EP2406578A1 - Device for the touch-sensitive characterisation of a surface texture - Google Patents

Device for the touch-sensitive characterisation of a surface texture

Info

Publication number
EP2406578A1
EP2406578A1 EP10708537A EP10708537A EP2406578A1 EP 2406578 A1 EP2406578 A1 EP 2406578A1 EP 10708537 A EP10708537 A EP 10708537A EP 10708537 A EP10708537 A EP 10708537A EP 2406578 A1 EP2406578 A1 EP 2406578A1
Authority
EP
European Patent Office
Prior art keywords
sensor
coating structure
disposed
projection
coating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP10708537A
Other languages
German (de)
French (fr)
Inventor
Florian De Boissieu
Bernard Guilhamat
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Original Assignee
Commissariat a lEnergie Atomique CEA
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Commissariat a lEnergie Atomique CEA, Commissariat a lEnergie Atomique et aux Energies Alternatives CEA filed Critical Commissariat a lEnergie Atomique CEA
Publication of EP2406578A1 publication Critical patent/EP2406578A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
    • G01B5/28—Measuring arrangements characterised by the use of mechanical techniques for measuring roughness or irregularity of surfaces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/16—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force
    • G01L5/161—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force using variations in ohmic resistance
    • G01L5/162—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring several components of force using variations in ohmic resistance of piezoresistors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/22—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers
    • G01L5/226—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers to manipulators, e.g. the force due to gripping
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/4998—Combined manufacture including applying or shaping of fluent material

Definitions

  • the invention relates to a surface texture tactile characterization device for exploring and characterizing the texture of a flat surface or not.
  • the invention can be applied to all fields related to the manufacture of products whose tactile characteristics are important.
  • the invention can be applied, for example, to the fields of the paper, textile, automotive, food or cosmetic industry in order to: estimate the sensations perceived by the consumer for a new product,
  • the invention can also be applied to the field of robotics, to provide a robot with a sense of touch, or even biomimetics, for example to manufacture active prostheses, or to perform medical tele-operations to render tactile sensations. to the surgeon during a remote operation.
  • This layer of elastomer allows both to mechanically protect the sensor while transmitting the reliefs perceived during an exploration of a surface.
  • Such a device has the particular disadvantage of having a contact surface between the sample studied and the coating layer of the sensor, poorly determined and highly dependent on the roughness of the sample. Thus, it is difficult to make an accurate analysis of the texture of the explored surface. In addition, the wear of this coating poses problems for the reproducibility of measurements over time and the change thereof, when worn, is not easy.
  • An object of the present invention is to provide a surface texture tactile characterization device for adapting to any type of surface and for measuring pressure and friction forces during the exploration of a surface. while offering a good reproducibility of measurements over time, and whose measurements are independent of the wear of the sensor.
  • the present invention proposes a device for surface texture tactile characterization comprising at least one triaxial force sensor at least partially covered by a coating structure comprising at least a first portion disposed against the sensor and at least one second portion disposed against the first portion such that the first portion is disposed between the sensor and the second portion, the second portion including at least one projection disposed on a side opposite the first portion and a shoulder disposed against a first face of the first portion; part of the coating structure lying on the side opposite to a second face of the first portion disposed against the sensor, the hardness of the material of the first part being lower than that of the material of the second part.
  • This device makes it possible to carry out an exploration and a characterization of any type of surface.
  • the two-part coating structure also makes it possible to transmit forces, from the contact surface, between the coating structure and the surface studied, to the sensor, which can be controlled and adapted to the sensitivity of the sensor. depending on the nature and roughness of the studied surface.
  • Such a coating structure also makes it possible to protect the sensor while forming an optimum interface between the studied surface and the sensor thanks to the protrusion, which is the part in contact with the studied surface, whose shape and dimensions are perfectly defined.
  • the protrusion which is the part in contact with the studied surface, whose shape and dimensions are perfectly defined.
  • the part in contact with the studied surface is the hardest
  • the hardness of the material of the second part, and in particular of the projection which is greater than that of the material of the first part, is chosen to minimize the wear of the coating structure (in particular of the projection).
  • the section is constant over the entire height of the projection, for example when the projection has a substantially cylindrical shape, it allows to maintain a constant contact surface regardless of the wear of the projection.
  • the first part of the coating structure has a hardness lower than that of the second part of the coating structure, this first part makes it possible to damp any impacts that the device may undergo, for example during contacting the device with the studied surface.
  • the invention therefore makes it possible to explore any type of surface, to maximize the transmission of forces to the sensor while protecting it and to minimize the effects of wear for better reproducibility of the measurements.
  • the force sensor is triaxial, it is possible to detect the normal and tangential forces or forces that the protrusion undergoes and which are transmitted to the sensor, and thus to detect any contact force experienced by the protrusion, whatever its orientation in space.
  • a surface texture tactile characterization device comprising at least one force sensor at least partially covered by a coating structure comprising at least a first portion disposed against the sensor and at least a second portion disposed against the first portion such that the first portion is disposed between the sensor and the second portion, the second portion including at least one projection disposed on a side opposite to the first portion, the hardness of the material of the first portion being less than that of the material of the second part.
  • the protrusion of the second part of the coating structure may be of substantially cylindrical shape and / or comprise an end of substantially semi-spherical shape and / or have a shape ratio equal to about 1.
  • the end of substantially semi-shape -spherical makes it possible to have an even better defined contact surface as a function of the contact pressure of the device on the studied surface.
  • the aspect ratio of the projection may be chosen such that the projection does not sag as it moves over the surface to be characterized, allowing a certain linearity between the components of the forces on the surface of the coating and the measurements made by the sensor.
  • the second portion of the encapsulation structure may include a shoulder disposed against a first face of the first portion of the encapsulant located on the opposite side to a second face of the first portion disposed against the sensor.
  • the shoulder may completely cover said first face of the first portion of the encapsulation structure, and / or have a substantially truncated conical shape comprising on one side a section substantially similar to that of the projection and a second side opposed to the first side, a section substantially similar to that of the first face of the first part of the coating structure.
  • the first part of the coating structure may have a substantially cylindrical shape and / or a section, in a plane parallel to one face of said first part in contact with the second part, of dimensions greater than the dimension of the first part according to an axis perpendicular to said section.
  • the radius R b of the cylinder section may be such that: with F Nmax : maximum pressure force applied to the device during a texture characterization of a surface;
  • the material of the first part of the coating structure and / or the material of the second part of the coating structure may be based on elastomer, for example polyurethane.
  • elastomer for example polyurethane.
  • by making the two parts of the coating structure from the same material, for example polyurethane good cohesion of these two parts is ensured, which makes it possible to avoid possible problems of separation of these two parts during use of the device.
  • the hardness of the material of the first part of the coating structure and / or the hardness of the material of the second part of the coating structure may be between about 10 and 100 Shore A and / or be greater than or equal to about 10 shore A and / or have a difference between about 20 and 30 shore A.
  • the sensor may be arranged against or embedded in a support based on a material whose hardness may be greater than that of the materials of the coating structure.
  • the first part of the coating structure can completely cover the sensor and at least a portion of the support.
  • the force sensor may be a triaxial force sensor.
  • the force sensor may comprise at least one deformable membrane and a rod mechanically connected to the deformable membrane.
  • the sensor rod can be arranged at least partly in the first part of the coating structure, which improves the transmission of forces to the sensor.
  • the device may further comprise a grippable body, the sensor and the coating structure may be arranged at one end of said gripping body.
  • the invention furthermore relates to a method for producing a surface texture characterization device comprising at least one molding of a first part of a coating structure intended to cover at least partly a force sensor. triaxial, said first portion being disposed against the sensor, and a molding of at least a second portion of the coating structure disposed against the first portion such that the first portion is disposed between the sensor and the second portion, the second portion comprising at least one projection disposed on a side opposite to the first part and a shoulder disposed against a first face of the first part of the coating structure lying on the opposite side to a second face of the first part disposed against the sensor the hardness of the material of the first part being lower than that of the material of the second part.
  • a method for producing a surface texture characterization device comprising at least one molding of a first part of a coating structure intended to cover at least part of a force sensor, said first part being arranged against the sensor, and a molding of at least a second part of the coating structure disposed against the first part such that the first part is arranged between the sensor and the second part, the second part comprising at least one projection disposed on a side opposite to the first part, the hardness of the material of the first part being lower than that of the material of the second part.
  • the molding of the second part of the coating structure can be carried out before the molding of the first part of the coating structure, these two moldings being obtainable at least by the implementation of the steps of:
  • the molding of the first part of the coating structure can be carried out before the molding of the second part of the coating structure, these two moldings being obtainable at least by the implementation of the steps of:
  • the materials poured into the mold can be solidified in an oven.
  • the molded materials may be based on elastomer and debulled under a vacuum bell prior to performing the molding steps.
  • FIG. 1 represents a surface texture tactile characterization device, object of the present invention, according to a particular embodiment
  • FIG. 2 represents a coating structure of a sensor of a tactile characterization device of FIG. surface texture, object of the present invention, according to the particular embodiment shown in FIG.
  • FIGS. 3 and 4 show an example of a triaxial sensor of a surface texture tactile characterization device, object of the present invention.
  • Identical, similar or equivalent parts of the different figures described below bear the same numerical references so as to facilitate the passage from one figure to another.
  • Figure 1 shows a sectional view of a surface texture tactile characterization device 100 according to a particular embodiment.
  • the device 100 is here an artificial finger and comprises a gripping body 102.
  • the device 100 comprises a triaxial force sensor 104, for example of the MEMS type and based on silicon.
  • the sensor 104 is embedded at one face of a plane support 106 based on a hard material, for example epoxy resin.
  • the sensor 104 is covered by a coating structure 108 comprising a first portion 110 in contact with the sensor 104 and the plane support 106, and a second portion 112 covering the first portion 110 of the encapsulation structure 108.
  • FIG. 2 which shows a detailed sectional view of the
  • the second portion 112 of the encapsulation structure 108 is composed of a protrusion 114 of substantially cylindrical shape, forming a point and having a disc-shaped section in the plane (X, Z) shown on FIG. Figure 2.
  • the projection 114 has an end 116 of rounded shape, for example semi-spherical.
  • the projection 114 and more particularly the end 116 of the projection 114, is the part which is in contact with the surface of the studied sample and which defines the surface of contact with the studied sample.
  • the second portion 112 of the encapsulation structure 108 also has a shoulder 118 on which the projection 114 is disposed.
  • This shoulder 118 is here conical, concave and asymptotically cylindrical, forming a junction between the projection 114 and the first part 110. of the encapsulation structure 108, and makes it possible to transfer the forces undergone by the projection 114 to the first part 110 of the encapsulation structure 108.
  • This shoulder 118 extends over the entire surface of a first face 120 of the first part 110 of the encapsulation structure 108, which allows on the one hand to optimize the transmission of stresses from the projection 114 to the first part 110 of the coating structure 108, and secondly to minimize possible problems of torsion or bending of the projection 114 may appear during a displacement of the device 100 on the surface of the sample studied.
  • the second portion 112 of the encapsulation structure 108 is the portion of the device 100 that is frictionally subjected to the surface of the sample being studied.
  • the material of the second part 112 is therefore chosen so that it has a sufficient hardness to minimize wear, but also soft enough to have a contact surface that is not reduced to a point and can thus cause sensor 104 friction force during the exploration of the surface of the sample studied.
  • the rounded end 116 of the projection 114 has a well-defined contact surface as a function of the contact pressure applied to the device 100.
  • the contact surface between the end 116 of the projection 114 and the surface of the sample studied remains constant, and this regardless of the size of the section of the projection 114.
  • the dimensions of the section of the projection 114, and therefore of the end 116, are for example chosen as a function of the size of the roughness of the surface of the sample inspected.
  • the cylindrical shape of the projection 114 whose shape ratio is for example equal to 1 (the diameter of the cylinder in the plane (X, Z) being in this case substantially equal to the height of the cylinder, that is to say the dimension along the Y axis), allows it to have sufficient mechanical strength so that it does not sag when brought into contact with the surface of the sample or when moving it on the surface of the sample.
  • the aspect ratio (width / height) of the first portion 110 is for example equal to about 5.
  • the size of the contact surface of the projection 114 generated during the crushing of the coating may be chosen sufficiently small to detect roughness larger than the size of this surface (for example of the order of 1 mm diameter).
  • the size of the projection 114 is also adapted to the roughnesses explored, such that it is well the end of the projection 114 which is in contact with the sample, and not another part (side or base of the projection, for example if roughness is greater than about 3 mm wide and deep greater than about 1 mm, and include for example steep edges).
  • the mesh 114 may be dimensioned such that the contact surface is of the order of 1 mm, and has a shoulder of rounded shape.
  • FIG. 3 shows in detail an example of a sensor 104 of the device 100.
  • This sensor 104 comprises a deformable membrane 124 provided at its center with a rod 126.
  • the rod 126 is disposed against or in a second face 122 of the first portion 110 of the encapsulation structure 108 and transmits the perceived contact forces to the rod 126.
  • the rod 126 can be "molded" into the first portion 110 of the encapsulation structure 108, that is, that is disposed in this first part 110 in order to optimize the transmission of forces from the coating structure 108 to the sensor 104.
  • the rod 126 Given the deformation that the coating structure 108 undergoes by the contact force applied to its surface, the rod 126 is also subjected to this force and deforms the membrane 124 due to the stresses and displacement induced in the center of the membrane 124 by the rod 126.
  • the deformation of the membrane 124 by the rod 126 is measured by transducing means 128, such as piezoresistive strain gages or capacitance-sensitive detectors, arranged on the membrane 124.
  • the strain gauges 128, eight in number form two Wheatstone bridges as in the example shown in Figure 4.
  • the membrane 124 seen from above, forms a disk in the plane (X, Z).
  • first strain gages 128 are disposed along a horizontal axis (parallel to the X axis) passing through the center of the disc formed by the membrane 124, and aligned in a first direction. These first four strain gages 128 are interconnected by interconnections and form a first Wheatstone bridge. Other interconnections also connect these first four strain gauges 128 to four electrical contacts forming the inputs and outputs of this first Wheatstone bridge.
  • Four second strain gages 128 are arranged along a vertical axis (parallel to the Z axis) passing through the center of the disk formed by the membrane 124, and aligned in a second direction perpendicular to the first direction.
  • strain gauges 128 are interconnected by interconnections and form a second Wheatstone bridge. Other interconnects also connect these four second strain gauges 128 to three other electrical contacts forming the inputs and outputs of this second Wheatstone bridge.
  • the strain gauges 128 are, for example, of rectangular parallelepiped shape and have their largest dimension parallel to the first or second direction.
  • the first portion 110 of the encapsulation structure 108 is substantially cylindrical in shape.
  • the second face 122 of the first portion 110 of the encapsulation structure 108 is in contact with the sensor 104 and has dimensions greater than the dimensions of the sensor 104, and in particular greater than the dimensions of the deformable membrane 124 of the sensor 104.
  • the first part 110 of the coating structure 108 thus covers the sensor 104 and a portion of the support 106 peripheral to the sensor 104.
  • the ratio between the section of the membrane 124 of the sensor 104 S c , in the plane (X, Z), and that of the first part 110 S b of the encapsulation structure 108, also in the plane (X, Z), makes it possible to define a proportionality factor between a force F Nc perceived by the sensor 104 parallel to the perpendicular Y axis at the plane of the diaphragm 124, and shown in FIG. 3, a force F Nb applied to the projection 114 in the same direction as the force F Nc , that is to say parallel to the axis Y, such that: O 1 ⁇ p is -j_ a pressure at the interface between the sensor 104 and the coating structure 108.
  • FI ⁇ C k * where ⁇ is the Tangential stress at the interface between the sensor 104 and the coating structure 108, and k is a multiplicative factor defined by the height of the rod used as lever arm and the hardness ratio between the first portion 110 and the second portion 112 of the encapsulation structure 108.
  • the material of the first part 110 of the coating structure 108 is chosen such that it has a hardness less than that of the material of the second portion 112 of the coating structure 108, in particular to dampen any shocks that the protrusion 114 could undergo, for example when the protrusion 114 is brought into contact with the sample studied, and thus not transmit these shocks to the sensor 104.
  • This lower hardness of the material of the first part 110 of the structure coating 108 with respect to the hardness of the material of the second portion 112 of the encapsulation structure 108 also makes it possible to amplify the lateral deformations originating from the second portion 112 of the encapsulation structure 108, and thus increases the perception of tangential forces transmitted to the rod 126 of the force sensor 104.
  • the first portion 110 and the second portion 112 of the coating structure 108 are for example based on elastomer, such as polyurethane, whose hardness is for example between about 10 and 100 shore A. Moreover, these materials will preferably be chosen such that the material of the first part 110 of the coating structure 108 has a hardness difference of between about 20 and 30 shore A with respect to the material of the second portion 112 of the coating structure 108.
  • An embodiment of the device 100 is now described for characterizing the surface of a mesh size of the order of 1 mm.
  • the diameter of the projection 114 is about 3 mm so that the protrusion 114 does not remain caught in the mesh of the fabric.
  • the material of the projection 114 that is to say the material of the second portion 112 of the encapsulation structure 108, is here based on polyurethane hardness equal to about 80 shore A, which reduces the abrasion the projection 114 when it is moved on this type of sample.
  • the first part 110 of the coating structure 108 is also based on polyurethane but of hardness equal to about
  • the materials of the first portion 110 and the second portion 112 of the coating structure 108 could be based on polydimethylsiloxane (PDMS), or more generally based on at least one suitable elastomer.
  • PDMS polydimethylsiloxane
  • the dimensions of the encapsulation structure 108, and in particular those of the first part 110, are chosen as a function of the forces to which the encapsulation structure 108 is intended to be subjected.
  • a maximum normal force F Nmax biassed force parallel to the Y axis
  • the section S b of the first part 110 corresponding to the surface of the faces 120 and 122 of the first part 110, is chosen such that: p NmnK ⁇ . T)
  • P max 10 bar
  • F Nmax 10 N
  • Rb> 1.8 mm is therefore chosen.
  • the radius Rb of the first disk-shaped portion 110 can be selected as :
  • the senor 104 is not a triaxial force sensor, but for example a biaxial force sensor making it possible to measure at least the tangential force undergone by the projection 114 during a displacement of it on a sample. Moreover, when the efforts to be measured are very small, it is possible to reduce the size of the structure coating, and thus obtain a coating structure 108 not completely covering the sensor 104 by the first portion 110 of the coating structure 108.
  • the elements of the encapsulation structure 108 may for example be made by molding.
  • the two liquid components (resin + hardener) used for obtaining the elastomer are first mixed. The mixture is then boiled under a vacuum bell to prevent the formation of bubbles in this mixture which would modify the mechanical properties of the elastomer.
  • the first part 110 and the second part 112 of the coating structure 108 may be made in the same mold.
  • the first part 112 is first made by injecting the exact quantity of material into the mold to form the second part 112, for example by means of a syringe.
  • the material of the first part 110 is then cast over the second part 112 still in the mold, and placed above the support 106 in which is embedded the sensor 104, thus closing the mold.
  • the mold is then removed after solidification of the coating structure 108.
  • the senor 104 is covered with an elastomer which is the material of the first part 110 of the encapsulation structure 108.
  • the surplus material that is to say the upper edge of the structure obtained, is then cut to form the first part 110 of the coating structure 108.
  • the remainder of the mold is then filled with the material of the second part 112 of the coating structure 108.
  • the mold is then removed after solidification of the coating structure 108.
  • This technique can in particular be implemented when it is desired to replace the second portion 112 of the structure coating 108, for example when it is worn to such a point that the projection 114 has completely disappeared.

Abstract

The invention relates to a device (100) for the touch-sensitive characterisation of a surface texture, comprising at least one three-axis pressure sensor (104) at least partially covered with a coating structure (108) including at least one first portion (110) placed against the sensor and at least one second portion (112) placed against the first portion so that the first portion is placed between the sensor and the second portion, wherein the second portion includes at least one protrusion provided on the side opposite the first portion and a shoulder provided against a first surface of the first portion of the coating structure located on the side opposite a second surface of the first portion placed against the sensor, the hardness of the material of the first portion being lower than that of the material of the second portion.

Description

DISPOSITIF DE CARACTERISATION TACTILE DE TEXTURE DE TOUCH TEXTURE CHARACTERIZATION DEVICE
SURFACEAREA
DESCRIPTIONDESCRIPTION
DOMAINE TECHNIQUETECHNICAL AREA
L'invention concerne un dispositif de caractérisation tactile de texture de surface permettant l'exploration et la caractérisation de texture d'une surface plane ou non. L'invention peut s'appliquer à tous les domaines liés à la fabrication de produits dont les caractéristiques tactiles sont importantes. L'invention peut s'appliquer par exemple aux domaines de l'industrie papetière, textile, automobile, alimentaire ou encore cosmétique pour : - estimer des sensations perçues par le consommateur pour un nouveau produit,The invention relates to a surface texture tactile characterization device for exploring and characterizing the texture of a flat surface or not. The invention can be applied to all fields related to the manufacture of products whose tactile characteristics are important. The invention can be applied, for example, to the fields of the paper, textile, automotive, food or cosmetic industry in order to: estimate the sensations perceived by the consumer for a new product,
- vérifier les propriétés tactiles d'un produit après sa fabrication (contrôle qualité) ,- check the tactile properties of a product after its manufacture (quality control),
- évaluer la variation des perceptions tactiles en fonction de différentes compositions ou modes de fabrication du produit.- Evaluate the variation of tactile perceptions according to different compositions or modes of manufacture of the product.
L'invention peut également s'appliquer au domaine de la robotique, pour doter un robot du sens du toucher, ou encore de la biomimétique, par exemple pour fabriquer des prothèses actives, ou encore réaliser des télé-opérations médicales pour rendre les sensations tactiles au chirurgien lors d'une opération à distance. ETAT DE LA TECHNIQUE ANTERIEUREThe invention can also be applied to the field of robotics, to provide a robot with a sense of touch, or even biomimetics, for example to manufacture active prostheses, or to perform medical tele-operations to render tactile sensations. to the surgeon during a remote operation. STATE OF THE PRIOR ART
Le document « A traction Stress SensorThe document "A traction Stress Sensor
Array for Use in High-Resolution Robotic TactilArray for Use in High-Resolution Robotic Tactil
Imaging » de B. J. Kane et al., Journal of Microelectromechanical Systems, vol. 9.4, 2000, décrit un dispositif de caractérisation tactile de texture de surface comportant un capteur d'effort enrobé d'une couche parallélépipédique d'élastomère de faible duretéImaging "by B. J. Kane et al., Journal of Microelectromechanical Systems, Vol. 9.4, 2000, describes a surface texture tactile characterization device comprising a force sensor coated with a parallelepiped layer of low-hardness elastomer
(40 shore A) . Cette couche d'élastomère permet à la fois de protéger mécaniquement le capteur tout en lui transmettant les reliefs perçus lors d'une exploration d'une surface.(40 shore A). This layer of elastomer allows both to mechanically protect the sensor while transmitting the reliefs perceived during an exploration of a surface.
Un tel dispositif a notamment pour inconvénient d'avoir une surface de contact, entre l'échantillon étudié et la couche d'enrobage du capteur, mal déterminée et très dépendante de la rugosité de l'échantillon. Ainsi, il est difficile de faire une analyse précise de la texture de la surface explorée. De plus, l'usure de cet enrobage pose des problèmes pour la reproductibilité des mesures au cours du temps et le changement de celui-ci, lorsqu'il est usé, n'est pas aisé.Such a device has the particular disadvantage of having a contact surface between the sample studied and the coating layer of the sensor, poorly determined and highly dependent on the roughness of the sample. Thus, it is difficult to make an accurate analysis of the texture of the explored surface. In addition, the wear of this coating poses problems for the reproducibility of measurements over time and the change thereof, when worn, is not easy.
Le document « The Rôle of Fingerprints in the Coding of Tactile Information Probed with a Biomimetic Sensor » de J. Scheibert et al., Science Report, 29 Janvier 2009, propose de réaliser, dans un dispositif de caractérisation tactile de texture de surface, un enrobage d'un capteur d'effort triaxial de forme semi-sphérique . Bien que la surface de contact entre le dispositif et un échantillon soit plus aisément déterminable que pour le dispositif précédemment décrit, lors d'une caractérisation de la texture d'une surface de cet échantillon, ce dispositif ne résout pas les problèmes liés à l'usure de la couche d'enrobage car, compte tenu du rayon de courbure important de cet enrobage, des changements importants de la surface de contact entre l'échantillon et l'enrobage apparaissent après plusieurs utilisations du dispositif .The document "The Role of Fingerprints in the Coding of Tactile Information Probed with a Biomimetic Sensor" by J. Scheibert et al., Science Report, January 29, 2009, proposes to perform, in a surface texture tactile characterization device, a coating of a semi-spherical triaxial force sensor. Although the contact surface between the device and a sample is more easily determinable than for the device previously described, during a characterization of the texture of a surface of this sample, this device does not solve the problems related to the wear of the coating layer because, given the large radius of curvature of this coating, significant changes in the contact area between the sample and the coating appear after several uses of the device.
EXPOSÉ DE L'INVENTIONSTATEMENT OF THE INVENTION
Un but de la présente invention est de proposer un dispositif de caractérisation tactile de texture de surface permettant de s'adapter à tout type de surface et de réaliser des mesures d'efforts de pression et de friction lors de l'exploration d'une surface tout en offrant une bonne reproductibilité des mesures dans le temps, et dont les mesures soient indépendantes de l'usure du capteur.An object of the present invention is to provide a surface texture tactile characterization device for adapting to any type of surface and for measuring pressure and friction forces during the exploration of a surface. while offering a good reproducibility of measurements over time, and whose measurements are independent of the wear of the sensor.
Pour cela, la présente invention propose un dispositif de caractérisation tactile de texture de surface comportant au moins un capteur d'effort triaxial recouvert au moins partiellement par une structure d'enrobage comprenant au moins une première partie disposée contre le capteur et au moins une seconde partie disposée contre la première partie telle que la première partie soit disposée entre le capteur et la seconde partie, la seconde partie comprenant au moins une saillie disposée d'un côté opposé à la première partie et un épaulement disposé contre une première face de la première partie de la structure d'enrobage se trouvant du côté opposé à une seconde face de la première partie disposée contre le capteur, la dureté du matériau de la première partie étant inférieure à celle du matériau de la seconde partie.For this, the present invention proposes a device for surface texture tactile characterization comprising at least one triaxial force sensor at least partially covered by a coating structure comprising at least a first portion disposed against the sensor and at least one second portion disposed against the first portion such that the first portion is disposed between the sensor and the second portion, the second portion including at least one projection disposed on a side opposite the first portion and a shoulder disposed against a first face of the first portion; part of the coating structure lying on the side opposite to a second face of the first portion disposed against the sensor, the hardness of the material of the first part being lower than that of the material of the second part.
Ce dispositif permet donc de réaliser une exploration et une caractérisation de tout type de surface. La structure d'enrobage en deux parties permet en outre de réaliser une transmission des efforts, depuis la surface de contact, entre la structure d'enrobage et la surface étudiée, vers le capteur qui peut être contrôlée et adaptée à la sensibilité du capteur en fonction de la nature et de la rugosité de la surface étudiée.This device makes it possible to carry out an exploration and a characterization of any type of surface. The two-part coating structure also makes it possible to transmit forces, from the contact surface, between the coating structure and the surface studied, to the sensor, which can be controlled and adapted to the sensitivity of the sensor. depending on the nature and roughness of the studied surface.
Une telle structure d'enrobage permet également de bien protéger le capteur tout en formant une interface optimum entre la surface étudiée et le capteur grâce à la saillie, qui est la partie en contact avec la surface étudiée, dont la forme et les dimensions sont parfaitement définies. Ainsi, lorsque la saillie s'use, étant donné que la surface de contact est déterminable en fonction de la pression appliquée sur le dispositif, cette surface de contact peut donc être constante quelque soit la taille de la section de la saillie. On obtient ainsi une très bonne reproductibilité des mesures réalisées. De plus, la différence de dureté des matériaux des deux parties de la structure d'enrobageSuch a coating structure also makes it possible to protect the sensor while forming an optimum interface between the studied surface and the sensor thanks to the protrusion, which is the part in contact with the studied surface, whose shape and dimensions are perfectly defined. Thus, when the projection wears, since the contact surface is determinable depending on the pressure applied to the device, this contact surface can be constant regardless of the size of the section of the projection. This gives a very good reproducibility of the measurements made. In addition, the difference in hardness of the materials of the two parts of the coating structure
(la partie en contact avec la surface étudiée étant la plus dure) permet de réaliser un bon transfert des efforts au capteur et de bien simuler la sensation de « toucher » de la surface étudiée par le dispositif. La dureté du matériau de la seconde partie, et notamment de la saillie, qui est supérieure à celle du matériau de la première partie, est choisie pour minimiser l'usure de la structure d'enrobage (notamment de la saillie) . Lorsque la section est constante sur toute la hauteur de la saillie, par exemple lorsque la saillie a une forme sensiblement cylindrique, cela permet de conserver une surface de contact constante quelque soit l'usure de la saillie. Enfin, étant donné que la première partie de la structure d'enrobage présente une dureté inférieure à celle de la seconde partie de la structure d'enrobage, cette première partie permet d'amortir les éventuels chocs que peut subir le dispositif, par exemple lors de la mise en contact du dispositif avec la surface étudiée.(The part in contact with the studied surface is the hardest) allows a good transfer of forces to the sensor and to simulate the feeling of "touch" of the surface studied by the device. The hardness of the material of the second part, and in particular of the projection, which is greater than that of the material of the first part, is chosen to minimize the wear of the coating structure (in particular of the projection). When the section is constant over the entire height of the projection, for example when the projection has a substantially cylindrical shape, it allows to maintain a constant contact surface regardless of the wear of the projection. Finally, since the first part of the coating structure has a hardness lower than that of the second part of the coating structure, this first part makes it possible to damp any impacts that the device may undergo, for example during contacting the device with the studied surface.
L'invention permet donc l'exploration de tout type de surface, de maximiser la transmission des efforts au capteur tout en le protégeant et de minimiser les effets de l'usure pour une meilleure reproductibilité des mesures.The invention therefore makes it possible to explore any type of surface, to maximize the transmission of forces to the sensor while protecting it and to minimize the effects of wear for better reproducibility of the measurements.
Du fait que le capteur d'effort soit triaxial, il est possible de détecter les forces ou efforts normaux et tangentiels que subit la saillie et qui sont transmis au capteur, et donc de détecter n'importe quelle force de contact subie par la saillie, quelle que soit son orientation dans l'espace.Since the force sensor is triaxial, it is possible to detect the normal and tangential forces or forces that the protrusion undergoes and which are transmitted to the sensor, and thus to detect any contact force experienced by the protrusion, whatever its orientation in space.
De plus, l'épaulement permet d'optimiser la transmission des efforts depuis la saillie vers le capteur, et notamment les efforts tangentiels. II est également décrit un dispositif de caractérisation tactile de texture de surface comportant au moins un capteur d'effort recouvert au moins partiellement par une structure d'enrobage comprenant au moins une première partie disposée contre le capteur et au moins une seconde partie disposée contre la première partie telle que la première partie soit disposée entre le capteur et la seconde partie, la seconde partie comprenant au moins une saillie disposée d'un côté opposé à la première partie, la dureté du matériau de la première partie étant inférieure à celle du matériau de la seconde partie.In addition, the shoulder makes it possible to optimize the transmission of the forces from the projection towards the sensor, and in particular the tangential forces. There is also described a surface texture tactile characterization device comprising at least one force sensor at least partially covered by a coating structure comprising at least a first portion disposed against the sensor and at least a second portion disposed against the first portion such that the first portion is disposed between the sensor and the second portion, the second portion including at least one projection disposed on a side opposite to the first portion, the hardness of the material of the first portion being less than that of the material of the second part.
La saillie de la seconde partie de la structure d'enrobage peut être de forme sensiblement cylindrique et/ou comporter une extrémité de forme sensiblement semi-sphérique et/ou avoir un rapport de forme égal à environ 1. L'extrémité de forme sensiblement semi-sphérique permet d'avoir une surface de contact encore mieux définie en fonction de la pression de contact du dispositif sur la surface étudiée. De plus, le rapport de forme de la saillie peut être choisi tel que la saillie ne fléchisse pas lors de son déplacement sur la surface à caractériser, permettant d'avoir une certaine linéarité entre les composantes des forces à la surface de l'enrobage et les mesures faites par le capteur.The protrusion of the second part of the coating structure may be of substantially cylindrical shape and / or comprise an end of substantially semi-spherical shape and / or have a shape ratio equal to about 1. The end of substantially semi-shape -spherical makes it possible to have an even better defined contact surface as a function of the contact pressure of the device on the studied surface. In addition, the aspect ratio of the projection may be chosen such that the projection does not sag as it moves over the surface to be characterized, allowing a certain linearity between the components of the forces on the surface of the coating and the measurements made by the sensor.
La seconde partie de la structure d'enrobage peut comporter un épaulement disposé contre une première face de la première partie de la structure d'enrobage se trouvant du côté opposé à une seconde face de la première partie disposée contre le capteur. L'épaulement peut recouvrir totalement ladite première face de la première partie de la structure d'enrobage, et/ou avoir une forme sensiblement conique tronquée comprenant d'un premier côté une section sensiblement similaire à celle de la saillie et d'un second côté, opposé au premier côté, une section sensiblement similaire à celle de la première face de la première partie de la structure d'enrobage. Lorsque l'épaulement recouvre totalement ladite première face de la première partie de la structure d'enrobage, on obtient une meilleure transmission des contraintes depuis la saillie vers la première partie de la structure d'enrobage, et donc vers le capteur. La première partie de la structure d'enrobage peut avoir une forme sensiblement cylindrique et/ou une section, dans un plan parallèle à une face de ladite première partie en contact avec la seconde partie, de dimensions supérieures à la dimension de la première partie selon un axe perpendiculaire à ladite section.The second portion of the encapsulation structure may include a shoulder disposed against a first face of the first portion of the encapsulant located on the opposite side to a second face of the first portion disposed against the sensor. The shoulder may completely cover said first face of the first portion of the encapsulation structure, and / or have a substantially truncated conical shape comprising on one side a section substantially similar to that of the projection and a second side opposed to the first side, a section substantially similar to that of the first face of the first part of the coating structure. When the shoulder completely covers said first face of the first part of the coating structure, a better transmission of the stresses is obtained from the projection towards the first part of the coating structure, and thus towards the sensor. The first part of the coating structure may have a substantially cylindrical shape and / or a section, in a plane parallel to one face of said first part in contact with the second part, of dimensions greater than the dimension of the first part according to an axis perpendicular to said section.
Lorsque la première partie de la structure d'enrobage a une forme sensiblement cylindrique, le rayon Rb de la section du cylindre peut être tel que : avec FNmax : force de pression maximale appliquée sur le dispositif lors d'une caractérisation de texture d'un surface ;When the first part of the coating structure has a substantially cylindrical shape, the radius R b of the cylinder section may be such that: with F Nmax : maximum pressure force applied to the device during a texture characterization of a surface;
Pmax : pression maximale supportée par le capteur. Le matériau de la première partie de la structure d'enrobage et/ou le matériau de la seconde partie de la structure d'enrobage peuvent être à base d' élastomère, par exemple du polyuréthane . De plus, en réalisant les deux parties de la structure d'enrobage à partir d'un même matériau, par exemple du polyuréthane, on assure une bonne cohésion de ces deux parties entre elles, ce qui permet d'éviter d'éventuels problèmes de séparation de ces deux parties lors d'une utilisation du dispositif.P max : maximum pressure supported by the sensor. The material of the first part of the coating structure and / or the material of the second part of the coating structure may be based on elastomer, for example polyurethane. In addition, by making the two parts of the coating structure from the same material, for example polyurethane, good cohesion of these two parts is ensured, which makes it possible to avoid possible problems of separation of these two parts during use of the device.
La dureté du matériau de la première partie de la structure d'enrobage et/ou la dureté du matériau de la seconde partie de la structure d'enrobage peuvent être comprises entre environ 10 et 100 shore A et/ou être supérieures ou égales à environ 10 shore A et/ou présenter une différence comprise entre environ 20 et 30 shore A.The hardness of the material of the first part of the coating structure and / or the hardness of the material of the second part of the coating structure may be between about 10 and 100 Shore A and / or be greater than or equal to about 10 shore A and / or have a difference between about 20 and 30 shore A.
Le capteur peut être disposé contre, ou encastré dans, un support à base d'un matériau dont la dureté peut être supérieure à celles des matériaux de la structure d'enrobage.The sensor may be arranged against or embedded in a support based on a material whose hardness may be greater than that of the materials of the coating structure.
La première partie de la structure d'enrobage peut recouvrir totalement le capteur et au moins une partie du support. Le capteur d'effort peut être un capteur d'effort triaxial.The first part of the coating structure can completely cover the sensor and at least a portion of the support. The force sensor may be a triaxial force sensor.
Le capteur d'effort peut comporter au moins une membrane déformable et une tige reliée mécaniquement à la membrane déformable. Dans ce cas, la tige du capteur peut être disposée au moins en partie dans la première partie de la structure d'enrobage, ce qui permet d'améliorer la transmission des efforts au capteur.The force sensor may comprise at least one deformable membrane and a rod mechanically connected to the deformable membrane. In this case, the sensor rod can be arranged at least partly in the first part of the coating structure, which improves the transmission of forces to the sensor.
Le dispositif peut comporter en outre un corps préhensible, le capteur et la structure d'enrobage pouvant être disposés à une extrémité dudit corps préhensible.The device may further comprise a grippable body, the sensor and the coating structure may be arranged at one end of said gripping body.
L' invention concerne en outre un procédé de réalisation d'un dispositif de caractérisation de texture de surface, comportant au moins un moulage d'une première partie d'une structure d'enrobage destinée à recouvrir au moins en partie un capteur d'effort triaxial, ladite première partie étant disposée contre le capteur, et un moulage d'au moins une seconde partie de la structure d'enrobage disposée contre la première partie telle que la première partie soit disposée entre le capteur et la seconde partie, la seconde partie comprenant au moins une saillie disposée d'un côté opposé à la première partie et un épaulement disposé contre une première face de la première partie de la structure d'enrobage se trouvant du côté opposé à une seconde face de la première partie disposée contre le capteur, la dureté du matériau de la première partie étant inférieure à celle du matériau de la seconde partie . II est également décrit un procédé de réalisation d'un dispositif de caractérisation de texture de surface, comportant au moins un moulage d'une première partie d'une structure d'enrobage destinée à recouvrir au moins en partie un capteur d'effort, ladite première partie étant disposée contre le capteur, et un moulage d'au moins une seconde partie de la structure d'enrobage disposée contre la première partie telle que la première partie soit disposée entre le capteur et la seconde partie, la seconde partie comprenant au moins une saillie disposée d'un côté opposé à la première partie, la dureté du matériau de la première partie étant inférieure à celle du matériau de la seconde partie.The invention furthermore relates to a method for producing a surface texture characterization device comprising at least one molding of a first part of a coating structure intended to cover at least partly a force sensor. triaxial, said first portion being disposed against the sensor, and a molding of at least a second portion of the coating structure disposed against the first portion such that the first portion is disposed between the sensor and the second portion, the second portion comprising at least one projection disposed on a side opposite to the first part and a shoulder disposed against a first face of the first part of the coating structure lying on the opposite side to a second face of the first part disposed against the sensor the hardness of the material of the first part being lower than that of the material of the second part. There is also described a method for producing a surface texture characterization device, comprising at least one molding of a first part of a coating structure intended to cover at least part of a force sensor, said first part being arranged against the sensor, and a molding of at least a second part of the coating structure disposed against the first part such that the first part is arranged between the sensor and the second part, the second part comprising at least one projection disposed on a side opposite to the first part, the hardness of the material of the first part being lower than that of the material of the second part.
Le moulage de la seconde partie de la structure d'enrobage peut être réalisé avant le moulage de la première partie de la structure d'enrobage, ces deux moulages pouvant être obtenus au moins par la mise en œuvre des étapes de :The molding of the second part of the coating structure can be carried out before the molding of the first part of the coating structure, these two moldings being obtainable at least by the implementation of the steps of:
- remplissage d'une partie d'un moule dont la forme correspond à la forme de la structure d'enrobage par le matériau de la seconde partie sous forme liquide,filling a part of a mold whose shape corresponds to the shape of the coating structure by the material of the second part in liquid form,
- solidification partielle de la seconde partie de la structure d'enrobage,partial solidification of the second part of the coating structure,
- remplissage du reste du moule par le matériau de la première partie sous forme liquide sur la seconde partie partiellement solidifiée,filling the remainder of the mold with the material of the first part in liquid form on the second partially solidified part,
- disposition de la première partie de la structure d'enrobage contre le capteur.- Provision of the first part of the coating structure against the sensor.
Dans une variante, le moulage de la première partie de la structure d'enrobage peut être réalisé avant le moulage de la seconde partie de la structure d'enrobage, ces deux moulages pouvant être obtenus au moins par la mise en œuvre des étapes de :In a variant, the molding of the first part of the coating structure can be carried out before the molding of the second part of the coating structure, these two moldings being obtainable at least by the implementation of the steps of:
- remplissage d'une partie ou de la totalité d'un moule disposé sur le capteur et dont la forme correspond à la forme de la structure d'enrobage, par le matériau de la première partie sous forme liquide,filling a part or the whole of a mold disposed on the sensor and whose shape corresponds to the shape of the coating structure, by the material of the first part in liquid form,
- solidification partielle du matériau précédemment versé dans le moule, - découpe du matériau partiellement solidifié, formant la première partie de la structure d' enrobage,partial solidification of the material previously poured into the mold; cutting of the partially solidified material forming the first part of the coating structure;
- remplissage du reste du moule par le matériau de la seconde partie sous forme liquide. Les matériaux versés dans le moule peuvent être solidifiés dans une étuve.filling the remainder of the mold with the material of the second part in liquid form. The materials poured into the mold can be solidified in an oven.
Les matériaux moulés peuvent être à base d'élastomère et débullés sous une cloche à vide préalablement à la réalisation des étapes de moulage.The molded materials may be based on elastomer and debulled under a vacuum bell prior to performing the molding steps.
BRÈVE DESCRIPTION DES DESSINSBRIEF DESCRIPTION OF THE DRAWINGS
La présente invention sera mieux comprise à la lecture de la description d'exemples de réalisation donnés à titre purement indicatif et nullement limitatif en faisant référence aux dessins annexés sur lesquels :The present invention will be better understood on reading the description of exemplary embodiments given purely by way of indication and in no way limiting, with reference to the appended drawings in which:
- la figure 1 représente un dispositif de caractérisation tactile de texture de surface, objet de la présente invention, selon un mode de réalisation particulier, - la figure 2 représente une structure d'enrobage d'un capteur d'un dispositif de caractérisation tactile de texture de surface, objet de la présente invention, selon le mode de réalisation particulier représenté sur la figure 1, - les figures 3 et 4 représentent un exemple de capteur triaxial d'un dispositif de caractérisation tactile de texture de surface, objet de la présente invention. Des parties identiques, similaires ou équivalentes des différentes figures décrites ci-après portent les mêmes références numériques de façon à faciliter le passage d'une figure à l'autre.FIG. 1 represents a surface texture tactile characterization device, object of the present invention, according to a particular embodiment; FIG. 2 represents a coating structure of a sensor of a tactile characterization device of FIG. surface texture, object of the present invention, according to the particular embodiment shown in FIG. FIGS. 3 and 4 show an example of a triaxial sensor of a surface texture tactile characterization device, object of the present invention. Identical, similar or equivalent parts of the different figures described below bear the same numerical references so as to facilitate the passage from one figure to another.
Les différentes parties représentées sur les figures ne le sont pas nécessairement selon une échelle uniforme, pour rendre les figures plus lisibles .The different parts shown in the figures are not necessarily in a uniform scale, to make the figures more readable.
Les différentes possibilités (variantes et modes de réalisation) doivent être comprises comme n'étant pas exclusives les unes des autres et peuvent se combiner entre elles.The different possibilities (variants and embodiments) must be understood as not being exclusive of each other and can be combined with one another.
EXPOSÉ DÉTAILLÉ DE MODES DE RÉALISATION PARTICULIERSDETAILED PRESENTATION OF PARTICULAR EMBODIMENTS
On se réfère tout d' abord à la figure 1 qui représente une vue en coupe d'un dispositif de caractérisation tactile de texture de surface 100 selon un mode de réalisation particulier.Referring first to Figure 1 which shows a sectional view of a surface texture tactile characterization device 100 according to a particular embodiment.
Le dispositif 100 est ici un doigt artificiel et comporte un corps préhensible 102.The device 100 is here an artificial finger and comprises a gripping body 102.
Le dispositif 100 comporte un capteur d'effort triaxial 104, par exemple de type MEMS et à base de silicium. Dans ce mode de réalisation, le capteur 104 est encastré au niveau d'une face d'un support plan 106 à base d'un matériau dur, par exemple de la résine d'époxyde. Le capteur 104 est recouvert par une structure d'enrobage 108 comportant une première partie 110 en contact avec le capteur 104 et le support plan 106, et une seconde partie 112 recouvrant la première partie 110 de la structure d'enrobage 108. On se réfère maintenant à la figure 2 qui représente une vue en coupe détaillée de la structure d'enrobage 108. La seconde partie 112 de la structure d'enrobage 108 est composée d'une saillie 114 de forme sensiblement cylindrique, formant une pointe et comportant une section en forme de disque dans le plan (X, Z) représenté sur la figure 2. La saillie 114 comporte une extrémité 116 de forme arrondie, par exemple semi-sphérique .The device 100 comprises a triaxial force sensor 104, for example of the MEMS type and based on silicon. In this embodiment, the sensor 104 is embedded at one face of a plane support 106 based on a hard material, for example epoxy resin. The sensor 104 is covered by a coating structure 108 comprising a first portion 110 in contact with the sensor 104 and the plane support 106, and a second portion 112 covering the first portion 110 of the encapsulation structure 108. Referring now to FIG. 2 which shows a detailed sectional view of the The second portion 112 of the encapsulation structure 108 is composed of a protrusion 114 of substantially cylindrical shape, forming a point and having a disc-shaped section in the plane (X, Z) shown on FIG. Figure 2. The projection 114 has an end 116 of rounded shape, for example semi-spherical.
La saillie 114, et plus particulièrement l'extrémité 116 de la saillie 114, est la partie qui est en contact avec la surface de l'échantillon étudié et qui définit la surface de contact avec l'échantillon étudié .The projection 114, and more particularly the end 116 of the projection 114, is the part which is in contact with the surface of the studied sample and which defines the surface of contact with the studied sample.
La seconde partie 112 de la structure d'enrobage 108 comporte également un épaulement 118 sur lequel est disposée la saillie 114. Cet épaulement 118 est ici de forme conique, concave et asymptotiquement cylindrique, formant une jonction entre la saillie 114 et la première partie 110 de la structure d'enrobage 108, et permet de transférer les efforts subis par la saillie 114 à la première partie 110 de la structure d'enrobage 108. Cet épaulement 118 s'étend sur toute la surface d'une première face 120 de la première partie 110 de la structure d'enrobage 108, ce qui permet d'une part d'optimiser la transmission des contraintes depuis la saillie 114 vers la première partie 110 de la structure d'enrobage 108, et d'autre part de minimiser d'éventuels problèmes de torsion ou de flexion de la saillie 114 pouvant apparaître lors d'un déplacement du dispositif 100 sur la surface de l'échantillon étudié. La seconde partie 112 de la structure d'enrobage 108 est la partie du dispositif 100 qui subit la friction avec la surface de l'échantillon étudié. Le matériau de la seconde partie 112 est donc choisi afin que celui-ci présente une dureté suffisante pour en minimiser l'usure, mais également assez molle pour présenter une surface de contact qui ne soit pas réduite à un point et pouvoir ainsi provoquer sur le capteur 104 des effort de friction lors de l'exploration de la surface de l'échantillon étudié. L'extrémité arrondie 116 de la saillie 114 présente une surface de contact bien définie en fonction de la pression de contact appliquée au dispositif 100. Ainsi, à partir d'une certaine pression, dont la valeur dépend de la dureté du matériau constituant la seconde partie 112 de la structure d'enrobage 108, la surface de contact entre l'extrémité 116 de la saillie 114 et la surface de l'échantillon étudié reste constante, et cela quelle que soit la taille de la section de la saillie 114. Les dimensions de la section de la saillie 114, et donc de l'extrémité 116, sont par exemple choisies en fonction de la taille des rugosités de la surface de l'échantillon inspecté. De plus, la forme cylindrique de la saillie 114, dont le rapport de forme est par exemple égal à 1 (le diamètre du cylindre, dans le plan (X, Z), étant dans ce cas sensiblement égal à la hauteur du cylindre, c'est-à-dire la dimension selon l'axe Y), permet à celle-ci de présenter une résistance mécanique suffisante pour qu'elle ne fléchisse pas lors de la mise en contact avec la surface de l'échantillon ou lors du déplacement de celle-ci sur la surface de l'échantillon. Enfin, étant donné que les dimensions de la section de la saillie 114 dans le plan (X, Z) sont sensiblement identiques sur toute la hauteur (dimension selon l'axe Y) de la saillie 114, il est donc possible de conserver une surface de contact constante même lorsque la saillie 114 s'use (l'usure se traduisant ici par une réduction de la hauteur de la saillie 114) .The second portion 112 of the encapsulation structure 108 also has a shoulder 118 on which the projection 114 is disposed. This shoulder 118 is here conical, concave and asymptotically cylindrical, forming a junction between the projection 114 and the first part 110. of the encapsulation structure 108, and makes it possible to transfer the forces undergone by the projection 114 to the first part 110 of the encapsulation structure 108. This shoulder 118 extends over the entire surface of a first face 120 of the first part 110 of the encapsulation structure 108, which allows on the one hand to optimize the transmission of stresses from the projection 114 to the first part 110 of the coating structure 108, and secondly to minimize possible problems of torsion or bending of the projection 114 may appear during a displacement of the device 100 on the surface of the sample studied. The second portion 112 of the encapsulation structure 108 is the portion of the device 100 that is frictionally subjected to the surface of the sample being studied. The material of the second part 112 is therefore chosen so that it has a sufficient hardness to minimize wear, but also soft enough to have a contact surface that is not reduced to a point and can thus cause sensor 104 friction force during the exploration of the surface of the sample studied. The rounded end 116 of the projection 114 has a well-defined contact surface as a function of the contact pressure applied to the device 100. Thus, from a certain pressure, the value of which depends on the hardness of the material constituting the second part 112 of the coating structure 108, the contact surface between the end 116 of the projection 114 and the surface of the sample studied remains constant, and this regardless of the size of the section of the projection 114. The The dimensions of the section of the projection 114, and therefore of the end 116, are for example chosen as a function of the size of the roughness of the surface of the sample inspected. In addition, the cylindrical shape of the projection 114, whose shape ratio is for example equal to 1 (the diameter of the cylinder in the plane (X, Z) being in this case substantially equal to the height of the cylinder, that is to say the dimension along the Y axis), allows it to have sufficient mechanical strength so that it does not sag when brought into contact with the surface of the sample or when moving it on the surface of the sample. Finally, since the dimensions of the section of the projection 114 in the plane (X, Z) are substantially identical over the entire height (dimension along the Y axis) of the projection 114, it is therefore possible to maintain a surface constant contact even when the projection 114 wears (the wear is reflected here by a reduction in the height of the projection 114).
De manière générale, pour chacune de la première partie 110 et de la seconde partie 112 de la structure d'enrobage 108, la largeur de la partieIn general, for each of the first portion 110 and the second portion 112 of the encapsulation structure 108, the width of the portion
(dimension dans le plan (X, Z), par exemple le diamètre) peut être de préférence supérieure à la hauteur(dimension in the plane (X, Z), for example the diameter) can be preferably greater than the height
(dimension selon l'axe Y) de celle-ci. Le rapport de forme (largeur / hauteur) de la première partie 110 est par exemple égal à environ 5.(dimension along the Y axis) thereof. The aspect ratio (width / height) of the first portion 110 is for example equal to about 5.
La taille de la surface de contact de la saillie 114 engendrée lors de l'écrasement de l'enrobage peut être choisie suffisamment petite pour détecter les rugosités de tailles supérieures à la taille de cette surface (par exemple de l'ordre de 1 mm de diamètre) . La taille de la saillie 114 est aussi adaptée aux rugosités explorées, telle que ce soit bien l'extrémité de la saillie 114 qui soit en contact avec l'échantillon, et non une autre partie (coté ou base de la saillie, par exemple si les rugosités sont de largeur supérieure à environ 3 mm et de profondeur supérieure à environ 1 mm, et comportent par exemple des bords abruptes) . Par exemple, pour des échantillons de type papier, tissu et autres matériaux de rugosité « moyenne » ou « fine » (diamètre inférieur à environ 3 mm) , la saille 114 peut être dimensionnée telle que la surface de contact soit de l'ordre de 1 mm, et comporte un épaulement de forme arrondie.The size of the contact surface of the projection 114 generated during the crushing of the coating may be chosen sufficiently small to detect roughness larger than the size of this surface (for example of the order of 1 mm diameter). The size of the projection 114 is also adapted to the roughnesses explored, such that it is well the end of the projection 114 which is in contact with the sample, and not another part (side or base of the projection, for example if roughness is greater than about 3 mm wide and deep greater than about 1 mm, and include for example steep edges). For example, for samples of the paper, fabric and other "medium" or "fine" roughness type (diameter less than about 3 mm), the mesh 114 may be dimensioned such that the contact surface is of the order of 1 mm, and has a shoulder of rounded shape.
La figure 3 représente de manière détaillée un exemple de capteur 104 du dispositif 100. Ce capteur 104 comporte une membrane déformable 124 munie en son centre d'une tige 126. La tige 126 est disposée contre, ou dans, une seconde face 122 de la première partie 110 de la structure d'enrobage 108 et transmet les forces de contact perçues à la tige 126. De préférence, la tige 126 peut être « moulée » dans la première partie 110 de la structure d'enrobage 108, c'est-à-dire disposée dans cette première partie 110 afin d'optimiser la transmission des efforts depuis la structure d'enrobage 108 vers le capteur 104. Compte tenu de la déformation que subit la structure d'enrobage 108 par la force de contact appliquée à sa surface, la tige 126 est également soumise à cette force et déforme la membrane 124 du fait des contraintes et du déplacement induits au centre de la membrane 124 par la tige 126. La déformation de la membrane 124 par la tige 126 est mesurée par des moyens de transduction 128, tels que des jauges de contraintes piézorésistives ou des détecteurs à variation de capacité, disposés sur la membrane 124. Dans ce mode de réalisation particulier, les jauges de contraintes 128, au nombre de huit, forment deux ponts de Wheatstone comme sur l'exemple représenté sur la figure 4. Sur cette figure, la membrane 124, vue de dessus, forme un disque dans le plan (X, Z) . Quatre premières jauges de contraintes 128 sont disposées le long d'un axe horizontal (parallèle à l'axe X) passant par le centre du disque formé par la membrane 124, et alignées selon une première direction. Ces quatre premières jauges de contraintes 128 sont reliées entre elles par des interconnexions et forment un premier pont de Wheatstone. D'autres interconnexions relient également ces quatre premières jauges de contraintes 128 à quatre contacts électriques formant les entrées et les sorties de ce premier pont de Wheatstone. Quatre secondes jauges de contraintes 128 sont disposées le long d'un axe vertical (parallèle à l'axe Z) passant par le centre du disque formé par la membrane 124, et alignées selon une seconde direction perpendiculaire à la première direction. Ces quatre secondes jauges de contraintes 128 sont reliées entre elles par des interconnexions et forment un second pont de Wheatstone. D'autres interconnexions relient également ces quatre secondes jauges de contraintes 128 à trois autres contacts électriques formant les entrées et les sorties de ce second pont de Wheatstone. Les jauges de contraintes 128 sont par exemple de forme parallélépipédique rectangle et comporte leur plus grande dimension parallèle à la première ou la seconde direction .FIG. 3 shows in detail an example of a sensor 104 of the device 100. This sensor 104 comprises a deformable membrane 124 provided at its center with a rod 126. The rod 126 is disposed against or in a second face 122 of the first portion 110 of the encapsulation structure 108 and transmits the perceived contact forces to the rod 126. Preferably, the rod 126 can be "molded" into the first portion 110 of the encapsulation structure 108, that is, that is disposed in this first part 110 in order to optimize the transmission of forces from the coating structure 108 to the sensor 104. Given the deformation that the coating structure 108 undergoes by the contact force applied to its surface, the rod 126 is also subjected to this force and deforms the membrane 124 due to the stresses and displacement induced in the center of the membrane 124 by the rod 126. The deformation of the membrane 124 by the rod 126 is measured by transducing means 128, such as piezoresistive strain gages or capacitance-sensitive detectors, arranged on the membrane 124. In this particular embodiment, the strain gauges 128, eight in number, form two Wheatstone bridges as in the example shown in Figure 4. In this figure, the membrane 124, seen from above, forms a disk in the plane (X, Z). Four first strain gages 128 are disposed along a horizontal axis (parallel to the X axis) passing through the center of the disc formed by the membrane 124, and aligned in a first direction. These first four strain gages 128 are interconnected by interconnections and form a first Wheatstone bridge. Other interconnections also connect these first four strain gauges 128 to four electrical contacts forming the inputs and outputs of this first Wheatstone bridge. Four second strain gages 128 are arranged along a vertical axis (parallel to the Z axis) passing through the center of the disk formed by the membrane 124, and aligned in a second direction perpendicular to the first direction. These four second strain gages 128 are interconnected by interconnections and form a second Wheatstone bridge. Other interconnects also connect these four second strain gauges 128 to three other electrical contacts forming the inputs and outputs of this second Wheatstone bridge. The strain gauges 128 are, for example, of rectangular parallelepiped shape and have their largest dimension parallel to the first or second direction.
Dans le mode de réalisation particulier décrit ici, la première partie 110 de la structure d'enrobage 108 est de forme sensiblement cylindrique. La seconde face 122 de la première partie 110 de la structure d'enrobage 108 est en contact avec le capteur 104 et a des dimensions supérieures aux dimensions du capteur 104, et notamment supérieures aux dimensions de la membrane déformable 124 du capteur 104. La première partie 110 de la structure d'enrobage 108 recouvre donc le capteur 104 et une partie du support 106 périphérique au capteur 104. Le rapport entre la section de la membrane 124 du capteur 104 Sc, dans le plan (X, Z), et celle de la première partie 110 Sb de la structure d'enrobage 108, également dans la plan (X, Z), permet de définir un facteur de proportionnalité entre une force FNc perçue par le capteur 104 parallèlement à l'axe Y perpendiculaire au plan de la membrane 124, et représentée sur la figure 3, d'une force FNb appliquée sur la saillie 114 selon la même direction que la force FNc , c'est-à-dire parallèlement à l'axe Y, tel que : O1^ p est -j_a pression à l'interface entre le capteur 104 et la structure d'enrobage 108.In the particular embodiment described herein, the first portion 110 of the encapsulation structure 108 is substantially cylindrical in shape. The second face 122 of the first portion 110 of the encapsulation structure 108 is in contact with the sensor 104 and has dimensions greater than the dimensions of the sensor 104, and in particular greater than the dimensions of the deformable membrane 124 of the sensor 104. The first part 110 of the coating structure 108 thus covers the sensor 104 and a portion of the support 106 peripheral to the sensor 104. The ratio between the section of the membrane 124 of the sensor 104 S c , in the plane (X, Z), and that of the first part 110 S b of the encapsulation structure 108, also in the plane (X, Z), makes it possible to define a proportionality factor between a force F Nc perceived by the sensor 104 parallel to the perpendicular Y axis at the plane of the diaphragm 124, and shown in FIG. 3, a force F Nb applied to the projection 114 in the same direction as the force F Nc , that is to say parallel to the axis Y, such that: O 1 ^ p is -j_ a pressure at the interface between the sensor 104 and the coating structure 108.
De même, on peut définir un rapport de proportionnalité entre une force tangentielle FTc perçue par le capteur 104 selon un axe du plan (X, Z) parallèle au plan de la membrane 124, et une force Fn appliquée sur la saillie 114 selon la même direction que la force FTc , c'est-à-dire parallèlement au plan (X, Z), tel que :Similarly, it is possible to define a ratio of proportionality between a tangential force F Tc perceived by the sensor 104 along an axis of the plane (X, Z) parallel to the plane of the membrane 124, and a force F n applied to the projection 114 according to the same direction as the force F Tc , that is to say parallel to the plane (X, Z), such that:
F IτC = k * où σ est la contrainte tangentielle à l'interface entre le capteur 104 et la structure d'enrobage 108, et k est un facteur multiplicatif défini par la hauteur de la tige utilisée comme bras de levier et le rapport de dureté entre la première partie 110 et la deuxième partie 112 de la structure d'enrobage 108.FI τ C = k * where σ is the Tangential stress at the interface between the sensor 104 and the coating structure 108, and k is a multiplicative factor defined by the height of the rod used as lever arm and the hardness ratio between the first portion 110 and the second portion 112 of the encapsulation structure 108.
Le matériau de la première partie 110 de la structure d'enrobage 108 est choisi tel que celui-ci ait une dureté inférieure à celle du matériau de la seconde partie 112 de la structure d'enrobage 108, afin notamment d'amortir les éventuels chocs que pourrait subir la saillie 114, par exemple lors de la mis en contact de la saillie 114 avec l'échantillon étudié, et ainsi ne pas transmettre ces chocs au capteur 104. Cette dureté inférieure du matériau de la première partie 110 de la structure d'enrobage 108 par rapport à la dureté du matériau de la seconde partie 112 de la structure d'enrobage 108 permet également d'amplifier les déformations latérales provenant de la seconde partie 112 de la structure d'enrobage 108, et augmente ainsi la perception des forces tangentielles transmises à la tige 126 du capteur d'effort 104. La première partie 110 et la seconde partie 112 de la structure d'enrobage 108 sont par exemple à base d' élastomère, tel que du polyuréthane, dont la dureté est par exemple comprise entre environ 10 et 100 shore A. De plus, on choisira de préférence ces matériaux tels que le matériau de la première partie 110 de la structure d'enrobage 108 présente une différence de dureté comprise entre environ 20 et 30 shore A par rapport au matériau de la seconde partie 112 de la structure d'enrobage 108. On décrit maintenant un exemple de réalisation du dispositif 100 pour caractériser la surface d'un tissu de taille de mailles de l'ordre 1 mm. Le diamètre de la saillie 114 est égal à environ 3 mm afin que la saillie 114 ne reste pas accrochée dans les mailles du tissu. Le matériau de la saillie 114, c'est-à-dire le matériau de la seconde partie 112 de la structure d'enrobage 108, est ici à base de polyuréthane de dureté égale à environ 80 shore A, ce qui réduit l'abrasion de la saillie 114 lorsque celle- ci est déplacée sur ce type d'échantillon. La première partie 110 de la structure d'enrobage 108 est également à base de polyuréthane mais de dureté égale à environThe material of the first part 110 of the coating structure 108 is chosen such that it has a hardness less than that of the material of the second portion 112 of the coating structure 108, in particular to dampen any shocks that the protrusion 114 could undergo, for example when the protrusion 114 is brought into contact with the sample studied, and thus not transmit these shocks to the sensor 104. This lower hardness of the material of the first part 110 of the structure coating 108 with respect to the hardness of the material of the second portion 112 of the encapsulation structure 108 also makes it possible to amplify the lateral deformations originating from the second portion 112 of the encapsulation structure 108, and thus increases the perception of tangential forces transmitted to the rod 126 of the force sensor 104. The first portion 110 and the second portion 112 of the coating structure 108 are for example based on elastomer, such as polyurethane, whose hardness is for example between about 10 and 100 shore A. Moreover, these materials will preferably be chosen such that the material of the first part 110 of the coating structure 108 has a hardness difference of between about 20 and 30 shore A with respect to the material of the second portion 112 of the coating structure 108. An embodiment of the device 100 is now described for characterizing the surface of a mesh size of the order of 1 mm. The diameter of the projection 114 is about 3 mm so that the protrusion 114 does not remain caught in the mesh of the fabric. The material of the projection 114, that is to say the material of the second portion 112 of the encapsulation structure 108, is here based on polyurethane hardness equal to about 80 shore A, which reduces the abrasion the projection 114 when it is moved on this type of sample. The first part 110 of the coating structure 108 is also based on polyurethane but of hardness equal to about
50 shore A, donc inférieure à celle du matériau de la seconde partie 112 de la structure d'enrobage 108. En choisissant des matériaux de même nature (polyuréthane) pour réaliser les deux parties 110 et 112 de la structure d'enrobage 108, on obtient une bonne cohésion entre ces éléments, permettant ainsi d'éviter une éventuelle séparation de ces deux parties 110, 112 lors du déplacement du dispositif 100 sur le tissu. Dans une variante, les matériaux de la première partie 110 et de la seconde partie 112 de la structure d'enrobage 108 pourraient être à base de polydiméthylsiloxane (PDMS) , ou plus généralement à base d'au moins un élastomère adapté .50 shore A, therefore less than that of the material of the second part 112 of the coating structure 108. By choosing materials of the same nature (polyurethane) to produce the two parts 110 and 112 of the coating structure 108, obtains a good cohesion between these elements, thus avoiding any possible separation of these two parts 110, 112 during the displacement of the device 100 on the fabric. Alternatively, the materials of the first portion 110 and the second portion 112 of the coating structure 108 could be based on polydimethylsiloxane (PDMS), or more generally based on at least one suitable elastomer.
Les dimensions de la structure d'enrobage 108, et notamment celles de la première partie 110, sont choisie en fonction des forces auxquelles la structure d'enrobage 108 est destinée à être soumise.The dimensions of the encapsulation structure 108, and in particular those of the first part 110, are chosen as a function of the forces to which the encapsulation structure 108 is intended to be subjected.
51 une force normale maximale FNmax (force orientée parallèlement à l'axe Y) est destinée à être appliquée sur la structure d'enrobage 108 (et donc sur la saillie 114) lors de l'exploration d'un échantillon, la section Sb de la première partie 110, correspondant à la surface des faces 120 et 122 de la première partie 110, est choisie telle que: p NmnK ^. T)51 a maximum normal force F Nmax (biased force parallel to the Y axis) is intended to be applied to the encapsulation structure 108 (and thus to the projection 114) during the exploration of a sample, the section S b of the first part 110, corresponding to the surface of the faces 120 and 122 of the first part 110, is chosen such that: p NmnK ^. T)
soit pour le rayon d'une section de la première partie 110 en forme de disque : for the radius of a section of the first part 110 in the form of a disk:
Le capteur d'effort triaxial 104 utilisé ici supporte une pression maximum Pmax = 10 bars = 10 N/m2. Ainsi, pour une force maximum FNmax = 10 N, on choisit donc Rb > 1,8 mm. De la même manière, si une force tangentielle maximale FTmax est destinée à être appliquée sur la structure d'enrobage 108 (et donc sur la saillie 114), on peut choisir le rayon Rb de la première partie 110 en forme de disque tel que: The triaxial force sensor 104 used here supports a maximum pressure P max = 10 bar = 10 N / m 2 . Thus, for a maximum force F Nmax = 10 N, Rb> 1.8 mm is therefore chosen. Similarly, if a maximum tangential force F Tmax is intended to be applied to the encapsulation structure 108 (and thus to the projection 114), the radius Rb of the first disk-shaped portion 110 can be selected as :
Dans une variante du dispositif 100, il est possible que le capteur 104 ne soit pas un capteur d'effort triaxial, mais par exemple un capteur d'effort biaxial permettant de mesurer au moins l'effort tangentiel subi par la saillie 114 lors d'un déplacement de celle-ci sur un échantillon. De plus, lorsque les efforts à mesurer sont très faibles, il est possible de réduire la taille de la structure d'enrobage, et obtenir ainsi une structure d'enrobage 108 ne recouvrant pas en totalité le capteur 104 par la première partie 110 de la structure d'enrobage 108.In a variant of the device 100, it is possible that the sensor 104 is not a triaxial force sensor, but for example a biaxial force sensor making it possible to measure at least the tangential force undergone by the projection 114 during a displacement of it on a sample. Moreover, when the efforts to be measured are very small, it is possible to reduce the size of the structure coating, and thus obtain a coating structure 108 not completely covering the sensor 104 by the first portion 110 of the coating structure 108.
Les éléments de la structure d'enrobage 108 (première partie 110 et seconde partie 112) peuvent par exemple être réalisés par moulage. Lorsque ces éléments sont à base d' élastomère, on mélange tout d'abord les deux composants liquides (résine + durcisseur) utilisés pour l'obtention de l' élastomère . On fait ensuite débuller le mélange sous une cloche à vide afin d'éviter la formation de bulles dans ce mélange qui modifieraient les propriétés mécaniques de 1' élastomère .The elements of the encapsulation structure 108 (first portion 110 and second portion 112) may for example be made by molding. When these elements are based on elastomer, the two liquid components (resin + hardener) used for obtaining the elastomer are first mixed. The mixture is then boiled under a vacuum bell to prevent the formation of bubbles in this mixture which would modify the mechanical properties of the elastomer.
La première partie 110 et la seconde partie 112 de la structure d'enrobage 108 peuvent être réalisées dans un même moule. Dans ce cas, on réalise tout d'abord la seconde partie 112 en injectant la quantité exacte de matière dans le moule pour former la seconde partie 112, par exemple au moyen d'une seringue. Lorsque celle-ci commence à réticuler, sans attendre la polymérisation complète, le matériau de la première partie 110 est alors coulé par-dessus la seconde partie 112 se trouvant encore dans le moule, et placé au-dessus du support 106 dans lequel est encastré le capteur 104, fermant ainsi le moule. Le moule est ensuite retiré après la solidification de la structure d'enrobage 108.The first part 110 and the second part 112 of the coating structure 108 may be made in the same mold. In this case, the first part 112 is first made by injecting the exact quantity of material into the mold to form the second part 112, for example by means of a syringe. When it begins to crosslink, without waiting for complete polymerization, the material of the first part 110 is then cast over the second part 112 still in the mold, and placed above the support 106 in which is embedded the sensor 104, thus closing the mold. The mold is then removed after solidification of the coating structure 108.
Dans une variante de réalisation, lors d'un premier moulage, on recouvre le capteur 104 d'un élastomère qui est le matériau de la première partie 110 de la structure d'enrobage 108. Une fois le premier matériau réticulé, on découpe alors le surplus de matériau, c'est-à-dire la tranche supérieure de la structure obtenue, afin de former la première partie 110 de la structure d'enrobage 108. On remplie alors le reste du moule par le matériau de la seconde partie 112 de la structure d'enrobage 108. Le moule est ensuite retiré après solidification de la structure d'enrobage 108. Cette technique peut notamment être mise en œuvre lorsque l'on souhaite remplacer la seconde partie 112 de la structure d'enrobage 108, par exemple lorsque celle-ci est usée à un point telle que la saillie 114 ait totalement disparue. In an alternative embodiment, during a first molding, the sensor 104 is covered with an elastomer which is the material of the first part 110 of the encapsulation structure 108. Once the first cross-linked material, the surplus material, that is to say the upper edge of the structure obtained, is then cut to form the first part 110 of the coating structure 108. The remainder of the mold is then filled with the material of the second part 112 of the coating structure 108. The mold is then removed after solidification of the coating structure 108. This technique can in particular be implemented when it is desired to replace the second portion 112 of the structure coating 108, for example when it is worn to such a point that the projection 114 has completely disappeared.

Claims

REVENDICATIONS
1. Dispositif (100) de caractérisation tactile de texture de surface comportant au moins un capteur d'effort triaxial (104) recouvert au moins partiellement par une structure d'enrobage (108) comprenant au moins une première partie (110) disposée contre le capteur (104) et au moins une seconde partieA device (100) for surface texture tactile characterization comprising at least one triaxial force sensor (104) at least partially covered by a coating structure (108) comprising at least a first portion (110) disposed against the sensor (104) and at least a second part
(112) disposée contre la première partie (110) telle que la première partie (110) soit disposée entre le capteur (104) et la seconde partie (112), la seconde partie (112) comprenant au moins une saillie (114) disposée d'un côté opposé à la première partie (110) et un épaulement (118) disposé contre une première face (120) de la première partie (110) de la structure d'enrobage (108) se trouvant du côté opposé à une seconde face (122) de la première partie (110) disposée contre le capteur (104), la dureté du matériau de la première partie (110) étant inférieure à celle du matériau de la seconde partie (112) .(112) disposed against the first portion (110) such that the first portion (110) is disposed between the sensor (104) and the second portion (112), the second portion (112) comprising at least one projection (114) disposed on a side opposite to the first portion (110) and a shoulder (118) disposed against a first face (120) of the first portion (110) of the encapsulating structure (108) on the opposite side to a second face (122) of the first portion (110) disposed against the sensor (104), the hardness of the material of the first portion (110) being less than that of the material of the second portion (112).
2. Dispositif (100) selon la revendication 1, dans lequel la saillie (114) de la seconde partie (112) de la structure d'enrobage (108) est de forme sensiblement cylindrique et/ou comporte une extrémité (116) de forme sensiblement semi-sphérique et/ou a un rapport de forme égal à environ 1.2. Device (100) according to claim 1, wherein the projection (114) of the second portion (112) of the coating structure (108) is of substantially cylindrical shape and / or has a shape end (116). substantially semispherical and / or has a shape ratio of about 1.
3. Dispositif (100) selon l'une des revendications précédentes, dans lequel l' épaulement3. Device (100) according to one of the preceding claims, wherein the shoulder
(118) recouvre totalement ladite première face (120) de la première partie (110) de la structure d'enrobage(118) completely covers said first face (120) of the first part (110) of the coating structure
(108) et/ou a une forme sensiblement conique tronquée comprenant d'un premier côté une section sensiblement similaire à celle de la saillie (114) et d'un second côté, opposé au premier côté, une section sensiblement similaire à celle de la première face (120) de la première partie (110) de la structure d'enrobage (108) .(108) and / or has a substantially truncated conical shape comprising at a first side a section substantially similar to that of the projection (114) and a second side, opposite to the first side, a section substantially similar to that of the first face (120) of the first portion (110) of the encapsulation structure (108).
4. Dispositif (100) selon l'une des revendications précédentes, dans lequel la première partie (110) de la structure d'enrobage (108) a une forme sensiblement cylindrique et/ou une section, dans un plan parallèle à une face (120) de ladite première partie (110) en contact avec la seconde partie (112), de dimensions supérieures à la dimension de la première partie (110) selon un axe perpendiculaire à ladite section .4. Device (100) according to one of the preceding claims, wherein the first portion (110) of the coating structure (108) has a substantially cylindrical shape and / or a section in a plane parallel to a face ( 120) of said first portion (110) in contact with the second portion (112), larger in size than the dimension of the first portion (110) along an axis perpendicular to said section.
5. Dispositif (100) selon la revendication 4, dans lequel, lorsque la première partie (110) de la structure d'enrobage (108) a une forme sensiblement cylindrique, le rayon Rb de la section du cylindre est tel que : avec FNmax : force de pression maximale appliquée sur le dispositif (100) lors d'une caractérisation de texture d'un surface ;5. Device (100) according to claim 4, wherein, when the first portion (110) of the encapsulation structure (108) has a substantially cylindrical shape, the radius R b of the cylinder section is such that: with F Nmax : maximum pressure force applied to the device (100) during a texture characterization of a surface;
Pmax : pression maximale supportée par le capteur (104) . P max : maximum pressure supported by the sensor (104).
6. Dispositif (100) selon l'une des revendications précédentes, dans lequel le matériau de la première partie (110) de la structure d'enrobage (108) et/ou le matériau de la seconde partie (112) de la structure d'enrobage (108) sont à base d' élastomère .6. Device (100) according to one of the preceding claims, wherein the material of the first portion (110) of the coating structure (108) and / or the material of the second portion (112) of the structure of coating (108) are based on elastomer.
7. Dispositif (100) selon l'une des revendications précédentes, dans lequel la dureté du matériau de la première partie (110) de la structure d'enrobage (108) et/ou la dureté du matériau de la seconde partie (112) de la structure d'enrobage (108) sont comprises entre environ 10 et 100 shore A et/ou présentent une différence comprise entre environ 20 et 30 shore A.7. Device (100) according to one of the preceding claims, wherein the hardness of the material of the first part (110) of the coating structure (108) and / or the hardness of the material of the second part (112) of the coating structure (108) are between about 10 and 100 shore A and / or have a difference of between about 20 and 30 shore A.
8. Dispositif (100) selon l'une des revendications précédentes, dans lequel le capteur (104) est disposé contre, ou encastré dans, un support (106) à base d'un matériau dont la dureté est supérieure à celles des matériaux de la structure d'enrobage (108) .8. Device (100) according to one of the preceding claims, wherein the sensor (104) is disposed against or embedded in a support (106) based on a material whose hardness is greater than those of the materials of the coating structure (108).
9. Dispositif (100) selon la revendication 8, dans lequel la première partie (110) de la structure d'enrobage (108) recouvre totalement le capteur (104) et au moins une partie du support (106) .9. Device (100) according to claim 8, wherein the first portion (110) of the coating structure (108) completely covers the sensor (104) and at least a portion of the support (106).
10. Dispositif (100) selon l'une des revendications précédentes, dans lequel le capteur d'effort (104) comporte au moins une membrane déformable (124) et une tige (126) reliée mécaniquement à la membrane déformable (124) .10. Device (100) according to one of the preceding claims, wherein the force sensor (104) comprises at least one membrane deformable element (124) and a rod (126) mechanically connected to the deformable membrane (124).
11. Dispositif (100) selon la revendication 10, dans lequel la tige (126) du capteur (104) est disposée au moins en partie dans la première partie (110) de la structure d'enrobage (108) .11. Device (100) according to claim 10, wherein the rod (126) of the sensor (104) is disposed at least in part in the first part (110) of the coating structure (108).
12. Dispositif (100) selon l'une des revendications précédentes, comportant en outre un corps (102) préhensible, le capteur (104) et la structure d'enrobage (108) étant disposés à une extrémité dudit corps (102) préhensible.12. Device (100) according to one of the preceding claims, further comprising a body (102) prehensile, the sensor (104) and the coating structure (108) being disposed at one end of said body (102) grippable.
13. Procédé de réalisation d'un dispositif13. Method of producing a device
(100) de caractérisation de texture de surface, comportant au moins un moulage d'une première partieSurface texture characterization (100) comprising at least one molding of a first part
(110) d'une structure d'enrobage (108) destinée à recouvrir au moins en partie un capteur d'effort triaxial (104), ladite première partie (110) étant disposée contre le capteur (104), et un moulage d'au moins une seconde partie (112) de la structure d'enrobage (108) disposée contre la première partie(110) of a coating structure (108) for at least partially covering a triaxial force sensor (104), said first portion (110) being disposed against the sensor (104), and a molding of at least a second portion (112) of the encapsulation structure (108) disposed against the first portion
(110) telle que la première partie (110) soit disposée entre le capteur (104) et la seconde partie (112), la seconde partie (112) comprenant au moins une saillie(110) such that the first portion (110) is disposed between the sensor (104) and the second portion (112), the second portion (112) comprising at least one projection
(114) disposée d'un côté opposé à la première partie(114) arranged on a side opposite to the first part
(110) et un épaulement (118) disposé contre une première face (120) de la première partie (110) de la structure d'enrobage (108) se trouvant du côté opposé à une seconde face (122) de la première partie (110) disposée contre le capteur (104), la dureté du matériau de la première partie (110) étant inférieure à celle du matériau de la seconde partie (112) .(110) and a shoulder (118) disposed against a first face (120) of the first portion (110) of the encasement structure (108) on the opposite side to a second face (122) of the first portion ( 110) disposed against the sensor (104), the hardness of the material of the first portion (110) being less than that of the material of the second portion (112).
14. Procédé selon la revendication 13, dans lequel le moulage de la seconde partie (112) de la structure d'enrobage (108) est réalisé avant le moulage de la première partie (110) de la structure d'enrobage (108), ces deux moulages étant obtenus au moins par la mise en œuvre des étapes de :The method of claim 13, wherein molding the second portion (112) of the coating structure (108) is performed prior to molding the first portion (110) of the coating structure (108), these two moldings being obtained at least by the implementation of the steps of:
- remplissage d'une partie d'un moule dont la forme correspond à la forme de la structure d'enrobage (108) par le matériau de la seconde partiefilling a part of a mold whose shape corresponds to the shape of the coating structure (108) by the material of the second part
(112) sous forme liquide, - solidification partielle de la seconde partie (112) de la structure d'enrobage (108),(112) in liquid form, - partial solidification of the second portion (112) of the coating structure (108),
- remplissage du reste du moule par le matériau de la première partie (110) sous forme liquide sur la seconde partie (112) partiellement solidifiée, - disposition de la première partie (110) de la structure d'enrobage (108) contre le capteur (104) .filling the remainder of the mold with the material of the first part (110) in liquid form on the second part (112) partially solidified, - provision of the first part (110) of the coating structure (108) against the sensor (104).
15. Procédé selon la revendication 13, dans lequel le moulage de la première partie (110) de la structure d'enrobage (108) est réalisé avant le moulage de la seconde partie (112) de la structure d'enrobageThe method of claim 13, wherein the molding of the first portion (110) of the coating structure (108) is performed prior to molding the second portion (112) of the coating structure.
(108), ces deux moulages étant obtenus au moins par la mise en œuvre des étapes de : - remplissage d'une partie ou de la totalité d'un moule disposé sur le capteur (104) et dont la forme correspond à la forme de la structure d'enrobage (108), par le matériau de la première partie (110) sous forme liquide,(108), these two moldings being obtained at least by the implementation of the steps of: filling a part or the whole of a mold disposed on the sensor (104) and whose shape corresponds to the shape of the coating structure (108), by the material of the first part (110) in liquid form,
- solidification partielle du matériau précédemment versé dans le moule,partial solidification of the material previously poured into the mold,
- découpe du matériau partiellement solidifié, formant la première partie (110) de la structure d'enrobage (108),- cutting the partially solidified material, forming the first part (110) of the coating structure (108),
- remplissage du reste du moule par le matériau de la seconde partie (112) sous forme liquide.filling the rest of the mold with the material of the second part (112) in liquid form.
16. Procédé selon l'une des revendications 14 ou 15, dans lequel les matériaux versés dans le moule sont solidifiés dans une étuve.16. Method according to one of claims 14 or 15, wherein the materials poured into the mold are solidified in an oven.
17. Procédé selon l'une des revendications 13 à 16, dans lequel les matériaux moulés sont à base d'élastomère et débullés sous une cloche à vide préalablement à la réalisation des étapes de moulage. 17. Method according to one of claims 13 to 16, wherein the molded materials are based on elastomer and debulled under a vacuum bell prior to performing the molding steps.
EP10708537A 2009-03-12 2010-03-12 Device for the touch-sensitive characterisation of a surface texture Withdrawn EP2406578A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0951546A FR2943129B1 (en) 2009-03-12 2009-03-12 TACTILE CHARACTERIZING DEVICE FOR SURFACE TEXTURE
PCT/EP2010/053178 WO2010103102A1 (en) 2009-03-12 2010-03-12 Device for the touch-sensitive characterisation of a surface texture

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EP2406578A1 true EP2406578A1 (en) 2012-01-18

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EP (1) EP2406578A1 (en)
JP (1) JP5443515B2 (en)
FR (1) FR2943129B1 (en)
WO (1) WO2010103102A1 (en)

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WO2010103102A1 (en) 2010-09-16
JP2012520451A (en) 2012-09-06
FR2943129A1 (en) 2010-09-17
JP5443515B2 (en) 2014-03-19
US20120118080A1 (en) 2012-05-17
US8833178B2 (en) 2014-09-16
FR2943129B1 (en) 2011-09-30

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