JP2017102012A - Force sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a force sensor capable of enhancing responsibility of detection and detecting six external forces.SOLUTION: A force sensor comprises: a supporting body; a first substrate supported by the supporting body; an elastic body in which one end is supported by the supporting body and the other end is movable; a second substrate which is supported by the elastic body and faces the first substrate; a first sensor to an eighth sensor which are installed on the first substrate; and a first protrusion to a forth protrusion which are installed on the second substrate protruding to the first substrate. The first sensor faces the first protrusion in the Z axis direction, the second sensor faces the second protrusion, the third sensor faces the third protrusion, and the forth sensor faces the forth protrusion. The fifth sensor faces the first protrusion in the Y axis direction, and the seventh sensor faces the third protrusion. The sixth sensor faces the second protrusion in the X axis direction, and the eighth sensor faces the forth protrusion.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a force sensor that can detect an external force.

  There is known a force sensor that detects a displacement of a structure caused by an external force by a sensor and detects an external force applied to the structure by calculating a detection result of the sensor. In particular, Patent Document 1 discloses a force sensor that detects a displacement of a structure caused by an external force with an optical sensor.

JP2015-129740A

  The force sensor disclosed in Patent Document 1 detects four external forces: a moment around the X axis (Mx), a moment around the Y axis (My), a moment around the Z axis (Mz), and a force in the Z axis direction (Fz). And the response of detecting these external forces can be improved. By the way, depending on the use of the force sensor, a force sensor capable of detecting six forces obtained by adding the force in the X-axis direction (Fx) and the force in the Y-axis direction (Fy) to the above four forces is required.

  The present invention has been made in view of the above problems, and an object thereof is to provide a force sensor that can improve detection responsiveness and can detect six external forces.

  To achieve the above object, a force sensor according to the present invention includes a support, a first substrate supported by the support, and an elastic body having one end supported by the support and the other end movable. A second substrate that is supported by the elastic body and faces the first substrate, and a first sensor, a second sensor, a third sensor, a fourth sensor, and a fifth sensor provided on the first substrate. A sixth sensor, a seventh sensor, and an eighth sensor; a first protrusion, a second protrusion, a third protrusion, and a fourth protrusion that are provided on the second substrate and project toward the first substrate; The first sensor faces the first protrusion, the second sensor faces the second protrusion in the Z-axis direction orthogonal to the first substrate, and the third A sensor is facing the third protrusion, the fourth sensor is facing the fourth protrusion, In the Y-axis direction orthogonal to the Z-axis direction, the fifth sensor faces the first protrusion, the seventh sensor faces the third protrusion, and the Z-axis direction and the In the X-axis direction orthogonal to the Y-axis direction, the sixth sensor faces the second protrusion, and the eighth sensor faces the fourth protrusion.

  Thereby, the force sensor is based on changes in the sensor outputs of the first sensor, the second sensor, the third sensor, the fourth sensor, the fifth sensor, the sixth sensor, the seventh sensor, and the eighth sensor. Two external forces can be detected. Further, each of the six external forces is obtained by adding or subtracting a change amount of each sensor output. For this reason, the arithmetic processing for obtaining the six external forces is easy. Therefore, the force sensor can improve the detection response and can detect six external forces.

  As a desirable mode of the present invention, the first sensor, the second sensor, the third sensor, and the fourth sensor are equally spaced in the circumferential direction centered on the elastic body when viewed from the Z-axis direction. It is preferable to arrange | position.

  Thus, when a moment around the X axis or a moment around the Y axis is applied, two sensor outputs of the first sensor, the second sensor, the third sensor, and the fourth sensor change, The remaining two sensor outputs do not change. For this reason, the force sensor can detect a moment around the X axis based on changes in the two sensor outputs, and can detect a moment around the Y axis based on changes in the remaining two sensor outputs. Therefore, the calculation for obtaining the moment about the X axis and the moment about the Y axis is easy.

  Moreover, as a desirable aspect of the present invention, it is preferable that the elastic body includes a spiral slit centering on an axis along the Z-axis direction.

  As a result, the elastic body is likely to be displaced in the X-axis direction, the Y-axis direction, and the Z-axis direction, and inclined around the X-axis, the Y-axis, and the Z-axis. For this reason, the change amount of each sensor output of the 1st sensor, the 2nd sensor, the 3rd sensor, the 4th sensor, the 5th sensor, the 6th sensor, the 7th sensor, and the 8th sensor becomes large. Therefore, the detection accuracy of the force sensor is improved.

  ADVANTAGE OF THE INVENTION According to this invention, the responsiveness of a detection can be improved and the force sensor which can detect six external forces can be provided.

FIG. 1 is a perspective view showing a force sensor according to the present embodiment. FIG. 2 is an exploded view of the force sensor according to the present embodiment. FIG. 3 is a perspective view showing the second substrate according to the present embodiment. FIG. 4 is a plan view showing the first substrate according to the present embodiment. FIG. 5 is a view taken in the direction of arrow A in FIG. FIG. 6 is a schematic plan view showing the sensor and the protrusion according to the present embodiment. FIG. 7 is a view taken in the direction of arrow B in FIG. FIG. 8 shows a view in the direction of arrow C in FIG. FIG. 9 is a schematic diagram illustrating the displacement of the protrusion in a state where a force in the X-axis direction is applied to the upper plate according to the present embodiment. FIG. 10 is a schematic diagram showing the displacement of the protrusion in a state where a force in the Y-axis direction is applied to the upper plate according to the present embodiment. FIG. 11 is a schematic diagram showing the displacement of the protrusion in a state where a force in the Z-axis direction is applied to the upper plate according to the present embodiment. FIG. 12 is a schematic diagram showing the displacement of the protrusion in a state where a moment around the X axis is applied to the upper plate according to the present embodiment. FIG. 13 is a schematic diagram showing the displacement of the protrusion in a state in which a moment about the Y axis is applied to the upper plate according to the present embodiment. FIG. 14 is a schematic diagram showing the displacement of the protrusion in a state where a moment around the Z axis is applied to the upper plate according to the present embodiment. FIG. 15 is a block diagram illustrating an arithmetic processing unit according to the present embodiment. FIG. 16 is a configuration diagram illustrating an arithmetic processing unit according to the present embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

(Embodiment)
FIG. 1 is a perspective view showing a force sensor according to the present embodiment. The force sensor 1 is a device that can detect an applied external force. The force sensor 1 is attached to a hand at the tip of an arm of an industrial robot, for example, and detects a force acting on the hand. The force detected by the force sensor 1 is used to control a motor or the like that drives an industrial robot. Specifically, the force sensor 1 detects the magnitude and direction of the applied external force and sends a control signal corresponding to the magnitude and direction of the applied external force to a control unit that controls the motor or the like. Can do. As shown in FIG. 1, the force sensor 1 includes a support body 2, an elastic body 4, a first substrate 3, a second substrate 5, and a top plate 6.

  FIG. 2 is an exploded view of the force sensor according to the present embodiment. The support 2 is a disk-shaped member and is formed of a metal such as aluminum. The support 2 is fixed to a hand at the tip of an industrial robot arm. In addition, a hole is provided in the central portion of the support 2. In the following description, an orthogonal coordinate system including a Z axis orthogonal to the support 2 and an X axis orthogonal to the Z axis, a Z axis, and a Y axis orthogonal to the X axis is used.

  As shown in FIG. 2, the elastic body 4 is a disk-shaped member, for example, and is formed of a metal such as aluminum. The elastic body 4 is fixed to the support body 2. More specifically, one end face of the elastic body 4 is fixed to the support body 2. A hole 40 is provided at the center of the elastic body 4 so as to overlap the hole of the support 2 in the Z-axis direction. The elastic body 4 includes a spiral slit 41 centered on the Z axis. In other words, the shape of the elastic body 4 is a coil spring shape. When an external force acts on the elastic body 4, no displacement occurs on one end face of the elastic body 4 fixed to the support 2 and displacement occurs on the other end face. For example, if a force in the X-axis direction acts on the elastic body 4, the other end face moves in the X-axis direction. If a force in the Y-axis direction acts on the elastic body 4, the other end face moves in the Y-axis direction. If a force in the Z-axis direction acts on the elastic body 4, the other end face moves in the Z-axis direction. Further, if a moment around the X axis acts on the elastic body 4, the other end face is inclined around the X axis. If a moment about the Y axis acts on the elastic body 4, the other end face is inclined about the Y axis. If a moment about the Z-axis acts on the elastic body 4, the other end face is inclined about the Z-axis.

  As shown in FIG. 2, the first substrate 3 is, for example, a disk-shaped member, and is a printed board formed of resin. The first substrate 3 is fixed to the support 2. A hole 30 is provided in the central portion of the first substrate 3, and the elastic body 4 passes through the hole 30. Since the first substrate 3 is fixed to the support 2, the first substrate 3 is not displaced when an external force acts on the elastic body 4.

  As shown in FIGS. 2 and 3, the second substrate 5 is a disk-shaped member, for example, and is formed of a metal such as aluminum. The second substrate 5 is fixed to the elastic body 4. More specifically, the second substrate 5 is elastic in a state where the end of the elastic body 4 opposite to the end fixed to the support body 2 is fitted in the recess 59 provided in the second substrate 5. It is fixed to the body 4. The second substrate 5 faces the first substrate 3 in the Z-axis direction. A hole 50 is provided at the center of the second substrate 5 so as to overlap the hole 40 of the elastic body 4 in the Z-axis direction. As shown in FIG. 3, the second substrate 5 includes a first protrusion 51, a second protrusion 52, a third protrusion 53, a fourth protrusion 54, and a convex portion 55. The first protrusion 51, the second protrusion 52, the third protrusion 53, and the fourth protrusion 54 are members that protrude from the second substrate 5 toward the first substrate 3, for example, in the circumferential direction when viewed from the Z-axis direction. It is arranged at equal intervals. For example, the first protrusion 51, the second protrusion 52, the third protrusion 53, and the fourth protrusion 54 have the same shape and are substantially rectangular parallelepiped. The convex portion 55 is a member that protrudes from the second substrate 5 to the opposite side of the first substrate 3 and has, for example, an annular shape when viewed from the Z-axis direction. In the following description, a direction from the first substrate 3 toward the second substrate 5 in the Z-axis direction is defined as a + Z direction, and a direction opposite to the + Z direction is defined as a −Z direction.

  As shown in FIG. 2, the top plate 6 is a disk-shaped member, for example, and is formed of a metal such as aluminum. The top plate 6 is fixed to the second substrate 5. More specifically, the top plate 6 is fixed to the second substrate 5 in a state where the convex portion 55 is fitted in the concave portion provided on the top plate 6. A hole 60 that overlaps the hole 50 of the second substrate 5 in the Z-axis direction is provided at the center of the top plate 6. For example, the outer diameter of the top plate 6 is larger than the outer diameter of the second substrate 5 and is substantially equal to the outer diameter of the support 2. When an external force acts on the top plate 6, the top plate 6 and the second substrate 5 move together with the deformation of the elastic body 4.

  FIG. 4 is a plan view showing the first substrate according to the present embodiment. FIG. 5 is a view taken in the direction of arrow A in FIG. FIG. 6 is a schematic plan view showing the sensor and the protrusion according to the present embodiment. FIG. 7 is a view taken in the direction of arrow B in FIG. FIG. 8 shows a view in the direction of arrow C in FIG. As shown in FIGS. 4 and 5, the first substrate 3 includes a first sensor 31, a second sensor 32, a third sensor 33, a fourth sensor 34, a fifth sensor 35, a sixth sensor 36, and a seventh sensor 37. And an eighth sensor 38 is provided. The first sensor 31, the second sensor 32, the third sensor 33, the fourth sensor 34, the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38 are, for example, photo reflectors, and are light emitting units. A light emitting diode and a phototransistor as a light receiving portion. The reflected light of the light emitted from the light emitting unit enters the light receiving unit, and the sensor output (voltage) output from the light receiving unit changes according to the intensity of the reflected light incident on the light receiving unit. The electronic components of the first sensor 31, the second sensor 32, the third sensor 33, the fourth sensor 34, the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38 are the first substrate 3. Is mounted on the surface. Thereby, the force sensor 1 is reduced in size.

  As shown in FIG. 4, the first sensor 31, the second sensor 32, the third sensor 33, and the fourth sensor 34 are, for example, arranged at equal intervals in the circumferential direction centered on the elastic body 4 when viewed from the Z-axis direction. ing. The third sensor 33 is arranged symmetrically with respect to the first sensor 31 with a straight line L1 passing through the center of the elastic body 4 and extending along the Y-axis direction as viewed from the Z-axis direction. The fourth sensor 34 is arranged symmetrically with respect to the second sensor 32 with a straight line L2 passing through the center of the elastic body 4 and extending along the X-axis direction as viewed from the Z-axis direction.

  As shown in FIGS. 6 to 8, the first sensor 31 faces the first protrusion 51 in the Z-axis direction, the second sensor 32 faces the second protrusion 52 in the Z-axis direction, and the third sensor 33 becomes Z The fourth sensor 34 faces the fourth protrusion 54 in the Z-axis direction, and faces the third protrusion 53 in the axial direction. The light emitting units of the first sensor 31, the second sensor 32, the third sensor 33, and the fourth sensor 34 emit light in the + Z direction. The light emitted from the light emitting unit of the first sensor 31 is reflected by the first protrusion 51 and enters the light receiving unit of the first sensor 31. The light emitted from the light emitting unit of the second sensor 32 is reflected by the second protrusion 52 and enters the light receiving unit of the second sensor 32. The light emitted by the light emitting unit of the third sensor 33 is reflected by the third protrusion 53 and enters the light receiving unit of the third sensor 33. The light emitted from the light emitting unit of the fourth sensor 34 is reflected by the fourth protrusion 54 and enters the light receiving unit of the fourth sensor 34. When no external force is applied to the top plate 6 (when the elastic body 4 is not deformed), the distance from the first sensor 31 to the first protrusion 51, the distance from the second sensor 32 to the second protrusion 52, the first The distance from the third sensor 33 to the third protrusion 53 and the distance from the fourth sensor 34 to the fourth protrusion 54 are distances H1 as shown in FIGS. 7 and 8, and are equal to each other.

  In the following description, a direction from the third sensor 33 toward the first sensor 31 in the X-axis direction is defined as a + X direction, and a direction opposite to the + X direction is defined as a −X direction. A direction from the second sensor 32 toward the fourth sensor 34 in the Y-axis direction is defined as a + Y direction, and a direction opposite to the + Y direction is defined as a -Y direction.

  As shown in FIG. 6, the fifth sensor 35 is disposed on the + Y direction side of the first sensor 31. The sixth sensor 36 is disposed on the + X direction side of the second sensor 32. The seventh sensor 37 is disposed on the + Y direction side of the third sensor 33. The eighth sensor 38 is disposed on the + X direction side of the fourth sensor 34. As shown in FIG. 4, the seventh sensor 37 is arranged symmetrically with respect to the fifth sensor 35 with the straight line L1 as the axis of symmetry when viewed from the Z-axis direction. The eighth sensor 38 is arranged symmetrically with respect to the sixth sensor 36 with the straight line L2 as the axis of symmetry when viewed from the Z-axis direction.

  As shown in FIG. 6, the fifth sensor 35 faces the first protrusion 51 in the Y-axis direction. The light emitting unit of the fifth sensor 35 emits light in the −Y direction. The light emitted from the light emitting unit of the fifth sensor 35 is reflected by the first protrusion 51 and enters the light receiving unit of the fifth sensor 35. The sixth sensor 36 faces the second protrusion 52 in the X-axis direction. The light emitting unit of the sixth sensor 36 emits light in the −X direction. The light emitted from the light emitting unit of the sixth sensor 36 is reflected by the second protrusion 52 and enters the light receiving unit of the sixth sensor 36. The seventh sensor 37 faces the third protrusion 53 in the Y-axis direction. The light emitting unit of the seventh sensor 37 emits light in the −Y direction. The light emitted from the light emitting unit of the seventh sensor 37 is reflected by the third protrusion 53 and enters the light receiving unit of the seventh sensor 37. The eighth sensor 38 faces the fourth protrusion 54 in the X-axis direction. The light emitting unit of the eighth sensor 38 emits light in the −X direction. The light emitted from the light emitting unit of the eighth sensor 38 is reflected by the fourth protrusion 54 and enters the light receiving unit of the eighth sensor 38. When no external force is applied to the top plate 6 (when the elastic body 4 is not deformed), the distance from the fifth sensor 35 to the first protrusion 51, the distance from the sixth sensor 36 to the second protrusion 52, the first The distance from the seventh sensor 37 to the third protrusion 53 and the distance from the eighth sensor 38 to the fourth protrusion 54 are distances D1 as shown in FIG.

  FIG. 9 is a schematic diagram illustrating the displacement of the protrusion in a state where a force in the X-axis direction is applied to the upper plate according to the present embodiment. FIG. 10 is a schematic diagram showing the displacement of the protrusion in a state where a force in the Y-axis direction is applied to the upper plate according to the present embodiment. FIG. 11 is a schematic diagram showing the displacement of the protrusion in a state where a force in the Z-axis direction is applied to the upper plate according to the present embodiment. FIG. 12 is a schematic diagram showing the displacement of the protrusion in a state where a moment around the X axis is applied to the upper plate according to the present embodiment. FIG. 13 is a schematic diagram showing the displacement of the protrusion in a state in which a moment about the Y axis is applied to the upper plate according to the present embodiment. FIG. 14 is a schematic diagram showing the displacement of the protrusion in a state where a moment around the Z axis is applied to the upper plate according to the present embodiment. In the following description, the state where no external force is applied to the top plate 6, that is, the state shown in FIGS. 6 to 8 is simply referred to as a reference state. 9 to 14 indicate the positions of the first protrusion 51, the second protrusion 52, the third protrusion 53, and the fourth protrusion 54 when no external force is applied to the top plate 6. FIG. Further, the magnitude of the force Fx shown in FIG. 9 is equal to the magnitude of the force Fy shown in FIG. The magnitude of the moment Mx shown in FIG. 12 is equal to the magnitude of the moment My shown in FIG.

  As shown in FIG. 9, when a force Fx acts on the top plate 6 in the + X direction, the first protrusion 51, the second protrusion 52, the third protrusion 53, and the fourth protrusion 54 move in the + X direction along with the deformation of the elastic body 4. Move to. As a result, the distance from the sixth sensor 36 to the second protrusion 52 and the distance from the eighth sensor 38 to the fourth protrusion 54 become the distance D2, as shown in FIG. The distance D2 is smaller than the distance D1 (see FIG. 6). As a result, the intensity of reflected light incident on the sixth sensor 36 and the eighth sensor 38 increases. For this reason, the sensor outputs of the sixth sensor 36 and the eighth sensor 38 are larger than those in the reference state. On the other hand, the distance from the fifth sensor 35 to the first protrusion 51 and the distance from the seventh sensor 37 to the third protrusion 53 remain the distance D1. The distance from the first sensor 31 to the first protrusion 51, the distance from the second sensor 32 to the second protrusion 52, the distance from the third sensor 33 to the third protrusion 53, and the distance from the fourth sensor 34 to the fourth protrusion 54 This distance remains the distance H1 (see FIGS. 7 and 8). For this reason, the sensor outputs of the first sensor 31, the second sensor 32, the third sensor 33, the fourth sensor 34, the fifth sensor 35, and the seventh sensor 37 are the same as the reference state. Further, when the force Fx acts on the top plate 6 in the −X direction, the sensor outputs of the sixth sensor 36 and the eighth sensor 38 become smaller than the reference state, contrary to the above description.

  As shown in FIG. 10, when the force Fy is applied to the top plate 6 in the + Y direction, the first protrusion 51, the second protrusion 52, the third protrusion 53, and the fourth protrusion 54 are moved in the + Y direction along with the deformation of the elastic body 4. Move to. Accordingly, the distance from the fifth sensor 35 to the first protrusion 51 and the distance from the seventh sensor 37 to the third protrusion 53 are the distance D2 as shown in FIG. The distance D2 is smaller than the distance D1 (see FIG. 6). As a result, the intensity of reflected light incident on the fifth sensor 35 and the seventh sensor 37 increases. For this reason, the sensor outputs of the fifth sensor 35 and the seventh sensor 37 are larger than those in the reference state. On the other hand, the distance from the sixth sensor 36 to the second protrusion 52 and the distance from the eighth sensor 38 to the fourth protrusion 54 remain the distance D1. The distance from the first sensor 31 to the first protrusion 51, the distance from the second sensor 32 to the second protrusion 52, the distance from the third sensor 33 to the third protrusion 53, and the distance from the fourth sensor 34 to the fourth protrusion 54 This distance remains the distance H1 (see FIGS. 7 and 8). For this reason, the sensor outputs of the first sensor 31, the second sensor 32, the third sensor 33, the fourth sensor 34, the sixth sensor 36, and the eighth sensor 38 are the same as the reference state. When the force Fy is applied to the top plate 6 in the −Y direction, the sensor outputs of the fifth sensor 35 and the seventh sensor 37 are smaller than that in the reference state, contrary to the above description.

  As shown in FIG. 11, when a force Fz acts on the top plate 6 in the −Z direction, the first protrusion 51, the second protrusion 52, the third protrusion 53, and the fourth protrusion 54 are − Move in the Z direction. Accordingly, the distance from the first sensor 31 to the first protrusion 51, the distance from the second sensor 32 to the second protrusion 52, the distance from the third sensor 33 to the third protrusion 53, and the fourth sensor 34 to the fourth The distance to the protrusion 54 is a distance H2, which is equal to each other. The distance H2 is smaller than the distance H1 (see FIGS. 7 and 8). Thereby, the intensity of reflected light incident on the first sensor 31, the second sensor 32, the third sensor 33, and the fourth sensor 34 is increased. For this reason, the sensor outputs of the first sensor 31, the second sensor 32, the third sensor 33, and the fourth sensor 34 are larger than those in the reference state. On the other hand, the distance from the fifth sensor 35 to the first protrusion 51, the distance from the sixth sensor 36 to the second protrusion 52, the distance from the seventh sensor 37 to the third protrusion 53, and the fourth protrusion from the eighth sensor 38. The distance to 54 remains the distance D1 (see FIG. 6). For this reason, the sensor outputs of the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38 are the same as in the reference state. When the force Fz acts on the top plate 6 in the + Z direction, the sensor outputs of the first sensor 31, the second sensor 32, the third sensor 33, and the fourth sensor 34 are compared with the reference state, contrary to the above description. And get smaller.

  As shown in FIG. 12, when the moment Mx is applied to the top plate 6 around the X axis, the second protrusion 52 moves in the −Z direction and the fourth protrusion 54 moves in the + Z direction as the elastic body 4 is deformed. To do. As a result, the distance from the second sensor 32 to the second protrusion 52 becomes the distance H3, and the distance from the fourth sensor 34 to the fourth protrusion 54 becomes the distance H4. The distance H3 is smaller than the distance H1 (see FIGS. 7 and 8). The distance H4 is larger than the distance H1. As a result, the intensity of the reflected light incident on the second sensor 32 increases, so that the sensor output of the second sensor 32 increases compared to the reference state. Since the reflected light intensity incident on the fourth sensor 34 becomes small, the sensor output of the fourth sensor 34 becomes small compared to the reference state. On the other hand, the distance from the first sensor 31 to the first protrusion 51 and the distance from the third sensor 33 to the third protrusion 53 remain the distance H1. The distance from the fifth sensor 35 to the first protrusion 51, the distance from the sixth sensor 36 to the second protrusion 52, the distance from the seventh sensor 37 to the third protrusion 53, and the distance from the eighth sensor 38 to the fourth protrusion 54 This distance remains the distance D1 (see FIG. 6). For this reason, the sensor outputs of the first sensor 31, the third sensor 33, the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38 are the same as in the reference state. When the moment Mx in the direction opposite to the direction shown in FIG. 12 acts on the top plate 6, the sensor output of the second sensor 32 becomes smaller than that in the reference state, contrary to the above description, and the first The sensor output of the four sensors 34 is larger than that in the reference state.

  As shown in FIG. 13, when the moment My acts on the top plate 6 around the Y axis, the third protrusion 53 moves in the −Z direction and the first protrusion 51 moves in the + Z direction as the elastic body 4 is deformed. To do. Thereby, the distance from the third sensor 33 to the third protrusion 53 becomes the distance H3, and the distance from the first sensor 31 to the first protrusion 51 becomes the distance H4. The distance H3 is smaller than the distance H1 (see FIGS. 7 and 8). The distance H4 is larger than the distance H1. As a result, the intensity of the reflected light incident on the third sensor 33 increases, so that the sensor output of the third sensor 33 increases compared to the reference state. Since the reflected light intensity incident on the first sensor 31 is small, the sensor output of the first sensor 31 is small compared to the reference state. On the other hand, the distance from the second sensor 32 to the second protrusion 52 and the distance from the fourth sensor 34 to the fourth protrusion 54 remain the distance H1. The distance from the fifth sensor 35 to the first protrusion 51, the distance from the sixth sensor 36 to the second protrusion 52, the distance from the seventh sensor 37 to the third protrusion 53, and the distance from the eighth sensor 38 to the fourth protrusion 54 This distance remains the distance D1 (see FIG. 6). For this reason, the sensor outputs of the second sensor 32, the fourth sensor 34, the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38 are the same as the reference state. Further, when a moment My acting in the direction opposite to the direction shown in FIG. 13 acts on the top plate 6, contrary to the above description, the sensor output of the third sensor 33 becomes smaller than that in the reference state, and the first The sensor output of one sensor 31 is larger than that in the reference state.

  As shown in FIG. 14, when the moment Mz is applied to the top plate 6 around the Z axis, the first protrusion 51 moves in the + Y direction and the second protrusion 52 moves in the + X direction as the elastic body 4 is deformed. The third protrusion 53 moves in the −Y direction, and the fourth protrusion 54 moves in the −X direction. Accordingly, the distance from the fifth sensor 35 to the first protrusion 51 and the distance from the sixth sensor 36 to the second protrusion 52 become the distance D3, and the distance from the seventh sensor 37 to the third protrusion 53 and the eighth sensor 38. The distance from the fourth protrusion 54 is the distance D4. The distance D3 is smaller than the distance D1 (see FIG. 6). The distance D4 is larger than the distance D1. Thereby, since the reflected light intensity which injects into the 5th sensor 35 and the 6th sensor 36 becomes large, the sensor output of the 5th sensor 35 and the 6th sensor 36 becomes large compared with a reference state. Since the intensity of the reflected light incident on the seventh sensor 37 and the eighth sensor 38 becomes small, the sensor outputs of the seventh sensor 37 and the eighth sensor 38 become small compared to the reference state. On the other hand, the distance from the first sensor 31 to the first protrusion 51, the distance from the second sensor 32 to the second protrusion 52, the distance from the third sensor 33 to the third protrusion 53, and the fourth protrusion from the fourth sensor 34 The distance to 54 remains the distance H1 (see FIGS. 7 and 8). For this reason, the sensor outputs of the first sensor 31, the second sensor 32, the third sensor 33, and the fourth sensor 34 are the same as in the reference state. When the moment Mz in the direction opposite to the direction shown in FIG. 14 acts on the top plate 6, the sensor outputs of the fifth sensor 35 and the sixth sensor 36 are compared with the reference state, contrary to the above description. The sensor output of the seventh sensor 37 and the eighth sensor 38 increases compared to the reference state.

  FIG. 15 is a block diagram illustrating an arithmetic processing unit according to the present embodiment. FIG. 16 is a configuration diagram illustrating an arithmetic processing unit according to the present embodiment. As shown in FIG. 15, the force sensor 1 includes an arithmetic processing unit 9. The force sensor 1 outputs the sensor outputs of the first sensor 31, the second sensor 32, the third sensor 33, the fourth sensor 34, the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38. Receive. And the force sensor 1 calculates the external force which is acting on the top plate 6 based on each sensor output, and transmits the information of external force to the control part 100. The control unit 100 controls, for example, a motor that drives an industrial robot.

  As shown in FIG. 16, the arithmetic processing unit 9 is a computer such as a microcomputer, and includes an input interface 9a, an output interface 9b, a CPU (Central Processing Unit) 9c, and a ROM (Read Only Memory) 9d. And a RAM (Random Access Memory) 9e and an internal storage device 9f. The input interface 9a, output interface 9b, CPU 9c, ROM 9d, RAM 9e and internal storage device 9f are connected to an internal bus.

  The input interface 9a outputs each sensor output from the first sensor 31, the second sensor 32, the third sensor 33, the fourth sensor 34, the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38. Receive and output to CPU 9c. The output interface 9b receives external force information from the CPU 9c and outputs the information to the control unit 100.

  A program such as BIOS (Basic Input / Output System) is stored in the ROM 9d. The internal storage device 9f is, for example, an HDD (Hard Disk Drive), a flash memory, or the like, and stores an operating system program and application programs. The CPU 9c implements various functions by executing programs stored in the ROM 9d and the internal storage device 9f while using the RAM 9e as a work area.

  The internal storage device 9f stores a coefficient for obtaining an external force based on each sensor output. The coefficient is a constant determined by the characteristics of the first sensor 31, the second sensor 32, the third sensor 33, the fourth sensor 34, the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38.

  As shown in FIG. 15, the arithmetic processing unit 9 includes an AD conversion unit 901, an AD conversion unit 902, an AD conversion unit 903, an AD conversion unit 904, an AD conversion unit 905, an AD conversion unit 906, and an AD conversion unit. Converter 907, AD converter 908, adder 91, subtractor 92, subtractor 93, adder 94, adder 95, adder 96, adder 97, subtractor 98, , Fz computing unit 991, Mx computing unit 992, My computing unit 993, Fx computing unit 994, Fy computing unit 995, and Mz computing unit 996. Each process performed in the arithmetic processing unit 9 is realized by a combination of an input interface 9a, an output interface 9b, a CPU 9c, a ROM 9d, a RAM 9e, and an internal storage device 9f.

  The AD conversion unit 901 receives the sensor output S1a as analog data of the first sensor 31, and converts the sensor output S1a into the sensor output S1 as digital data. The AD conversion unit 901 outputs the sensor output S1 to the addition unit 91 and the subtraction unit 93.

  The AD conversion unit 902 receives the sensor output S2a as analog data of the second sensor 32, and converts the sensor output S2a into the sensor output S2 as digital data. The AD conversion unit 902 outputs the sensor output S2 to the addition unit 91 and the subtraction unit 92.

  The AD conversion unit 903 receives the sensor output S3a as analog data of the third sensor 33, and converts the sensor output S3a into the sensor output S3 as digital data. The AD conversion unit 903 outputs the sensor output S3 to the addition unit 91 and the subtraction unit 93.

  The AD conversion unit 904 receives the sensor output S4a as analog data of the fourth sensor 34, and converts the sensor output S4a into the sensor output S4 as digital data. The AD conversion unit 904 outputs the sensor output S4 to the addition unit 91 and the subtraction unit 92.

  The AD conversion unit 905 receives the sensor output S5a as analog data of the fifth sensor 35, and converts the sensor output S5a into the sensor output S5 as digital data. The AD conversion unit 905 outputs the sensor output S5 to the addition unit 95 and the addition unit 96.

  The AD conversion unit 906 receives the sensor output S6a as analog data of the sixth sensor 36, and converts the sensor output S6a into sensor output S6 as digital data. The AD conversion unit 906 outputs the sensor output S6 to the addition unit 94 and the addition unit 96.

  The AD conversion unit 907 receives the sensor output S7a as analog data of the seventh sensor 37, and converts the sensor output S7a into the sensor output S7 as digital data. The AD conversion unit 907 outputs the sensor output S7 to the addition unit 95 and the addition unit 97.

  The AD conversion unit 908 receives the sensor output S8a as analog data of the eighth sensor 38, and converts the sensor output S8a into the sensor output S8 as digital data. The AD conversion unit 908 outputs the sensor output S8 to the addition unit 94 and the addition unit 97.

  In the following description, it is assumed that the values of sensor output S1, sensor output S2, sensor output S3, sensor output S4, sensor output S5, sensor output S6, sensor output S7, and sensor output S8 in the reference state are zero. The values of sensor output S1, sensor output S2, sensor output S3, sensor output S4, sensor output S5, sensor output S6, sensor output S7 and sensor output S8 in the state where external force is applied to the top plate 6 are respectively s1, Let s2, s3, s4, s5, s6, s7, and s8.

  The adder 91 calculates the sum of the sensor output S1, the sensor output S2, the sensor output S3, and the sensor output S4. That is, the adder 91 calculates (s1 + s2 + s3 + s4). The adding unit 91 outputs the sensor output sum S91, which is the calculation result, to the Fz calculating unit 991.

  The Fz calculation unit 991 calculates a force Fz based on the sensor output sum S91. When the value of the force Fz is fz and the coefficient for converting the sensor output sum S91 to the force Fz is α, the Fz calculation unit 991 performs the calculation of the following equation (1). α is a constant obtained by a prior experiment or the like. Then, the Fz calculation unit 991 outputs a force Fz that is a calculation result to the control unit 100.

  fz = α × (s1 + s2 + s3 + s4) (1)

  The subtractor 92 calculates the difference between the sensor output S2 and the sensor output S4. That is, the subtraction unit 92 calculates (s2−s4). The subtraction unit 92 outputs the sensor output difference S92, which is the calculation result, to the Mx calculation unit 992.

  The Mx calculation unit 992 calculates the moment Mx based on the sensor output difference S92. When the value of the moment Mx is mx and the coefficient for converting the sensor output difference S92 to the moment Mx is β, the Mx calculation unit 992 performs the calculation of the following equation (2). β is a constant obtained by a prior experiment or the like. Then, the Mx calculation unit 992 outputs the moment Mx that is the calculation result to the control unit 100.

  mx = β × (s2-s4) (2)

  The subtraction unit 93 calculates the difference between the sensor output S1 and the sensor output S3. That is, the subtraction unit 93 calculates (s1−s3). The subtraction unit 93 outputs the sensor output difference S93, which is the calculation result, to the My calculation unit 993.

  The My calculation unit 993 calculates the moment My based on the sensor output difference S93. Assuming that the value of the moment My is my and the coefficient for converting the sensor output difference S93 into the moment My is γ, the My calculation unit 993 performs the calculation of the following equation (3). γ is a constant obtained by a prior experiment or the like. And My calculating part 993 outputs moment My which is a calculation result to control part 100.

  my = γ × (s1−s3) (3)

  The adder 94 calculates the sum of the sensor output S6 and the sensor output S8. That is, the adding unit 94 calculates (s6 + s8). The adder 94 outputs the sensor output sum S94, which is the calculation result, to the Fx calculator 994.

  The Fx calculation unit 994 calculates a force Fx based on the sensor output sum S94. Assuming that the value of the force Fx is fx and the coefficient for converting the sensor output sum S94 to the force Fx is δ, the Fx calculation unit 994 performs the calculation of the following equation (4). δ is a constant obtained by a prior experiment or the like. Then, the Fx calculation unit 994 outputs a force Fx that is a calculation result to the control unit 100.

  fx = δ × (s6 + s8) (4)

  The adding unit 95 calculates the sum of the sensor output S5 and the sensor output S7. That is, the adding unit 95 calculates (s5 + s7). The adding unit 95 outputs the sensor output sum S95, which is the calculation result, to the Fy calculating unit 995.

  The Fy calculation unit 995 calculates a force Fy based on the sensor output sum S95. If the value of the force Fy is fy and the coefficient for converting the sensor output sum S95 to the force Fy is ε, the Fy calculation unit 995 performs the calculation of the following equation (5). ε is a constant obtained by a prior experiment or the like. Then, the Fy calculation unit 995 outputs a force Fy that is a calculation result to the control unit 100.

  fy = ε × (s5 + s7) (5)

  The adder 96 calculates the sum of the sensor output S5 and the sensor output S6. That is, the adding unit 96 calculates (s5 + s6). The adder 96 outputs the sensor output sum S96, which is the calculation result, to the subtractor 98.

  The adder 97 calculates the sum of the sensor output S7 and the sensor output S8. That is, the adder 97 calculates (s7 + s8). The adding unit 97 outputs the sensor output sum S97, which is the calculation result, to the subtracting unit 98.

  The subtraction unit 98 calculates the difference between the sensor output sum S96 and the sensor output sum S97. That is, the subtraction unit 98 calculates {(s5 + s6) − (s7 + s8)}. The subtraction unit 98 outputs the sensor output difference S98, which is the calculation result, to the Mz calculation unit 996.

  The Mz calculating unit 996 calculates a moment Mz based on the sensor output difference S98. When the value of the moment Mz is mz and the coefficient for converting the sensor output difference S98 to the moment Mz is ζ, the Mz calculating unit 996 performs the calculation of the following equation (6). ζ is a constant obtained by a prior experiment or the like. Then, the Mz calculation unit 996 outputs a moment Mz that is a calculation result to the control unit 100.

  mz = ζ × {(s5 + s6) − (s7 + s8)} (6)

  As described above, the force sensor 1 can detect the force Fz in the Z-axis direction based on changes in sensor outputs of the first sensor 31, the second sensor 32, the third sensor 33, and the fourth sensor 34. The force sensor 1 can detect the moment Mx around the X axis based on changes in sensor outputs of the second sensor 32 and the fourth sensor 34. The force sensor 1 can detect a moment My around the Y axis based on changes in sensor outputs of the first sensor 31 and the third sensor 33. The force sensor 1 can detect the force Fx in the X-axis direction based on changes in sensor outputs of the sixth sensor 36 and the eighth sensor 38. The force sensor 1 can detect the force Fy in the Y-axis direction based on changes in sensor outputs of the fifth sensor 35 and the seventh sensor 37. The force sensor 1 can detect the moment Mz around the Z axis based on changes in sensor outputs of the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38. That is, the force sensor 1 can detect six external forces.

  The control unit 100 controls the motor based on the force Fz, moment Mx, moment My, force Fx, force Fy, and moment Mz received from the arithmetic processing unit 9. Specifically, the control unit 100 controls the rotation direction and the number of rotations of the motor.

  Note that the shapes of the support 2, the first substrate 3, the elastic body 4, the second substrate 5, and the top plate 6 viewed from the Z-axis direction are not necessarily circular, and may be, for example, an ellipse or a polygon. Good. Moreover, the shape of the 1st protrusion 51, the 2nd protrusion 52, the 3rd protrusion 53, and the 4th protrusion 54 does not necessarily need to be a rectangular parallelepiped shape, for example, a polygonal column etc. may be sufficient as it.

  The positions of the first sensor 31, the second sensor 32, the third sensor 33, the fourth sensor 34, the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38 are shifted from the positions described above. It may be. Further, it is sufficient that at least the first sensor 31, the second sensor 32, the third sensor 33, the fourth sensor 34, the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38 are provided. In addition, a sensor may be provided.

  In the above description, each sensor output in the reference state is set to 0. However, each sensor output in the reference state is not always 0. For example, the values of sensor output S1, sensor output S2, sensor output S3, sensor output S4, sensor output S5, sensor output S6, sensor output S7, and sensor output S8 in the reference state are s10, s20, s30, s40, s50, respectively. Assume that s60, s70, and s80. And when external force acts on the top plate 6, it will be assumed that each sensor output changes to s11, s21, s31, s41, s51, s61, s71, s81, respectively. In such a case, (s11-s10) is substituted for s1, (s21-s20) is substituted for s2, and (s31-s30) is substituted for s3 in the above-described equations (1) to (6), (s41-s40) is substituted for s4, (s51-s50) is substituted for s5, (s61-s60) is substituted for s6, (s71-s70) is substituted for s7, and (s81-s80) ) Should be substituted.

  As described above, the force sensor 1 includes the support 2, the first substrate 3 supported by the support 2, the elastic body 4 supported at one end by the support 2 and movable at the other end. The second substrate 5 is supported by the elastic body 4 and faces the first substrate 3. The force sensor 1 includes a first sensor 31, a second sensor 32, a third sensor 33, a fourth sensor 34, a fifth sensor 35, a sixth sensor 36, a seventh sensor 37 and a first sensor provided on the first substrate 3. Eight sensors 38 are provided. The force sensor 1 includes a first protrusion 51, a second protrusion 52, a third protrusion 53, and a fourth protrusion 54 that are provided on the second substrate 5 and protrude toward the first substrate 3. In the Z-axis direction orthogonal to the first substrate 3, the first sensor 31 faces the first protrusion 51, the second sensor 32 faces the second protrusion 52, and the third sensor 33 The third sensor 53 faces the third protrusion 53, and the fourth sensor 34 faces the fourth protrusion 54. The fifth sensor 35 faces the first protrusion 51 and the seventh sensor 37 faces the third protrusion 53 in the Y-axis direction orthogonal to the Z-axis direction. The sixth sensor 36 faces the second protrusion 52 and the eighth sensor 38 faces the fourth protrusion 54 in the X-axis direction orthogonal to the Z-axis direction and the Y-axis direction.

  Accordingly, the force sensor 1 includes the first sensor 31, the second sensor 32, the third sensor 33, the fourth sensor 34, the fifth sensor 35, the sixth sensor 36, the seventh sensor 37, and the eighth sensor 38. Based on the sensor output change, six external forces (force Fx, force Fy, force Fz, moment Mx, moment My, moment Mz) can be detected. Further, each of the six external forces is obtained by adding or subtracting a change amount of each sensor output. For this reason, the arithmetic processing for obtaining the six external forces is easy. Therefore, the force sensor 1 can improve the detection responsiveness and can detect six external forces.

  Furthermore, compared to the technique of Patent Document 1 described above, in the force sensor 1, since the sensor is not disposed on the + Z direction side of the second substrate 5, the thickness in the Z-axis direction tends to be small. For this reason, the force sensor 1 can be reduced in size more easily than the technique of patent document 1. FIG.

  In the force sensor 1, the first sensor 31, the second sensor 32, the third sensor 33, and the fourth sensor 34 are arranged at equal intervals in the circumferential direction around the elastic body 4 when viewed from the Z-axis direction. Has been.

  Thereby, when the moment Mx around the X axis or the moment My around the Y axis is applied, two of the sensor outputs of the first sensor 31, the second sensor 32, the third sensor 33, and the fourth sensor 34 are detected. While the output changes, the remaining two sensor outputs do not change. For this reason, the force sensor 1 can detect the moment Mx based on changes in the two sensor outputs, and can detect the moment My based on changes in the remaining two sensor outputs. Therefore, the calculation for obtaining the moment Mx and the moment My is easy.

  In the force sensor 1, the elastic body 4 includes a spiral slit 41 centering on an axis along the Z-axis direction.

  As a result, the elastic body 4 is likely to be displaced in the X-axis direction, the Y-axis direction, and the Z-axis direction, and more easily inclined around the X-axis, the Y-axis, and the Z-axis. For this reason, the change amount of each sensor output of the 1st sensor 31, the 2nd sensor 32, the 3rd sensor 33, the 4th sensor 34, the 5th sensor 35, the 6th sensor 36, the 7th sensor 37, and the 8th sensor 38 is obtained. growing. Therefore, the detection accuracy of the force sensor 1 is improved.

DESCRIPTION OF SYMBOLS 1 Force sensor 100 Control part 2 Support body 3 1st board | substrate 30 Hole 31 1st sensor 32 2nd sensor 33 3rd sensor 34 4th sensor 35 5th sensor 36 6th sensor 37 7th sensor 38 8th sensor 4 Elasticity Body 40 Hole 41 Slit 5 Second substrate 50 Hole 51 First protrusion 52 Second protrusion 53 Third protrusion 54 Fourth protrusion 55 Convex part 6 Top plate 60 Hole 9 Arithmetic processing part Fx, Fy, Fz Force Mx, My, Mz Moment

Claims (3)

A support;
A first substrate supported by the support;
An elastic body having one end supported by the support and the other end movable;
A second substrate supported by the elastic body and facing the first substrate;
A first sensor, a second sensor, a third sensor, a fourth sensor, a fifth sensor, a sixth sensor, a seventh sensor, and an eighth sensor provided on the first substrate;
A first protrusion, a second protrusion, a third protrusion, and a fourth protrusion that are provided on the second substrate and project toward the first substrate;
With
In the Z-axis direction orthogonal to the first substrate, the first sensor faces the first protrusion, the second sensor faces the second protrusion, and the third sensor Facing the third protrusion, the fourth sensor facing the fourth protrusion,
In the Y-axis direction orthogonal to the Z-axis direction, the fifth sensor faces the first protrusion, the seventh sensor faces the third protrusion,
The sixth sensor faces the second protrusion and the eighth sensor faces the fourth protrusion in the X-axis direction orthogonal to the Z-axis direction and the Y-axis direction. Sensor.   The first sensor, the second sensor, the third sensor, and the fourth sensor are arranged at equal intervals in a circumferential direction centered on the elastic body when viewed from the Z-axis direction. The force sensor described.   The force sensor according to claim 1, wherein the elastic body includes a spiral slit having an axis along the Z-axis direction as a center.

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