Device for controlling the movement of a part

Abstract

Disclosed is a device (1) for controlling the movement of a mechanical part (30), comprising: - a first resonator (101) that is in contact with the part; - a support (20) positioned so as to be in contact with the part, the part thus being held between the support and the first resonator; - a control unit (40) configured to activate the resonator, the resonator being configured to cause the part to vibrate in an in-plane vibration mode when activated; - such that the activation of the resonator reduces friction between the resonator (101) and the part in order to facilitate the movement of the part between the resonator and the support.

Description

[0001] Description

[0002] Title: Device for controlling the movement of a part

[0003] TECHNICAL FIELD

[0004] The technical field of the invention is the implementation of acoustic lubrication to control the movement of a part. One of the targeted applications is the creation of a haptic interface.

[0005] PREVIOUS ART

[0006] Haptic interfaces allow a user to experience sensations of touch or texture. For example, haptic gloves have been developed that can be paired with virtual reality headsets. This allows a user wearing the headset to feel a sensation of touch or contact with an object based on the position of their finger in a virtual environment.

[0007] Haptic interfaces are described in documents US6154201 or EP1349050. These documents describe control buttons for devices intended to be moved, in particular in rotation. Haptic interfaces are intended to provide feedback on the torque exerted by the user to turn the button. However, these interfaces have a relatively complex design and are bulky. They are not compact enough to be integrated into interfaces intended to be worn by a user, for example a haptic glove.

[0008] W02018011523 describes a haptic interface, intended to apply a haptic pattern to a control button intended to be manipulated by a user's finger. The control button is arranged on a vibrating plate. The principles of ultrasonic lubrication are used, allowing a controlled reduction of friction between the vibrating plate, according to an in-plane vibration mode, and the button. The application of the vibration facilitates the rotation of the button relative to the vibrating plate. Conversely, stopping the vibration results in a perception of resistance to rotation by the user. Another haptic device, using the same principles, is described in EP3485349.

[0009] The publication Koyama T et al. "Development of an Ultrasonic Brake", Journal of Advanced Mechanical Design Systems and Manufacturing 1, No. 1 (2007): 122-129, describes an ultrasonic brake comprising a vibrating stator arranged under a rotor. The stator is configured to vibrate in an out-of-plane vibration mode. This causes the rotor to move relative to the vibrating stator, in a direction perpendicular to the plane along which the stator extends. Thus, the out-of-plane vibration causes the stator to break contact with the rotor. Such a device is considered relatively bulky. The vibration induces a movement of the rotor perpendicular to the stator. This assumes that the stator exerts a sufficiently high pressure. The device must be sized accordingly: it is relatively bulky, and consumes a significant amount of energy

[0010] The inventors have designed a simple, compact, and inexpensive device that can be easily integrated into a haptic interface.

[0011] STATEMENT OF THE INVENTION

[0012] A first object of the invention is a device for controlling the movement of a mechanical part, comprising:

[0013] - a first resonator, in contact with the part, forming a first support;

[0014] - a second support, arranged in contact with the part, so that the part is held between the first resonator and the second support;

[0015] - a control unit, configured to activate the first resonator, the first resonator being configured to vibrate the part according to an in-plane vibration mode when activated;

[0016] - such that activation of the first resonator reduces friction between the first resonator and the part, to facilitate movement of the part between the first resonator and the second support.

[0017] The movement of the part can be a translation or a rotation.

[0018] The second support may comprise a bearing, in contact with the part, configured to rotate against the part under the effect of the movement of the part.

[0019] According to one possibility:

[0020] - the second support comprises a second resonator, arranged in contact with the part;

[0021] - the second resonator is connected to the control unit, so that the second resonator transmits a vibration to the part when it is activated;

[0022] - such that activation of the second resonator reduces friction between the second resonator and the part, to facilitate movement of the part relative to the second support. According to one possibility, the device comprises a return means, connected to the part, and configured to return the part to a predetermined position following movement of the part relative to the first resonator and the second support.

[0023] The part can be a plate or a cylinder or a sphere.

[0024] According to one possibility, the control unit is configured to activate the piezoelectric resonator according to different vibration amplitudes, so as to modulate the friction between the first resonator and the part.

[0025] The device may comprise a fastener, secured to the part, the fastener being configured to be connected to an object, so as to set the object in motion depending on the movement of the part. The fastener may be connected to the part by a flexible link.

[0026] The device may comprise a button, configured to be moved by a pressing force exerted by an external body, the button being integral with the part, so that the friction between the first resonator and the part makes it possible to condition the pressing force exerted by the external body to move the button.

[0027] The device may comprise an assembly part, configured to hold the first resonator in contact with the second support, so as to exert a prestress on the part. According to one possibility:

[0028] - the first resonator comprises a central part, arranged opposite a transducer, and a peripheral part, extending around the central part;

[0029] - the first resonator rests against the part in a support zone, the support zone being located at the peripheral part, so that the support is exerted around the transducer.

[0030] A second object of the invention is a haptic interface, comprising a device according to the first embodiment.

[0031] The haptic interface may include a support face, intended to be touched by an external body, the support face being connected to the mechanical part.

[0032] The invention will be better understood by reading the description of the exemplary embodiments presented in the remainder of the description, in conjunction with the figures listed below.

[0033] FIGURES

[0034] Figure 1A represents a first embodiment of the invention.

[0035] Figure 1B represents a variant of the first embodiment of the invention.

[0036] Figure IC shows a variation of the configuration shown in Figure 1B.

[0037] Figure 1D shows another variant of the first embodiment of the invention. Figure 2 shows a second embodiment of the invention.

[0038] Figure 3 shows a diagram of an integration of a device according to the invention in a haptic glove type interface.

[0039] Figure 4 shows a third embodiment of the invention.

[0040] Figure 5 shows a fourth embodiment of the invention.

[0041] PRESENTATION OF SPECIAL EMBODIMENTS

[0042] Figure 1A represents a device a first embodiment of the invention. The device comprises a first support 10 and a second support 20. The device comprises a part 30, interposed between the first support 10 and the second support 20. The device is intended to control a displacement of the part 30, in translation, between the first support 10 and the second support 20. In this example, the part is a plate, for example a rigid plate, for example made of glass or brass.

[0043] The first support 10 comprises a base 11, on which rests a cylindrical base 12. An annular wall 13 extends, from the cylindrical base 12, towards the part 30. The annular wall 13 holds a thin cylindrical plate 17. A pillar 14, bypassed by the annular wall 13, holds a first piezoelectric transducer 16. The connection between the pillar 14 and the first piezoelectric transducer 16 can be ensured by a point of glue 15. The glue used can be a cyanoacrylate, or neoprene, or epoxy type glue. When the first piezoelectric transducer 16 is activated, it begins to vibrate, usually at a resonant frequency. The vibration is transmitted to the part 30 by the cylindrical connecting plate 17. The connecting plate forms a mechanical interface between the piezoelectric transducer 16 and the part 30. According to one possibility, the first piezoelectric transducer 16 is directly in contact with the part 30.The first support 10 forms a first resonator 101.

[0044] The second support 20 forms a second resonator 102, arranged symmetrically with respect to the first resonator 101. Thus, the second support 20 comprises a base 21, on which rests a cylindrical base 22. An annular wall 23 extends, from the cylindrical base 22, towards the first resonator 101. The annular wall 23 holds a thin cylindrical plate 27. A pillar 24, bypassed by the annular wall 23, holds a second piezoelectric transducer 26. The connection between the pillar 24 and the second piezoelectric resonator 26 can be ensured by a point of glue 25. As in the first resonator 101, when the second piezoelectric transducer is activated, it begins to vibrate, usually at a resonance frequency. The vibration is transmitted to the part 30 by the cylindrical connecting plate 27. The connecting plate 27 forms a mechanical interface between the piezoelectric transducer 26 and the part 30.According to one possibility, the second piezoelectric transducer 26 is directly in contact with the part 30.

[0045] According to one possibility, each piezoelectric transducer 16, 26 is connected to a cylindrical base 12, 22 by means of an adhesive, the latter replacing the pillar. The adhesive may be a polyurethane foam.

[0046] The diameter of the annular walls 13, 23 is for example of the order of 2 cm. The thickness of the cylindrical plates 17, 27 is for example of the order of a millimeter. The diameter and thickness of each piezoelectric transducer 16, 26 may be respectively equal to 15 mm and 0.75 mm. The connecting plates 17, 27 may be made of brass or glass.

[0047] Each piezoelectric transducer 16, 26 is connected to a control unit 40, allowing activation of each transducer at their respective resonant frequencies.

[0048] Preferably, the vibration frequency is greater than a few kHz, or even 10 kHz or 100 kHz. The vibration frequency may be ultrasonic, i.e. greater than 15 kHz or 20 kHz, or even 40 kHz, which makes the vibration inaudible. The vibration propagates in a plane parallel to the resonator, which corresponds to an “in-plane” vibration mode. Thus, the vibration propagates in directions in the plane in which the part is applied against the plate. The amplitude of the vibration is generally between 0.05 pm and 1 pm. The vibration is preferably oriented parallel to the movement of the part 30, which is obtained by construction for the different implementations of figures 1A, 1B, 1C, 1D, 2 and 4

[0049] The piezoelectric transducer can be made of lead zirconate titanate (PZT) or polyvinylidene fluoride (PVDF). Its thickness can be a few hundred μm or around 1 mm. Its diameter is, for example, between 5 mm and 20 mm. Alternatively, the transducer can include a magnetostrictive material.

[0050] The plate 30 is held between the first resonator 101, acting as the first support 10, and the second resonator 102, acting as the second support 20. The first support and the second support may be connected by an assembly part 32, clipped around each support, so that the first support is held in abutment against the second support and vice versa. This makes it possible to exert a prestress on the part 30, so that the latter is held immobile between the first support 10 and the second support 20, when none of the transducers is activated. The prestress opposes the movement of the part 30. In FIG. 1A, the pressure prestress is shown by two vertical arrows. In FIG. 1A, the assembly part is a flange. The assembly part 32 may take other forms, for example a screw.

[0051] The activation of each piezoelectric transducer has the effect of setting each connecting plate 17, 27 into vibration, in the plane. By vibration in the plane, we mean a vibration propagating along the plane along which the part extends. During the vibration of the connecting plate 17, 27, the part 30 remains in contact with each connecting plate. According to the principles of ultrasonic lubrication, described in EP3485349, the vibration of each connecting plate 17, 27 reduces the friction with the part 30. Despite the pressure to which the part 30 is subjected, the reduction in friction between the part 30 and each support allows a translation of the part, between the supports, along a translation axis. In Figure 1A, the translation is shown by a double arrow.

[0052] To the first order, the reduction of the friction force can be considered linear with respect to the vibration amplitude, and this for vibration amplitudes between 1 pm and 10 pm. Advantageously, the control unit is configured so that the vibration amplitude can be modulated.

[0053] The formation of an in-plane vibration, propagating along a plane parallel to the part, is considered more efficient compared to an out-of-plane vibration, leading to a levitation effect, described in the prior art, in connection with the publication Koyama T et al. "Development of an Ultrasonic Brake".

[0054] Optionally, the device may comprise a return means 31, configured to return the part to a predetermined position. The return means 31 may be a spring or a motorized system, for example an electric motor.

[0055] A protective layer may be deposited on the connecting plates 17 and 27 or on the part 30. The protective layer may be useful for modifying the tribological properties of the surfaces and / or preventing wear. The protective layer may be made with, for example, epoxy or a polymer material.

[0056] When the protective layer is applied to the connecting plates 17, 27, its thickness can advantageously be greater in a part of the supports arranged opposite the periphery of the transducers, and less in a part of the supports pressing on the transducers. This makes it possible to limit the friction between each support and the transducers. When the activation of the resonators ceases, the ultrasonic lubrication effect is interrupted. The part is again immobile in translation, held between the first support 10 and the second support 20.

[0057] The control unit 40 may be configured to measure a displacement of the part 30.

[0058] Figure 1B shows a variant in which the first resonator 101, forming the first support 10, is inclined relative to the second resonator 102, forming the second support 20. The angle of inclination may be a few degrees, for example 2°. The part 30 is then pinched between the resonators. The prestress is only exerted on a reduced surface of the part 30. This improves the performance of the device. The ratio between the resistive forces between the state in which the resonators are activated, and the state in which the resonators are not activated, is improved.

[0059] In Figure 1C, a variant of the configuration shown in Figure 1B is shown. According to this variant, each glue point 15 and 25 is arranged between the annular wall 13, 23 and the connecting plate 17, 27, opposite the point in which the part 30 is pinched. This makes it possible to increase the vibration amplitude. Thus, each glue point, making it possible to connect the connecting plate 17, 27, to a piezoelectric transducer, is arranged on the periphery of each resonator 10, 20, being distant from the area in which the part 30 is pinched between the two resonators.

[0060] Figure 1D shows a variant in which the assembly part 32 forms a housing. The assembly part comprises a base 32i and a cover 322. The base 32i and the cover 322 are rotatable relative to each other, around a hinge 32a. The cover can be closed around the base, by means of a lug 324. This causes the part 30 to be stressed between the supports 10, 20. The assembly part 32 described in connection with Figure 1D can be used in all the embodiments described.

[0061] In Figure 2, an embodiment is shown, in which the second support 20 does not form a resonator, but comprises a bearing 28, connected to a base 21 by an arm 29. The bearing 28 is free to rotate. The bearing is held in abutment against the part. Thus, the part is held between a first resonator 101, similar to the first resonator described in connection with Figures 1A, 1B, 1C, forming a first support 10, and the bearing 28, the latter forming part of the second support 20. In the absence of activation of the first resonator 101, the part is held stationary relative to the supports 10, 20. When the first resonator 101 is activated, the reduction in friction between the connecting plate 17 and the part 30 allows a translation of said part. When the part 30 is moved in translation, the bearing 28 rotates in contact with the part 30.According to one possibility, the bearing is replaced by a contact element whose friction with the part 30 is low, for example a Teflon part.

[0062] The configurations of Figures 1B, 1C and 2 are considered advantageous because the pressure applied to the part by the first and second supports is exerted in a point support zone, around the transducer, or each transducer, and not directly above a transducer. Thus, the support of each transducer on the part is not exerted within a perimeter, corresponding to the perimeter of each transducer. This avoids compression of the transducer or each transducer, which can impair the operation of the transducers. The pressure is applied in an optimal point zone with regard to the direction and amplitude properties of the acoustic wave produced by each resonator. Each support has a central part, in contact with the transducer, as well as a peripheral part, around the central part. The pressure is applied against the peripheral part.The area to which the pressure is applied can be determined by studying the vibration modes of the connecting plates 17, 27. For example, a laser vibrometer can be used to measure the speed of movement at different points on the surface of the connecting plates 17, 27. The laser is first pointed perpendicular to the surface of a support. This gives the normal component of this movement. The laser is then pointed at an angle of 45° to the surface of each connecting plate. A component is then obtained combining the normal component and the component in the plane of the plate. A geometric calculation makes it possible to obtain the component in the plane.

[0063] The device may be intended to be integrated into a haptic interface, for example a haptic glove. Figure 3 shows an example of use, in which the device comprises attachments, configured to connect it to a limb of a user. In the example shown, the mechanical part 30 is movable in translation. The mechanical part 30 is connected to a flexible link 3, for example a wire. The wire 3 is guided by a wheel 2, to an attachment 4, configured to be connected to a finger. The device comprises an attachment 5, allowing it to be secured to a hand. The device 1 forms a haptic interface, allowing movement of the finger to be blocked or allowed. When the part 30 is blocked, the finger is kept immobile, and cannot move away from the device. Vibration of the resonator, or of each resonator, making up the device 1 allows movement of the finger to be allowed. The finger can bend and move away from the device.The possible return means allows the finger to be brought back to a predetermined position.

[0064] According to this embodiment, the control unit 40 can be configured to measure a displacement of the part 30 and / or a force exerted on the flexible link 3. The force exerted can be measured by coupling with the return means 31, or by using a strain gauge secured to the part 30 or the flexible link 3.

[0065] Figure 4 illustrates an embodiment in which the part 30 is connected, at one of its ends, to a bearing surface 8, forming a push button. Depending on the activated or non-activated state of the transducers, the push button can be actuated, or not, by an external body, for example a finger or a stylus. The return means can return the push button to a predetermined initial position. The bearing surface 8 can comprise a contact sensor, for example a capacitive effect sensor. It is understood that the actuation of the push button depends on the activation of the resonators. In the absence of activation, the button is blocked. The activation of the transducers allows the push button to be moved. When the amplitude of the vibrations of the transducers is adjustable, the higher the latter is, the more the friction between the transducers and the part 30 is reduced, which facilitates the actuation of the button.The push button can be configured to control a piece of equipment, such as a musical instrument. For example, the push button might be a key on a piano. In other applications, the equipment might be industrial or consumer equipment, such as a computer or a machine control box.

[0066] As in the previous embodiment, the control unit 40 can be configured to measure a displacement of the part 30 and / or a force exerted on the latter, by coupling with the return means 31 and / or implementing a strain gauge secured to the part 30.

[0067] In the examples described in the preceding figures, the part 30 is movable in translation. A movement of the part in translation, relative to the resonators, is considered optimal. Indeed, the translation movement is preferentially oriented parallel to the propagation of the vibrations exerted at the interface between the part 30 and the resonators. Figure 5 represents a configuration according to which the part is a cylindrical part, for example cylindrical of revolution, and movable in rotation. According to this configuration, the part 30 is held between a first support 10, forming a first resonator 101 and a second support 20, forming a second resonator 102. The first support comprises a base 11, holding a piezoelectric transducer 16, connected to a connecting plate 17. The second support 20 comprises a base 21, holding a piezoelectric transducer 26, connected to a connecting plate 27.The materials and dimensions of the main components are similar to those of the embodiment of Figure 1A.

[0068] An assembly part 32 connects the first support and the second support, so as to exert a constraint on the part 30, opposing a rotation of said part. When the resonators are activated, the friction force between each resonator and the part decreases, the part remaining in contact with each resonator. This allows a rotation of the part 30, for example under the action of a finger. As in the previous embodiments, each vibration produced by a resonator propagates in the plane of each connecting plate. The part 30 is always in contact with each support. This embodiment makes it possible to produce a haptic interface of the adjustment wheel type.

[0069] The invention provides a compact and lightweight device that can be easily integrated into a glove or any other compact haptic interface. The absence of electric motors ensures stable operation of the interface, which contributes to good safety of use. Furthermore, a part in the form of a plate or a cylinder has been described. Other shapes can be envisaged, for example a spherical or partially spherical shape.

Claims

CLAIMS 1. Device (1) for controlling the movement of a mechanical part (30), comprising: - a first resonator (101), in contact with the part, forming a first support (10); - a second support (20), arranged in contact with the part, so that the part is held between the first resonator and the second support; - a control unit (40), configured to activate the first resonator, the first resonator being configured to vibrate the part according to an in-plane vibration mode when activated; - such that activation of the first resonator reduces friction between the first resonator (101) and the part, to facilitate movement of the part between the first resonator and the second support.

2. Device according to claim 1, in which the movement of the part is a translation or a rotation.

3. Device according to any one of the preceding claims, in which the second support comprises a bearing (28), in contact with the part, configured to rotate against the part under the effect of the movement of the part.

4. Device according to any one of claims 1 or 2, in which: - the second support (20) comprises a second resonator (102), arranged in contact with the part; - the second resonator is connected to the control unit (40), so that the second resonator transmits a vibration to the part when it is activated; - such that the activation of the second resonator reduces friction between the second resonator and the part, to facilitate the movement of the part relative to the second support.

5. Device according to any one of the preceding claims, comprising a return means (31), connected to the part, and configured to return the part to a predetermined position following a movement of the part relative to the first resonator and to the second support.

6. Device according to any one of the preceding claims, in which the part is a plate or a cylinder or a sphere.

7. Device according to any one of the preceding claims, in which the control unit is configured to activate the piezoelectric resonator according to different vibration amplitudes, so as to modulate the friction between the first resonator and the part.

8. Device according to any one of the preceding claims, comprising an attachment (4, 5), integral with the part, the attachment being configured to be connected to an object, so as to set the object in motion depending on the movement of the part.

9. Device according to claim 8, in which the fastener is connected to the part by a flexible link (3).

10. Device according to any one of claims 1 to 7, comprising a button, configured to be moved by a pressing force exerted by an external body, the button being integral with the part, so that the friction between the first resonator and the part makes it possible to condition the pressing force exerted by the external body to move the button.

11. Device according to any one of the preceding claims, comprising an assembly part (32), configured to hold the first resonator in contact with the second support, so as to exert a prestress on the part.

12. Device according to claim 11, in which: - the first resonator comprises a central part, arranged opposite a transducer, and a peripheral part, extending around the central part; - the first resonator rests against the part in a support zone, the support zone being located at the peripheral part, so that the support is exerted around the transducer.

13. Haptic interface, comprising a device according to any one of the preceding claims.

14. Haptic interface, according to claim 13, comprising a support face (8), intended to be touched by an external body, the support face being connected to the mechanical part (30).

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