part. According to the embedded part detection method provided by the invention, manual measurement and detection are not needed, time and labor are saved, the detection result is accurate, a photographing mode is adopted, the detection time is saved, an actual image of the embedded part can be photographed, accurate identification of the embedded part is facilitated, a new prefabricated part does not need to establish an image standardization template, and the operation process is simplified.

The invention discloses an intelligent robot for power station inspection and maintenance and a control system of the intelligent robot. The intelligent robot comprises an inspection and maintenance robot body and a remote console. The robot body is of a tracked manipulator structure. A four-track mobile platform provides sufficient power and steering performance for the robot for movement in a complex terrain of a power station. Track wheels can further rotate along track wheel connecting shafts, and therefore terrain adaptability is improved. A monitoring system is installed on the robot body to provide control information for inspection and maintenance. The robot has two modes of autonomous navigation and artificial remote operation. In the mode of autonomous navigation, inspection on a predetermined route is autonomously completed according to information provided by a composite navigation system. In the mode of artificial remote operation, movement of the robot and the maintenance of a manipulator are artificially operated. The robot has the advantages of being high in automated degree and intelligentialized degree, flexible and small and exquisite.

The present invention discloses a passive underwater sound positioning method based on moving a time window periodically. The method is composed of a strapdown inertial navigation system (SINS), a single hydrophone (receiver) at the bottom of an autonomous underwater vehicle (AUV) and a seafloor single hydrophone (band sound source), adopts a time window model which moves based on the cycle of an ultrasonic wave sent out by the seafloor hydrophone, and comprises the steps of carrying out the generalized cross correlation on the sound source signals received when the AUV is located at different positions in a time window to obtain the delay inequality, and then calculating a time window internal AUV multi-point model to obtain the latest position coordinate of the AUV. According to the present invention, by calculating the time window internal AUV multi-point model, the AUV does not need to navigate too far, so that a positioning error of an inertial navigation system which accumulates along with the time continuously is reduced effectively. According to the present invention, the AUV does not need to emerge from the water to update the position, does not need the digital communication, and receives an ultrasonic signal passively, so that the position of the AUV is difficult to expose, and the invisibility and the safety of the AUV are improved.

The invention discloses a slanted image positioning method and system of an unmanned aerial vehicle. The slanted image positioning method comprises the steps that POS information of a slanted image ofthe unmanned aerial vehicle is acquired; the POS information is utilized to position the slanted image of the unmanned aerial vehicle to obtain a first position coordinate; a stereo satellite image is utilized to extract second position coordinate of a ground control point; the second position coordinate is utilized to optimize the first position coordinate, and a third position coordinate of theslanted image of the unmanned aerial vehicle is obtained. It is visible that in the slanted image positioning method, the ground control point is calculated by utilizing the stereo satellite image and the ground control point obtaining process in the prior art is omitted, so that the measurement cost during positioning of the slanted image of the unmanned aerial vehicle is greatly decreased. Accordingly, the invention also discloses a slanted image positioning system and system of the unmanned aerial vehicle, a medium and a device. Similarly, the system had the above advantages.

The invention discloses a high-sensitivity obstacle avoidance system and method for an AGV robot. By obtaining the safe running width of the AGV robot and the shortest distance between the road base point and the obstacle model; when the shortest distance between the road base point and the obstacle model is less than the safe running width , select the N+1th road for obstacle avoidance; when the shortest distance between the road base point and the obstacle model is greater than or equal to the operating safety width, use the road base point as the driving boundary point for obstacle avoidance, and the AGV robot can accurately avoid obstacles. The current obstacle avoidance system is dynamic obstacle avoidance, and the sensor fails at one point, and the obstacle avoidance cannot be avoided; the present invention loads the pre-established three-dimensional model map into the AGV robot to avoid information delay caused by data transmission, and at the same time through the three-dimensional The positioning of the road boundary on the model map makes it possible to avoid obstacles through the coordinate points in the three-dimensional model map even when the obstacle avoidance sensor fails.

The present invention relates to a template file processing method, device, computer equipment and storage medium. The method includes: acquiring a first template and a second template corresponding to a scanned file, monitoring the operation of the first template; receiving an extraction frame Add an instruction, add a corresponding extraction frame in the first template according to the addition instruction; obtain the position coordinates of the extraction frame; calculate the size change ratio of the first template relative to the second template; when listening When the coordinates and size change ratio, add a corresponding extraction frame in the second template according to the coordinates and size change ratio; use the second template after adding the extraction frame to extract information in the scanned file. By adopting the method, the accuracy of the position of the extraction frame on the template file can be improved, so that the information extracted from the template file is more accurate.

The invention proposes a dual-network-based aerial image difference detection method, including image acquisition and processing, building a dual-network model, training the dual-network model and using the model. The present invention adds deep learning to the difference detection, since the deep learning does not need to manually design features, it can avoid the problem of difficult selection of effective feature descriptors in image segmentation and difference detection. The use of deep learning methods can also overcome the shortcomings of low robustness to illumination in the difference detection task of RGB images. At the same time, the present invention uses object detection to replace the traditional segmentation method, which can better distinguish individual objects, and the position coordinates of the objects are more accurate and easier to express. By calculating the ROI of the predicted frame after detection to determine the related objects of the two images, the requirements for registration accuracy can also be reduced. The important thing is that in the present invention, the semantic information of the object is added, and with the object category information, the anti-interference ability is stronger, and the difference type can be better analyzed.

The present invention provides an athlete positioning method and a positioning system, wherein the positioning method includes: gridding the sports field, establishing a first rectangular coordinate system with the center point of the sports field as the coordinate origin; selecting multiple reference nodes on the sports field, and measuring each The RSSI value of the grid vertex, establish the matching database of the grid vertex RSSI value; determine the value of the radio frequency parameter A and the signal transmission constant n; measure the RSSI value at the athlete's position in real time, and calculate the distance from the athlete's position to each reference node ; Calculate the initial coordinates of the athlete; determine the grid where the athlete is based on the initial coordinates of the athlete; calculate the distance from the athlete to each grid vertex of the grid where the athlete is; calculate the precise coordinates of the athlete. The positioning system includes a positioning receiver set at the reference node, a positioning transmitter set on the athlete and a host computer. The athlete positioning method and the positioning system provided by the invention can more accurately locate the athlete's position.