Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
  • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
  • G01S17/06—Systems determining position data of a target
  • G01S17/42—Simultaneous measurement of distance and other co-ordinates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64F—GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR
  • B64F5/00—Designing, manufacturing, assembling, cleaning, maintaining or repairing aircraft, not otherwise provided for; Handling, transporting, testing or inspecting aircraft components, not otherwise provided for
  • B64F5/60—Testing or inspecting aircraft components or systems
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
  • G01S17/88—Lidar systems specially adapted for specific applications
  • G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/16—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using electromagnetic waves other than radio waves
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/4808—Evaluating distance, position or velocity data
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
  • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
  • G01S7/481—Constructional features, e.g. arrangements of optical elements
  • G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone
  • G01S7/4815—Constructional features, e.g. arrangements of optical elements of transmitters alone using multiple transmitters
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
  • G05D1/10—Simultaneous control of position or course in three dimensions
  • G05D1/101—Simultaneous control of position or course in three dimensions specially adapted for aircraft
  • G05D1/106—Change initiated in response to external conditions, e.g. avoidance of elevated terrain or of no-fly zones
  • G05D1/1064—Change initiated in response to external conditions, e.g. avoidance of elevated terrain or of no-fly zones specially adapted for avoiding collisions with other aircraft
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
  • G06V20/00—Scenes; Scene-specific elements
  • G06V20/10—Terrestrial scenes
  • G06V20/13—Satellite images
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
  • G06V20/00—Scenes; Scene-specific elements
  • G06V20/10—Terrestrial scenes
  • G06V20/17—Terrestrial scenes taken from planes or by drones
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
  • G06V20/00—Scenes; Scene-specific elements
  • G06V20/60—Type of objects
  • G06V20/64—Three-dimensional objects
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
  • G06V2201/00—Indexing scheme relating to image or video recognition or understanding
  • G06V2201/12—Acquisition of 3D measurements of objects

Definitions

• the invention relates to a method and a system for determining the relative position of a mobile machine with respect to an environment.
• the invention relates to a method and a system for determining the position of a drone (aerial, for example of the multi-rotor or helicopter type) or a robot for inspecting surfaces in an environment known as example a shed in which is the object whose surface is to be inspected.
• a drone anerial, for example of the multi-rotor or helicopter type
• a robot for inspecting surfaces in an environment known as example a shed in which is the object whose surface is to be inspected.
• Mobile devices such as drones or robots moving in space autonomously require to know permanently their position in the environment in which they move.
• the positioning of mobile machines is generally done by geolocation, for example via the GPS system (Global Positioning System in English), which provides good accuracy.
• GPS system Global Positioning System in English
• a proposed solution was to start from a known position of the mobile machine and determine the position of the machine by measuring the movements made by the machine from this known position.
• This solution does not detect errors or inaccuracies of movement over time, which accumulate and therefore lead to erroneous positioning that can not be corrected.
• the solution uses inertial units which, although having a good accuracy to minimize these errors, have a high cost and a significant weight (often greater than 1kg) incompatible with use of aerial drone.
• beacon systems installed at advance in the environment, such as radio transceivers.
• a transceiver By equipping the mobile machine with a transceiver, it is then possible to estimate its position by triangulation techniques vis-à-vis the other tags.
• this solution is expensive and takes a long time to implement because it requires to have the tags and determine their precise positions (via calibration).
• the invention aims to overcome at least some of the disadvantages of known methods and positioning systems.
• the invention aims to provide, in at least one embodiment of the invention, a positioning method for positioning a mobile machine in an indoor environment.
• the invention also aims to provide, in at least one embodiment, a rapid positioning method, which can be executed on low power processors.
• the invention also aims to provide, in at least one embodiment, a precise positioning method.
• the invention also aims to provide, in at least one embodiment, a positioning method that does not require modifications of the environment in which it moves.
• the invention also aims to provide, in at least one embodiment, a positioning system that can be embedded.
• the invention relates to a method for determining the relative position of a mobile machine with respect to an environment modeled by a set of geometric surfaces forming a 3D modeling according to a reference of the environment, comprising:
• a method according to the invention therefore allows the positioning of a mobile machine in a totally or partially known environment without requiring the installation of beacon.
• the environment refers to the volume in which the mobile craft moves, with the elements that compose it: for example, a hangar in which there is an aircraft whose surfaces are to be inspected.
• the elements inspected are known and can be modeled in 3D, or are already modeled for other applications, by drawing software supported by computer (DAO).
• the method continuously uses the distance measurements of the machine with the environment, and determines its relative position with respect to the environment. For example, a drone flying around an aircraft for its inspection will know its position permanently and can, if it spots a defect on the surface of the aircraft, determine the position of this defect with respect to its own position and therefore locate it on the aircraft.
• the method implemented is thus fast and inexpensive in execution resources: it can be easily embedded on the mobile machine, having an embedded processor that consumes little energy and allows real-time processing. Part of the process, including steps to be performed only once and independent of the position of the mobile machine or measured distances (eg, pre-processing steps related to 3D modeling), may be performed outside the process. mobile machine, the results of these steps being provided to the embedded processor to improve the speed of execution of the steps processed by it.
• the speed of execution of the method also allows its execution more frequently and thus ensures rapid monitoring of the position of the mobile machine: it can then move more quickly.
• the process is particularly advantageous indoors because of the absence of geolocation, it can also be used outdoors for applications requiring increased accuracy in a known environment: for example, the inspection of an aircraft outdoors, the surface of a wind turbine or a ship in dry dock.
• the 3D modeling is a polygonal 3D mesh and the geometric surfaces are polygons.
• the modeling of the 3D environment by a polygonal 3D mesh allows a simple modeling and a faster processing of the different steps of the process.
• any 3D modeling with more complex geometric surfaces can be approximated by a polygonal 3D mesh according to techniques well known to those skilled in the art.
• the step of measuring a plurality of distances is performed by at least one scanning laser rangefinder.
• the step of measuring a plurality of distances is performed by at least two scanning laser rangefinders configured to perform scans in secant planes.
• each additional laser rangefinder is configured to perform scans in intersecting planes at the scanning planes of the other rangefinders.
• the step of evaluating a gap between the set of points and the 3D modeling of the environment comprises:
• attitude of the mobile machine corresponds to the orientation of the machine in space, expressed by angles ⁇ , ⁇ and ⁇ of Euler, known to those skilled in the art.
• a method according to the invention comprises, prior to said calculation step, for each point of said cloud of points, a norm between said point and a surface of the 3D modeling of the environment:
• a norm between said point and a surface of the 3D modeling of the environment comprises:
• a step of determining the nearest surface of the point among the near surfaces said closest surface being the surface whose standard between it and the point is the weakest, said norm being considered as the norm between the point and the 3D modeling of the environment.
• the step of decomposing the environment in superimposed cubes, and the step of determining, for each cube, the surfaces of the 3D modeling of the environment having a non-zero intersection with the cube may be previously executed and the result of these steps saved in a memory of the mobile machine to allow faster processing. Indeed, these The steps are not related to the position of the machine or the distance measurements made.
• the decomposition of the environment in cubes and the calculation of the norm between each point and the near surfaces allows a fast and inexpensive calculation of the resources of the standard between each point and the 3D modeling of the environment, because only a calculation of standards with nearby surfaces is done, rather than with all surfaces.
• the point cloud gap with 3D modeling is the set of standards between each point in the point cloud with 3D modeling, especially with the 3D modeling surface closest to that point.
• the points whose point standard is greater than a predetermined threshold, said isolated points, are extracted from the point cloud, and the method comprises an obstacle detection step in which the close isolated points are grouped together to form volumes representing obstacles, and said volumes are recorded.
• the method allows the isolation of points corresponding to obstacles that are not included in the 3D modeling of the environment, their processing and their consideration in the positioning of the mobile machine, to prevent the mobile device from coming into contact with these obstacles.
• the volumes representing the obstacles are recorded and allow to be taken into account in navigation and to be tracked as and when the mobile device moves.
• a method according to the invention comprises a step of suppression, of the point cloud, of points corresponding to the ground or the ceiling of the environment.
• the method makes it possible to limit the number of points to be treated by removing from the cloud of points the points corresponding to the ground or the ceiling of the environment which are of little use when the altitude of the mobile machine or an estimate of this altitude is available: the mobile machine knows that the ground and the ceiling correspond to particular and constant altitudes and does not require know the points forming the ground or the ceiling.
• the altitude is known either by direct measurement or by estimation.
• the process is thus faster because of the reduction in the number of points to be treated.
• a method according to the invention comprises a step of deletion, the cloud of points, ambiguous or redundant points.
• the method makes it possible to limit the number of points to be treated by removing from the cloud of points the points corresponding to ambiguous or redundant distance measurements.
• Ambiguous points are the points corresponding to a measurement of points on the edges of a surface or a measurement on a surface with a low angle of incidence, which may be erroneous.
• the redundant points are the points on a surface whose point cloud already has enough points to define said surface.
• the process is thus faster because of the reduction in the number of points to be treated.
• the invention also relates to a method of navigation of a mobile machine in an environment, comprising at least one step of moving the mobile machine, characterized in that a position of the mobile machine is determined during the step displacement, by a determination method according to the invention.
• the invention also relates to a method of navigation of a mobile machine in an environment, comprising at least one step of moving the mobile machine, characterized in that a position of the mobile machine and volume positions corresponding to obstacles are determined by a determination method according to the invention, and in that it comprises at least one step of avoiding said volumes corresponding to obstacles.
• the invention also relates to a system for determining the relative position of a mobile machine with respect to an environment modeled by a 3D modeling according to a reference of the environment, embedded in said mobile machine and characterized in that it comprises:
• modules for determining the relative position of the mobile machine in the environment mark from said deviation.
• the measuring means are, for example, sensors embedded by the module such as at least one scanning laser rangefinder, preferably two scanning laser rangefinders configured to perform scans in intersecting planes, a depth measurement camera (of the RGBD for Red Green Blue Depth), a stereovision device, a millimetric radar, etc., or a combination of these sensors.
• sensors embedded by the module such as at least one scanning laser rangefinder, preferably two scanning laser rangefinders configured to perform scans in intersecting planes, a depth measurement camera (of the RGBD for Red Green Blue Depth), a stereovision device, a millimetric radar, etc., or a combination of these sensors.
• the deviation evaluation module and the module for determining the relative position of the mobile machine are embedded in the mobile machine. However, some calculations unrelated to the measured distances or the position of the mobile machine may be performed in a separate computer, and provided prior to the determination system to improve the processing speed of the various means it comprises.
• the invention also relates to a computer program product downloadable from a communication network and / or recorded on a computer readable medium and / or executable by a processor, characterized in that it comprises program code instructions for the implementation of the determination method according to the invention.
• Such a computer program product makes it possible to determine the position of a mobile machine in which it is executed quickly, requiring little processor resources and thus with a low energy consumption.
• the invention also relates to a computer readable storage means, totally or partially removable, storing a computer program comprising a set of instructions executable by a computer to implement the determination method according to the invention.
• a determination system according to the invention implements a determination method according to the invention.
• a determination method according to the invention is implemented by a system according to the invention.
• the invention also relates to a computer program product downloadable from a communication network and / or recorded on a computer readable medium and / or executable by a processor, characterized in that it comprises program code instructions for the implementation of the determination method according to the invention.
• the invention also relates to a computer readable storage means, totally or partially removable, storing a computer program comprising a set of instructions executable by a computer to implement the determination method according to the invention.
• the invention also relates to a determination method, a navigation method, a system, a computer program product and storage means characterized in combination by all or some of the features mentioned above or below.
• FIG. 1 is a schematic representation of a method according to one embodiment of the invention
• Figure 2 is a representation of a polygon of a 3D mesh of the environment.
• FIG. 1 schematically represents a method for determining the position of a mobile machine with respect to an environment modeled by a set of geometric surfaces forming a 3D modeling according to an environment reference, according to one embodiment of the invention . All or part of this determination method is implemented by a determination system embedded in a mobile machine, according to one embodiment of the invention. The method is advantageously described for a mobile machine moving in three dimensions, such as a flying machine such as a drone, for example of the helicopter or multi-rotor type.
• the 3D modeling is a polygonal 3D mesh, that is to say that the geometric surfaces forming the 3D modeling are polygons.
• the invention also applies to any type of 3D modeling, including 3D models with more complex geometric surfaces (spheres, cylinders, ellipses & cones in particular).
• the determination method comprises a first step 10 of measuring a plurality of distances of the mobile machine to the environment in at least one direction, so as to obtain a set of points defined in a reference of the mobile machine, by means for measuring a plurality of distances from the craft to the environment in at least one direction.
• These measuring means are, for example, sensors such as at least one scanning laser rangefinder, preferably two scanning laser range finders in secant planes, a depth measurement camera (RGBD type for Red Green Blue Depth). , a stereovision device, a millimetric radar, etc., or a combination of these sensors.
• the distance measurements take the form of pairs (solid angle, distance measured in this solid angle) according to a reference of the mobile machine and with respect to a known point on the mobile machine, typically the position of the measuring means, known relative to the center of gravity of the mobile machine.
• a scanning laser rangefinder can measure distances with a small angular step (for example 0.25 °) and a wide angular field (270 ° or more), making it possible to obtain a large number of pairs (solid angle; distance).
• a small angular step for example 0.25 °
• a wide angular field 270 ° or more
• the use of several rangefinders with different orientations and / or mirrors makes it possible to obtain measurements in different planes.
• RGBD or stereovision camera, radar or sonar acquisition means make it possible to obtain measurements of distances on several dimensions without requiring scanning.
• the pairs form a set of points in a reference of the mobile machine: the pairs correspond to the spherical coordinates of the points of the set of points in a reference of the mobile machine.
• the method then comprises an optional step 12 of suppression, of the scatterplot, of points corresponding to the ground or the ceiling of the environment, by a suppression module, the cloud of points, of points corresponding to the ground or the ceiling of the 'environment.
• the extraction of the measured distances corresponding to the ground or the ceiling from the set of distances measured makes it possible to reduce the number of distances taken into account in the subsequent determination process.
• This extraction requires knowing the attitude of the machine, and in one embodiment, its altitude, measured by a specific sensor, or an estimate of the altitude of the mobile machine, deduced from the previous position of the mobile device taking into account the approximate displacement from this last position.
• ZC is calculated using the altitude of the machine:
• ZC is calculated directly from the Z coordinates of the points:
• the first embodiment has the advantage of being faster since the interval is known immediately without having to calculate minimum or maximum on all points and has the advantage of operating even with "holes" in the ground or ceiling.
• the second embodiment has the advantage of not using the altitude of the machine, and can in particular operate even if the altitude estimate no longer works.
• a third embodiment, the preferred mode is to use the first mode when a good estimate of the altitude is available and to use the second mode otherwise.
• the method then comprises an optional step 14 of deletion, cloud of points, ambiguous or redundant points, by means of suppression, cloud of points, ambiguous or redundant points.
• This step includes several objectives: a first objective is to avoid the duplication of measured distances that are too similar, for example a set of measured distances representing the same plane. It is not necessary to keep several hundred points to define a flat surface.
• a second objective is to reduce the number of unreliable measured distances, especially when the distance measuring means are laser range finders whose measurements are made by scanning. For example, for close solid angles, the measured distance may vary significantly when the environment includes distant surfaces: the points intermediate between these remote distances may be erroneous. In addition, measurements on a surface with which the laser rangefinder has a low angle of incidence (close to 0 °) may be erroneous.
• a third objective is to ensure the presence of a minimum number of points in all directions, in order to obtain a consistent result.
• a predetermined threshold for example 0.5
• points very close to a selected measure can be used to consolidate said selected measure before being deleted.
• the consolidation is for example an average or a median on 3 points.
• a reduced list of distance measurements is thus obtained which makes it possible to speed up the processing of the following steps while suppressing data that may be erroneous and keeping a sufficient number of points in each angular sector.
• the method then comprises a step of evaluating a gap between said set of points and the 3D mesh of the environment and a step 20 of determining the relative position of the mobile machine in the reference of the environment from said deviation. These steps can be performed several times in a loop to refine the position of the mobile machine.
• the step of evaluating a gap between said set of points and the 3D mesh of the environment comprises a step 16 of converting the set of points in the reference of the mobile machine to a cloud of points in the environment. reference of the environment from an estimation of the position of the mobile machine and a step 18 of calculating, for each point of said cloud of points, a norm between said point and a polygon of the 3D mesh of the environment.
• the conversion is carried out by determining the matrix of passage of the marker of the mobile machine to the reference of the environment, based on an estimate of the position and attitude of the machine.
• the reference of the environment is preferably orthonormed of type Oxyz.
• the position of the machine can be estimated in several different ways depending on the embodiment.
• the attitude of the machine is generally known thanks to an inertial system, such as a low cost inertial unit.
• the last position provided by the method can be used as the position estimate.
• This last position can possibly be refined if the mobile machine knows approximately the speed and direction of movement of the machine, for example via an accelerometer.
• this position and orientation are provided as an estimate of the position of the machine and the following steps of the determination method are executed a fixed number of times (for example 5), then the consistency of this position is verified: a position is said to be coherent if a precision indicator, representative of the average of the standards of each point with an area of the environment (described below) is less than a threshold (eg the average deviation is less than 20cm) and the percentage of points whose standard between that point and the environment is less than one maximum deviation is greater than a threshold (eg more than 75%). If the position is consistent, the position is used as an estimate of the position, otherwise the method below, called the mesh method is used.
• a precision indicator representative of the average of the standards of each point with an area of the environment (described below) is less than a threshold (eg the average deviation is less than 20cm) and the percentage of points whose standard between that point and the environment is less than one maximum deviation is greater than a threshold (eg more than 75%).
• Some environments allow an approximate determination of the initial position of the mobile machine. For example, in the case where the environment includes an aircraft, it is possible to extract the distance between the mobile craft and a fuselage of the airplane, and / or the distance between the mobile craft and a wing of the airplane, This considerably limits the number of positions to be tested.
• the mesh method makes it possible to find a valid position in the case where one would have lost the positioning of the mobile machine during its displacement.
• the search mesh consists of points on a sphere around the last known position (for example, of radius lm). . Similarly, the points closest to the last known position will be tested first. The algorithm continues until finding a position validating the consistency criterion. If none is found on the sphere, the radius of the sphere is increased (for example, in steps of lm) and the algorithm begins again.
• the estimation of the altitude can come from the results of the optional step of extracting the measured distances corresponding to the soil of the environment, if it has been executed.
• the 3D mesh of the environment is for example a representation of the environment in the form of a set of associated polygons to form an approximation of the surfaces of the environment.
• These polygons are for example triangles or quadrangles.
• the objective of the calculation step 18, for each point of said cloud of points, of a norm between said point and a polygon of the 3D mesh of the environment is to determine, for each point of the point cloud, the norm from this point with the nearest polygon, and deduce a point cloud standard with the mesh
• 3D representative of the error of the position used in the conversion step of measured distances to a scatter plot in the environment marker.
• the 3D mesh of the environment (represented by the reference 100) is previously divided by a cubic pattern comprising superimposed cubes covering the entire environment.
• This step of decomposing the environment into superimposed cubes, so that each point of the environment is included in a plurality of cubes follows, for example, the following steps:
• the length of the sides of a cube is lm.
• duplication of the new cube pattern and translation of the duplication of half a cubic length along the axis Oy of the reference of the environment We obtain twice as many cubes as in the previous step and four times more cubes than in the initial pattern.
• any point of the environment not included in a face of a cube and not at the edge of the environment is in exactly eight cubes, and among these eight cubes there is always a cube, said centered cube, from which the point is the furthest apart from each of the faces of said cube, that is to say that it is more than a quarter length of edge of each face of the cube (ie 25cm for a cube of edge lm).
• a list of cubes of the cube pattern is advantageously organized so that from a point whose coordinates are expressed in the reference of the environment, a simple mathematical formula makes it easy to find the centered cube corresponding to this point: cubes have an index linked to their position in the environment.
• the method then comprises a step of determining, for each cube, polygons of the 3D mesh of the environment having a non-zero intersection with the cube.
• the list of polygons is traversed to retrieve those whose intersection with the volume of the cube is non-zero, that is to say the polygons that are contained in the cube or that cut at the same time. minus one side of the cube.
• the results of this step are stored for quick access by an embedded system. This method would apply similarly to the list of surfaces to define which surfaces have a non-nu- merous intersection with the cubes.
• steps of decomposing the environment in superimposed cubes and determining, for each cube, the polygons of the 3D mesh of the environment having a non-zero intersection with the cube are steps that are not related to distance measurements or at the position of the mobile gear and that can be executed once for the environment. They can therefore be executed by an external computer, and only the results including the list of indexed cubes and the triangles associated with each indexed cube having an intersection with this cube are stored by the embedded system.
• the method comprises, in step 18 of calculation, for each point of said cloud of points, of a norm between said point and a polygon of the mesh 3 D of the environment, a step of selecting one of the cubes, said centered cube, from which the point of the cloud of points is the most distant from each of its faces. Thanks to the preferential indexing of the cubes described above, the centered cube is determined quickly by the coordinates of the point. For example, the calculation for determining the index of the cube for a point P with coordinates (x p , y p , z p ) is:
• the method then comprises a step of retrieving the list of polygons having an intersection with the centered cube, said close polygons. These polygons are quickly recovered from the centered cube, thanks to the previously described storage associating with each cube the polygons with which it presents a non-zero intersection.
• the point is said isolated point and is removed from the list of points for the continuation of the step of evaluating a gap between the set of points and the 3D mesh of the environment .
• the isolated points are grouped in a list of isolated points, allowing the detection of obstacles.
• the method then comprises a step of calculating a norm between the point and each near polygon.
• T (s, t) A + sB + tC
• (s, t) e D ⁇ (s, t), te [0,1], s + t ⁇ 1 ⁇
• the distance from the square of P to a point T (s, t) of the triangle is
• the purpose of the algorithm is to find the pair (s, t) corresponding to the minimizing point Q.
• the algorithm for quickly calculating the norm of a point to a triangle is defined as follows:
• the candidate point is in this case the orthogonal projection of P on the plane defined by the triangle, but this point does not belong to the closed surface of the triangle.
• the space of the plane defined by the triangle is then partitioned into several regions as represented with reference to FIG. 2, representing the triangle ABC and on a 2D reference (A, s, t).
• the candidate point is in one of the regions 1 to 6, respectively numbered R1, R2, R3, R4, R5, R6, the region 0 (numbered R0) corresponding to case 2 described above.
• Region 1 The contour lines of Q are ellipses centered on the candidate point. The minimizing point is thus located on] CB [if the gradient is zero on this domain, in which case the pair (s, t) minimizing is obtained, either on C or on B. The algorithm stops.
• Region 2 The contour lines of Q are also ellipses, so the minimizing point is either on [CA] or on [CB]. Geometric considerations on the gradient from Q to C make it possible to determine if the minimizing point is on [CA] or [CB]. According to the same principle as region 1, the nullity or otherwise of the gradient on the segment makes it possible to obtain the minimizing pair (s, t). The algorithm stops.
• Regions 3 and 5 The reasoning is similar to that of Region 1.
• Regions 4 and 6 The reasoning is similar to that of Region 2.
• the calculations can be further accelerated by the pre-calculation of a certain number of parameters on the triangles and stored in memory with the information of said triangles.
• each polygon can be replaced with a set of triangles.
• Step 18 of calculation then comprises a step of determining the polygon closest to the point among the near polygons, said closest polygon being the polygon whose standard between it and the point is the weakest, said norm being considered the standard between the point and the 3D mesh of the environment.
• the method also calculates the vector error, in the form of three-dimensional vectors, between each point and the nearest polygon.
• the vector error comprises three components along the three axes x, y, z of the reference of the environment.
• step 20 of determining the relative position of the mobile machine in the environment reference the set of these standards between each point, representative of the difference between the set of points and the 3D mesh of the environment, are treated in such a way as to minimize this difference.
• Each iteration of the algorithm uses a POS init estimate of the position (according to x, y and z) to calculate an estimate POS_calc of the position (according to x, y and z), and comprises the following steps:
• POS_calc POS nit - ⁇ * (J T * * * / * r
• the calculation can be made by fixing the position along the z axis to the known altitude value, thus improving the speed of calculation.
• the correction to be made is in the positive direction, and the correction is at least equal to x min . This correction of x min can therefore be made directly to reach the corrected position more quickly.
• the correction to be made is in the negative direction, and the correction is at least equal to x max .
• This correction of x max can therefore be made directly to reach the corrected position more quickly.
• the method also includes a step 22 of processing isolated points, said step of obstacle detection, wherein the isolated points are grouped together to form volumes representing obstacles.
• the environment is decomposed into adjacent cubes of the boxel type, and the process goes through all the boxels to determine if it includes at least one isolated point: if it is the case, the boxel is considered as boxel d 'obstacle.
• the close obstacle boxes are grouped together to form volumes for example by mathematical morphology operations such as two dilation stages followed by an erosion stage.
• the boxels contained in these volumes are listed and recorded as obstacles, thus defining a position of the detected obstacles.
• This recorded obstacle position information can aid navigation (obstacle avoidance) and allow tracking of obstacles over time.
• the method is implemented at a predetermined frequency so as to follow the evolution of the position of the mobile machine according to the desired constraints (for example 50 Hz).
• the mobile machine can use them to implement a method 24 navigation and guidance necessary for its movement.
• the navigation method 24 comprises at least one moving step during which the position of the mobile machine and possible obstacles is determined, in particular regularly during the displacement.
• the different steps of the process are implemented by different modules such as processors, microcontroller, calculators, etc.
• a step can be implemented by a single dedicated module, or several steps can be implemented by the same module.
• the invention is not limited to the embodiment described.
• the invention can be applied to mobile rolling machines, in which case the calculations can be simplified by limiting the calculations to the x and y coordinates corresponding to a 2D displacement on the ground.

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• 2016
  • 2016-01-14 FR FR1650303A patent/FR3046848B1/fr active Active
  • 2016-12-19 US US16/070,502 patent/US20210200246A1/en not_active Abandoned
  • 2016-12-19 WO PCT/FR2016/053546 patent/WO2017121936A1/fr active Application Filing
  • 2016-12-19 EP EP16829265.4A patent/EP3403117A1/fr not_active Withdrawn
  • 2016-12-19 JP JP2018536268A patent/JP2019504418A/ja active Pending
  • 2016-12-19 CN CN201680078920.2A patent/CN108474836A/zh active Pending

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