JP2005257412A - Tactile sensor and multipoint type tactile sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate a circuit connection work by simplifying arrangement of a lead wire for bridge circuit constitution provided on each strain gage. <P>SOLUTION: Each pair of two strain gages 4a and 4b, 4c and 4d, 5a and 5b, 5c and 5d is disposed above and below respectively on one surface of a second or a fifth strain generation parts 2a, 2b, 2c, 2d, and the surface where the strain gages are disposed on the second or fifth strain generation parts 2a, 2b, 2c, 2d and the surface where gage terminals are disposed on a first or a fourth foot parts 12a, 12b, 13a, 13b are on the same side respectively as the surface where diaphragm-shaped strain gages 8a, 8b, 8c, 8d are disposed on a first strain generation part 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a tactile sensor and a multi-point tactile sensor that detect a force (pressure) applied to a mounting surface, and in particular, a tactile sensor suitable for detecting a three-component force of an externally applied force with high accuracy. And a multipoint tactile sensor.

  As a tactile sensor that can be attached to a fingertip, for example, there is one used in a “flexible object gripping device” described in Japanese Patent Application Laid-Open No. 8-323678. This tactile sensor detects a contact area by installing a large number of minute ON / OFF switches. The size and flexibility of the object are recognized from the relationship between the detected contact area and the opening amount of the fingertip, and it is intended that optimal object grasping is performed. The tactile sensor basically detects a force in a direction (Z direction) perpendicular to the mounting surface.

  As such a tactile sensor, a sensor in which pressure-sensitive elements are arranged in a resin film and can be mounted on a curved surface has been proposed. However, stress resolution in the Z (vertical) direction is small, and X and Y directions (horizontal) are proposed. ) Stress in the direction cannot be detected. On the other hand, a tactile sensor having a small three-component force sensor structure has been proposed.

The tactile sensor having the three-component force sensor structure is configured to generate both tensile stress and compressive stress in the strain generating body regardless of any composite force applied from three external directions. The strain generating body includes a disk-shaped first strain generating portion, plate-shaped second to fifth strain generating portions connected to the first strain generating portion, and these second to fifth strain generating portions. It consists of a foot part connected to a different side from the disc-shaped first strain part with respect to the strain part.
JP-A-8-323678

  However, in the tactile sensor having the three-component force sensor structure, the strain gauges are arranged on both sides of the strain generating body so as to be connected to the four sides of the bridge circuit, and the bridge circuit is connected between the terminals for each strain gauge. It is necessary to connect with configuration lead wires, and further connect power supply wiring and signal output wiring. Therefore, a large number of wirings have entered, and an extremely fine and complicated circuit connection work has been required.

  The present invention provides a bridge circuit configuration provided for each strain gauge by disposing a strain gauge and a gauge terminal on the same surface side of the first, second to fifth strain generating portions and the first to fourth foot portions. It is an object of the present invention to provide a tactile sensor and a multipoint tactile sensor that can simplify the arrangement of the lead wires for the circuit, thereby facilitating the circuit connection work and ensuring the reliability of the circuit connection portion.

  In order to solve the above-mentioned problems, a tactile sensor according to the present invention is formed in a plate shape from a disc-shaped first strain generating portion and a position where the periphery of the first strain generating portion is divided into four at substantially equal angles. Second to fifth structures that are extended and serve as legs of the first strain-generating portion to support the first strain-generating portion and form 90 to 130 degrees with respect to the first strain-generating portion. The first to fourth leg portions extending from the second to fifth strain-generating portions to a side different from the first strain-generating portion, and the first to the first strain-generating portion. Diaphragm-shaped strain gauges disposed on the disk surface of the strain portion, strain gauges respectively disposed on the plate surfaces of the second to fifth strain-generating portions, and the first to fourth A tactile sensor having a gauge terminal disposed on a foot portion, wherein two strain gauges are disposed on one side of the second to fifth strain-generating portions. The surface on which the strain gauge is disposed on the second to fifth strain generating portions and the surface on which the gauge terminal is disposed on the first to fourth foot portions are formed as diaphragm-like strains on the first strain generating portion. It is characterized in that the surface on the same side with respect to the surface on which the gauge is disposed is used.

When this tactile sensor receives a force in a direction perpendicular to the mounting surface (Z), the four strain gauges formed in the first strain-generating portion decrease and increase in resistance value according to the force, respectively. Indicates.
The force in the Z direction can be detected from the change in output voltage based on the change in each resistance value of the bridge circuit having four sides of these strain gauges.

Further, when the tactile sensor receives a force in the horizontal (X) direction, a change corresponding to the strain occurs in two opposing strain-generating portions among the second to fifth strain-generating portions. One of the two opposing strain-generating portions is such that the upper strain gauge on the same plane of the strain-generating portion receives a compressive stress and decreases its resistance value, while the lower strain gauge receives a tensile stress and increases its resistance value. . On the other side of the opposing strain generating portion, the upper strain gauge on the same surface of the strain generating portion receives a tensile stress and increases its resistance value, while the lower strain gauge receives a compressive stress and decreases its resistance value.
The force in the X direction can be detected from the change in the output voltage based on the increase / decrease of each resistance value for each bridge circuit having these strain gauges as four sides. The force in the horizontal (Y) direction received by the second to fifth strain generating portions can be detected in the same manner.
In this case, almost no strain is generated in the first strain generating section, so that there is almost no change in the resistance value of the diaphragm-shaped strain gauge, and therefore, almost no bridge circuit output is generated.

  Since each of the strain generating portions is plate-like and easily bent, the strain can be detected with a small force. In addition, by providing a dedicated strain gauge for force detection in the X, Y, and Z directions, for example, mutual interference can be reduced and detection accuracy can be improved.

  Further, in the tactile sensor, an angle between the disc of the first strain generating portion supported by the second to fifth strain generating portions and the plate of the second to fifth strain generating portions is 90 degrees to 130 degrees. It is. This angle is designed such that the height of the tactile sensor is kept small and an area for installing the strain gauge is secured on the plate surfaces of the second to fifth strain generating portions. In terms of the simplicity of the structure, 90 degrees can be said to be the most common angle, but by making the angle slightly larger than this, it is easy to ensure the plate surface area without increasing the height.

  In addition, the antenna sensor according to the present invention includes a diaphragm-like strain gauge disposed on the disk surface of the first strain-generating portion, and two per one surface on the second to fifth strain-generating portions. The strain gauges having the individual pieces and the gauge terminals arranged on the first to fourth legs are integrally formed of the same resistor.

The strain generating body including the first strain generating section, the second to fifth strain generating sections that support the first strain generating section, and the first to fourth foot sections is obtained by pressing one phosphorus It is formed by punching a bronze plate into a cross shape. Accordingly, the strain gauge on each strain generating portion and the gauge terminal on the foot portion can be integrally formed (surface mounted) without being interrupted by the same resistor on the same side surface of the strain generating body.
This simplifies the process of forming strain gauges, gauge terminals, and wiring connecting them.

Moreover, the tactile sensor according to the present invention is characterized in that the entire strain generating body provided with a strain gauge is covered with a resin having a longitudinal elastic modulus of 0.2 to 4.0 MPa.
Resin having flexibility such as urethane resin prevents adhesion of moisture, dust, oil, etc. to the strain-generating body while having flexibility that does not inhibit strain detection by the strain-generating body.
Therefore, it is possible to perform highly reliable tactile pressure detection without increasing the mutual interference of outputs by the respective strain gauges that detect the nonlinearity of the output characteristics of the strain gauge and the forces in the Z direction and the X and Y directions. it can.

In the multipoint tactile sensor according to the present invention, a plurality of the tactile sensors are arranged on the circuit board, and are installed on the circuit board and gauge terminals arranged on the first to fourth legs. The wiring land is solder-connected, and the periphery of the connecting portion between the foot portion and the circuit board is fixed with an adhesive.
By mounting a plurality of tactile sensors on the circuit board, the number of tactile points on the mounting surface can be increased, so that it is possible to detect forces on objects of various shapes and sizes.

Also, by providing wiring that constitutes the bridge circuit and input / output wiring in advance on the circuit board, all wiring can be completed by soldering the gauge terminal of the tactile sensor onto the circuit board. Work can be greatly simplified.
Furthermore, by adhering to the circuit board with an adhesive, it is possible to prevent the tactile sensor from being detached from the mounting portion even if a large external force is inadvertently applied.

  The multipoint tactile sensor according to the present invention includes a plurality of tactile sensors arranged on a circuit board, gauge terminals disposed on the first to fourth legs, and wiring installed on the circuit board. The land is bonded with a conductive resin, and the periphery of the connecting portion between the foot and the circuit board is fixed with an adhesive.

  As described above, by using the conductive resin for joining the gauge terminal and the wiring land, the thermal energy applied to the sensor at the time of wiring joining becomes smaller than that of solder joining. Therefore, the heat damage of the resin material used for the gauge part can be prevented.

  According to the present invention, by providing the strain gauge only on one side of the strain generating body, the three-component force sensor can be configured with a simple wiring structure without degrading the performance. In addition, the single-sided arrangement of the strain gauge allows easy wiring connection between the strain gauge and the wiring board by surface mounting. This surface mounting improves the durability and reliability of the wiring connection part.

  In the tactile sensor of the present invention, two strain gauges are arranged on one side of the second to fifth strain generating portions, and the strain gauges of the second to fifth strain generating portions are the first strain generating portions. Are disposed on the same surface as the surface on which the diaphragm-shaped strain gauge is disposed.

  The boundary between the second to fifth strain generating portions and the first strain generating portion is connected at an angle of 90 degrees to 130 degrees with a curvature of 1 to 3 times the plate thickness. The boundary portion between the first strain portion and the first to fourth foot portions has an angle of 90 to 130 degrees and a curvature of 1 to 3 times the plate thickness, and is opposite to the first strain portion. Connected to.

  When a force is applied to the strain generating portion structure, the plate-like second to fifth strain generating portions bend into an S shape regardless of the direction of the force, and on the surface of one side of the second to fifth strain generating portions. Both tensile stress and compressive stress are generated. Therefore, if a strain gauge is provided at each of the tensile stress generation position and the compression stress generation position, the force applied to the strain generating body can be detected.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Fig.1 (a) is sectional drawing which shows the typical structure of the tactile sensor which concerns on embodiment of this invention. FIG. 1B is a bottom view of the tactile sensor shown in FIG. FIG. 2 is a schematic diagram of a strain gauge attached to the strain body, and FIG. 3 is a perspective view showing the strain body.

  As shown in FIG. 1, this tactile sensor has a disc-shaped strain generating portion 1 supported by plate-shaped strain generating portions 2a, 2b, 3a, 3b extending from a position where the periphery thereof is divided into almost four parts. It has become a shape. The plate-shaped strain generating portions 2a, 2b, 3a, 3b are legs of the disk-shaped strain generating portion 1, and feet for fixing to the mounting surface on the side opposite to the strain generating portion 1 side, respectively. The parts 12a, 12b, 13a, 13b are connected.

Diaphragm strain gauges 8a, 8b, 8c and 8d are attached to the lower surface of the disc-shaped strain generating portion 1, and are attached to one side (inner surface) of the plate-shaped strain generating portions 2a, 2b, 3a and 3b. Are provided with two uniaxial strain gauges 4a, 4b, 4c, 4d, 5a,.
The strain gauges 4a, 4b, 4c, 4d, 5a,... On the plate-like strain generating portions 2a, 2b, 3a, 3b are each in the direction from the periphery of the strain generating portion 1 to the foot portions 12a, 12b, 13a, 13b. In order to detect strain against deformation such as bending in the plate, the gauge shaft direction is parallel to that direction.

In this embodiment, the angle formed by the disk-shaped strain generating portion 1 and the plate-shaped strain generating portions 2a, 2b, 3a, 3b, which are the legs, is 90 to 130 degrees, which is 1 to 3 times the plate thickness. It is connected with the curvature of.
Thereby, the area of the plate-like strain generating portions 2a, 2b, 3a, 3b can be ensured without increasing the height as the tactile sensor. The short axis strain gauges 4a, 4b, 4c, 4d, 5a, 5b, 5c, 5d and the diaphragm-like strain gauges 8a, 8b, 8c, 8d, and all of these lead wires are collectively formed by the same resistor. Is formed.

  FIG. 2 schematically shows the configuration of the diaphragm-like strain gauges 8a, 8b, 8c, and 8d attached to the lower surface of the disc-shaped strain generating portion 1, and corresponds to the components shown in FIG. Are denoted by the same reference numerals.

  As shown in FIG. 2, the strain gauges 8a, 8b, 8c, and 8d are provided on a circular sheet (not shown) as a whole. Each of the strain gauges 8a, 8b, 8c, 8d, each of the strain gauges 4a, 4b, 4c, 4d, and each of the strain gauges 5a, 5b, 5c, 5d are connected to form a bridge as shown in FIG. Has been. Input voltages are applied from the input terminals I1 and I2 to supply voltages to all three bridge circuits. The output of each bridge is obtained from output terminals O1, O2, O3, and O4.

  The strain gauges 8a and 8b on the peripheral side and the strain gauges 8c and 8d on the center side in the strain generating portion 1 detect opposite strains (ie, compressive strain and tensile strain) due to deformation of the strain generating portion 1. .

  FIG. 5 is a diagram for explaining the principle by which the tactile sensor shown in FIGS. 1 and 2 detects a force in the Z direction. In FIG. 5, components corresponding to the components already described are given the same reference numerals.

Now, when a force Fz in the Z direction is applied to the tactile sensor strain generating body, the strain gauges 8c and 8d on the disc center side increase in resistance according to the tensile stress. On the other hand, the resistance of the peripheral strains 8a and 8b decreases according to the compressive stress.
Therefore, when a force Fz in the Z direction is applied to the strain generating portion 1, a voltage is generated between the connection pads of the output terminals O1 and O2. By detecting this voltage, the force in the Z direction can be detected (measured). The output voltage due to this force is proportional to Fz within the elastic limit of the first strain generating portion 1.
An output voltage is generated between the connection pads of the output terminals O1 and O2 of the bridge circuit including the strain gauges 8a, 8b, 8c, and 8d.

On the other hand, when a force Fx in the X direction is applied to the tactile sensor strain generating body, the resistance of the upper strain gauge 4a of the second strain generating portion 2a decreases according to the compressive stress, and the lower strain gauge 4b responds to the tensile stress. Resistance increases. The resistance of the upper strain gauge 4c of the third strain generating portion 2b increases according to the tensile stress, and the resistance of the lower strain gauge 4d decreases according to the compressive stress.
Therefore, when the force Fx in the X direction is applied to the tactile sensor strain generating body, an output voltage is generated between the terminals O3 and O4.
By detecting this voltage, the force Fx in the X direction can be detected. The output voltage due to this force is well proportional to Fx within the elastic limit of the first strain generating portion 1. The same applies to the case where the force Fy in the Y direction is applied.

  Next, mutual interference will be described. Now, when a force Fz in the Z direction is applied to the strain generating body, strain is also generated in the second and third strain generating portions 2a and 2b provided with the strain gauges 4a, 4b, 4c and 4d. As shown in FIG. 5, the upper strain gauges 4a and 4c are subjected to compression, and the lower strain gauges 4b and 4d are subjected to tensile stress. Here, the strain gauges 4a, 4b, 4c, and 4d constitute a bridge shown in FIG.

  Therefore, the resistances of the strain gauges 4a and 4c are lowered, and the resistances of 4b and 4d are increased, and the equilibrium condition of the bridge is maintained. In this sense, interference from Fz detection to Fx detection (or Fy detection) is greatly reduced. This is a great advantage of the present invention.

  On the other hand, FIG. 6 is a diagram for explaining changes in the strain gauges 8a, 8b, 8c, and 8d for detecting the Z-direction force generated when the X-direction force Fx is applied. As shown in FIG. 6, almost no strain is generated in the first strain generating portion 1 provided with the strain gauges 8a, 8b, 8c, and 8d. Accordingly, since the resistance change hardly occurs in the strain gauges 8a, 8b, 8c, and 8d, the bridge is kept in balance. That is, there is almost no interference from Fx detection to Fz detection (or Fy detection to Fz detection).

As described above, in this embodiment, the diaphragm-shaped strain gauges 8a, 8b, 8c, and 8d are formed on the lower surface of the first strain generating portion 1, and the second to fifth strain generating portions 2a, 2b, Two uniaxial strain gauges are formed on the inner side surfaces of 3a and 3b. These strain gauges constitute a bridge circuit for detecting force in the X direction, a bridge circuit for detecting force in the Y direction, and a bridge circuit for detecting force in the Z direction.
Thereby, mutual interference of stresses in different directions can be reduced, and a three-component force (X direction, Y direction, Z direction) can be accurately detected from a small force.

Examples will be described below.
As shown in FIG. 7, a phosphor bronze plate for springs with a plate pressure of 0, 1 mm is punched into a cross shape with a press and bent while leaving the central plane portion, so that a strain generating body as shown in FIG. 3 is obtained. Had made. The height of the strain body was 1.0 mm. The strain gauge was formed by bonding a 2.5 μm thick Ni—Cr resistance foil onto a 12.5 μm thick polyimide film and forming the strain gauge pattern shown in FIG. 2 by photolithography.

The nominal resistance value of each strain gauge is 120Ω. This strain gauge pattern was punched with a press, adhered to a strain generating body with an adhesive, and lead wires were drawn out to constitute a bridge circuit. The foot bottom surface of the tactile sensor thus made was fixed to the metal plate for evaluation, and evaluation was performed by applying a force of Fx = 500 g in the X direction. Evaluation items are output voltage, detection nonlinearity, and interference.
As a result, the bridge input voltage was 5 V, the output voltage was 1.3 mV to 1.5 mV, the non-linearity was within ± 4%, and the interference between Fx detection and Fy detection was within 15%.

Next, a tactile sensor according to still another embodiment of the present invention will be described with reference to FIG. The tactile sensor according to this embodiment is a multipoint tactile sensor in which a plurality of tactile sensors S shown in FIGS. 1 and 2 are arranged on a circuit board P, and the distribution of three component forces on the mounting surface can be detected. It is.
For example, the circuit board P is mounted on a fingertip or palm, and the three component forces applied to these surfaces are integrated for each component force to obtain a total of three component forces. In the case of FIG. 8, the tactile sensor S includes five tactile sensors S, but more strain sensors can be mounted with this as a minimum unit.

  Under each touch sensor S, a strain gauge is connected to each other to form a bridge circuit, and a wiring board for supplying power and extracting output voltage is accompanied.

Further, the entire multipoint tactile sensor of FIG. 8 may be molded with a low elasticity resin. As shown in FIG. 8, on the circuit board P, a plurality of tactile sensors S,. As the molding resin, a urethane resin having a longitudinal elastic modulus after curing of 0.5 MPa is used and cast so as to have a thickness of 1.5 mm.
As for the characteristics after molding, the output voltage was reduced by about 15% compared to the characteristics before molding, but the nonlinearity was within ± 5% and the mutual interference was within 20%. There was little.

  Thus, in the present invention, by providing the strain gauge only on one side of the strain generating body, the three component force sensor can be configured with a simple wiring structure without degrading the performance. Moreover, the wiring connection between the strain gauge and the wiring board can be realized by surface mounting by arranging the strain gauge on one side. For this reason, wiring becomes easy and the durability and reliability of the wiring connection portion can be improved.

(A) is sectional drawing which shows the typical structure of the tactile sensor which concerns on embodiment of this invention, (b) is a bottom view of the tactile sensor shown to (a). The schematic diagram of the strain gauge attached to a strain body. Sectional drawing which shows the typical structure of the tactile sensor which concerns on embodiment of this invention. The circuit diagram which shows the bridge circuit which consists of a strain gauge shown in FIG. Explanatory drawing which shows the deformation | transformation state by the force of the Z direction of the strain body shown in FIG. Explanatory drawing which shows the deformation | transformation state by the force of the X direction of the strain body shown in FIG. The top view which shows the shape before the bending of another strain body in this invention. The perspective view which shows the multipoint type touch sensor by other embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... 1st strain part, 2a ... 2nd strain part, 2b ... 3rd strain part, 3a ... 4th strain part, 3b ... 5th strain part, 4a, 4b, 4c , 4d, 5a ... strain gauge, 8a, 8b, 8c, 8d ... strain gauge, 12a, 12b, 13a, 13b ... foot

Claims (5)

A disk-shaped first strain generating portion;
The peripheral edge of the first strain generation portion is extended in a plate shape from a position that is divided into four at substantially equal angles, and serves as a leg of the first strain generation portion to support the first strain generation portion, Second to fifth strain generating portions having a structure of 90 to 130 degrees with respect to the first strain generating portion;
First to fourth legs extending from the second to fifth strain-generating portions to a different side from the first strain-generating portion;
A diaphragm-like strain gauge disposed on the disk surface of the first strain-generating portion;
Strain gauges respectively disposed on the plate surfaces of the second to fifth strain generating portions;
A tactile sensor comprising gauge terminals disposed on the first to fourth feet,
Two strain gauges are disposed on one side of the second to fifth strain generating portions, a surface on which strain gauges are disposed on the second to fifth strain generating portions, and first to fourth. The tactile sensor is characterized in that the surface on which the gauge terminal is disposed on the foot is a surface on the same side as the surface on which the diaphragm-shaped strain gauge is disposed on the first strain-generating portion.   Diaphragm-shaped strain gauges disposed on the disk surface of the first strain generating portion, two strain gauges disposed on each side of the second to fifth strain generating portions, and the first The tactile sensor according to claim 1, wherein the gauge terminals disposed on the first to fourth legs are collectively formed of the same resistor.   The tactile sensor according to claim 1 or 2, wherein the entire strain generating body provided with the strain gauge is covered with a resin having a longitudinal elastic modulus of 0.2 to 4.0 MPa.   A plurality of tactile sensors according to claim 1 are arranged on a circuit board, and gauge terminals arranged on the first to fourth legs are connected to wiring lands installed on the circuit board by soldering. A multi-point tactile sensor characterized in that the periphery of the connection portion between the circuit portion and the circuit board is fixed with an adhesive.   A plurality of tactile sensors according to claim 1 are arranged on a circuit board, and gauge terminals arranged on the first to fourth feet and wiring lands installed on the circuit board are joined with a conductive resin. A multi-point tactile sensor characterized in that the periphery of the connecting portion between the foot and the circuit board is fixed with an adhesive.

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