Method and a device for recognizing, collecting and repositioning objects

• US 8,467,898 B2
• Filed: 03/04/2008
• Issued: 06/18/2013
• Est. Priority Date: 03/08/2007
• Status: Expired due to Fees

• Current Assignee: S.M.V S.r.l.
• Original Assignee: S.M.V S.r.l.
• Inventors: Cardoni, Patrizio
• Primary Examiner(s): Crawford, Gene
• Assistant Examiner(s): LOGAN, KYLE O
• Application Number:
  US12/529,257
• Publication Number:
  US 20100114363A1
• Time in Patent Office: 1,932 Days
• Field of Search: 700/218, 700/214
• US Class Current: 700/218
• CPC Class Codes: B25J 9/1612 characterised by the hand, wrist, grip control
• CPC Class Codes: B25J 9/1694 characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
• CPC Class Codes: G05B 2219/37054 Digitize every grid point of a raster
• CPC Class Codes: G05B 2219/37286 Photoelectric sensor with reflection, emits and receives modulated light
• CPC Class Codes: G05B 2219/37319 Derive acceleration, force, torque from current
• CPC Class Codes: G05B 2219/39487 Parallel jaws, two fingered hand
• CPC Class Codes: G05B 2219/39497 Each finger can be controlled independently
• CPC Class Codes: G05B 2219/39507 Control of slip motion
• CPC Class Codes: G05B 2219/39513 Tip prehension grasp, grasp with tip of fingers
• CPC Class Codes: G05B 2219/39531 Several different sensors integrated into hand
• CPC Class Codes: G05B 2219/39532 Gripping force sensor build into finger
• CPC Class Codes: G05B 2219/39534 By positioning fingers, dimension of object can be measured
• CPC Class Codes: G05B 2219/40053 Pick 3-D object from pile of objects
• CPC Class Codes: G05B 2219/40252 Robot on track, rail moves only back and forth
• CPC Class Codes: G05B 2219/40564 Recognize shape, contour of object, extract position and orientation
• CPC Class Codes: G05B 2219/40567 Purpose, workpiece slip sensing
• CPC Class Codes: G05B 2219/45045 Maintenance, automatic storage and retrieval system

Abstract

A method for recognizing, collecting and repositioning objects (1) having non-predetermined dimensional characteristics and which are arranged on a support surface (2) is implemented by means of a gripper group (30). The gripper group (30) is mobile in at least a lengthwise direction of movement relative to an object (1) to be handled, a direction of moving towards/away from the object (1), and a direction of adjustment of the height relative to the object (1). The gripper group (30) is controlled by a computerized control unit. The method comprises the following operating stages: a stage of approaching and recognizing an object (1), comprising the approximately-set approach of the gripper group (30) to the object (1), performed with the assistance of positional information stored in the control unit; identification of the outline of the object (1), by perpendicular three-dimensional scanning performed, using sequences of movements of the gripper group (30), by means for gauging punctual distance (50) arranged near at least one finger (35, 36) of the gripper group (30), and by sensor means (55) for detecting the presence of the object (1), which identify the depth of the object and are arranged at the head of the fingers (35, 36); a stage of gripping the object (1); a stage of collection the object (1), comprising operations of lifting and moving the object (1).

Claims

1. A method for recognizing, collecting and repositioning objects, which objects (1) exhibit non-predetermined dimensional characteristics, said method comprising the steps of:

providing a gripper group (30) having fingers, the gripper group being movable in at least a longitudinal direction relative to an object (1) to be handled, a direction towards/away from the object (1), and a direction of height adjustment relative to the object (1),

controlling the gripper group (30) using a computerized control unit, said method further comprising any suitable combination of the following operating steps;

directing the gripper group to approach the object (1) using positional information stored in the control unit;

performing a perpendicular three-dimensional scanning for recognizing an outline of the object using sequences of displacements of the gripper unit (30) by gauging punctual distances (50), using a gauge arranged on at least one finger (35, 36) of the gripper group (30);

providing a presence sensor (55) for detecting a depth of the object, and arranging the presence sensor (55) at a top of the fingers (35, 36) of the gripper group (30);

gripping the object (1) using the gripper group (30), and progressively tightening the gripper group (30) for gripping the object (1) until a predetermined intensity of grip is reached, said predetermined grip intensity depending on physical characteristics of the object (1);

collecting the object (1) by lifting and moving the object (1);

directing the gripper group (30) to approach a support surface (2);

moving the gripper group (30) until the object (1) makes contact with the support surface (2);

opening the fingers (35, 36) of the gripper group (30) until the object (1) is released and extracting the fingers (35, 36) from where the object (1) is located; and

wherein at least one finger of the gripping group has at least one oscillating rod (350) provided on an inner surface thereof, and gripping the object by the gripping fingers (35, 36) with interpositioning of the at least one oscillating rod (350).

2. The method of claim 1, wherein the performing of the perpendicular three-dimensional scanning for recognizing the outline of the object comprises the steps of:

acquiring a set of punctual distance data regarding the object (1) by positioning the gauge on various points of data acquisition of the object, by moving the fingers (35, 36) of the gripper unit (30) along trajectories controlled by the control unit, and processing the set of punctual distance data using the control unit to obtain the dimensional outline of the object and a distance of the object from the gripper group (30).

3. The method of claim 1, wherein the presence sensor acquires data regarding a depth of the object (1), by determining a presence or absence of a signal which is transmitted and received respectively by a transmitter and a receiver belonging to the presence sensor (55).

4. The method of claim 3, characterized in that the signal is a light signal.

5. The method of claim 1, wherein at least one oscillating rod (350) is provided for each finger (35, 36).

6. The method of claim 1, further comprising, during gripping of the object (1) by the gripping fingers (35, 36), controlling the intensity of the grip in one of at least two different ways, depending on the dimensions of the object (1).

7. The method of claim 6, characterized in that, when gripping objects (1) of large dimensions, grip intensity is controlled by reading a value of a current feedback signal of a motor activating the gripper fingers (35, 36).

8. The method of claim 6, characterized in that, when gripping objects of small dimensions, grip intensity is controlled by reading a pressure exerted on the object (1) by the fingers, the reading obtained using a load gauge (355) arranged at a distal portion of at least one of the gripper fingers (35, 36).

9. The method of claim 8, further comprising operating the load gauge in conjunction with interpositioning of an outer arm (351) of at least one oscillating rod (350).

10. A method for recognizing, collecting and repositioning objects, which objects (1) exhibit non-predetermined dimensional characteristics, said method comprising the steps of:

providing a gripper group (30) having fingers, the gripper group being movable in at least a longitudinal direction relative to an object (1) to be handled, a direction towards/away from the object (1), and a direction of height adjustment relative to the object (1),

controlling the gripper group (30) using a computerized control unit, said method further comprising any suitable combination of the following operating steps;

directing the gripper group to approach the object (1) using positional information stored in the control unit;

performing a perpendicular three-dimensional scanning for recognizing an outline of the object using sequences of displacements of the gripper unit (30) by gauging punctual distances (50), using a gauge arranged on at least one finger (35, 36) of the gripper group (30);

providing a presence sensor (55) for detecting a depth of the object, and arranging the presence sensor (55) at a top of the fingers (35, 36) of the gripper group (30);

gripping the object (1) using the gripper group (30), and progressively tightening the gripper group (30) for gripping the object (1) until a predetermined intensity of grip is reached, said predetermined grip intensity depending on physical characteristics of the object (1);

collecting the object (1) by lifting and moving the object (1);

directing the gripper group (30) to approach a support surface (2);

moving the gripper group (30) until the object (1) makes contact with the support surface (2);

opening the fingers (35, 36) of the gripper group (30) until the object (1) is released and extracting the fingers (35, 36) from where the object (1) is located;

wherein the performing of the perpendicular three-dimensional scanning for recognizing the outline of the object comprises the steps of;

acquiring a set of punctual distance data regarding the object (1) by positioning the gauge on various points of data acquisition of the object, by moving the fingers (35, 36) of the gripper unit (30) along trajectories controlled by the control unit, and processing the set of punctual distance data using the control unit to obtain the dimensional outline of the object and a distance of the object from the gripper group (30); and

,

wherein the points of acquisition are organized in a grid having a predefined step.

11. A method for recognizing, collecting and repositioning objects, which objects (1) exhibit non-predetermined dimensional characteristics, said method comprising the steps of:

providing a gripper group (30) having fingers, the gripper group being movable in at least a longitudinal direction relative to an object (1) to be handled, a direction towards/away from the object (1), and a direction of height adjustment relative to the object (1),

controlling the gripper group (30) using a computerized control unit, said method further comprising any suitable combination of the following operating steps;

directing the gripper group to approach the object (1) using positional information stored in the control unit;

performing a perpendicular three-dimensional scanning for recognizing an outline of the object using sequences of displacements of the gripper unit (30) by gauging punctual distances (50), using a gauge arranged on at least one finger (35, 36) of the gripper group (30);

providing a presence sensor (55) for detecting a depth of the object, and arranging the presence sensor (55) at a top of the fingers (35, 36) of the gripper group (30);

gripping the object (1) using the gripper group (30), and progressively tightening the gripper group (30) for gripping the object (1) until a predetermined intensity of grip is reached, said predetermined grip intensity depending on physical characteristics of the object (1);

collecting the object (1) by lifting and moving the object (1);

directing the gripper group (30) to approach a support surface (2);

moving the gripper group (30) until the object (1) makes contact with the support surface (2);

opening the fingers (35, 36) of the gripper group (30) until the object (1) is released and extracting the fingers (35, 36) from where the object (1) is located, and

providing an initial lifting stage of the object (1) by the gripper group (30), and controlling slippage of the object (1) during the lifting stage by arranging a mobile anti-fall support arrangement (60) below the gripper group (30).

12. The method of claim 11, further comprising moving the anti-fall support arrangement (60) independently of the movement of the gripper unit (30).

13. The method of claim 11, wherein the directing of the gripper unit to approach the support surface (2) comprises the steps of first moving of the object (1) to a raised position above the support surface (2), and subsequently withdrawing the anti-fall support arrangement (60) from below a base of the object (1).

14. A device for recognizing, collecting and repositioning objects, which objects exhibit non-predetermined dimensional characteristics, the device (10) being movable with degrees of freedom corresponding to at least a direction of longitudinal movement with respect to an object (1), a direction of movement towards/away from the object (1), and a direction of adjustment of a height relative to the object (1), the device (10) also being controlled by a computerized control unit, the device comprising:

a support (20);

a mobile gripper group (30), associated to the support and movable relative to the support in at least a first direction, the gripper group (30) being provided with at least a pair of fingers (35, 36) positioned facing one another, the fingers being movable in a second direction, and adapted for opening and closing with respect to one another in order respectively to grip and release an object (1), the fingers (35, 36) being movable together in a third direction towards/away from the object (1);

a measuring device (50) for measuring a punctual distance, arranged relative to at least one finger of the gripper group (30) for performing punctual gauging of a distance between a distal end of the at least one finger (35) and the object (1), suitable sequences of movements of the fingers (35, 36) used for performing an orthogonal three-dimensional scan of the object (1);

a presence sensor (55) for detecting a presence of the object (1), and for identifying a depth of the object (1), the presence sensor being arranged at distal ends of the fingers (35, 36);

a computerized control unit for directing movement of the gripper group (30) and for processing information received from the measuring device (50) and the presence sensor (55); and

,

wherein each finger (35, 36) has an oscillating rod (350), arranged on an inner surface of the relative finger (35, 36) and being pivoted at a central portion of the finger (35, 36), the oscillating rod (350) being adapted for facilitating gripping of objects (1) having widely differing dimensions.

15. The device of claim 14, wherein the presence sensor (55) has a photoelectric emitter and a relative receiver, which are arranged facing each other on distal ends of the inner surfaces (35a, 36a) of the fingers (35, 36).

16. The device of claim 14, characterized in that the support (20) comprises a vertical column element (21), which slidingly supports the gripper group (30), and that the first direction of movement defined by the support (20) coincides with a height adjustment direction of the gripper group (30).

17. The device of claim 16, characterized in that the vertical column element (21) is provided with guides (22) of recirculating ball type.

18. The device of claim 14, characterized in that the gripper group (30) comprises a support body (33) for supporting the fingers (35, 36), the support body being slidingly cantilever mounted on a sliding bracket (31) in the third direction of moving towards/away, the sliding bracket (31) being in turn slidingly mounted on the support (20) in the first direction of height adjustment.

19. The device of claim 18 wherein the sliding bracket (31) is mounted on the support (20) in a horizontal position and parallel to the support (20), the support body being mounted in a horizontal position and perpendicular to the sliding bracket (31), the fingers (35, 36) being mounted perpendicularly to the sliding bracket and being mutually parallel.

20. The device of claim 14, characterized in that at least one finger (35, 36) is provided with a load gauge (355), arranged in a distal portion of the finger (35, 36) for detecting a pressure exerted by the finger (35, 36) on small objects (1).

21. The device of claim 20 wherein the load gauge is a miniaturized load cell.

22. The device of claim 20, wherein the load gauge is activated by an interpositioning of an outer arm (351) of the oscillating rod (350).

23. The device of claim 14, characterized in that the measuring device comprises at least one emitter of a laser beam, which emits the beam towards the object (1), and a relative sensitive element which receives an echo of the laser beam reflected by the object (1).

24. The device of claim 23, characterized in that a laser emitter and a relative sensitive element are provided on each gripper finger (35, 36).

25. The device of claim 14, wherein the device is mounted, at a lower end (25) of the support (20), on a mobile and self-stabilizing base (80) which is controlled by a processor and which operates as a robotic mobile handling and transporting unit in order to manage the objects (1) in an automated shop or store (200).

26. A device for recognizing, collecting and repositioning objects, which objects exhibit non-predetermined dimensional characteristics, the device (10) being movable with degrees of freedom corresponding to at least a direction of longitudinal movement with respect to an object (1), a direction of movement towards/away from the object (1), and a direction of adjustment of a height relative to the object (1), the device (10) also being controlled by a computerized control unit, the device comprising:

a support (20);

a mobile gripper group (30), associated to the support and movable relative to the support in at least a first direction, the gripper group (30) being provided with at least a pair of fingers (35, 36) positioned facing one another, the fingers being movable in a second direction, and adapted for opening and closing with respect to one another in order respectively to grip and release an object (1), the fingers (35, 36) being movable together in a third direction towards/away from the object (1);

a measuring device (50) for measuring a punctual distance, arranged relative to at least one finger of the gripper group (30) for performing punctual gauging of a distance between a distal end of the at least one finger (35) and the object (1), suitable sequences of movements of the fingers (35, 36) used for performing an orthogonal three-dimensional scan of the object (1);

a presence sensor (55) for detecting a presence of the object (1), and for identifying a depth of the object (1), the presence sensor being arranged at distal ends of the fingers (35, 36);

a computerized control unit for directing movement of the gripper group (30) and for processing information received from the measuring device (50) and the presence sensor (55); and

,

an anti-fall group, mounted on the support (20), below the gripper group (30) for preventing an object (1) from falling, and an anti-slip arrangement (60b), mounted on the anti-fall group (60a) for assuring that the object is lifted without any slippage relative to the gripper group (30).

27. The device of claim 26, characterized in that the anti-fall group is slidingly mounted on the support (20).

28. The device of claim 27, characterized in that the anti-fall group comprises:

a second sliding bracket (61), horizontally mounted on the support (20) and provided with guides (62);

a second support body (63) horizontally cantilever mounted on the second sliding bracket (61) and sliding in the guides (62);

an anti-fall finger (66), which is horizontally mounted in the second body support (63) and directed toward the objects (1) to be supported, the anti-fall finger (66) being operable, together with the relative second support body (63) and in a phase relation with the operation of the gripper group (30), so as to be positioned immediately below a base of the object (1).

29. The device of claim 26, characterized in that the anti-fall group comprises:

a second sliding bracket (61), horizontally mounted on the support (20) and provided with guides (62);

a second support body (63) horizontally cantilever mounted on the second sliding bracket (61) and sliding in the guides (62);

an anti-fall finger (66), which is horizontally mounted in the second body support (63) and directed toward the objects (1) to be supported, the anti-fall finger (66) being operatable, together with the relative second support body (63) and in a phase relation with the operation of the gripper group (30), so as to be positioned immediately below a base of the object (1).

30. The device of claim 26, characterized in that the anti-slip arrangement (60b) comprises:

an optical distance detector (67) electrically connected to the control unit, an optical axis (69) of the optical distance detector (67) being directed toward the object (1), the anti slip arrangement being operated in a phase relation with the operation of the gripper group (30) in such a way as to maintain the optical axis (69) immediately below a lower edge of the object (1).

31. The device of claim 30, characterized in that the optical axis (69) is arranged parallel to, and immediately above, the anti-fall finger (66).

32. The device of claim 30, wherein the optical distance detector (67) comprises a laser distance sensor (67a), which is mounted in the second support body (63) and is provided with a prismatic lens (68), which prismatic lens (68) orients the laser beam emitted by the sensor according to the optical axis (69).

33. The device of claim 32, characterized in that the optical axis (69) is arranged parallel to, and immediately above, the anti-fall finger (66).

34. The device of claim 26, characterized in that, during the first lifting of the object (1), the anti-fall group is maintained at a height which is immediately below the base of the object (1), by raising the anti-fall group which follows a corresponding raising of the gripper group (30), an amount of the raising of the anti-fall group being defined by data relative to any slippage of the object (1) transmitted by the anti-slip arrangement to the control unit.