GRIPPER JAW WITH TACTILE SENSOR AND GRIPPING DEVICE WITH ONE OR MORE SUCH GRIPPER JAWS

Abstract

A gripper jaw to grip an object, the jaw having a gripping surface with a recess therein, the jaw including: a tactile sensor with a sensor surface and a sensor thickness integrated in the recess in a z-direction, wherein the sensor includes: a base arranged lowermost in the recess, a sensor array arranged on the base with a plurality of taxels being sensitive elements arranged over an area of the base, the taxels configured to detect externally applied forces along the z-direction, wherein each taxel is reversibly deformable, and an elastic layer arranged above and overlapping the array, the layer acting as a mechanical low-pass filter and, in an unloaded state, having a layer thickness, wherein an outwardly facing surface of the layer forms a partial area of the sensor surface, wherein the sensor integrated in the recess projects with the sensor surface beyond the gripping surface in the z-direction.

Claims

1. A gripper jaw to grip an object, the gripper jaw having a gripping surface with a recess therein, the gripper jaw comprising: a tactile sensor comprising a sensor surface and a sensor thickness D.sub.z, the tactile sensor replaceably integrated in the recess in a z-direction, wherein the z-direction in an integrated state of the tactile sensor is perpendicular to the sensor surface and perpendicular to the gripping surface, and wherein the sensor surface and the gripping surface are arranged substantially in parallel, wherein the tactile sensor comprises: i. a sensor base located lowermost in the recess, ii. a sensor array arranged on the sensor base with a plurality of taxels T.sub.n,m, the taxels T.sub.n,m being tactilely sensitive sensor elements that are arranged over an area of the sensor base, with n=1, 2, . . . , N, m=1, 2, . . . , M, N>1 and M>1, wherein the taxels T.sub.n,m are configured to detect externally applied forces F.sub.ext along the z-direction in an interval: [zmin.sub.n,m, zmax.sub.n,m], wherein each taxel of the taxels T.sub.n,m is elastically reversibly deformable with: zmax.sub.n,m: maximum extension of the taxel in the z-direction with no deformation, F.sub.ext=0, zmin.sub.n,m: minimum extension of the taxel in the z-direction at maximum reversible deformation, F.sub.ext>0, and iii. an elastic layer ES arranged directly above the sensor array and overlapping the sensor array, the elastic layer ES acting as a mechanical low-pass filter, wherein the elastic layer ES, in an unloaded state, has a layer thickness D.sub.ES,unloaded, wherein an outwardly facing surface of the elastic layer ES forms at least a partial area of the sensor surface, and wherein the tactile sensor integrated in the recess projects with the sensor surface beyond the gripping surface in the z-direction by a height H in a range of at least D.sub.ES,unbel to a maximum (zmax.sub.n,m−zmin.sub.n,m): Hϵ[D.sub.ES,unbel, (zmax.sub.n,m−zmin.sub.n,m)].

2. The gripper jaw according to claim 1, wherein the tactile sensor integrated in the recess is arranged and dimensioned on the gripper jaw in such a way that, when gripping and/or holding the object and H=0, the gripper jaw simultaneously contacts the object with at least a partial area of the gripping surface and the partial area of the sensor surface.

3. The gripper jaw according to claim 1, wherein the tactile sensor comprises a resistive sensor part and a capacitive sensor part, wherein the tactile sensor is capable of capturing external forces F.sub.ext acting on the sensor surface with the resistive part, and is capable of capturing electrical capacitance measurement data with the capacitive part.

4. The gripper jaw according to claim 1, an inwardly facing surface of the elastic layer ES facing into an interior of the sensor has in each case an elevation EH.sub.n,m at its positions opposite respective taxels T.sub.n,m, wherein the elevation concentrates the externally applied forces F.sub.ext that are applied to the layer locally to the respective taxels T.sub.n,m, wherein the elevation EH.sub.n,m in its lateral cross section Q.sub.EHn,m does not exceed a lateral cross section of associated taxels T.sub.n,m in each case.

5. The gripper jaw according to claim 4, wherein all elevations EH.sub.n,m have an identical longitudinal section LE.sub.Hn,m in a form of a square, a rectangle, a triangle, a quadrilateral, a pentagon, or a hexagon.

6. The gripper jaw according to claim 1, wherein between an inwardly facing surface of the elastic layer ES facing into an interior of the tactile sensor and a respective taxel T.sub.n,m a spacer AH.sub.n,m is arranged in each case, wherein the spacer AH.sub.n,m concentrates the externally applied forces F.sub.ext applied to the layer ES locally to the respective taxel T.sub.n,m, wherein spacers AH.sub.n,m in their lateral cross section QA.sub.Hn,m do not exceed a lateral cross-section of an associated taxel T.sub.n,m in each case.

7. The gripper jaw according to claim 6, wherein all spacers AH.sub.n,m have an identical longitudinal section LA.sub.Hn,m in a form of a square, a rectangle, a triangle, a quadrilateral, a pentagon, or a hexagon.

8. The gripper jaw according to claim 1, wherein the elastic layer ES is designed to be rigid such that, when an externally applied force F.sub.ext is applied at a position of the surface of the elastic layer ES overlapping the sensor array, at least two taxels T.sub.n,m are deformed.

9. The gripper jaw according to claim 1, wherein the elastic layer ES is fixed in a frame and the frame is replaceably attached to the sensor.

10. The gripper jaw according to claim 1, wherein an electrical conductor is meanderingly integrated into the elastic layer.

11. A gripping device comprising: one or more gripper jaws according to claim 1, at least one actuator for each of the one or more gripper jaws, the at least one actuator configured to drive each of the one or more gripper jaws; and a control unit configured to control one or more actuators of the one or more gripper jaws, wherein the control unit is configured to determine a desired movement of the one or more gripper jaws taking into account measured values of the tactile sensor, and to control the one or more actuators of the one or more gripper jaws in order to implement the desired movement.

12. The gripping device according to claim 11, further comprising an evaluation unit connected to the tactile sensor, the evaluation unit configured, based on values determined by a taxel T.sub.n,m, to determine a sub-taxel accurate position of an externally applied force F.sub.ext(t) on the sensor surface and a force amount |F.sub.ext| of the externally applied force F.sub.ext.

13. The gripping device according to claim 12, wherein the evaluation unit is connected to an electrical conductor of the elastic layer ES, wherein the evaluation unit is configured to use the electrical conductor to determine a capacitive coupling of the sensor with an environment of the sensor.

14. The gripping device according to claim 12, wherein the evaluation unit is connected to an electrical conductor of the elastic layer, and evaluation unit is configured to use the electrical conductor to determine a wear of the elastic layer ES.

15. The gripping device according to claim 12, wherein the evaluation unit is configured to determine and issue, based on a determined sub-taxel-precise position POS.sub.Fext(t) and the amount |F.sub.ext| of the externally applied F.sub.ext(t) on the sensor surface, an orientation of a known object held by the one or more gripper jaws.

16. A robot comprising a robot manipulator with a gripper jaw according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In the drawings:

[0044] FIG. 1a shows a highly schematic top view of the gripping surface 102 or the sensor surface 105 of a gripper jaw 101 according to the invention;

[0045] FIG. 1b shows a highly schematized cross-sectional view along a line of intersection A-A′ through a gripper jaw 101 according to the invention; and

[0046] FIG. 2 shows a schematized cross-sectional view along section line A-A′ through a gripper jaw 101 according to the invention.

DETAILED DESCRIPTION

[0047] FIG. 1a shows a highly schematized top view of the gripping surface 102 or the sensor surface 105 of a gripper jaw 101 according to the invention. Referring to FIG. 1a, the sensor surface 105 is elongated and narrow compared to the gripping surface 102. Both the sensor surface 105 and the gripping surface 102 are flat.

[0048] FIG. 1b shows a highly schematized cross-sectional view along a line of intersection A-A′ through a gripper jaw 101 according to the invention. Shown is the tactile sensor 104 integrated into a recess of the gripper jaw 101. It can further be seen from FIG. 1a that the sensor 104 integrated in the recess with the sensor surface 105 protrudes beyond the gripping surface 102 in the z-direction by a height H. The sensor 104 itself has a thickness in the z-direction D.sub.z.

[0049] FIG. 2 also shows a schematized cross-sectional view along the line of intersection A-A′ through a gripper jaw 101 for a gripping device according to the invention. The gripper jaw 101 has a gripping surface 102 and is characterized by the following features.

[0050] The gripper jaw 101 has a recess on the gripping surface 102 into which a tactile sensor 104 having a sensor surface 105 and a sensor thickness D.sub.z is replaceably integrated in the z-direction, wherein the z-direction is perpendicular to the sensor surface 105 and perpendicular to the gripping surface 102 in the integrated state of the sensor 104, and wherein the sensor surface 105 and the gripping surface 102 are arranged substantially parallel.

[0051] The tactile sensor 104 has: a sensor base 106 arranged at the bottom of the recess, which in the present case is formed by the bottom of a housing of the sensor 104, a sensor array arranged on the sensor base 106 and having a plurality of tactilely sensitive sensor elements arranged over an area, so-called taxels T.sub.n,m 108, with n=1, 2, . . . , N, m=1, 2, . . . , M, N>1 and M>1, wherein the taxels T.sub.n,m 108 for the detection of externally applied forces F.sub.ext along the z-direction in an interval: [zmin.sub.n,m, zmax.sub.n,m] are elastically reversibly deformable with:

[0052] zmax.sub.n,m: maximum extension of the taxel T.sub.n,m 108 in z-direction with no deformation, i.e., F.sub.ext=0 and

[0053] zmin.sub.n,m: minimum extension of the taxel T.sub.n,m 108 in z-direction at maximum reversible deformation, i.e., F.sub.ext>0, and

[0054] an elastic layer ES 108 arranged directly above the sensor array overlaps the sensor array and acts as a mechanical low-pass filter, which in the unloaded state has a layer thickness D.sub.ES,unloaded wherein the outwardly facing surface of the elastic layer ES 108 forms at least a partial area of the sensor surface 105.

[0055] The sensor 104 integrated in the recess projects with the sensor surface 105 beyond the gripping surface 102 in the z-direction by a height H in the range of at least D.sub.ES,unbel to a maximum (zmax.sub.n,m−zmin.sub.n,m), wherein Hϵ[D.sub.ES,unbel, (zmax.sub.n,m−zmin.sub.n,m)].

[0056] The tactile sensor 104 integrated in the recess is arranged and dimensioned on the gripper jaw 101 in such a way that the gripper jaw 101, when gripping and/or holding an object, contacts the object with at least a partial area of the gripping surface 102 and a partial area of the sensor surface 105 simultaneously.

[0057] A surface of the elastic layer ES 108 facing into the interior of the sensor 104 at its positions opposite to the respective taxels T.sub.n,m has an elevation EH.sub.n,m which applies external forces F.sub.ext to the layer ES 108 locally to the respective taxels T.sub.n,m and therefore serve as force concentrators, wherein the elevation EH.sub.n,m in its lateral cross section Q.sub.EHn,m does not exceed the lateral cross section of the associated taxel T.sub.n,m in each case. In the present case, all elevations EH.sub.n,m have an identical longitudinal section L.sub.EHn,m in the form of a triangle, whose bases are in contact with the inwardly facing surface of the elastic layer ES 108 and the tips of which are in contact with the taxel T.sub.n,m respectively.

[0058] Although the invention has been further illustrated and explained in detail by example embodiments, the invention is not limited by the disclosed examples and other variations may be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention. It is therefore clear that a wide range of variations exists. It is also clear that example embodiments are really only examples which are not to be understood in any way as limiting, for example, the scope of protection, the possibilities of use or the configuration of the invention. Rather, the preceding specification and the figure description enable the person skilled in the art to implement the example embodiments in a concrete manner, wherein the person skilled in the art, being aware of the disclosed inventive idea, can make a variety of changes for example with respect to the function or the arrangement of individual elements mentioned in an example embodiment, without leaving the scope of protection defined by the claims and their legal equivalents, such as further explanations in the specification.

LIST OF REFERENCE NUMERALS

[0059] 101 Gripper jaw [0060] 102 Gripping surface [0061] 104 Tactile sensors [0062] 105 Sensor surface [0063] 106 Sensor base [0064] 108 Sensor elements, taxel T.sub.n,m