Haptic feedback module and hand kinesthetic device with such a feedback module

Abstract

The invention relates to a haptic feedback module (2) for a hand kinesthetic device (1), comprising: a) a honeycomb structure layer (9), b) at least one layer element (11) that is in frictional contact with the honeycomb structure layer (9), c) a membrane (7) in the interior (15) of which the honeycomb structure layer (9) and the at least one layer element (11) are at least partially contained, wherein the membrane (7) has a receiving surface (6) for a fingertip (5a) of a user, and d) a pneumatic vacuum system (16) pneumatically connected to the interior (15) of the membrane (7) and configured to adjust a frictional force between the at least one layer element (11) and the honeycomb structure layer (9) by changing a negative pressure level within the interior (15) in order to change the stiffness of the honeycomb structure layer (9). The invention further relates to a hand-kinesthetic device (1) comprising such a feedback module (2).

Description

[0001] The invention relates to a haptic feedback module for a hand kinesthetic device and to a hand kinesthetic device with such a feedback module.

[0002] Haptic feedback is crucial for human perception and enhances the sense of presence when using human-machine interfaces (HMIs) in extended reality (XR) and telerobotics. Haptic feedback devices are divided into finger-cutaneous and kinesthetic devices: Finger-cutaneous devices stimulate mechanoreceptors in the skin, particularly at the fingertips, and simulate tactile stimuli such as texture, vibration, or pressure. Kinesthetic devices support finger proprioception and enable the perception of forces, resistance, or weight.

[0003] Existing devices typically offer only either cutaneous or kinesthetic feedback, which is insufficient for a precise perception of interaction forces and softness. Kinesthetic devices often lack tactile stimuli because they are rigidly mounted on the fingertips, while finger-cutaneous devices are frequently bulky and offer limited feedback. This impairs the sense of presence and the ability to adjust, for example, grip strength or the softness of an object.

[0004] US 2023 / 0259212 A1 describes a 3D-printed, soft, haptic device worn on the finger. It generates feedback through shear forces, pressure, and vibrations using foldable actuators that interact with a tactile stimulator. Changes in the shape of the actuators cause movement of the stimulator, which provides the haptic feedback.

[0005] Furthermore, US 2020 / 0 387 246 A1 discloses a system for providing haptic feedback, comprising at least one cell, a plurality of particles arranged in the at least one cell, a first actuator configured to change the pressure of the at least one cell, a valve configured to control the pressure of the at least one cell, and a processor communicatively connected to the first actuator and the valve.The processor is configured to receive an activation signal, determine a pressure change value for the at least one cell based on the activation signal, transmit a first pressure change signal to the first actuator to cause the first actuator to change the stiffness of the at least one cell, at least partially, based on the pressure change value, and transmit a second pressure change signal to the valve to cause the valve to change the stiffness of the at least one cell based on the pressure change value.

[0006] Furthermore, EP 3 477 431 A1 discloses an interaction device for providing user input to a second device, wherein the interaction device has a deformable shape.The interaction device comprises an inner shell made of a flexible, airtight material, enclosed around a cavity filled with a multitude of semiconducting elastic spheres, the interior of which is provided with a multitude of conductive elements; a pump configured to control the pressure of the inner shell and thus influence the stiffness of the multitude of semiconducting spheres; a processor configured to measure the conductivity between the multitude of conductive elements and from this determine a conductivity matrix representing the forces exerted on the interaction device by a user; and to control the pump in two modes: a first mode in which the pressure of the inner shell is normal, allowing the shape of the device to be formed, and a second mode in which the inner shell is pressurized to stabilize the shape formed in the first mode.Furthermore, a communication interface is available to transmit the conductivity matrix to the second device.

[0007] The object of the invention is to provide a compact and lightweight finger-cutaneous or haptic feedback module that allows for adjustable contact stiffness and does not place any additional strain on the fingers. The invention is intended to combine both finger-cutaneous and kinesthetic feedback, thereby improving the perception of the softness of objects. This object is achieved by the subject matter of claim 1 and claim 8. Preferred embodiments are described in the dependent claims, the description, and the figures.

[0008] A haptic feedback module according to the invention for a hand kinesthetic device comprises a honeycomb structure layer, at least one layer element that is in frictional contact with the honeycomb structure layer, a membrane in the interior of which the honeycomb structure layer and the at least one layer element are at least partially received, wherein the membrane has a receiving surface for a user's fingertip, and a pneumatic vacuum system that is pneumatically connected to the interior of the membrane and is designed to adjust a frictional force between the at least one layer element and the honeycomb structure layer by changing a negative pressure level within the interior in order to change the stiffness of the honeycomb structure layer.The combination of the honeycomb structure layer with at least one adjacent layer element and the pneumatic vacuum system enables precise adjustment of the stiffness of the feedback module and thus improves the perception of the softness of objects.

[0009] By varying the pressure, friction within the membrane is adjusted between the honeycomb structure layer and at least one layer element, leading to a change in the stiffness of the honeycomb structure layer. This change in the stiffness of the honeycomb structure layer directly alters the stiffness of the entire feedback module.

[0010] A negative pressure or vacuum inside the membrane causes the at least one layer element and the honeycomb structure layer to be compressed, increasing the friction between them. This results in a more rigidly perceptible structure of the feedback module. Changing the pressure level increases or decreases the rigidity of the feedback module as perceived by the finger. A higher negative pressure feels stiffer to the user due to the increased friction, while a lower negative pressure feels softer or less rigid due to the same friction. Without applied negative pressure, or at normal or medium air or atmospheric pressure, the friction between the at least one layer element and the honeycomb structure layer is minimal, resulting in a flexibly perceptible structure on the skin of the finger.

[0011] The honeycomb structure layer is a planar component consisting of a material with a hexagonal or honeycomb-shaped cell structure. This structure gives the layer high stiffness at low weight and allows for flexible adjustment of its mechanical properties by varying the external load conditions. The honeycomb structure layer is many times thicker than the at least one layer element. In the invention, the honeycomb structure serves to modulate the stiffness of the haptic feedback module by being in frictional contact with the layer elements. A longitudinal axis of each hexagonal or honeycomb-shaped cell is preferably oriented perpendicular to a surface or friction surface of the at least one layer element facing the honeycomb structure layer. In other words, an open end of the respective cell of the honeycomb structure layer faces the at least one layer element.

[0012] Preferably, the honeycomb structure layer comprises materials such as plastic, metal, especially aluminum, and / or Nomex™ fiber material. Nomex™ fibers are aramid fibers that are mechanically stable and chemically resistant. Furthermore, Nomex™ fibers have a comparatively low weight.

[0013] The at least one layer element is a planar, in particular flat, component that is in frictional contact with the honeycomb structure layer. The at least one layer element is made of a flexible, non-stretchable material with sufficient friction against the honeycomb structure layer. The at least one layer element preferably consists of materials such as plastic, metal, textile, hook and loop fastener, paper, and / or sandpaper. By influencing the negative pressure within the membrane, and taking into account the material of the at least one layer element and the honeycomb structure layer, the frictional force in the friction surface between the friction partners of the layer structure can be regulated. The selection of the respective material and / or the friction partners determines the specific friction properties and the adaptability of the feedback module to various tactile requirements.

[0014] The term "negative pressure" describes a pressure that is lower than the ambient atmospheric pressure. In the present invention, this negative pressure is used to control the frictional force between the at least one layer element and the honeycomb structure layer. "Vacuum" here refers to the state in which a controlled mechanical effect is generated by reducing the air pressure within a closed space of the membrane, such as pressing the at least one layer element or several layer elements against the honeycomb structure layer.

[0015] The pneumatic vacuum system is a device designed to generate and regulate a negative pressure in a closed space, such as the interior of the membrane. It typically comprises a vacuum pump, lines, and valves that precisely control the pressure within the membrane's interior. In the present invention, the pneumatic vacuum system serves to adjust the frictional force between the honeycomb structure layer and the at least one layer element by changing the negative pressure, thereby influencing the stiffness of the haptic feedback module. The pneumatic vacuum system is configured to operate with variable pressure levels ranging from atmospheric pressure down to a predetermined negative pressure sufficient to achieve the desired stiffness setting.

[0016] The membrane is a flexible and elastic component that spatially encloses or delimits the interior of the haptic feedback module. It is preferably made of plastic, in particular silicone or elastic polymers, which exhibit high deformability and mechanical strength. The membrane serves several purposes, firstly, to house the components of the feedback module. The membrane contains the honeycomb structure layer and the at least one layer element, which are partially or completely enclosed within its interior. Secondly, the membrane provides an interaction surface, featuring a specially designed contact area for the user's fingertip. This enables direct tactile interaction between the finger and the feedback module.Since the membrane is connected to the pneumatic vacuum system, it allows the negative pressure to be transferred to the internal components, thereby influencing the stiffness of the feedback module. The membrane significantly contributes to the functionality and ergonomics of the feedback module by providing a direct contact surface and enabling the adjustment of the module's mechanical properties.

[0017] In one embodiment, the honeycomb structure layer is spatially arranged between two layer elements. The feedback module is thus implemented within the membrane in a sandwich construction, with the honeycomb structure layer located between the two planar layer elements. In this sense, one open end of each cell of the honeycomb structure layer faces one of the layer elements and is oriented perpendicular to it. By pressing the layer elements against the honeycomb structure layer as a result of the creation of a vacuum inside the membrane, each cell of the honeycomb structure layer is covered by the layer elements.

[0018] The honeycomb structure layer and the layer elements are arranged in such a way as to allow sliding movement under reduced vacuum pressure, which in turn allows for flexible module behavior and improved tactile feedback.

[0019] The friction between the honeycomb structure layer and the respective layer element can be increased by adding additional layers, such as Velcro or similar materials, between the respective layer element and the honeycomb structure layer. This allows the range of stiffness adjustment to be expanded.

[0020] Preferably, the pneumatic vacuum system is positioned spatially separate from the honeycomb structure layer and pneumatically connected to the interior of the membrane via a piping system. By positioning the pneumatic vacuum system, in particular the vacuum pump, valves, and optionally a control system, spatially separate from the honeycomb structure layer and the at least one layer element, the weight and strain on the user's finger can be minimized. The aforementioned piping system can comprise a hose and / or a tube. The feedback module is designed to be mounted on various platforms, including table-mounted systems and portable devices.

[0021] Preferably, the stiffness of the feedback module is proportional to the negative pressure level applied by the pneumatic vacuum system. In other words, the haptic feedback module is designed to have a stiffness corresponding to the pressure level, thereby simulating precise tactile feedback and replicating the softness of objects.

[0022] Furthermore, a control system is preferably provided which is configured to control and regulate the pneumatic vacuum pressure of the vacuum system in order to achieve specific stiffness levels based on user inputs or task requirements.

[0023] A hand-kinesthetic device according to the invention comprises a first frame segment to which a haptic feedback module according to the first aspect of the invention is attached. The feedback module is designed such that it can be easily integrated into existing hand-kinesthetic devices or equipment.

[0024] Preferably, the first frame segment is designed to receive a user's finger in such a way that the tip of the finger rests on a receiving surface of the membrane.

[0025] Preferably, the first frame segment is articulated to a second frame segment, the second frame segment being designed such that the middle phalanx of the user's finger can be fixed to it, while the end phalanx of the user's finger remains freely movable within the first frame segment. The articulated frame segments allow for guided flexion and extension of the end phalanx relative to the middle phalanx of the finger. A strap or similar device can be provided on the second frame segment to fix the middle phalanx of the user's finger to the second frame segment. In contrast to the middle phalanx in the first frame segment, the end phalanx of the user's finger is free of any fixation and simply rests on the receiving surface of the membrane. The respective frame segment can be designed with a skeletal structure, making it particularly lightweight. This allows the device to be used for different finger sizes.

[0026] The hand kinesthetic device may include a sensor system configured to detect finger force applied by the user and to control the vacuum system in such a way as to adjust the negative pressure accordingly to simulate the perceived softness of objects.

[0027] The haptic feedback module and hand kinesthetic device offer numerous advantages for use in various applications. Particularly in Extended Reality (XR), including Virtual Reality (VR), Augmented Reality (AR), and Mixed Reality (MR), they enable enhanced haptic feedback. Users can experience realistic interactions with virtual objects, as the softness, hardness, or texture of the objects is precisely simulated through the variable stiffness of the feedback module. This immersive experience significantly increases the sense of presence and usability in virtual environments.

[0028] Furthermore, the invention is ideally suited for the teleoperation of robots in hazardous or difficult-to-access environments, such as the deep sea, space, or industrial and medical settings. In industry, users can handle products from a safe distance or train robots to perform complex tasks. In medicine, the devices enable therapists and physicians to conduct remote interactions, for example, during diagnosis and palpation by physiotherapists or during massage therapy.

[0029] Another area of ​​application is robot-assisted surgery. Surgeons can use the haptic feedback module to feel the softness or texture of organs, even when direct access is limited. This precise tactile feedback supports crucial assessments during minimally invasive procedures and increases the safety and effectiveness of such operations. Overall, the hand-kinesthetic device improves immersion in virtual environments and increases the precision and safety of remotely controlling robots.

[0030] The above definitions and explanations regarding technical effects, advantages and advantageous embodiments of the haptic feedback module according to the first aspect of the invention also apply analogously to the hand kinesthetic device according to the second aspect of the invention, and vice versa.

[0031] Further measures improving the invention are described in more detail below, together with a description of a preferred embodiment of the invention, with reference to the figures. Fig. 1 a simplified schematic side view of a hand kinesthetic device according to an embodiment of the invention and Fig. 2 a simplified schematic perspective representation of a haptic feedback module according to the invention of the hand kinesthetic device according to the invention Fig. 1 to illustrate a layer structure of the feedback module.

[0032] Fig. Figure 1 shows a side view of a hand-kinesthetic device 1 equipped with a haptic or finger-cutaneous feedback module 2. The device 1 comprises a first frame segment 3 and a second frame segment 4, each with a skeletal construction, designed to accommodate a user's finger 5. The feedback module 2 is attached to the first frame segment 3.

[0033] A fingertip 5a of the user rests on a receiving surface 6 of a membrane 7 of the feedback module 2 and can exert a force F on the feedback module 2. The second frame segment 4 is articulated to the first frame segment 3. A middle segment 5b of the finger 5 is fixed to the second frame segment 4, for example by a strap 8, a loop, or the like. The distal end segment 5c of the finger 5, which has the fingertip 5a, remains freely movable. The second frame segment 4 can be connected on a side facing away from the first frame segment 3 to further frame segments or components – not shown here.

[0034] The haptic feedback module 2 includes, according to Fig. 2 a honeycomb structure layer 9 with a plurality of identically shaped, hexagonal cells 10, wherein the cells 10 are arranged upright or vertically oriented. The openings of the cells 10 each face a layer element 11, 12. Accordingly, the honeycomb structure layer 9 is spatially arranged between a first and a second layer element 11, 12. The cells 10 are thus oriented perpendicular to the layer elements 11, 12. In the present case, four and three cells 10 are arranged alternately next to each other in the longitudinal direction of the feedback module 2. The layer elements 11, 12 are in frictional contact with the honeycomb structure layer 9 via mutually facing friction surfaces 13, 14. The layer elements 11, 12 and the honeycomb structure layer 9 are in an interior space 15 of the in Fig. 1 completely and in Fig. 2, only partially shown, arranged in the membrane 7. For example, the honeycomb structure layer 9 is made of plastic, metal, in particular aluminum, and / or Nomex fiber material. For example, the layer elements 11, 12 are made of plastic, metal, textile, one or more hook and loop fasteners, paper, and / or sandpaper.

[0035] After Fig.The feedback module 2 also includes a pneumatic vacuum system 16, comprising a vacuum pump 17 for generating and controlling a negative pressure level within the interior 15, and a line 18 of a piping system 19. The vacuum pump 17 is pneumatically connected to the interior 15 of the membrane 7 via the line 18. The vacuum system 16, in particular the vacuum pump 17 and any other components of the vacuum system 16 (not shown here), are spatially separated from the membrane 7, in particular from the honeycomb structure layer 9 and the layer elements 11, 12 arranged therein, so that the user's finger 5 is not subjected to any additional mechanical stress.

[0036] The vacuum system 16 is connected to a control unit 20 of the hand kinesthetic device 1 via signal transmission. The control unit 20 is specifically designed to control the vacuum pump 17, such that a negative pressure level in the interior 15 of the membrane 7 can be regulated. By changing the negative pressure level within the interior 15, a frictional force between the layer elements 11, 12 and the honeycomb structure layer 9 is adjusted, so that the stiffness of the honeycomb structure layer 9, in particular of the feedback module 2, can be changed.

[0037] The controller 20 can receive user input commands and / or other task requirements and process them to control the vacuum system 16, in particular to regulate the vacuum level in the interior 15. For this purpose, sensor signals from a sensor system (not shown here) and / or other information can be received and processed. Based on the aforementioned inputs and requirements, specific stiffness levels of the diaphragm 7 can be set at the feedback module 2 by adjusting the vacuum in the interior 15. The stiffness of the feedback module 2 is proportional to the applied vacuum level. Reference symbol list 1 Hand kinesthetic device 2 Haptic feedback module 3 First frame segment 4 Second frame segment 5 fingers 5a Fingertip 5b Middle joint of the finger 5c End joint of the finger 6 Recording area 7 Membran 8 strap 9 honeycomb structure layer 10 cells of the honeycomb structure layer 11 First layer element 12 Second layer element 13 Friction surface of the first layer element 14 Friction surface of the second layer element 15 Interior 16 Pneumatic vacuum system 17 Pump 18 Management 19 Pipeline system 20 Control F force

Claims

[1] Haptic feedback module (2) for a hand kinesthetic device (1), comprising: a) a honeycomb structure layer (9), b) at least one layer element (11) that is in frictional contact with the honeycomb structure layer (9), c) a membrane (7) in the interior (15) of which the honeycomb structure layer (9) and the at least one layer element (11) are at least partially contained, wherein the membrane (7) has a receiving surface (6) for a fingertip (5a) of a user, and d) a pneumatic vacuum system (16) which is pneumatically connected to the interior (15) of the membrane (7) and is designed to adjust a frictional force between the at least one layer element (11) and the honeycomb structure layer (9) by changing a vacuum level within the interior (15) in order to change the stiffness of the honeycomb structure layer (9). [2] Feedback module (2) according to claim 1, characterized by, that the honeycomb structure layer (9) is made of plastic and / or metal. [3] Feedback module (2) according to any one of the preceding claims, characterized by , that at least one layer element (11) is made of plastic, metal, textile, hook and loop fastener, paper and / or sandpaper. [4] Feedback module (2) according to any of the preceding claims, characterized by , that the honeycomb structure layer (9) is spatially arranged between two layer elements (11, 12). [5] Feedback module (2) according to any one of the preceding claims, characterized by , that the membrane (7) is made of plastic, in particular of silicone and / or elastic polymers. [6] Feedback module (2) according to any one of the preceding claims, characterized by , that the pneumatic vacuum system (16) is positioned spatially separate from the honeycomb structure layer (9) and is pneumatically connected to the interior (15) of the membrane (7) via a line system (19). [7] Feedback module (2) according to any one of the preceding claims, characterized by , that the stiffness of the feedback module (2) is proportional to the level of negative pressure applied by means of the pneumatic vacuum system (16). [8] Hand kinesthetic device (1) comprising a first frame segment (3) to which a haptic feedback module (2) according to one of the preceding claims is attached. [9] Device (1) according to claim 8, characterized by , that the first frame segment (3) is designed to receive a finger (5) of the user in such a way that a fingertip (5a) of the finger (5) rests on a receiving surface (6) of the membrane (7). [10] Device (1) according to claim 9, characterized by, that the first frame segment (3) is articulated to a second frame segment (4), wherein the second frame segment (4) is designed such that a middle segment (5b) of the user's finger (5) can be fixed to it, while a terminal segment (5c) of the user's finger (5) remains freely movable in the first frame segment (3).

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