Device for the acquisition and reconstruction of objects by visual inspection

Abstract

The present invention is a device for the complete acquisition of the shape of an object by means of a plurality of image sensors arranged around a space for image capture. Image sensors capture a plurality of images that are carried to a reconstruction system formed from said plurality of images corresponding to different views of the object. Document EP2511653 discloses a system where the object falls through the trap area so that there is no type of fastener or support which hides some part of the object. The present invention is a device for the acquisition and reconstruction of objects characterized by the use of an actuator serving as launcher and configured so that the object is positioned at the point of capture of images at either zero or very close to zero speed to improve the resolution of each image without blurring due to movement, even with relatively long exposure times. Additionally, the actuator is configured so that the fall of the object is such that it prevents damage by the impact effect.

Claims

1. Device (1) for the acquisition and reconstruction of objects (O) by visual inspection, comprising: a plurality of image sensors (2) adapted for image acquisition; a computational equipment (3) for reconstruction of volumes from images captured by the plurality of sensors (2) wherein the sensors (2) are spatially distributed in positions of a sphere (E) having a lower part according to the direction of gravity ({right arrow over (g)}), with their optical axis oriented towards the inside of the sphere; at least one access (A) disposed in the lower part of the sphere (E) for the input/output of an object (O) to be inspected; at least one holder (S) for the object to be inspected, movable in a longitudinal direction X-X′, located under the access (A) of the lower part of the sphere (E), with the longitudinal direction X-X′oriented towards said access (A); impulsion means (4) for moving the at least one holder (S); a control unit (5) in communication with the impulsion means (4) adapted to establish the movement of the at least one holder (S) according to at least the following launching steps: upward acceleration of the at least one holder (S) for accelerating an object (O) to be inspected laying on the holder (S), deceleration of the ascent of the at least one holder (S) until reaching zero speed for separation between the object (O) and the holder (S), and, according to at least the following reception steps: downward acceleration of the at least one holder (S) for the reception during the fall of the object (O), deceleration of the descent of the holder (S) to reach zero speed; and, wherein the control unit (5) is in communication with the computer equipment (3) and is adapted to establish at least one activation of the image capture of the object (O) at a time instant between the instant (t.sub.3) of the end of the ascent deceleration of the at least one holder (S) and the instant (t.sub.5) of start of the descent acceleration of the at least one holder (S).

2. Device (1) according to claim 1, wherein the longitudinal direction X-X′ of movement of the at least one holder is vertical.

3. Device (1) according to claim 1 wherein the longitudinal direction X-X′ of movement of the at least one holder passes through the center of the sphere (C).

4. Device (1) according to claim 1, wherein the optical axes of the sensors (2) are oriented either towards the center of the sphere (C) or to a point inside the sphere through which the trajectory of the object (O) launched by the at least one holder (S) passes.

5. Device (1) according to claim 1, wherein the control unit (5) is adapted to determine the upward acceleration that provides the upward thrust to the object (O) to be inspected and which can position said object (O) at the center of the sphere (E).

6. Device (1) according to claim 1, wherein the control unit (5) is adapted to determine the upward acceleration that provides the upward thrust to the object (O) to be inspected and which can position said object (O) and at the center of the sphere (E).

7. Device (1) according to claim 1, wherein the control unit (5) is adapted for activating image capture at least at the moment when the object (O) reaches the apogee of the trajectory of the object (O) released by the at least one holder (S) at the point to where the axes of the optical sensors (2) are oriented inside the sphere (E).

8. Device (1) according to claim 1, wherein the control unit (5) is adapted for activating image capture in at least one of the two instants at which the object (O) reaches the point towards which the optical axes of the sensors (2) are oriented inside of the sphere (E), being these instants respectively before and after the instant of pass through the apogee located above that point.

9. Device (1) according to claim 1, wherein the sphere (E) has at least one opening (A) positioned for the access of the object (O) and the at least one holder (S).

10. Device (1) according to claim 1, wherein the control unit (5) is configured to determine the activation time of image capture by establishing the instant at which the object (O) reaches the point of image capture as a function of the movement of the at least one holder (S) launching the object (O).

11. Device (1) according to claim 1 wherein the control unit (5) comprises a sensor (6) adapted to measure whether the object (O) launched by the holder (S) reaches a preset position (P) within the sphere (E); and wherein the control unit (5) is further configured to determine the activation instant when the sensor (6) measures if the object has reached a preset position.

12. Device (1) according to claim 1, comprising a feeding conveyor (7) for carrying objects (O) to be inspected a holder (S) configured to launch the object into the sphere (E).

13. Device (1) according to claim 1, comprising an output conveyor (8) for evacuating the objects (O) that have been inspected from a reception holder (S), and wherein the reception holder (S) comprises an actuator (10) for transferring the inspected object (O) to the output conveyor (8).

14. Device (1) according to claim 1, wherein said device (1) is adapted to capture continuously a plurality of objects (O) fed through the feeding conveyor (7) and with evacuation through the output conveyor (8); and wherein the device (1) comprises a sensor (9) for detecting whether an object (O) reaches the at least one holder (S) in communication with the control unit (5) such that the control unit (5) is adapted so that upon detection of an object (O) that reaches the at least one holder (S) the launching steps of the object (O) and the image capture are followed; and subsequently to image capture and reception on the at least one holder (S), it activates the actuator (10) for transferring the inspected object (O) to the output conveyor (8).

15. Device (1) according to claim 1, wherein the sensors (2) are spatially distributed in positions of the sphere (E) with their optical axes oriented towards the center of the sphere (C).

16. Device (1) according to claim 1, wherein: either the same holder (S) is intended to carry out the release and reception of the object (O), or a first holder (S.sub.1) is intended to carry out the launch and a second holder (S.sub.2) is intended to carry out the reception.

17. Device (1) according to claim 16, wherein the device comprises a single holder (S) that is disposed relative to the sphere (E) to both launch and receive the object (O).

18. Device (1) according to claim 16, wherein the device comprises a first holder (S1) that is disposed relative to the sphere (E) to launch the object (O) and a second holder disposed relative to the sphere (E) to receive the object (O).

Description

DESCRIPTION OF THE DRAWINGS

(1) These and other features and advantages of the invention will be more clearly apparent from the following detailed description of a preferred embodiment given purely as an illustrative and non-limiting example, with reference to the accompanying figures.

(2) FIG. 1 This figure schematically shows an embodiment of the invention with a single holder and with input and output feed means of the captured objects.

(3) FIG. 2 In this figure, the velocities and accelerations of the holder are schematically shown in time, linking these variables to the positions of the device and of the object that is captured by the image sensors.

(4) FIG. 3 This figure schematically shows an embodiment of the invention having a launching holder and a receiving holder.

DETAILED DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows a schematic view of an embodiment of the invention formed by a device (1) for the acquisition and reconstruction of objects (O) by visual inspection where, on the same schematic representation, more than one position of the object (O) to be captured and of the moving parts are shown to explain their operation.

(6) The device (1) comprises a plurality of sensors (2) distributed over a surface (Sf) of spherical configuration (E). This surface (Sf), in this embodiment, serves as support element of the plurality of sensors (2) allowing them to have their main axis oriented towards inside the surface (Sf). In particular, the axes (not shown graphically to avoid an excess of lines) are oriented towards the center (C) of the sphere (E). The plurality of sensors (2) provide multiple images of the same object (O) from different points of view covering the entire outer surface of the object (O) to capture.

(7) Although the axes are not shown, two diverging straight lines representing the amplitude of the visual field of each of the image sensors (2) are depicted. The intersection of the conical volumes defined by the image sensors (2) is an internal volume where the simultaneous capture of the object (O) is performed by all the sensors (2).

(8) The object (O) to capture not only must be located in this volume but the depth of field of each of the image sensors (2) should be enough to cover the visible part of the object (2).

(9) In the graphical representation, it is shown at the bottom a holder (S) with a upward concave shape that can accommodate the object (O) to capture. This holder (S) is connected to impulsion means (4) which in this embodiment is formed by a linear actuator acting vertically moving a rod which at its upper end is attached to the holder (S).

(10) The device (1) comprises a control unit (5) in communication with the linear actuator (4). The communication is represented by dashed line. Thus, the monitoring unit (5) sets the position of the holder (S) by sending commands to the linear actuator (4). The control unit (5) according to this embodiment determines, as a function of time, the position, velocity and acceleration of the holder (S).

(11) A little later, a way to carry out this control by the control unit (5) will be described, especially by imposing movements to the holder (S) that are part of a launching step of the object and movements corresponding to a subsequent reception of the released object.

(12) The thrown object (O) object rises and passes through a low opening (A) of the sphere (E) reaching the apogee in its upward motion in the capture volume, located either in the center (C) or in points near the center (C) of the sphere (E).

(13) As shown in FIG. 1, the control unit (5) comprises a sensor (6) adapted to measure whether the object (O) launched by the holder (S) reaches a preset position within the sphere (E); and wherein the control unit (5) is further configured to determine the activation instant when the sensor (6) measures if the object has reached the preset position.

(14) The control unit (5) measures the time that elapses from a time reference, knowing that the throwing motions have been performed. The control unit (5) is also in communication with each of the image sensors (2) activating the capture of multiple images at the time when the control unit (5) estimates the object (O) is either in the center (C) or in points near the center (C) of the sphere (E). At the apogee, the object velocity is zero and therefore the images are not blurred due to movement for a suitable rate of capture speed, always much less than the capture speed required for an object that is already in free fall and whose movement must “freeze”.

(15) The control unit (5) sends the images captured by the image sensors (2) to a computer equipment (3), which may be any of those known in the prior art to combine the multiple images of the object (O) captured from different directions to reproduce the entire volume.

(16) Since the object has been photographed suspended in air, there is no holder that prevents visual access from the image sensors (2) to the object (O) or any part of it.

(17) The object launching and reception processes to solve the referred problems, is described with the help of FIG. 2.

(18) FIG. 2 shows a timeline whose initial reference t.sub.0 considers that the object to be captured (O) is already placed on the holder (S) and it (S) is in a lower position (h.sub.0).

(19) On the same timeline, the object (O), the sphere (E), the holder (S) at the position corresponding to the instant indicated by the timeline, and the impulsion means acting on the holder (S) are represented very schematically.

(20) In this initial rest position until reference t.sub.0, the holder velocity is zero v.sub.0=0. The release process is a step having a first time interval up to t.sub.1 with positive acceleration a.sub.1 imposing an impulsion that transmits acceleration from the holder (S) to the object (O).

(21) This acceleration increases the speed of the holder (S) to a speed v.sub.1 which corresponds to the release speed of the object (O). This speed v.sub.1 is the one that the object (O) must acquire so that, in its ascent, its apogee (identified as h.sub.a) is at the center (C) of the sphere (E) or at a point near said center (C), understood by near that the object (O) at the time of the capture of the plurality of images is within the volume wherein the plurality of image sensors (2) are focusing, its speed being zero or near zero such that the sensors (2) adequately capture (in angle of view and focus) the totality of said object (O).

(22) FIG. 2 shows an instant of the ascent in the position of the holder (S) where its height is (h.sub.1) with a constant ascent speed.

(23) Reached the moment identified as t.sub.2, the impulsion means (4) cause a deceleration a.sub.2 (negative acceleration) to the holder (S) causing a decrease in speed until the holder is stopped (speed v.sub.2=0 at instant t.sub.3) reaching the holder (S) a maximum height (h.sub.2).

(24) During the deceleration phase, the object (O) is not able to follow the holder (S) and separates from it, following its own ascent until it reaches the apogee at time t.sub.4.

(25) According to one embodiment the apogee may be positioned slightly above the center (C) of the sphere (E) therefore the object will pass twice through said center (C) at a reduced speed. Thus, the control unit (5) has at least two launching possibilities with the object (O) at a speed close to zero and therefore in good conditions for capture. FIG. 2 shows two time instants in which the object passes through the center (C) of the sphere (E), the instant t.sub.4−Δ and the instant t.sub.4+Δ being 2Δ the space of time between the two capture instants of the plurality of images.

(26) After the image capture, the object starts its free fall by gravity ({right arrow over (g)}′) approaching the holder (S) in a uniformly accelerated motion. To avoid the impact in the fall, the holder starts at an instant t.sub.5 a downward motion with negative acceleration a.sub.3 up to an instant t.sub.6 approaching the speed of descent of the holder (S) to the fall speed of the object (O). The holder (S), after reaching a certain speed v.sub.3 at instant t.sub.6 maintains this constant speed until an instant of time t.sub.7. The instant of collection of the object (O) with minimal impact, when the height of the object (O) is the same as the height h.sub.4 of the holder (S), may occur either during the interval of negative acceleration of the holder (S) between the time instants t.sub.5 and t.sub.6, or during the constant speed interval of the holder (S) between time instants t.sub.6 and t.sub.7.

(27) Once the time instant reached t.sub.7 with the object (O) laying on the holder (S), a positive acceleration a.sub.4 starts to reduce the speed of descent of the holder (S) until it is stopped (speed v.sub.4=0) from time instant t.sub.8 recovering a height h.sub.5=h.sub.0, the height in its lower position that the holder (S) had at the start of the release process.

(28) While this is an embodiment, it is possible to establish shorter release and collection processes, for example reducing or even eliminating the time intervals where the speed v.sub.1 and v.sub.3 are constant.

(29) It is also possible the use of two holders (S) arranged so that they are nearly parallel, with their axes oriented towards the opening (A) such that the launching step is performed by the first holder (S), and the collecting step is performed by the second holder (S). The launch trajectory should be such that the apogee is in the center (C) of the sphere (E) or close to it as described, and the branch descent trajectory matches the second holder (S). An embodiment arranges the holders (S) substantially vertical with a slight tilt such that their longitudinal directions X-X′ converge at a point located above the center (C) of the area (E).

(30) In this case, a holder (S) is for launch and the other holder (S) is for reception. When there is only a holder(S), the same holder is for launch and reception.

(31) If two holders (S) are present, the launch holder (S) recovers the initial position after the upward accelerated and upward decelerated movements to proceed with the next launch. Conversely, after collection by the receiving holder (5), it (S) recovers its upper position to receive again another object (O).

(32) Returning to FIG. 1, additional elements are described that allow the device, for instance, to capture multiple objects (O) in a sequential manner.

(33) According to one embodiment, combinable with any of the ones described above, the objects (O) to capture are fed by an input or feeding conveyor (7). A sensor (9) detects the object (O) arrival verifying by means of the control unit (5) that the holder (S) is free. If so, the object (O) is deposited on the release holder (S) and, if not, the control unit (5) stops the input conveyor (7) until the release holder (S) release is free to allow new objects (O) for their capture.

(34) Once the object (O) has been captured according to any of the embodiments described, a rocker (10) located on the collecting holder (S) transfers the object (O) to an output conveyor (8) leaving the holder (S) free.