SENSOR DEVICE, GRIPPING DEVICE, METHOD AND CONTROL UNIT FOR A GRIPPING DEVICE

Description

[0001] The invention relates to a sensor device, in particular for a gripping device or a robot, a gripping device, in particular for a robot, and a use of the sensor device. Furthermore, the invention relates to a method and a control unit for aligning a gripping device and applying a force to the gripping device. State of the art

[0002] In robotics, parts or objects to be grasped or picked up by a robot are usually optically detected to determine the relative position between the robot and the object. This can lead to situations where part of the robot obscures the object being grasped. Robots are also known that are equipped with force sensors to measure the force acting on an object being grasped and adjust it accordingly.

[0003] DE 10 2014 221 294 A1 discloses a sensor device having at least one sensor field comprising at least two pressure sensors, wherein the sensor device is further provided with an elastomer layer arranged over the at least one sensor field. US 2008 / 0174321 A1 relates to a capacitive sensor for tactile detection and distance detection. US 2017 / 334070 A1 discloses a sensorized cover used to cover at least part of a movable structure of an automated device, wherein the sensorized cover comprises contact sensor means and proximity sensor means. US 2009 / 285664 A1 relates to a robot, a robot hand, and a method for controlling the robot hand. US 2013 / 325181 A1 discloses optical distance sensors used for approaching, gripping, and manipulating.DE 10 2015 208 702 A1 relates to a collision detection device for a medical device. Disclosure of the invention

[0004] Against this background, the approach presented here discloses a sensor device, in particular for a gripping device or a robot, wherein the sensor device comprises a first, in particular tactile, sensor configured to determine a force acting between the sensor device and an object. Furthermore, the sensor device comprises a second, in particular capacitive, sensor configured to determine a distance between the sensor device and the object.

[0005] An object can be understood as an item located in the vicinity of the sensor device. An object can also be understood as a human or an animal, or a body part of a human or an animal. Advantages of the invention

[0006] The sensor device can advantageously determine both the distance to an object and the proximity of the object to the sensor device, as well as the force acting between the sensor device and the object, as soon as the sensor device comes into mechanical contact with the object. This dual functionality also allows the sensor device to be designed to be particularly compact.

[0007] Further advantages arise from the subclaims.

[0008] In a preferred embodiment, at least the first sensor and / or the second sensor are configured to be substantially planar, in particular as a flexible multi-layer system, and arranged one above the other. This allows for the realization of large sensor surfaces that are flexible, particularly due to their low layer thickness, and can therefore also be applied to or attached to uneven surfaces.

[0009] In a further preferred embodiment, the first sensor and the second sensor have at least one common sensor element. This allows for efficient material and / or installation space savings.

[0010] According to the invention, the first sensor comprises a first layer and a second layer made of a conductive material, and a third layer made of a piezoelectric material is arranged between the first layer and the second layer. The third layer also serves as an insulating layer between the first layer and the third layer. This makes it easy to create a tactile sensor. The first layer and the second layer can, for example, comprise metal, in particular copper, and act as electrodes of the first sensor. By means of a suitable electrical connection of the electrodes, forces acting between an object and the first sensor can be measured.

[0011] It is particularly advantageous if the third layer comprises the piezoelectric plastic polyvinylidene fluoride (PVDF). As the sensor device, and thus also the first sensor, is stretched or compressed, the third layer made of PVDF is also stretched or compressed. This causes electrical charges to shift within the third layer, which can be tapped via the first layer and the third layer, passed to an external evaluation unit and evaluated there. By using PVDF, voltages in the range of a few volts can be detected even with stretching or compressing in the micrometer range. A sensor with a third layer made of PVDF is particularly suitable for detecting a change in stretching or compressing or a change in a force acting on the first sensor.

[0012] According to the invention, the second sensor has a layer referred to as the fourth layer, wherein the fourth layer comprises a first subregion and a third subregion made of a conductive material, and a second subregion made of a dielectric. The second subregion made of the dielectric can be arranged, in particular concentrically, between the first and third subregions. The fourth layer can have a layer thickness ranging from a few nanometers to several hundred micrometers or more.

[0013] This makes it easy to implement a capacitive sensor for determining a distance between the object and the sensor, with the second sensor and the first capacitive sensor being configured in an integrated design as a single sensor device. The first sub-region and the third sub-region of the fourth layer can comprise a metal such as copper or aluminum, or a conductive plastic. The second sensor can, in particular, be constructed similarly to a cylindrical capacitor and arranged on the first sensor.

[0014] In a further preferred embodiment, the first layer or the second layer of the first sensor comprises, at least in part, the first sub-region and / or the third sub-region of the fourth layer of the second sensor. As a result, this sub-region of the fourth layer can be functional for both the first and the second sensor. In other words, this sub-region of the fourth layer can represent a first electrode for the second sensor and, at least in part, an electrode for the first sensor. As a result, the first sub-region and the third sub-region of the fourth layer, as well as the first or second layer of the first sensor complementary to the sub-region, can be suitably electrically contacted in order to maintain the full functionality of the sensor device.

[0015] It is further advantageous if the second sensor has an electrically insulating film on a side facing away from the first sensor. This protects the sensor device, while also allowing electrical lines to be provided on the electrically insulating film for contacting the sensors underneath.

[0016] The advantages mentioned above also apply to a

[0017] A gripping device, in particular for a robot, comprising a sensor device according to one of the aforementioned embodiments. Such a gripping device can advantageously determine both a distance to or proximity to an object and, after contact with the object, a force acting between the object and the sensor device or gripping device.

[0018] In a preferred embodiment, the gripping device has at least two gripping elements that are movable relative to one another and at least two sensor devices according to one of the previously described embodiments. Furthermore, at least one sensor device is arranged on each gripping element in such a way that the sensor device is oriented in the direction of the object to be gripped during a gripping process. This allows an object to be gripped to be gripped particularly carefully by the gripping device or by the robot. By determining the distance between the object to be gripped and the individual gripping elements, the gripping device can align the gripping elements at a uniform distance from the object, whereby the object comes into contact with the gripping elements and the subsequent application of a force by the gripping elements to the object takes place particularly carefully.

[0019] The aforementioned advantages also apply accordingly to a method for aligning a gripping device according to one of the previously described embodiments with an object to be gripped and applying a force to the gripping device. The method comprises a step of aligning a sensor device arranged on a gripping element of the gripping device in the direction of the object to be gripped. The method further comprises a step of detecting a first distance between the first sensor device and the object. Furthermore, the method comprises a step of approaching the gripping element to the object depending on the detected first distance, wherein the approach takes place such that the gripping element comes into contact with the object.The method further comprises a step of adjusting the force acting on the object by the gripping element as a function of measurement data from the first sensor of the sensor device.

[0020] In a further preferred embodiment, it is provided that in the aligning step, at least one second sensor device arranged on at least one second gripping element of the gripping device is aligned in the direction of the object. It is further provided that in the detecting step, a second distance between the second sensor device and the object is detected. It is further provided that in the approaching step, the at least two gripping elements are approached to the object depending on the detected first distance and the detected second distance such that the two gripping elements come into contact with the object essentially at the same time. In the adjusting step, it is further provided that the force acting on the object by the two gripping elements is additionally adjusted depending on measurement data from the first sensor of the second sensor device.This ensures that the two gripping elements come into contact with the object, or touch and pick up the object, at essentially the same time. Furthermore, it advantageously achieves that the forces acting between each gripping element and the object are measured, and the force to be applied to the object by the gripping element can be adjusted accordingly. This is particularly advantageous for objects that have an inhomogeneous material composition, density, and / or texture and therefore have volumes and / or surface areas with varying strengths.

[0021] The aforementioned advantages apply correspondingly to a control unit for a gripping device having means configured to carry out the method according to the previously described embodiments.

[0022] The method can be implemented, for example, in software or hardware or in a hybrid form of software and hardware in the control unit. For this purpose, the control unit can have at least one evaluation unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface to a detection unit or an actuator for reading in sensor signals or parameters from the detection unit or for outputting control signals to the actuator and / or at least one communication interface for reading in or outputting data embedded in a communication protocol. The evaluation unit can, for example, be a signal processor, a microcontroller or the like, wherein the memory unit can be a flash memory, an EPROM memory or a magnetic storage unit.The communication interface can be configured to read or output data wirelessly and / or via a wired connection. A communication interface that can read or output wired data can, for example, read this data electrically or optically from a corresponding data transmission line or output it to a corresponding data transmission line.

[0023] The invention further relates to the use of a sensor device according to one of the previously described embodiments as a tactile distance sensor in or on a sensor skin in robotics. A sensor skin can be understood as at least one region of a surface of a robot or a part of a robot, such as a gripper arm, through which the robot can obtain information about the immediate surroundings of the robot, in particular about distances to objects in the vicinity of the robot. Short description of the drawings

[0024] Embodiments of the invention are schematically illustrated in the drawings and explained in more detail in the following description. The same reference numerals are used for the elements shown in the figures and with similar functions, and a repeated description of the elements is omitted.

[0025] They show: Fig. 1 A schematic representation of a sensor device according to an embodiment; Fig. 2 A schematic representation of a gripping device and an object to be gripped according to an embodiment; Fig. 3 Shows a schematic representation of a control unit for a gripping device according to an embodiment; Fig. 4 A flowchart of a method for aligning a gripping device to an object to be gripped and applying a force to the gripping device according to an embodiment.

[0026] As already stated above, the present invention describes a sensor device, a gripping device, a method and a control unit for a gripping device, which make it possible to align the gripping device with the object to be gripped without visual contact by means of optical systems, and to determine and specifically adjust the force acting between the gripping device and the object when the gripping device comes into contact with the object.

[0027] In Fig. 1 A sensor device 1 is shown schematically in a side view. The sensor device 1 has a first sensor 10, which is designed as a tactile sensor. By means of the first sensor 10, a force acting between the sensor device 1 and an object can be determined. The sensor device 1 also has a second sensor 20, which is designed as a capacitive sensor. By means of the second sensor 20, a distance or proximity between the object and the sensor device 1 can be determined or detected.

[0028] The first sensor 10 is designed as a multi-layer system. The first sensor 10 has a first layer 11 and a second layer 12, which are made of a conductive material. The conductive material can comprise copper or aluminum, for example. A third layer 13 made of a piezoelectric material is arranged between the first layer 11 and the second layer 12. The piezoelectric material electrically insulates the first layer 11 and the second layer 12 from one another. The third layer 13 can preferably comprise polyvinylidene fluoride (PVDF) 14. The first layer 11, the second layer 12, and the third layer 13 have a small layer thickness compared to their surface area, in the range of a few nanometers to several hundred micrometers or more, so that the first sensor 10 is designed as a flexible multi-layer sensor.

[0029] The second sensor 20 is arranged directly on the first sensor 10. The second sensor 20 has a fourth layer 21, which is arranged at least partially over the third layer 13 of the first sensor 10. The fourth layer 21 has a first partial region 22 and a third partial region 24, which are made of a conductive material such as copper or aluminum.

[0030] The first subregion 22 and the third subregion 24 are electrically separated from one another by a second subregion 23. The second subregion 23 can comprise a dielectric. The third subregion 24 can be arranged concentrically around the second subregion 23, which in turn can be arranged concentrically around the first subregion 22. In such a configuration, the second sensor 20 can be designed essentially as a cylindrical capacitor.

[0031] Here, the first sensor 10 and the second sensor 20 have a common sensor element. In the exemplary embodiment shown here, the common sensor element is formed by the first partial region 22 of the fourth layer 21, which simultaneously also forms the second layer 12 of the first sensor 10, at least in part. This configuration allows for the realization of a flexible, planar sensor device.

[0032] Optionally, the sensor device 1 can be provided with an electrically insulating film 30. The film 30 can be arranged above the fourth layer 21, on a side facing away from the first sensor 10. For example, conductive paths can be routed via the film 30 to the individual subregions or layers of the first sensor 10 and / or the second sensor 20.

[0033] In Fig. 2 A gripping device 50 is shown schematically. The gripping device 50 can represent a robot or part of a robot. The gripping device 50 has a first gripping element 51, on which a sensor device 1, in particular according to one of the previously described embodiments, is arranged. A distance (indicated by the first double arrow 61) to an object 70 can be determined via the sensor device 1.

[0034] The object 70 can be an object, a person, or an animal in the vicinity of the gripping device 50. If the object 70 approaches the gripping device 50 or the first gripping element 51, the approach can be registered by the sensor device 1, or a distance between the object 70 and the sensor device 1 can be determined. Furthermore, if the object 70 comes into contact with the sensor device 1, a force acting between the object 70 and the sensor device 1 can be determined. Depending on the determined distance or the force acting between the object 70 and the sensor device 1, the gripping device 50 can, for example, be switched off, or the first gripping element 51 can be moved away from the object 70.

[0035] Optionally, the gripping device 50 can have a second gripping element 52 or, as shown in this exemplary embodiment, a third gripping element 53. The second gripping element 52 and the third gripping element 53 each have a sensor device 1, which is alignable or aligned with the object 70 to be gripped. Each of the sensor devices 1 is configured to determine a distance (indicated by the further double arrows 62, 63) between the second gripping element 52 and the object 70 and between the third gripping element 53 and the object 70. Furthermore, the sensor devices 1, which are arranged on the second gripping element 52 and the third gripping element 53, are configured to determine the forces acting between the object 70 and the second gripping element 52, or the third gripping element 53, respectively.

[0036] In Fig. 3 a schematic representation of a control unit 80 is shown, which is a Fig. 4 can carry out the method described below for operating the gripping device 50. The control unit 80 has an evaluation unit 81, which is connected to an optional memory unit 82 for signaling purposes. Via an input interface, the evaluation unit 81 receives a first variable E1 from the second sensor 20, which represents a distance between the sensor device 1 and an object 70, in particular an object to be gripped. If and / or as soon as the sensor device 1 comes into contact with the object 70, the evaluation unit 81 receives a second variable K1 from the second sensor 20, which represents a force acting between the object 70 and the sensor device 1. Depending on the determined distance orthe determined distance between the object 70 and the sensor device 1 and / or depending on the force acting between the object 70 and the sensor device 1, the evaluation unit 81 generates a control signal A1, which the evaluation unit 81 forwards to the gripping device 50 via an output interface.

[0037] In Fig. 4 A flowchart of a method 100 for aligning the gripping device 50 with the object 70 to be gripped and applying a force to the gripping device 50 according to an exemplary embodiment is shown. In an optional first step 101, at least two gripping elements 51, 52 are aligned with the sample 70 to be gripped such that the sensor devices 1 arranged on the gripping elements 51, 52 point in the direction of the sample 70. If the gripping elements 51, 52 are equipped with sensor devices 1 over their entire surface, this alignment can be omitted.

[0038] Furthermore, in step 101, the gripping elements 51, 52 are skillfully positioned relative to the sample 70 to be gripped. In particular, the distances between the sensor devices 1 of the gripping elements 51, 52 and the sample to be gripped are averaged. In the case that the sample 70 to be gripped is to be gripped by three gripping elements 51, 52, 53, the gripping elements 51, 52, 53 are arranged substantially uniformly around the sample 70 to be gripped.

[0039] In a further method step 102, the distances between the gripping elements 51, 52 and the object 70 to be gripped are detected. In a further method step 103, the gripping elements 51, 52 approach the sample 70 to be gripped depending on the detected distance. In particular, the approaching step continues until the gripping elements 51, 52 come into contact with the object 70.

[0040] In a subsequent method step 104, the force acting between the gripping elements 51, 52 and the sample 70 to be gripped is adjusted as a function of measurement data K1 of the first sensor 10 of the sensor device 1.

[0041] In particular, it is checked whether a specific, in particular a previously definable, force has been reached between the gripping elements 51, 52 or the sensor devices 1 arranged thereon and the object 70. If this is not the case, the force acting between the gripping elements 51, 52 and the object 70 is increased. If the previously defined force is reached, an output signal can subsequently be sent to the gripping device 50 to prevent further application of a force to the object 70.

Claims

1. Sensor device (1), in particular for a gripping device (50) or a robot, having a first tactile sensor (10), which is configured to determine a force acting between the sensor device (1) and an object (70), having a second capacitive sensor (20), which is configured to determine a distance (61, 62, 63) between the sensor device (1) and the object (70), wherein the first sensor (10) comprises a first layer (11) and a second layer (12) composed of a conductive material, wherein the second sensor (20) has a layer (21), wherein the layer (21) comprises a first subregion (22) and a third subregion (24) composed of a conductive material and a second subregion (23) composed of a dielectric, which is arranged, in particular concentrically, between the first subregion (22) and the third subregion (24), characterized in that a third layer (13) composed of a piezoelectric material is arranged between the first layer (11) and the second layer (12) of the first sensor (10).

2. Sensor device (1) according to Claim 1, characterized in that at least the first sensor (10) and / or the second sensor (20) are / is designed to be substantially flat, in particular as a flexible multilayer system, and are arranged one above the other.

3. Sensor device (1) according to Claim 1 or 2, characterized in that the first sensor (10) and the second sensor (20) have at least one common sensor element.

4. Sensor device (1) according to Claim 1, characterized in that the third layer (13) contains polyvinylidene fluoride (14).

5. Sensor device (1) according to any of the preceding claims, characterized in that the first layer (11) or the second layer (12) of the first sensor (10) comprises, at least in regions, the first subregion (22) and / or the third subregion (24) of the layer of the second sensor (20).

6. Sensor device (1) according to Claim 2, characterized in that the second sensor (20) has an electrically insulating film (30) on a side facing away from the first sensor (10).

7. Gripping device (50), in particular for a robot, having a sensor device (1) according to any of the preceding claims.

8. Gripping device (50) according to Claim 7, characterized in that the gripping device (50) has at least two gripping elements (51, 52, 53) which are movable relative to one another and at least two sensor devices (1) according to one of Claims 1 to 6, wherein at least one sensor device (1) is arranged on each gripping element (51, 52, 53) in such a way that the sensor device (1) is oriented in the direction of the object (70) to be gripped during a gripping operation.

9. Method (100) for orienting a gripping device (50) according to Claim 7 or 8 with respect to an object (70) to be gripped and applying a force to the gripping device (50), comprising the steps of: - orienting (101) a first sensor device (1) arranged on a gripping element (51) of the gripping device (50) in the direction of the object (70) to be gripped; - detecting (102) a first distance (61) between the first sensor device (1) and the object with the first sensor device (1); - moving (103) the gripping element (51) closer to the object (70) depending on the detected first distance (61) in such a way that the gripping element (51) comes into contact with the object (70); - adjusting (104) the force acting on the object by the gripping element depending on measurement data (K1) from a first sensor (10) of the sensor device (1).

10. Method (100) according to Claim 9, characterized in that, in the orienting step (101), at least one second sensor device (1) arranged on at least one second gripping element (52, 53) of the gripping device (50) is oriented in the direction of the object (70); in the detecting step (102), at least one second distance (62, 63) between the second sensor device (1) and the object (70) is detected; in the moving-closer step (103), the at least two gripping elements (51, 52, 53) are moved closer to the object (70) depending on the detected first distance (61) and the detected second distance (62, 63) in such a way that the two gripping elements (51, 52, 53) come into contact with the object (70) substantially simultaneously; and in the adjusting step (104), the force acting on the object (70) by the two gripping elements (51, 52, 53) is adjusted depending on measurement data (K1) from the respectively first sensor (10) of the two sensor devices (1).

11. Control unit (80) for a gripping device (50) having means (81, 82) which are configured to carry out the method (100) according to Claim 9 or 10.

12. Use of a sensor device (1) according to any of Claims 1 to 6 as a tactile distance sensor in or on a sensor skin in robotics.