Method And A Device For Recognizing, Collecting and Repositioning Objects

• US 20100114363A1
• Filed: 03/04/2008
• Published: 05/06/2010
• Est. Priority Date: 03/08/2007
• Status: Active Grant

• Current Assignee: S.M.V S.r.l.
• Original Assignee: S.M.V S.r.l.
• Inventors: Cardoni, Patrizio
• Granted Patent: US 8,467,898 B2
• Time in Patent Office: Days
• 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 and are arranged on a support surface (2), which method is realized by means of a gripper group (30) which moves 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), the gripper group (30) being controlled by a computerized control unit, which method being characterized in that it includes any suitable combination of following operating stages:

approaching and recognizing a said object (1), comprising an approach to the object (1) by an approximately-set mobile gripper group (30), which approaching and recognizing is performed with assistance of positional information stored in the control unit;

identification of the outline of the object (1), by a perpendicular three-dimensional scanning, performed using sequences of displacements of the gripper unit (30) by means for gauging punctual distances (50), which means are arranged at least one finger (35, 36) of the gripper group (30), and by a presence sensor means (55) for detecting the depth of the object, which presence sensor means (55) is arranged at a top of the fingers (35, 36) of the gripper group (30);

gripping the object (1), including an operation performed by the gripper group (30) for progressively tightening the object (1) until a predetermined intensity of grip is reached, which intensity of grip depends on physical characteristics of the object (1);

collecting the object (1), including operations of lifting and moving the object (1);

releasing the object (1), including;

operations in which the gripper group (30) approaches 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 mobile gripper group (30) until contact with the object (1) is lost; and

extracting the fingers (35, 36) from the place where the object (1) is located.

2. The method of claim 1, characterized in that the identification of the outline of the object (1) comprises acquiring a set of punctual distance data regarding the object (1) by the means for gauging punctual distance (50), the positioning on the various points of acquisition being obtained through movements of the fingers (35, 36) of the mobile gripper unit (30) along trajectories controlled by the control unit, and processing of this information by the control unit to obtain the dimensional outline and distance of the object from the gripper group (30).

3. The method of claim 2, characterized in that the points of acquisition are organized in a grid fashion having a predefined step.

4. The method of claim 1, characterized in that identifying the outline of the object (1) comprises acquisition, via the presence sensor means (55), of data regarding a depth of the object (1), in a form of presence or absence of a signal which is transmitted and received respectively by a transmitter and a receiver belonging to the presence sensor means (55).

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

6. The method of claim 1, characterized in that in the gripping stage, the object (1) is gripped by the gripping fingers (35, 36) with interpositioning of at least one oscillating rod (350), which is provided in the inner surface of the fingers (35, 36).

7. The method of claim 6, characterized in that a said oscillating rod (350) is provided for each finger (35, 36).

8. The method of claim 1, characterized in that, in the gripping stage, the intensity of grip exerted on an object (1) by the gripping fingers (35, 36) of the mobile gripper group (30) is controlled by the control unit in at least two different ways, depending on the dimensions of the object (1) to be collected.

9. The method of claim 8, characterized in that, in order to grip objects of small dimensions, grip intensity is controlled by reading a pressure exerted on the object (1), the reading being shown on load gauging means (355) arranged at a distal portion of at least one of the gripper fingers (35, 36).

10. The method of claim 9, characterized in that the load measuring means (355) are operated with interpositioning of an outer arm (351) of a oscillating rod (350).

11. The method of claim 8, characterized in that, to grip objects (1) of large dimensions, the intensity of grip is controlled by reading a value of a current feedback signal of a motor activating the gripper fingers (35, 36).

12. The method of claim 1, characterized in that the lifting operation comprises an initial lifting stage of the object (1) by the gripper group (30), in which initial lifting stage control of slippage of the object (1) is provided by mobile anti-fall support means (60), arranged below the gripper group (30).

13. The method of claim 12, characterized in that the movement of the anti-fall support means (60) is independent of the movement of the mobile gripper unit (30).

14. The method of claim 1, characterized in that the approach part of the release stage comprises a first moving of the object (1) to a raised position of the object (1) itself above the support surface (2), and a subsequent withdrawal operation of the anti-fall support means (60) from the base of the object (1), up until disengagement of the anti-fall support means (60) from the object (1).

15. A device for recognizing, collecting and repositioning objects, which objects exhibit non-predetermined dimensional characteristics and are arranged on a support surface (2), the device (10) being provided with degrees of freedom corresponding to at least a direction of longitudinal movement with respect to an object (1) to be handled, a direction of movement towards/away from the object (1), and a direction of adjustment of the height relative to the object (1), the device (10) also being controlled by a computerized control unit, which device (10) is characterized in that it comprises:

a support (20);

a mobile gripper group (30), associated to the support and mobile 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, which are mobile in the second direction, and which can open and close with respect to one another in order respectively to grip and release an object (1), the fingers (35, 36) also being mobile together in a third direction towards/away from the object (1);

means for measuring punctual distance (50), which are arranged at least a finger of the gripper group (30) and which perform punctual gauging of a distance between a distal end of the finger (35) and the object (1) in order to enable, in cooperation with suitable sequences of movements of the fingers (35, 36), performance of an orthogonal three-dimensional scan of the object (1);

presence sensor means (55) for detecting a presence of the object (1), which presence sensor means (55) identify a depth of the object (1) and are arranged at distal ends of the fingers (35, 36);

a computerized control unit, which pilots the gripper group (30) and receives and processes information from the means for gauging punctual distance (50) and the presence sensor means (55).

16. The device of claim 15, 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 15, characterized in that the gripper group (30) comprises a support body (33) of the fingers (35, 36), which support body (33) is slidingly cantilevered 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 15, characterized in that the sliding bracket (31) is mounted on the support (20) in a horizontal position and parallel to the support (20), in that the support body (33) is mounted in a horizontal position and perpendicular to the sliding bracket (31), and in that the fingers (35, 36) are mounted perpendicularly to the sliding bracket and are mutually parallel.

20. The device of claim 15, characterized in that each finger (35, 36) comprises a oscillating rod (350), arranged on an inner surface of the relative finger (35, 36) and pivoted at the central portion of the finger (35, 36), the oscillating rod (350) being designed to facilitate the gripping of objects (1) having widely differing dimensions.

21. The device of claim 15, characterized in that at least one finger (35, 36) is provided with means for gauging load (355), arranged in the distal portion of the finger (35, 36) and designed to detect a pressure exerted by the finger (35, 36) on small objects (1).

22. The device of claim 20, characterized in that the organs for gauging load (355) are constituted by a miniaturized load cell.

23. The device of claim 20, characterized in that the load gauging organs (355) are activated with interpositioning of the outer arm (351) of the oscillating rod (350).

24. The device of claim 15, characterized in that the presence sensor means (55) comprise 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).

25. The device of claim 15, characterized in that the means for measuring punctual distance (50) comprise at least one emitter of a light laser beam, which emits the beam towards the object (1) to be analysed, and a relative sensitive element which receives an echo of the light laser beam reflected by the object (1), in order to measure the distance of the object (1) using triangulation techniques.

26. The device of claim 25, characterized in that a laser emitter and a relative sensitive element are provided on each gripper finger (35, 36).

27. The device of claim 15, characterized in that it further comprises anti-fall organs (60a), mounted on the support (20), below the gripper group (30) and designed to prevent an object (1) from falling, and comprises anti-slip means (60b), mounted on the anti-fall organs (60a) and designed to control that the object is lifted without any slippage relative to the gripper group (30).

28. The device of claim 27, characterized in that the anti-fall organs (60a) are slidingly mounted on the support (20).

29. The device of claim 27, characterized in that the anti-fall organs comprise:

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

a second support body (63) horizontally cantilevered 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 the base of the object (1) to be collected.

30. The device of claim 27, characterized in that the anti-slip means (60b) comprise optical distance detecting means (67) which are electrically connected to the control unit, an optical axis (69) of the optical distance detecting means (67) being directed toward the object (1), which anti-slip means (60b) are operated in a phase relation with the operation of the gripper unit (30) in such a way as to maintain the optical axis (69) immediately below the lower edge of the object (1).

31. The device of claim 29, characterized in that the optical distance detecting means (67) comprise 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).

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

33. The device of claim 27, characterized in that, during the first lifting of the object (1), the anti-fall organs (60a) are maintained at a height which is immediately below the base of the object (1), by raising the anti-fall organs which follows a corresponding raising of the gripper group (30), an amount of the raising of the anti-fall organs (60a) being defined by data relative to any slippage of the object (1) transmitted by the anti-slip organs to the control unit.

34. The device of claim 15, characterized in that it is mounted, at the lower end (25) of the vertical 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).

35. The device of claim 17, characterized in that the sliding bracket (31) is mounted on the support (20) in a horizontal position and parallel to the support (20), in that the support body (33) is mounted in a horizontal position and perpendicular to the sliding bracket (31), and in that the fingers (35, 36) are mounted perpendicularly to the sliding bracket and are mutually parallel.

36. The device of claim 21, characterized in that the organs for gauging load (355) are constituted by a miniaturized load cell.

37. The device of claim 21, characterized in that the load gauging organs (355) are activated with interpositioning of the outer arm (351) of the oscillating rod (350).

38. The device of claim 28, characterized in that the anti-fall organs comprise:

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

a second support body (63) horizontally cantilevered 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 the base of the object (1) to be collected.

39. The device of claim 30, characterized in that the optical distance detecting means (67) comprise 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).

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