FR2858415A1 - Seat materials characteristics measuring device for e.g. car, has measuring head with sensor supplying signal representing characteristics of material, and heating module received in housing of head and removable from housing - Google Patents

Abstract

The device has a measuring head (12) including a body (14) delimiting an open housing and a sensor arranged in a lower measuring zone (13). The sensor supplies a signal representing the characteristics of a given material, when a user touches the material. An integrated heating module (50) in the form of a sub-assembly is received in the housing of the head and is removable from the housing.

Description

i

  The invention relates to a measuring device for the characterization of a given material, in particular the touch rendering of the material, and a characterization installation comprising such a measuring device.

  The invention more particularly relates to a measuring device for the characterization of a given material, of the type which comprises a measuring head consisting of a body delimiting an open housing and at least one sensor arranged in a measurement zone 10 determined providing a signal representative of the touch rendering of the material.

  In certain areas, particularly in the automobile industry, comfort plays an important role in the decision to purchase a product such as a car or commercial vehicle.

  It is therefore important to identify and quantify objectively and reproducibly the sensations that the user perceives, such as the rendering of touch, and which are related to comfort.

  The comfort integrates in particular the tactile perception which although complex decomposes into elementary sensations such as the thermal rendering or the mechanical rendering of a given material.

  The thermal rendering of a material is characterized in particular by the sensation of hot or cold during the contact between the body of the user and a given material at a given temperature.

  Similarly, the mechanical rendering is characterized by the sensation felt by the body of the user during the contact of the skin, for example that of the hands or the fingertips with a given material.

  In addition, the sensations of the mechanical rendering vary according to the conditions in which the contact between the user and the material is established, such as the intensity of the pressure exerted on the material or a dynamic contact during which the user encounters more or less resistance.

  Unlike some areas such as visual evaluation with spectrocolorimetry devices, no measuring device is able to quantify in a representative and reproducible way the human perception of the sensations related to the mechanical rendering, but also to the thermal rendering with a given material.

  Indeed, in the case of thermal rendering, there are different measurement devices that make it possible to evaluate the thermal behavior of various materials comparatively.

  These include the "Touchau" and the thermal module of the Kawabata machine whose results provided, however, can not be directly related to the thermal rendering of a material or the human perception of sensations related to touch.

  It is also known from a patent application of the applicant, filed on 30.08. 2002 as FR-0210749, a device for measuring a representative characteristic of the thermal rendering of a given material. For this purpose during its implementation, the measuring device is thermally conditioned by being placed inside an enclosure whose temperature is regulated by means of heating means.

  When the entire measuring device is preheated to a substantially homogenous stabilized temperature, for example of the order of 35 ° C. which corresponds to the temperature of the end of the human finger, it has left the enclosure and its end The lower part is then placed on a part of the given material to be characterized, which is for example at an ambient temperature of 20 C.

  Such a measuring device, however, does not give complete satisfaction. Indeed, it turns out to be impractical use because of the need to conduct thermal conditioning prior to measurement and does not allow to maintain similar operating conditions to proceed to a series of successive measurements without proceeding to new thermal conditioning operations.

  It is also known from another Applicant's patent application, filed on 31 October 2002 under No. FR-0213661, an apparatus for characterizing the mechanical touch rendering of a material.

  Thus, the thermal rendering or the mechanical rendering of a given material are currently still evaluated by experts 10 who quantify the sensation of hot or cold, of softness or roughness, during the contact between the end of their fingers and a given material.

  The materials are then classified according to the results obtained. This way of proceeding, while giving satisfactory results, requires highly qualified personnel and a number of important measures, so as to minimize possible misperceptions.

  The determination of the touch rendering of a material, whether thermal rendering or mechanical rendering, is therefore long and expensive.

  In order to solve these problems, the invention proposes a measuring device of the type described above, characterized in that it comprises an integrated heating module produced in the form of a subset that is capable of being received. at least partly in the housing of the measuring head.

  Advantageously, the device comprises gripping means so as to constitute an easily transportable and autonomous system which makes it possible in particular to carry out measurements in real implementation conditions, such as on board a motor vehicle prototype.

  According to other characteristics of the invention - the measuring head and the heating module constitute a homeothermic system forming an artificial finger, whose thermal characteristics are close to those of the skin of the end of a human finger; - The integrated heating module is removable from the housing of the measuring head; - The heating module comprises an outer wall which defines a blind cavity containing an electrolyte of high heat coefficient and in which are housed heating means; the heating module comprises a cap for closing the blind cavity which is made of insulating material; the outer wall of the module is made of a heat conducting material; the heating module comprises means for controlling and regulating the temperature which control the heating means; - the measuring device comprises at least one sensor forming a measuring element which is arranged at a lower end of the body and the housing is open at the other upper end of the body of the measuring head; the device comprises, in the measurement zone, at least one temperature sensor providing a signal representative of the thermal rendering of the material's touch; it comprises at least one force sensor providing a signal representative of the mechanical rendering of the material's touch; It comprises at least one pressure sensor providing a signal representative of the hardness of the material; it comprises measuring means, for a given force, of the contact surface between the material and the measuring zone of the head; - At least a portion of the measurement zone is covered with a membrane having mechanical and / or thermal characteristics similar to those of human skin.

  Other features and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended figures in which: FIG. 1 is a view in axial section of a measuring head a measuring device according to an exemplary embodiment of the invention; - Figure 2 is a schematic axial sectional view of a removable heating module may be received in the housing of the measuring head of the device according to Figure 1; - Figure 3 shows a schematic view in operation of the measuring device according to the invention.

  The invention proposes a measuring device 10 for the characterization of the touch rendering of a given material, also called "finger" because it approximates in its forms and in its structure a human finger.

  In the remainder of the description a non-limiting, upper, lower orientation will be used, in accordance with the top-down orientation of the measuring device 10 according to FIG.

  In the embodiment illustrated in FIGS. 1 to 3, the measuring device 10 comprises a measuring head 12 which is capable of characterizing the touch rendering of a material, that is to say the sensations perceived by a user. finger when it is brought into contact with a material to then be able to classify each material according to characteristics such as its thermal rendering or its mechanical rendering.

  FIG. 1 more particularly proposes a measuring head 12 of a device 10 for measuring the thermal rendering of a material.

  The measuring head 12 is arranged in contact with a given material 11. The contact between the measuring device 10 and the given material 11 defines a lower measurement zone 13.

  The measuring head 12 mainly comprises a body 14 which is made of a rigid material such as metal, and which is cylindrical in shape with a generally vertical axis of revolution A so as to be close to the shape of a human finger.

  The body 14 constitutes the framework of the measuring head 12, and in particular it makes it possible to support a measuring element 16 which is here a temperature sensor providing a signal representative of the thermal rendering of the material's feel.

  The body 14 is open axially upwards at its upper end and defines an inner housing 18 of axis A such that a hole is made from the upper face 20 of the body 14 on the almost all of the height of the body. latest.

  The thicknesses of the tubular side wall 22 and of the bottom bottom 24 of the body 14 are substantially equal, thus ensuring a substantially homogeneous thermal behavior, whatever the zone of the body 14.

  The dimensions of the body 14 are substantially the same as those of a human finger. The height H is for example equal to 60 mm while the diameter D1 may be equal to 30 mm.

  A flexible disk-shaped member 30 is placed in contact with the underside of the body 14. It imitates the elastic mechanical behavior of the end and the skin of a human finger when in contact with the body. the given material 11.

  The diameter D2 of the flexible element 30 is smaller than the diameter D1 of the body 14. Its thickness E is, in the example 25 proposed in FIG. 1, of the order of 5 mm. Preferably, the flexible member 30 is flexible rubber.

  The assembly constituted by the body 14 and the flexible element 30 is covered by the measuring element 16 which has a U-shaped section. The measuring element 16 consists of a first outer membrane 32 to the inside which are arranged successively a network of thermal sensors 34 and a second membrane 36 inner latex.

  Preferably, asperities are made on the outer surface of the first membrane 32 so as to reproduce the slight undulations of the skin such as fingerprints.

  The sensor array 34 proposed in FIG. I comprises four thermocouples 38 which make it possible to measure the temperature at the measurement zone 13 between the measuring device 10 and the given material 11. The four thermocouples 38 make it possible to measure the deviations possible temperature in the measuring zone in contact and thus reduce the measurement errors due to a poor homogeneity of the temperature at the measuring zone 13.

  However, it is possible to use a single thermocouple 38, if the latter makes it possible to overcome measurement errors by its arrangement or its design.

  The thermocouples 38 are connected to a connection connector 40 which is fixed on the cover 14.

  Other sensors such as a flow sensor can be used.

  Advantageously, the lower end of the measuring device 10 is curved so as to approximate the shape of the end of the human finger and comprises means for measuring, for a given force, the contact surface between the material 11. and the measuring zone 13.

  The operation of the device 10 for measuring the touch rendering, here of the thermal rendering, of a material 11 is as follows.

  The aim is to measure a characteristic which is representative of the thermal rendering of a given material 11. This then makes it possible to classify the given material 11 in a category which corresponds to the sensation perceived by a human finger when it is put in contact with each other. with this material.

  So that the finger perceives a thermal sensation, which is due to the heat exchange, it is necessary that the temperature of the given material 11 is at a temperature different from that of the finger.

  Thus, in a first step, the measuring device 10 is thermally conditioned by means of an integrated heating module 50 according to the invention, which is represented in FIG.

  The heating module 50 is in the form of a cylindrical subassembly which can be accommodated in the housing 18 of the measuring head 12.

  The heating module 50 comprises an outer wall 52 which delimits a blind cavity 54 containing an electrolyte 56 of high heating coefficient and in which heating means 58 are accommodated.

  The outer wall 52, which forms the body of the module 50, is electrically insulated and is made of a material having good heat conduction properties, such as a metallic material such as aluminum.

  Alternatively, the electrolyte 56 contained in the cavity 54 can be economically replaced by air.

  The heating means 58 consist of a heating resistor generally having a U-shape.

  The heating module 50 has in its upper part, at its open end, a cap 60 of insulating material which closes the cavity 54.

  The cap 60 has on its upper face a connector 62 for the electrical supply of the heating resistor 58.

  The heating means 58 are integral with the cap from the lower face of which they extend axially downwardly inside the cavity 54. The heating module 50 comprises means for controlling and regulating the temperature which control the heating means 58.

  The means for controlling the temperature are for example made using at least one thermocouple 64 which is integral with the wall 52.

  The regulation of the temperature of the module 50 is obtained by means of a control device 66 to which the temperature control means 64 and the supply of the heating means 58 are connected.

  The heating module 50 makes it possible to continuously regulate the temperature of the measurement head 12 accurately so that the temperature, especially in the measurement zone, is generally of the order of 35.degree. C., which corresponds to the temperature of the end of a human finger when the ambient temperature is about 20 OC.

  FIG. 3 shows the assembly of the measuring device 10 in the position of use, that is to say a measuring head 12 in the housing 18 from which the heating module 50 has been placed axially from top to low.

  Advantageously, there are provided fixing means (not shown) which intervene between the module 50 and the head 12 so as to guarantee in particular a good positioning of the module in the housing 18.

  The fastening means consist, for example, of clips 20 or similar means such as an intervening screwing, at the end of the introduction stroke of the module, between the outer wall 52 of the latter and the inner wall of the body 14 delimiting the housing. 18.

  After its thermal conditioning, the measuring device 10 and the heating module 50 constitute a homeothermic system 25 or an artificial finger whose particular thermal characteristics are close to those of the skin of the end of a human finger.

  It is therefore possible to perform series of measurements with the homeotherm finger thus obtained.

  To do this, the lower end of the measuring device is placed on a part of the given material 11 to be characterized in accordance with FIG. 3. In order for the contact between the device 10 and the given material 11 to be reproducible, it is necessary to apply sufficient force which is of the order of 2N.

  A data acquisition device 68 immediately triggers the measurement, here of the temperature supplied by the thermocouples 38 at the measurement zone 13. When the measurement is completed, it is possible to immediately carry out other measurements without it is necessary as before to proceed again to the thermal conditioning of the measuring device 10.

  For more details on the operation of such a measuring device for characterizing each material according to its thermal rendering of the touch, reference will be made to the applicant's patent application, filed on 30.08.2002 under the number FR-0210749.

  However, the measuring device 10 according to the invention is not limited to the characterization of the thermal rendering of the touch of a material 11 which is given here only by way of example.

  In a variant not shown, the measuring head 12 of the device 10 comprises at least one pressure sensor providing a signal representative of the hardness of the material and / or measuring means, for a given force, of the contact surface between the material 11 and the measurement zone 13 of the head 12.

  The measuring element 16 of the head 12 consists, for example, of a half-sphere simulating the flexibility of the end of a human finger, which is covered with a pressure layer produced by means of piezo-type sensors. electric.

  Advantageously, such a half sphere is made of a material identical to that of the membrane 32 so as to have mechanical and / or thermal characteristics similar to those of human skin.

  Thus, this type of measurement element makes it possible in particular to know the forces involved during a sensory evaluation of the flexible nature of the material 11 to be characterized.

  According to another variant not shown, the measuring head 12 of the device 10 comprises at least one force sensor 11 providing a signal representative of the mechanical rendering of the touch of the material.

  To do this, one or more dynamometric sensors can be used to obtain a signal representative of the dynamic contact between the skin and the surface of the material 11.

  With a measuring element comprising at least two force sensors each providing a signal representative of the tangential force and the force normal to the plane of the surface of the material exerted by the measuring head 12.

  It is thus possible to characterize the touch rendering either the sensation perceived in contact with the material 11 as its sliding or blocking nature. For this purpose, the ratio between the value of the tangential force and the value of the normal force which is representative of the coefficient of friction 15 occurring between the artificial skin of the measuring zone 13 and the material 11.

  The measuring head 12 of the device 10 may therefore comprise different types of sensors forming measurement elements depending on what it is desired to characterize for a given material 20.

  Advantageously, the heating module 50 which is removable being standard, it can be received in a complementary housing 18 that comprise different measuring heads 12 each comprising one or more measuring elements 16 of different type depending on the applications.

  For applications aimed at determining the mechanical rendering of the touch, it is desirable to use a fixed installation to make reliable measurements since it is then possible to control with greater precision the relative displacements between the measuring device 10 and the material 11.

  Thus, the measuring device 10 according to the invention can be integrated into an installation (not shown) for characterizing the touch rendering of a material.

  The device 10 is for example integral with a controlled arm which is mounted movable in the space along the three longitudinal, vertical and transverse directions so that the membrane 32 of the measuring element 16 comes into contact with the surface of the material 11 of a sample holder according to a determined path.

  Advantageously, the measuring device 10 can be transported so as to carry out characterization measurements of material on finished products such as seats or other components of a motor vehicle, without necessarily having to use samples of material.

Claims (13)

  Measuring device (10) for the characterization of a given material (11), of the type comprising a measuring head (12) consisting of a body (14) delimiting an open housing (18) 5 and at least one sensor (16, 38) arranged in a given measuring zone (13) providing a signal representative of the touch rendering of the material, characterized in that it comprises an integrated heating module (50) made in the form of a subassembly which is receivable at least partly in the housing (18) of the measuring head (12).   2. Measuring device (10) according to claim 1, characterized in that the measuring head (12) and the heating module (50) constitute a homeothermic system forming an artificial finger.   3. Measuring device (10) according to one of claims 1 or 2, characterized in that the integrated heating module (50) is removable from the housing (18) of the measuring head (12).   Measuring device (10) according to one of the preceding claims, characterized in that the heating module (50) has an outer wall (52) defining a blind cavity (54) containing an electrolyte (56). of high heat coefficient and in which are housed heating means (58).   5. Measuring device (10) according to claim 4, characterized in that the heating module (50) comprises a cap for closing the blind cavity (54) which is made of insulating material.   6. Measuring device (10) according to one of claims 4 or 5, characterized in that the outer wall (52) of the module (50) 30 is made of a heat conducting material.   7. Measuring device (10) according to one of claims 4 to 6, characterized in that the heating module (50) comprises control means (64) and control (66) of the temperature which control the means heating (58).   8. Measuring device (10) according to any one of the preceding claims, characterized in that it comprises at least one sensor (38) forming a measuring element (16) which is arranged at a lower end of the body (14). ) and that the housing (18) is open at the other upper end of the body (14) of the measuring head (12).   9. Measuring device (10) according to any one of the preceding claims, characterized in that it comprises, in the measurement zone (13), at least one temperature sensor (38) providing a signal representative of the rendering thermal touch of the material (11).   10. Measuring device (10) according to any one of the preceding claims, characterized in that it comprises at least one force sensor providing a signal representative of the mechanical rendering of the touch of the material (11).   11. Measuring device (10) according to any one of the preceding claims, characterized in that it comprises at least one pressure sensor providing a signal representative of the hardness of the material (11).   12. Measuring device (10) according to any one of the preceding claims, characterized in that it comprises means for measuring, for a given force, the contact surface between the material (11) and the measurement zone. (13) of the head (12).   Measuring device (10) according to any one of the preceding claims, characterized in that at least a part of the measuring zone (13) is covered with a membrane (32) having mechanical characteristics and / or thermals similar to those of human skin.