Finger unit for a robotic hand, robotic hand and a method for operating a robotic hand

Abstract

The invention relates to a finger unit (1), in particular a fingertip, for a robot hand, comprising a rigid component (3), a deformable component (2), a light source (7) and an optical sensor (4) which is configured to detect light emitted by the light source (7) which is reflected at the rigid component (3) or the deformable component (2) or at an object (8) arranged externally to the finger unit.

Description

[0001] The invention relates to a finger unit for a robot hand and to a robot hand comprising at least one finger unit. Furthermore, the invention relates to a method for operating a robot hand.

[0002] Robotic arms are finding increasing application in industry and other fields. To enable more precise functions and expand the range of applications for these robotic arms, they often feature a robotic hand modeled after a human hand. Such robotic hands can, for example, perform assembly work in the automotive industry or assist in research and development in science. These robotic hands have multiple finger units to perform tasks similar to a human hand. The potential applications of robotic hands are vast, but the demands placed on them are extremely high, especially when handling delicate components and / or performing precise work steps. For instance, to handle fragile or slippery objects, a robotic hand requires appropriate sensors.

[0003] In industry, conventional grippers typically use gripper jaws that are specifically adapted to the object being gripped. This allows the grippers to handle the objects as efficiently as possible. Robotic hands, on the other hand, do not have fingers adapted to the object being gripped, although this allows them to handle multiple different objects. However, this can result in the object being grasped in an unfavorable or unknown position, particularly relative to the robotic hand's fingers. This initially presents the problem that an object gripped in an unfavorable position is more likely to slip out of the robotic hand's grasp, which the robotic hand might compensate for, for example, by increasing its gripping force. This, in turn, increases the risk of damaging the objects.Furthermore, multiple robot hands are often used in conjunction with robot arms, arranged in a space and performing tasks simultaneously. For example, the robot hands can be moved along assigned paths. With an undirected or unknown orientation of the object, the space along this path would have to be designed larger than necessary. For instance, if a primarily elongated component is picked up perpendicular to the conveyor direction, the space around the assigned path would have to be significantly larger to prevent damage to other objects or the object being picked up. Additionally, an object picked up with an undirected orientation makes it more difficult to place the object precisely. Disclosure of the invention

[0004] As explained above, orienting an object to be grasped is a complex and essential task.

[0005] Against this background, the task arises to provide a simple and cost-effective finger unit that enables the determination of the orientation of an object to be grasped.

[0006] The task is solved by a finger unit, in particular a fingertip, for a robot hand, comprising a rigid component, a deformable component, a light source and an optical sensor configured to detect light emitted by the light source which is reflected by the rigid component or the deformable component or by an object arranged externally to the finger unit.

[0007] The finger unit according to the invention comprises a deformable component and a rigid component, the rigid component preferably being arranged below the deformable component. The deformable component can be designed to be deformable relative to the rigid component. The finger unit comprises at least one light source and at least one optical sensor, the optical sensor being configured to detect light emitted by the light source. For this purpose, the light emitted by the light source is reflected by a rigid component, the deformable component, or an object arranged externally to the finger unit. The advantage of the invention lies in the fact that the orientation of an object to be grasped with the finger unit can be determined simply and, in particular, cost-effectively based on the light detected by the optical sensor.The combination of light source and optical sensor allows the detected light to determine the orientation of the object to be grasped relative to the finger unit. Advantageously, the light source, in combination with the optical sensor, can also detect deformation or movement of the deformable component, from which further relevant parameters can be determined. These parameters might include, for example, the force acting on the deformable component, the position of a contact surface between the deformable component and an external object, and / or the size of such a contact surface.

[0008] According to a further advantageous embodiment of the invention, the rigid or deformable component has a target surface for reflecting light. The target surface preferably represents a target area for the emitted light of the light source, which reflects the emitted light, particularly in the direction of the optical sensor, at least partially. The reflected light can be detected by the optical sensor. Preferably, the optical sensor can generate an image of the target surface using the detected light. The surface texture of the respective component or object can be determined from this image of the target surface, in particular allowing the detection of knurling or other surface patterns. More preferably, if an external object is in contact with the deformable component, the orientation of the object can be determined based on the detected image of the target surface.The deformation or movement of the flexible component can be detected using the optical sensor depending on the target area.

[0009] In a preferred embodiment of the invention, the optical sensor generates a first image of the target surface and a second image of the target surface based on the detected light. The first image is preferably a reference image, and a change, in particular a deformation or movement, can be detected by comparing the first and second images. The first image can, for example, be acquired by the optical sensor in an initial state, particularly without an external object, while the second image can be acquired in an operating state, particularly with an external object in contact with the deformable component. Preferably, the orientation of the external object and / or the deformation or movement of the deformable component can be determined based on the difference between the two images.The first and / or the second image can be continuously renewed, in particular regularly, with the second image preferably being taken after the first image.

[0010] According to a further advantageous embodiment of the invention, the target surface is designed as a section of the rigid component or the deformable component. The target surface can be configured as a surface on the rigid component or the deformable component, and in particular, it is arranged on a surface of the deformable component or the rigid component facing the rigid component or the deformable component. The respective surface structure of the component can generate different reflections, which are advantageously detectable by the optical sensor. The optical sensor can generate an image of the respective target surface, and changes caused by deformations, movements of the components, or grasped objects can be detected by the optical sensor.

[0011] In a preferred embodiment of the invention, the target surface is designed as a structured surface, the structured surface preferably being incorporated into the section of the rigid component or the deformable component. Advantageously, this ensures that the illuminated element has a sufficiently structured surface in the target area to detect changes and / or movement of the respective component by means of the optical sensor.

[0012] According to a further advantageous embodiment of the invention, the target surface is designed as an element arranged on a surface of the deformable component facing the rigid component, or as an element arranged on a surface of the rigid component facing the deformable component. The target surface can be designed as a separate element and be arranged either on a surface of the deformable component facing the rigid component or on a surface of the rigid component facing the deformable component. The target surface can be arranged at least partially within the rigid component or the deformable component. Preferably, the target surface is made of a deformable material, in particular a material similar to or identical to that of the deformable component.Advantageously, the target surface can be arranged on the deformable component without significantly affecting its properties. The target surface can also be advantageously positioned on a surface facing the component, for example, to protect it from external influences and to prevent distortion of the emitted light by other components.

[0013] According to a further advantageous embodiment of the invention, the target surface has a first pattern. A pattern can simplify the detection or determination of movement and / or deformation of a respective component. The pattern of the target surface can be detected by the optical sensor using the light emitted from the light source, with the optical sensor being able to generate an image of the pattern. Advantageously, even a small change in or on the target surface can be detected by the pattern, which in turn allows conclusions to be drawn about the deformation or movement of the respective component or the orientation of the external object. Depending on the pattern, more precise detection using the optical sensor is possible. A detailed or fine pattern can enable higher precision, while a coarser pattern can enable faster and more efficient detection.The first pattern can be arranged directly on the surface of the deformable component facing the rigid component, or on a surface of the rigid component facing the deformable component. Alternatively, the target surface can be designed as a separate element, with the first pattern arranged on the target surface. The first pattern can, for example, be designed as a grid, preferably with further first patterns arranged within the grid.

[0014] According to a further advantageous embodiment of the invention, the light source is configured to project a second pattern onto the target surface. The advantages and design of the first pattern also apply to the second pattern. Preferably, the light source has a mask configured such that a second pattern can be projected onto the target surface. The mask can be arranged between the light source and the target surface, in particular directly on the light source. The mask can have one or more openings arranged relative to each other to generate the second pattern. The mask is preferably interchangeable, so that a multitude of different second patterns can be generated. The light source can have several masks arranged one above the other.

[0015] In an advantageous embodiment of the invention, the target surface has the first pattern, and the second pattern is additionally projected onto the target surface. The advantage of combining the first and second patterns can lie primarily in higher accuracy. Alternatively and / or additionally, the respective patterns can be of a coarser design and, in combination, particularly by superimposing the patterns, produce a sufficiently high accuracy.

[0016] According to a further advantageous embodiment of the invention, the optical sensor is arranged on the rigid component. Preferably, the light source is also arranged on the rigid component, with the target surface being located either on the deformable component or on the external object. The finger unit can have one or more optical sensors, which are preferably arranged on or in the rigid component.

[0017] In an advantageous embodiment of the invention, the optical sensor is arranged on a surface of the deformable component facing the rigid component, or on a surface of the rigid component facing the deformable component. The optical sensor can be arranged at least partially within the rigid component or the deformable component. Accordingly, the finger unit can be designed to be as compact as possible.

[0018] According to a further advantageous embodiment of the invention, the optical sensor is configured to detect light reflected from the deformable component. Preferably, the deformable component can reflect the emitted light from the light source, which can then be detected by the optical sensor.

[0019] In an advantageous embodiment of the invention, the light source is configured such that the emitted light is emitted substantially perpendicular to the target surface, with the optical sensor being arranged such that the reflected light can be detected by the optical sensor. Alternatively, the light source can be configured such that the emitted light is emitted at an angle between 10 and 80 degrees, preferably 20 and 70 degrees, and particularly preferably 30 and 60 degrees, relative to the target surface, with the optical sensor being arranged such that the reflected light can be detected by the optical sensor. A substantially perpendicular arrangement can allow for a more compact design of the finger unit.

[0020] In a further advantageous embodiment of the invention, the finger unit comprises multiple light sources and / or multiple target surfaces and / or optical sensors, wherein the finger unit preferably has one light source and one optical sensor per target surface. The multiple target surfaces can be evenly distributed on the respective component, in particular the deformable component. Thus, changes can advantageously be detected over a large area of ​​the deformable component. Deformations of the deformable component are preferably localized, along a line, and / or over an area. Multiple light sources and / or multiple optical sensors can advantageously enable the detection of the different deformations.

[0021] According to a further advantageous embodiment of the invention, the deformable component is at least partially transparent, and the optical sensor is configured to detect light that penetrates the deformable component and is reflected by the object arranged externally to the finger unit. An external object can, for example, be an object to be grasped. Alternatively, the external object can be an element to be slipped over the finger unit, in particular a glove. Furthermore, this element to be slipped over can be at least partially transparent, in particular translucent. If the external object is arranged on the finger unit, it can reflect the emitted light from the light source. Preferably, the object can have a target surface, wherein the target surface is particularly preferably generated by a section of the object's surface.Preferably, the object has a structure that can represent a target surface. The deformable component can be at least partially transparent, in particular translucent. Advantageously, the emitted light from the light source can thus pass through the deformable component to the object and be reflected by it. This reflection can be detected by the optical sensor, and, for example, the orientation of the object can be determined.

[0022] According to a further advantageous embodiment of the invention, the light source comprises a light-emitting diode or a laser, and / or the optical sensor comprises a light-emitting diode, a photosensitive electrical resistor, a CMOS detector, or a CCD detector. Depending on the application, the optical sensor and / or the light source can be selected based on reliability, precision, compactness, energy efficiency, and / or cost-effectiveness.

[0023] A further aspect of the invention is a robot hand comprising at least one finger unit, preferably several finger units, according to one of the preceding embodiments, and an evaluation unit, wherein the evaluation unit is configured to determine, based on measured values ​​from the optical sensor, a deformation of the deformable component and / or a force acting on the deformable component and / or the position of a contact surface between the deformable component and an external object and / or the size of a contact surface between the deformable component and an external object. The evaluation unit can process the light detected by the optical sensor, for example, in the form of signals or measured values ​​and, for example, determine the orientation of the object to be grasped or the object already grasped.Furthermore, the evaluation unit can additionally or alternatively determine the deformation of the deformable component, the force acting on the deformable component, the position of a contact surface between the deformable component and an external object, and / or the size of a contact surface between the deformable component and an external object. The evaluation unit can also determine the weight of the object to be grasped based on the detected signals. This can be done indirectly, in particular, via the deformation and other parameters. Preferably, the evaluation unit knows the geometry of the object to be grasped.

[0024] Preferably, the evaluation unit is configured such that slippage of the object to be grasped is detected by means of high-frequency changes, particularly at the target surface. Lifting can, for example, be stopped when the object slips, or the gripping force of the finger unit can be increased.

[0025] In a preferred embodiment of the invention, it is provided that the geometry of the external object to be grasped is stored in the evaluation unit, wherein the orientation of the object can be determined by means of the evaluation unit, based on the geometry of the object and depending on the detected signals.

[0026] Preferably, a connecting element can be arranged between the finger unit and the robot hand, wherein a joint is arranged, in particular, between the finger unit and the connecting element and / or between the connecting element and the robot hand. This allows the finger unit to perform more numerous and complex movements. Preferably, the connecting element can be configured as a further finger unit.

[0027] A further object of the invention is a method for operating a robot hand comprising at least one finger unit, preferably several finger units, according to one of the preceding embodiments, wherein, based on measured values ​​of the optical sensor, a deformation of the deformable component and / or a force acting on the deformable component and / or a position of a contact surface between the deformable component and an external object and / or a size of a contact surface between the deformable component and an external object is determined.

[0028] In an advantageous embodiment of the invention, the finger unit is connected to an evaluation unit via a connecting cable, and a signal generated by the optical sensor can be sent to the evaluation unit via this cable. The optical sensor can detect the light reflected from the target surface and transmit it to the evaluation unit as a signal. An image of the target surface can be generated from this signal. The evaluation unit can detect changes in the target surface, particularly in the first and / or second pattern, and use these to determine deformations and / or movements of the deformable component and / or the orientation of a grasped external object. The evaluation unit can also determine the aforementioned parameters additionally or alternatively.

[0029] The robotic hand and the method according to the invention can achieve the same technical effects and advantages as those already described in connection with the finger unit according to the invention. The advantageous embodiments and features described in connection with the finger unit according to the invention can also be applied to the robotic hand and the method for operating a robotic hand, alone or in combination.

[0030] Further details and advantages of the invention will be explained below with reference to the exemplary embodiments shown in the drawings. These show: Fig. 1 An embodiment of a finger unit according to the invention in a side sectional view; and Fig. 2a, b a perspective view of two embodiments of a finger unit from a top-down view.

[0031] Fig. Figure 1 shows a side sectional view of an embodiment of a finger unit 1, in particular a fingertip, for a robot hand according to the invention. The finger unit 1 can, in particular, serve to detect the orientation of an object 8 to be grasped. Such finger units 1 are preferably used in humanoid robot hands and are preferably used to lift objects. The robot hands have at least one finger unit 1, preferably at least two finger units 1, wherein the orientation of the grasped object 8, in particular relative to the finger unit 1, can be essential for lifting and placing the object 8. Objects 8 that are poorly gripped can slip out of the robot hand more easily or be damaged by increased gripping force. Targeted placement of the object 8 would also not be possible.Furthermore, other factors such as damage to other elements in the vicinity or to the object 8 itself are possible if the orientation of the object 8 relative to the finger unit 1 is unknown. The finger unit 1 according to the invention enables a simple and, in particular, cost-effective determination of the orientation of an object 8 to be grasped with the finger unit 1.

[0032] This is shown in the Fig. Figure 1 shows a finger unit 1 comprising a deformable component 2, a rigid component 3, a light source 7, and an optical sensor 4. Preferably, the optical sensor 4 is arranged on the rigid component 3. The light source 7 can emit light, indicated by the arrows, which is reflected either by the rigid component 3, the deformable component 2, or an object 8 arranged externally to the finger unit 1. The optical sensor 4 is configured to detect the reflected light. In the illustrated embodiment, the deformable component 2 has a target surface 5, which can reflect the emitted light from the light source 7. Alternatively, the target surface 5 could also be arranged on the rigid component 3. The finger unit 1 is preferably modeled after a human finger, and can be divided into a shaft region 2.1 and a tip region 2.2. In the shaft region 2.1, the finger unit 1 is divided into a shaft region 2.1 and a tip region 2.2.In the embodiment shown, the deformable component 2 and the rigid component 3 preferably extend in a substantially parallel direction. In the tip region 2.2, the deformable component 2 preferably extends towards the rigid component 3 in a fingertip shape, and the deformable component 2 can be connected to the rigid component 3 in the tip region 2.2. The tip region 2.2 can be modeled on a fingertip. The rigid component 3 can be arranged below the deformable component 2. In the illustrated embodiment, the target surface 5 is designed as a separate element, which is arranged on or at least partially within the deformable component 2. The target surface 5 is arranged on a surface of the deformable component 2 facing the rigid component 3. Alternatively, the target surface 5 could also be arranged on or at least partially within a surface of the rigid component 3 facing the deformable component 2.Furthermore, the target surface 5 could be represented by only a section of the rigid component 3 or the deformable component 2. It is conceivable that the target surface 5 is formed by a partial surface of the rigid component 3 or the deformable component 2. The optical sensor 4 can detect the surface structure of the respective component 2, 3 by means of reflection, whereby, for example, deformations or movements of the respective components 2, 3 can be determined by the optical sensor using the detected light.

[0033] The illustrated embodiment of the Fig. Figure 1 shows several different detection mechanisms a, b, c, which include, in particular, the emission of light by the light source 7, the reflection by the target surface 5, and the detection by the optical sensor 4. The first detection mechanism a shows light emitted essentially perpendicularly from the light source 7, which is reflected essentially perpendicularly by the target surface 5. The optical sensor 4 and the light source 7 are arranged in close proximity to each other. This allows for a very compact design. Furthermore, it is shown that Fig. As can be seen from Figure 1, either a light source 7 can emit several individual light signals, or a finger unit 1 can have several light sources 7. For each light source 7 or each generated light signal, the finger unit 1 can have one or more optical sensors 4. Changes over a large area of ​​the deformable component 2 can be detected by means of several light sources 7 and / or optical sensors 4. Changes preferably include point deformations, deformations along a line, and / or area deformations. For example, the contact surface of the object 8 to be grasped or the orientation of the object 8 to be grasped can be determined with high accuracy. In the illustrated embodiment, the finger unit 1 comprises only one target area 5, which extends over a large area of ​​the deformable component 2.Alternatively, the finger unit 1 can have several smaller target surfaces 5, wherein the target surfaces 5 and the one or more light sources 7 are arranged relative to each other in such a way that the one or more optical sensors 4 can detect the reflection through the target surfaces 5.

[0034] The second detection mechanism b differs from the first detection mechanism a in that the one or more light sources 7 emit the emitted light in an angular range between 10 and 80 degrees, preferably 20 and 70 degrees, particularly preferably 30 and 60 degrees, relative to the target surface 5.

[0035] In the third detection mechanism c, the deformable component 2 is designed to be at least partially transparent, in particular translucent, wherein the optical sensor 5 is configured to detect light that penetrates the deformable component 2 and is reflected by the object 8 arranged externally to the finger unit 1. The surface of the grasped object 8 facing the light source 7 can be considered the target surface 5, wherein in particular a section of the grasped object 8 reflects the emitted light of the light source 7. Fig. In the third detection mechanism c, the light emitted by the light source 7 is emitted essentially perpendicular to the rigid component 3. Alternatively, this can also be done at an angle between 10 and 80 degrees, preferably 20 and 70 degrees, and particularly preferably 30 and 60 degrees, relative to the target surface 5.

[0036] In another detection mechanism, not shown, the emitted light from the light source 7 can be reflected by the deformable component 2, with the optical sensor 4 being configured to detect this reflected light. The deformable component 2 can have the target surface 5 on the surface facing the light source 7 or the rigid component 3, wherein the target surface 5 is particularly well formed as a section on the surface of the deformable component 2.

[0037] It is quite conceivable that the multiple detection mechanisms are used individually and / or in combination in a finger unit 1. Furthermore, it is also conceivable that the first detection mechanism a and the second detection mechanism are implemented in reverse. The light source 7 and the optical sensor 4 are preferably arranged on or at least partially in a surface of the deformable component 2 facing the rigid component 3, wherein the optical sensor 4 is configured to detect light reflected from the rigid component 3. For this purpose, a target surface 5 can be arranged as a separate element on the rigid component 3, or a section of the surface of the rigid component 3 facing the deformable component 2 can function as the target surface.

[0038] Several finger units 1 can be part of a robot hand, which is suitable, for example, for picking up and repositioning objects 8. For this purpose, a robot hand can have at least one, preferably at least two, finger units 1 and an evaluation unit, wherein the evaluation unit is configured to determine, based on measured values, in particular as a signal, from the optical sensor 4, a deformation of the deformable component 2 and / or a force acting on the deformable component 2 and / or the position of a contact surface between the deformable component 2 and an external object 8 and / or the size of a contact surface between the deformable component 2 and an external object 8. To transmit the signals or measured values ​​from the optical sensor 4, the finger unit 1 can be electrically connected to the evaluation unit via a connecting line 9.

[0039] Preferably, a connecting element can be arranged between finger unit 1 and the robot hand, wherein a joint is arranged, in particular, between finger unit 1 and the connecting element and / or between the connecting element and the robot hand. This allows finger unit 1 to perform more numerous and complex movements. Preferably, the connecting element can be configured as a further finger unit 1. It is conceivable that the connecting cable 9 is routed through the connecting element.

[0040] The finger unit 1, in particular the optical sensor 4, can detect the reflected emitted light from the light source 7 via the target surface 5. The optical sensor 4 can transmit the measured values ​​to the evaluation unit in the form of a signal. Based on the measured values, and in particular the known geometry of the object 8 to be grasped, the evaluation unit can determine a deformation of the deformable component 2 and / or a force acting on the deformable component 2 and / or the position of a contact surface between the deformable component 2 and an external object 8 and / or the size of a contact surface between the deformable component 2 and an external object 8. The position of a contact surface between the deformable component 2 and an external object 8 can also be understood as the orientation of the external object 8 relative to the finger unit 1.Additionally, position can describe the arrangement of the grasped object 8 relative to the finger unit 1. For example, it can be determined whether the object is positioned centrally on the finger unit 1 or, for instance, rather on a lateral surface of the deformable component 2. A lateral positioning may increase the risk of slippage.

[0041] The evaluation unit can determine the orientation of the external object 8 relative to the finger unit 1 based on the measured values ​​of the optical sensor 4.

[0042] Fig. 2a and Fig. Figure 2b shows two different embodiments of the finger unit 1 in a perspective view from above. The perspective view clearly shows the outer shape of the finger unit 1, which can essentially be modeled on a human finger. Fig. 2b, unlike the Fig. 2a To illustrate the light source 7 and the optical sensor 4, the deformable component 2 has been omitted or only indicated.

[0043] The illustrated embodiment in Fig. Figure 2a shows a finger unit 1 with a deformable component 2, which has a target surface. The target surface is formed by a section of the deformable component 2 that reflects at least part of the emitted light from the light source 7. The finger unit 1 has a first pattern 6, particularly on the target surface. The pattern 6 can be detected by the optical sensor 4, and in particular, an image can be generated. By means of the pattern, the detection or determination of a movement and / or a deformation of the respective component can be simplified and / or the accuracy increased. Movements can, for example, include the movement of the rigid component 3, the deformable component 2, and / or the object 8 to be grasped, in particular relative to each other.Deformations preferably comprise deformations of the deformable component 2, wherein the deformation is essentially generated by the arrangement of the gripped object 8 on the deformable component 2. For example, the change in position, the distortion of the pattern 6, and / or the distance of the pattern 6 to the optical sensor 4 and / or the light source 7 can be determined by means of a pattern 6. The pattern 6 can be designed as a structure applied in or onto the target surface, in particular a repeating structure.

[0044] The in Fig.The embodiment shown in Figure 2b can generate an alternative or additional second pattern on the target surface. A second pattern can, for example, be superimposed on the first pattern, thus advantageously further increasing the detection accuracy. It is conceivable that even slight changes in the target surface are detectable. The light source 7 can have a mask 6' arranged such that a second pattern can be projected onto the target surface. The mask 6' can be a separate element that can be placed on the light source 7. The mask preferably has one or more openings arranged such that a second pattern is created on the target surface. Preferably, the light source 7 can have one or more masks 6', in particular arranged one above the other. The light source 7 preferably comprises one or more light-emitting diodes or one or more lasers.The optical sensor 4 can comprise one or more light-emitting diodes, one or more light-sensitive electrical resistors, one or more CMOS detectors, or one or more CCD detectors. Reference symbol list 1 finger unit 2 deformable component 2.1 Shaft area 2.2 Summit area 3 rigid component 4 optical sensors 5 Target area 6 patterns 6' Mask 7 Light source 8. Object to be grasped 9 Connecting cable a first detection mechanism b second detection mechanism c third detection mechanism

Claims

[1] Finger unit (1), in particular fingertip, for a robot hand, comprising a rigid component (3), a deformable component (2), a light source (7) and an optical sensor (4) configured to detect light emitted by the light source (7) which is reflected by the rigid component (3) or the deformable component (2) or by an object (8) arranged externally to the finger unit. [2] Finger unit (1) according to claim 1, characterized by , that the rigid component (3) or the deformable component (2) has a target surface (5) for reflecting the light. [3] Finger unit (1) according to claim 2, characterized by , that the target surface (5) is formed as a section of the rigid component (3) or the deformable component (2). [4] Finger unit (1) according to claim 2, characterized by, that the target surface (5) is designed as an element (4) which is arranged on a surface of the deformable component (2) facing the rigid component (3) or as an element which is arranged on a surface of the rigid component (3) facing the deformable component (2). [5] Finger unit (1) according to any one of claims 2 to 4, characterized by that the target area (5) exhibits a first pattern (6). [6] Finger unit (1) according to any one of claims 2 to 5, characterized by , that the light source (7) is configured to project a second pattern (6) onto the target surface. [7] Finger unit (1) according to any one of the preceding claims, characterized by , that the optical sensor (4) is arranged on the rigid component (3). [8] Finger unit (1) according to claim 6, characterized by , that the optical sensor (4) is configured to detect light reflected from the deformable component (2). [9] Finger unit (1) according to one of claims 6 or 7, characterized by , that the deformable component (2) is at least partially transparent, and the optical sensor (4) is configured to detect light which passes through the deformable component (2) and is reflected by the object (8) located external to the finger unit (1). [10] Finger unit (1) according to any one of the preceding claims, characterized by , that the light source (7) comprises a light-emitting diode or a laser and / or the optical sensor (4) comprises a light-emitting diode, a photosensitive electrical resistor, a CMOS detector or a CCD detector. [11] Robot hand comprising at least one finger unit (1), preferably several finger units (1), according to one of the preceding claims and an evaluation unit, wherein the evaluation unit is configured to determine, based on measured values ​​from the optical sensor (4), a deformation of the deformable component (2) and / or a force acting on the deformable component (2) and / or a position of a contact surface between the deformable component (2) and an external object (8) and / or a size of a contact surface between the deformable component (2) and an external object (8). [12] Method for operating a robot hand comprising at least one finger unit (1), preferably several finger units (1), according to any one of claims 1 to 10, wherein a deformation of the deformable component (2) and / or a force acting on the deformable component (2) and / or a position of a contact surface between the deformable component (2) and an external object (8) and / or a size of a contact surface between the deformable component (2) and an external object (8) is determined on the basis of measured values ​​of the optical sensor (4).

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