Gripping device with bistable magnetic wires arranged in several layers in the finger as a sensor device and robot

Abstract

The invention relates to a gripper device (1) for a robot arm of a robot for gripping or releasing an object, comprising at least one finger unit (2) and a sensor device for measuring a temperature, a pressure, a voltage, a magnetic field and / or a linear position on the at least one finger unit (2). • at least one bistable magnetic wire (3) arranged in the area of ​​a surface of the at least one finger unit (2), • at least one excitation element (4) for generating a magnetic field, wherein the at least one excitation element (4) is arranged within reach of the at least one bistable magnet wire (3) on the at least one finger unit (2), • at least one sensor element (5) for receiving a response from the at least one bistable magnet wire (3), wherein the at least one sensor element (5) is arranged within range of the at least one bistable magnet wire (3) on the at least one finger unit (2), and • a signal processing unit (6) which is connected to the at least one excitation element (4) and the at least one sensor element (5) for signal transmission and is configured to generate and receive electrical signals. Furthermore, the invention relates to a robot comprising at least one robot arm with such a gripper device (1).

Description

[0001] The invention relates to a gripper device for a robot arm of a robot comprising at least one finger unit with a sensor device for measuring temperature, pressure, voltage, magnetic field and / or linear position. The invention further relates to a robot comprising at least one robot arm with such a gripper device.

[0002] Grippers designed as "soft grippers" for robots represent a significant advancement in the field of robotics. These grippers are intended to mimic the dexterity and gentleness of the human hand. Due to their properties, which are determined by the materials used and their operating mechanisms, such grippers are employed in many sectors, including industry, agriculture, everyday life, and healthcare.

[0003] For example, US patent 2022 / 0305668A1 discloses a soft joint gripper comprising a palm body and five soft finger units connected to the palm body. Each soft finger unit is equipped with two soft finger joints and two finger bones, the finger bones being formed from 3D-printed resin. The soft finger joints are two symmetrical, bilayer thin-film soft finger joint actuators. The bilayer thin-film soft finger joint actuator consists of a liquid crystal elastomer and an electrothermal polyimide film. The bending angle of each bilayer thin-film soft finger joint actuator can be changed by applying energy or applying heat. The bilayer thin-film soft finger joint actuator is used to control the soft finger unit to perform a reversible bending movement of the finger unit.

[0004] Furthermore, EP 4 257 929 A1 discloses a system for measuring a physical quantity and / or a position. The system comprises a bistable magnet wire, an excitation element for generating a magnetic field within whose range the bistable magnet wire is arranged, wherein the bistable magnet wire is provided for magnetization reversal by a Barkhausen jump from a first end to a second end or vice versa, and a sensor element for receiving the response of the bistable magnet wire. The excitation element and the bistable magnet wire are arranged in such a position that the amplitude of the magnetic field excited by the excitation element at the first end differs from the amplitude of the magnetic field excited by the excitation element at the second end.

[0005] German patent DE 10 2006 005 896 A1 describes a magnetostrictive position sensor comprising a magnetic and a magnetostrictive element with a predetermined distance between them, a detector, and a pulse generator. The magnetic and / or magnetostrictive element is designed to be flexible such that its distance decreases under pressure. The sensor includes a reset device that restores the predetermined distance after pressure is applied.

[0006] DE 10 2010 005 673 A1 describes a gripper with an elastically deformable gripper element that can be deformed by a force in order to grasp an object. A sensor for measuring the deformation of the gripper element is integrated.

[0007] DE 10 2018 205 337 A1 describes a gripper for grasping objects, comprising a base body, a gripping jaw, a connecting section, a hinge mechanism, and a gripping section. The connecting section is coupled to the base body, and the hinge mechanism connects a first end face associated with the connecting section to a second end face opposite the first end face and associated with the gripping section. The joint mechanism is designed for elastic pivoting of the gripping section relative to the connecting section. The gripper also includes a measuring device for distance detection between the end faces. A control circuit detects and evaluates electrical coil signals from a coil arrangement associated with an end face.

[0008] The subsequently published German patent DE 10 2023 134 169 B3 describes a method for aligning a coupling component with an optical or electronic application component. The coupling component can be optical or electrical.

[0009] EP 3 809 211 A1 describes a data generation unit for generating state data, which contains information about a state variable of a gripping device, further comprising a detection unit for detecting the state variable of the gripping device and a data preprocessing unit for generating the state data.

[0010] The JP H03-252577A describes a magnetic field detection method and a magnetic field sensor that can be used for azimuth sensors, rotation sensors, position sensors, tilt sensors, etc., which can detect the presence, size, angle, etc. of a magnetic field using a magnetic core with bistable magnetic properties.

[0011] The object of the invention is to improve a gripper device for a robot arm. In particular, physical quantities and / or the position of a finger unit of the gripper device should be precisely detected by a sensor device. Furthermore, the sensor device should be cost-effective and robust. These objects are achieved by the subject matter of claim 1. Preferred embodiments can be found in the dependent claims, the description, and the figures.

[0012] A gripper device according to the invention for a robot arm of a robot is provided for gripping or releasing an object and comprises at least one finger unit with a sensor device for measuring a temperature, a pressure, a voltage, a magnetic field and / or a linear position, wherein the sensor device has the following: at least one bistable magnetic wire arranged in the region of a surface of the at least one finger unit, at least one excitation element for generating a magnetic field, wherein the at least one excitation element is arranged on the at least one finger unit within range of the at least one bistable magnetic wire, at least one sensor element for receiving a response from the at least one bistable magnetic wire, wherein the at least one sensor element is arranged on the at least one finger unit within range of the at least one bistable magnetic wire, and a signal processing unit.which is connected to the at least one excitation element and the at least one sensor element in a signal-transmitting manner and is configured to generate and receive electrical signals.

[0013] The at least one bistable magnetic wire is made of a magnetizable material and forms a passive sensor, generating signals through magnetic induction. These signals are altered by environmental influences, enabling the measurement of at least temperature, pressure, voltage, magnetic field, and / or linear position. In particular, the at least one bistable magnetic wire is encased in a layer of insulating material, such as glass. This not only makes the bistable magnetic wire more robust but also increases its durability. The excitation element preferably comprises an excitation coil configured to remagnetize the at least one bistable magnetic wire. The sensor element preferably comprises a sensor coil configured to receive responses from the at least one bistable magnetic wire.In particular, the sensor coil of the sensor element is separate from the excitation coil of the excitation element. For example, the excitation element and the sensor element are arranged in a common housing and connected to the signal processing unit via a cable. For example, a large number of bistable magnetic wires, in particular up to one hundred magnetic wires, can be excited by a single excitation element and read out via a single sensor element. Depending on the measured data acquired at the at least one finger unit, gripping by means of a gripping device can be controlled very precisely and sensitively. The direct measured quantities acquired by the sensor device at the at least one finger unit are mechanical stress, temperature, and a magnetic field. Indirectly, pressures, torques, bends, and positions, for example, can be determined from these measured quantities.

[0014] In particular, the at least one bistable magnet wire is provided for magnetization reversal by a Barkhausen jump from a first end to a second end or vice versa, wherein the at least one excitation element and the at least one bistable magnet wire are positioned such that the amplitude of the magnetic field excited by the at least one excitation element at the first end differs from the amplitude of the magnetic field excited by the at least one excitation element at the second end.

[0015] According to one embodiment, the at least one bistable magnetic wire is embedded in the outer skin of the at least one finger unit. For example, several bistable magnetic wires are embedded at different segments of the finger unit and / or at the tip of the finger unit. A bistable magnetic wire embedded in the finger unit is understood to be one that is already firmly connected to the finger unit during the manufacturing process of the finger unit, for example, by injection molding or lamination, by means of a force-fit, material-fit, and / or form-fit connection, and is integrated into the finger unit, particularly in the area of ​​a surface, i.e., on or below the surface. For example, bistable metal wires are arranged in composite material mats that form a surface of the finger unit. Preferably, the composite material mats comprise glass or carbon fibers.

[0016] Preferably, the bistable metal wires are embedded in a fiber composite mat as a semi-finished product, the fiber composite mat being laminated onto the outer shell of the finger unit to enable sensory integration. The tip and / or the segments of the finger unit are preferably manufactured using an injection molding process, wherein the bistable metal wires are inserted into the injection mold and overmolded to produce the finger unit. For example, the at least one excitation element and the at least one sensor element can also be inserted into the injection mold and overmolded to produce the finger unit.

[0017] According to one embodiment, the at least one bistable magnetic wire is bonded to the surface of the at least one finger unit. For example, several bistable magnetic wires are bonded to different segments of the finger unit and / or to the tip of the finger unit, thus being firmly attached to the surface of the finger unit. Preferably, the at least one bistable magnetic wire is coated with a protective layer. The protective layer is particularly flexible and durable, providing additional protection and fixation to the surface of the at least one finger unit.

[0018] According to the invention, several bistable magnetic wires are arranged in different surface layers on the at least one finger unit. Due to the different depths of the bistable magnetic wires in the surface areas of the at least one finger unit, different elasticity profiles can be detected for the respective layer during deformation.

[0019] According to one embodiment, bistable magnetic wires of different lengths, diameters, and / or orientations are arranged on the at least one finger unit. The length, diameter, and orientation of each magnetic wire influence its magnetizability and thus its response to changes in its environment. In particular, this allows the sensitivity and response to be adapted to the specific application. For example, the sensor device can be calibrated by gripping adjustment components.

[0020] According to one embodiment, the at least one excitation element and the at least one sensor element are arranged inside the at least one finger unit and are at least partially surrounded by a filler material. This protects the at least one excitation element and the at least one sensor element. The filler material can be a flexible potting compound and / or have solid elements. The filler material can be a rubber compound. The filler material can be produced by an additive manufacturing process, in particular by 3D printing, whereby local compliance can be adjusted by the geometric design of the filler material. For example, the filler material comprises different honeycomb structures to adjust local compliance. For example, the filler material is porous.In particular, the filling material is designed to establish a distance between the at least one bistable magnet wire and the at least one excitation element, as well as between the bistable magnet wire and the at least one sensor element. Thus, the bistable magnet wire, the excitation element, and the sensor element can be positioned relative to each other via the filling material. Alternatively, the at least one excitation element and the at least one sensor element are arranged in the area of ​​a surface that is at least mechanically unloaded.

[0021] According to one embodiment, the at least one excitation element and the at least one sensor element are arranged on a rigid core element inside the at least one finger unit. This decouples the at least one excitation element and the at least one sensor element from any local displacement of the at least one magnet wire. The rigid core element corresponds, in particular, to a bone element of a human finger and is rigid relative to the filling material and thus essentially inflexible.

[0022] According to one embodiment, the signal processing unit is arranged outside the at least one finger unit and connected via cables to the at least one excitation element and the at least one sensor element. For example, the signal processing unit is located in the robot arm or at another point on the robot. This allows the finger unit to be designed to be particularly compact.

[0023] The invention also relates to a robot comprising at least one robot arm with a gripper device according to the invention. Preferably, the robot is designed as a cobot or humanoid robot. A cobot, short for "collaborative robot," is a robot designed to work in close cooperation with humans. Unlike industrial robots, which often operate in enclosed areas and require strict safety measures, cobots are designed to operate safely and efficiently directly alongside human workers. Cobots support human workers in repetitive or ergonomically demanding tasks, thus contributing to improved working conditions and increased production quality. A humanoid robot is a robot that has human-like characteristics and a human-like appearance.Humanoid robots are trained to mimic human shape, movements, and even behaviors.

[0024] Further measures improving the invention are described in more detail below, together with a description of preferred embodiments of the invention, with reference to the figures. Fig. 1 a highly simplified schematic representation of a gripper device according to the invention for a robot, only partially shown, Fig. 2 a further highly simplified schematic representation of the gripper device according to the invention Fig. 1 and Fig. 3 a highly simplified schematic representation of a gripper device according to a second embodiment, only partially shown.

[0025] Fig. Figure 1 shows a section of a robot arm, specifically a finger unit 2 of a gripper device 1, which is only partially depicted. The gripper device 1 also includes a sensor device for measuring a physical quantity on the finger unit 1. In this case, the mechanical stress on the surface of the finger unit 1 is relevant. The sensor device comprises several bistable magnetic wires 3 arranged in the region of the surface of the finger unit 2, an excitation element 4 arranged within the finger unit 2, within reach of the bistable magnetic wires 3, for generating a magnetic field, a sensor element 5 arranged within the finger unit 2, within reach of the bistable magnetic wires 3, for receiving a response of the bistable magnetic wire 3 to the generated magnetic field, and a signal processing unit 6 arranged outside the finger unit 2, which is electrically connected to the excitation element 4 and the sensor element 5 via a cable 10.The signal processing unit 6 is arranged in a part of the gripper device 1 connected to the finger unit 2 via a joint 11 and can generate and receive electrical signals. In this case, the bistable magnetic wires 3 are embedded in the outer skin of the finger unit 2, in particular due to… Fig. 2 emerges better.

[0026] Fig. 2 shows another representation of the in Fig. 1. Finger unit shown 2. From Fig. Figure 2 shows that the bistable magnetic wires 3 are embedded in the outer skin of the finger unit 2. During the manufacturing process of the finger unit 2, for example by lamination, the bistable magnetic wires 3 are bonded to the finger unit 2 in a force-fit, material-fit, and form-fit manner, and are integrated into the finger unit 2, particularly in the surface area. In this case, several bistable metal wires 3 are integrated into a fiber composite material 12, which forms the surface of the finger unit 2. The bistable magnetic wires 3 are arranged on the finger unit 2 with different lengths, different diameters, and different orientations. Furthermore, the bistable magnetic wires 3 can also be arranged at different depths on different layers, i.e., in particular, on different surface layers.The length, diameter, and orientation of each magnet wire 3 influence its magnetizability and thus its response to changes in its environment. In particular, this allows the sensitivity and response to be adapted to the specific application. For example, the sensor device can be calibrated by gripping adjustment parts. The excitation element 4 and the sensor element 5 are fixedly arranged on a rigid core element 9 inside the finger unit 2 and are at least partially surrounded by a flexible filler material 8. Therefore, the bistable magnet wires 3 can shift, at least slightly, relative to the excitation element 4 and the sensor element 5. Alternatively, the filler material 8 can be rigid, preventing any deformation.

[0027] Fig. Figure 3 shows a further embodiment of the gripper device 1, which is essentially the same as the gripper device 1 according to Fig. 1 and Fig. 2, to which reference is made. The only difference between these two embodiments of the gripper device 1 is that the bistable magnetic wires 3 are not integrated into the finger unit 2, but are glued to the surface of the finger unit 2 and covered with a protective layer 7. The protective layer 7 is flexible and durable to provide additional protection and fixation of the bistable magnetic wires 3 to the surface of the finger unit 2. Reference symbol list 1 gripper device 2-finger unit 3 bistable magnet wire 4. Stimulus element 5 sensor element 6 Signal processing unit 7 Protective layer 8 Filling material 9 Core element 10 cables 11 joint 12 Fiber composite material

Claims

[1] Gripper device (1) for a robot arm of a robot for gripping or releasing an object, comprising at least one finger unit (2) and a sensor device for measuring a temperature, pressure, voltage, magnetic field and / or a linear position on the at least one finger unit (2) • at least one bistable magnetic wire (3) arranged in the area of ​​a surface of the at least one finger unit (2), • at least one excitation element (4) for generating a magnetic field, wherein the at least one excitation element (4) is arranged within reach of the at least one bistable magnet wire (3) on the at least one finger unit (2), • at least one sensor element (5) for receiving a response from the at least one bistable magnet wire (3), wherein the at least one sensor element (5) is arranged within range of the at least one bistable magnet wire (3) on the at least one finger unit (2), and • a signal processing unit (6) which is connected to the at least one excitation element (4) and the at least one sensor element (5) for signal transmission and is configured to generate and receive electrical signals, characterized by , that several bistable magnetic wires (3) are arranged in different surface layers on the at least one finger unit (2). [2] Gripper device (1) according to claim 1, characterized by , that the at least one bistable magnetic wire (3) is embedded in the outer skin of the at least one finger unit (2). [3] Gripper device (1) according to claim 1, characterized by, that the at least one bistable magnet wire (3) is glued to the surface of the at least one finger unit (2). [4] Gripper device (1) according to one of the preceding claims, characterized by , that the at least one bistable magnet wire (3) is coated with a protective layer (7). [5] Gripper device (1) according to one of the preceding claims, characterized by , that bistable magnetic wires (3) of different lengths, different diameters and / or different orientations are arranged on the at least one finger unit (2). [6] Gripper device (1) according to one of the preceding claims, characterized by , that the at least one excitation element (4) and the at least one sensor element (5) are arranged inside the at least one finger unit (2) and are at least partially surrounded by a filling material (8). [7] Gripper device (1) according to one of the preceding claims, characterized by , that the at least one excitation element (4) and the at least one sensor element (5) are arranged on a rigid core element (9) inside the at least one finger unit (2). [8] Gripper device (1) according to one of the preceding claims, characterized by , that the signal processing unit (6) is arranged outside the at least one finger unit (2) and is connected via cables (10) to the at least one excitation element (4) and the at least one sensor element (5). [9] Robot comprising at least one robot arm with a gripper device (1) according to any of the preceding claims.

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