JP2011033607A - Force or motion sensor and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-sensitivity and reliable force or a motion sensor having a simple structure and low manufacturing cost. <P>SOLUTION: In the sensor comprises a base 2, a table 21 having six degrees of freedom with respect to the base 2 and facing to the base 2; six connecting parts arranged in parallel so as to connect the base to the table 21; a plurality of detecting elements for detecting displacements and/or deformations between the base 2 and the table 21; and an operation section for comprehensively computing displacements and/or deformations of each detection element, a first bearing 12 of each connecting part on the side of the table is constituted in such a way as to be fitted from the back side of the table 21 and held and fixed by both a pressing plate 22 to be fixed to the table 21 and the table 21. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a force sensor or a motion sensor that can simultaneously detect six-axis components.

  The force sensor is a device that detects a force (external force) acting on a traveling table (object) included in the force sensor, and is used, for example, to realize a tactile sensation of a human fingertip in a robot hand. The force sensor can simultaneously detect a total of six components including a force component in the three-axis direction of a three-dimensional space orthogonal coordinate system (x-axis, y-axis, and z-axis) and a moment component around the three axes. There is something. Thus, a force sensor that can detect six components is also called a six-axis force sensor.

  In Japanese Patent Laid-Open No. 10-274573 (Patent Document 1), a top plate and a bottom plate are connected by a plurality of rods, and these plates are connected to each other by a joint having two degrees of freedom on one end and three degrees of freedom on the other side. A force sensor using a joint is disclosed. The rod of the force sensor is provided with a detection element capable of detecting a compression / tensile force in the rod axis direction.

  Further, a force sensor (structure deformation mode) for detecting a force by deforming a structure is disclosed in Japanese Patent Laid-Open No. 9-318469 (Patent Document 2). For example, a 6-axis force sensor of a combination of a strain gauge and an elastic body is widely used for applications such as external force measurement in a robot that performs force control. When force or moment acts on the elastic body to which the strain gauge is attached and the elastic body is deformed, stress is generated in each strain gauge accordingly. The resulting change in the electrical resistance value of each strain gauge is output as a voltage value via a well-known bridge circuit, and further converted into a six-axis force by a predetermined calculation circuit or software processing.

  Japanese Patent Laid-Open No. 5-149811 (Patent Document 3) discloses triaxial forces orthogonal to each other by a plurality of strain gauges affixed to an optimum site set by FEM analysis of a strain generating body on a flat plate, and these A six-axis force sensor is disclosed that includes a strain detection circuit including a plurality of bridge circuits that independently detect moments about an axis.

  Japanese Patent Application Laid-Open No. 9-131690 (Patent Document 4) discloses a six-axis load detection device that controls the position and posture of a predetermined movable plate by cooperation of a plurality of actuators. A six-axis load acting on a predetermined point on a predetermined movable plate is detected by holding the movable plate at a predetermined position and posture by the cooperative operation of a plurality of actuators.

  Japanese Patent Laid-Open No. 2000-148382 (Patent Document 5) discloses that a force sense presentation mechanism for presenting and transmitting a force sense to a user wears an operating device for connecting the user and the operating device. Haptic interface with 6-axis force feedback, including 6 motion sets, 6 link sets supporting the motion platforms, 6 drive units for independently driving each link set, and 6 sensors An apparatus is disclosed.

  Incidentally, the acceleration sensor is a device that detects the acceleration of an object having a mass, and is used, for example, for posture control of a robot or collision detection of an air bag of an automobile. An angular velocity sensor (for example, a gyro sensor) is a device that detects an angular velocity at which an object having a mass rotates, and is used, for example, for industrial robots or detection of a rollover of an automobile. These acceleration sensors and angular velocity sensors are devices (motion sensors) that detect an inertial force generated from the movement of an object with respect to a force sensor that detects a force (external force) applied to the object.

  In order to detect accelerations in the x-axis, y-axis, and z-axis directions, for example, three uniaxial acceleration sensors must be arranged in directions orthogonal to each other. Also, three uniaxial acceleration sensors are required to detect the angular velocities in the rotational directions of the x-axis, y-axis, and z-axis. Accordingly, there is a need for a 6-axis motion sensor that simultaneously detects 3-axis acceleration and 3-axis angular velocity.

  In the present application, a motion sensor will be described as a superordinate concept of an acceleration sensor and an angular velocity sensor. That is, the motion sensor can detect acceleration and / or angular velocity.

JP-A-10-274573 JP 9-318469 A Japanese Patent Laid-Open No. 5-149811 JP-A-9-131690 JP 2000-148382 A

  The conventional force or motion sensor as described above has problems such as insufficient sensitivity, poor reliability, difficult force control, complicated structure, large manufacturing cost, and inability to detect synthetic force. There was a point. Therefore, an object of the force sensor or motion sensor according to the present invention is to provide a force sensor or motion sensor that has high sensitivity and reliability, has a simpler structure, and is less expensive to manufacture.

  In order to solve the above-described problems, in the force sensor or motion sensor according to the present invention, a base, a table having six degrees of freedom with respect to the base, and arranged to face the base, the base and the table A total of six connecting portions arranged in parallel to be connected, a plurality of detecting elements for detecting displacement and / or deformation between the base and the table, and displacements and / or deformation amounts of the detecting elements. In the sensor comprising the calculation unit for calculating automatically, the first bearing on the table side of each connecting part is configured to be fitted from the back side of the table, and is held by the pressing plate fixed to the table and the table. It is fixed.

  Each of the connecting portions includes a first bearing connected to the table, a rod connected to the first bearing, a second bearing provided at an end of the rod opposite to the first bearing, Preferably, the arm is fixed to the base and connected to the second bearing, and the arm is formed of a plate-like member that can be connected to each of the six connecting portions.

  The first bearing of the connecting portion is installed perpendicular to the table, the second bearing is installed perpendicular to the arm, and the arm includes the first bearing and the second bearing. It is preferable to be configured in a shape to be supported.

  The arm may include an elastic member, and the base may include an overload protection unit that prevents the arm from being destroyed when the arm is over-displaced and / or over-deformed.

  The first bearing and / or the second bearing of the connecting portion may be a ball joint, and at least the ball portion and the bearing portion may be integrally formed. In this case, metal sintering or resin molding can be used as a method. Further, it is preferable that the bearing portion is divided into two.

  It is desirable that the holder portion of the first bearing and / or the second bearing has a clearance adjusting function for adjusting a backlash between the ball portion and the bearing portion.

  Furthermore, it is more effective to cover the outside of the base and the table with a stretchable cover.

  According to another aspect of the present invention, there is provided a method for manufacturing a force sensor or a motion sensor. A plurality of first bearings provided at the table-side end, a second bearing provided at the opposite end of the rod to the first bearing, and an arm connected to the second bearing. After fixing the connecting portion, the pressing plate is arranged, and the first bearing of each connecting portion is fitted and assembled at a predetermined position of the table, and then the table and the pressing plate are connected by connecting means. Each connecting portion is fixed to the table.

  According to the present invention, it is possible to provide a highly reliable force sensor or motion sensor that is simple in structure, low in manufacturing cost, and easy to downsize. Furthermore, according to the present invention, it is possible to provide a method for manufacturing a highly reliable force sensor or motion sensor.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an embodiment of a force or motion sensor according to the present invention. First, the overall configuration of the sensor of this embodiment includes an attachment 11, a base 2 connected to the attachment 1, and six arms 11 including six sets of first and second bearings 12 and 20. The table 21 is supported by the bearing 12.

  The attachment 1 is not directly related to the function of the force sensor or the motion sensor according to the present invention, but functions as an attachment portion when the sensor is attached to a robot or the like, for example. When the attachment 1 is attached to a robot or the like, it is fixed with an attachment attachment screw 5.

  The base 2 is a base for the sensor of this embodiment, and includes a bottom surface portion 61 that contacts the attachment 1, a convex portion 62 that supports the arm, and a side wall portion 63 that protects the sensor element from the outside. . A base positioning protrusion 4 is provided at the center of the bottom surface portion 61, and is thereby fitted and positioned on the attachment 1. A plurality of substrate receiving step portions 51 are provided on the periphery of the base 2, and substrate positioning protrusions 53 formed at the same height as the substrate receiving step portion 51 and substrate positioning pins extending from the base bottom surface portion 61. The circuit board 9 is supported by 8. Further, another step portion as the overload protection means 3 of the arm 11 is formed on the base bottom surface portion 61 along the side wall portion 63 as shown in FIG. Yes.

  As shown in FIG. 4, the circuit board 9 is formed in an irregular disk shape when viewed from above, and is configured to fit around the convex portion 62 protruding from the base bottom surface portion 61. The reason why the circuit board 9 has a notch shape above the overload protection means 3 is that the arm 11 and the second bearing 20 supported by the arm 11 are arranged at the position of the overload protection means 3. This is not to interfere. The circuit board 9 includes six sensors 24 (for example, eddy current elements) on the front surface, and a circuit for driving these sensors 24 is formed on the back surface. The circuit board 9 is positioned by inserting the board positioning pin hole 28 into the board positioning pin 8, and is fixed to the board supporting projection 53 by the board fixing screw 7 through the board mounting screw hole 27.

  As shown in FIG. 5, the arm 11 includes a circular arm base 30 and six arm operation units 32. Each arm operating part 32 is composed of an elastic member, and the second bearing 20 is arranged and fixed at the tip. Further, the arm 11 is positioned by the substrate pressing projection 44 with respect to the convex portion 62 of the base 2 at the arm base 30 and fixed by the arm fixing screw 10 via the arm pressing 43. The arm operating unit 32 of the fixed arm 11 is maintained at a predetermined interval (about 0.3 mm) with respect to the sensor 24 arranged on the circuit board 9.

  On the other hand, the base 2 to which the arm 11 is connected is fixed to the attachment 1 by the sensor mounting screw 6 on the arm presser 43.

  The second bearing 20 preferably has two degrees of freedom. In this embodiment, a ball joint is disposed. The second bearing 20 is installed perpendicular to the arm operating unit 32, and therefore the rod 35 extends straight upward as shown in FIG. On the other hand, it is desirable that the first bearing 12 has three degrees of freedom. In this embodiment, a ball joint is also used. The first bearing 12 is also installed perpendicular to the table 21 and the rod 31 extends straight downward. Since the first bearing 12 and the second bearing 20 must be connected with rigidity, the first bearing 12 and the second bearing 20 are connected by the connection fixing screw 19 using the rod connection plate 33. If the linear rod is used, the first bearing 12 and the second bearing 20 can be coupled linearly, but instead, the first bearing 12 and the second bearing 20 need to be inclined with respect to the table 21 and the arm 11. This sensor has six arms, and it is very difficult to tilt the bearings in each of them. By connecting the first bearing 12 and the second bearing 20 in a crank shape using the rod connecting plate 33, each bearing can be easily attached without impairing rigidity.

  Each first bearing 12 is fitted into the through hole of the table 21 from the back side, and is locked to the table 21 by the holder step 41. A pressing plate 22 is disposed below the first bearing holder portion 14. After all the first bearings 12 are fitted to the table 21, the first bearing fixing screw 23 is tightened, whereby the holder step portion 41. Is fixed between the table 21 and the pressing plate 22. As shown in FIG. 6, a plurality of hand mounting screw holes 52 are provided on the surface of the table 21, and are connected to, for example, a robot hand.

  The first bearing 12 and the second bearing 20 include rods 31 and 35, ball portions 13 and 17, bearing portions 25 and 26, and holder portions 14 and 18. The bearing part is divided into two parts, an upper bearing part 25 and a lower bearing part 26, and is housed in the holders 14 and 18 so as to sandwich the ball parts 13 and 17. These bearing portions are formed so as to be slidable with respect to the holders 14 and 18, and by rotating a ball portion adjustment plate screwed into a female screw portion 42 formed at the ends of the holders 14 and 18, The smoothness and play of movement can be adjusted.

  The bearing used in the present invention can be formed, for example, by integrally molding the bearing portion with a molten metal ball portion by metal sintering or resin molding. Although it can be used as it is, the smoothness of the operation and the adjustment of play can be adjusted as described above by cutting the formed bearing portion up and down and storing it in the holder.

  In the above-described embodiment, as shown in FIG. 1, the base 2 is provided with the side wall portion 63, so the gap with the table 21 is small but cannot be completely eliminated. Covering from the table 21 to the side wall portion 63 with the cover can prevent the entry of dust and the like from the outside, thereby preventing contamination inside the sensor and is more effective.

  Now, regarding the operation of the sensor 24 according to the above-described embodiment, when the table 21 receives a force from the outside, it is transmitted from the six first bearings 12 to the arm 11 through the second bearing 20, and the arm is deformed. When the distance between the sensor 24 and the arm 11 changes due to this deformation, the eddy current value changes, so this change is detected, and the values of the six sensors are calculated by the CPU, whereby the six-axis force component is calculated. . As the sensor 24, not only an eddy current element but also other elements such as a capacitive element can be used.

  In the above-described embodiment, the sensor 24 is disposed on the circuit board 9. However, if the acceleration sensor 24 is disposed on the arm operation unit 32, the sensor 24 can be used as a motion sensor.

  In the sensor manufacturing method according to the above embodiment, the circuit board 9 is first accommodated in the base 2 and fixed by the board fixing screws 7. Next, the second bearing 20 is attached to the arm 11 and fixed by the second bearing fixing screw 36. Subsequently, the arm 11 is placed on the convex portion 62 of the base 2 and fixed by the arm fixing screw 10 through the arm pressing 43. Next, after the pressing plate 22 is housed in the base 2, each first bearing 12 is fitted to the table 21, and finally the table 21 and the pressing plate 22 are tightened by the first bearing fixing screw 23, thereby the first bearing. 12 is fixed. When this sensor is attached to a robot or the like, a screwdriver or the like is inserted into the attachment 1 previously attached on the robot from the sensor attachment through hole 64 on the table and fixed by the sensor attachment screw 6.

  FIG. 7 shows another embodiment of the force or motion sensor according to the present invention. FIG. 7 is a cross-sectional view of the main part of this embodiment. In the embodiment described above, the overload protection means 3 is provided only on the bottom surface portion 61 of the base 2 as shown in FIG. 3, but in this embodiment, not only the protection means 3A of the bottom surface portion 61 but also the side wall portion. 63 also has another protection means 3B. In the first embodiment, the direction of overload is considered only in the downward direction in FIG. 3, but in this embodiment, by providing the protection means 3B, not only the downward direction in FIG. It is possible to protect even when an overload is applied upward.

  The force or motion sensor according to the present invention has been described above, but it goes without saying that many modifications can be made without departing from the spirit of the present invention.

  According to the present invention, it is possible to provide a highly reliable force sensor or motion sensor that is simple in structure, low in manufacturing cost, and easy to downsize. Furthermore, according to the present invention, it is possible to provide a method for manufacturing a highly reliable force sensor or motion sensor. Therefore, it can greatly contribute to the field of force sensor and motion sensor.

It is sectional drawing which shows the Example of the force sensor or motion sensor by this invention. It is the fragmentary sectional view which showed the relationship between the 1st bearing in the Example shown in FIG. 1, and a 2nd bearing. It is an expanded sectional view which shows the structure of the 2nd bearing in the Example shown in FIG. It is a top view which shows the relationship between the base in the Example shown in FIG. 1, and a circuit board. It is a top view which shows the relationship between the base and arm in the Example shown in FIG. It is a top view of the sensor of the Example shown in FIG. It is an expanded sectional view which shows the structure of the 2nd bearing in another Example of the force sensor or motion sensor by this invention.

DESCRIPTION OF SYMBOLS 1 Attachment 2 Base 3, 3A, 3B Overload protection means 4 Base positioning protrusion 5 Attachment mounting screw 6 Sensor mounting screw 7 Substrate fixing screw 8 Substrate positioning pin 9 Circuit board 10 Arm fixing screw 11 Arm 12 First bearing 13 Ball portion 14 Holder 15 Ball portion adjusting plate 16 Rod 17 Ball portion 18 Holder 19 Connecting plate fixing screw 20 Second bearing 21 Table 22 Press plate 23 First bearing fixing screw 24 Sensor element 25 Upper bearing portion 26 Lower bearing portion 27 Board mounting screw hole 28 Board Positioning Pin Hole 30 Arm Base 31 First Bearing Rod 32 Arm Acting Unit 33 Rod Connecting Plate 34 Connecting Plate Fixing Screw 35 Second Bearing Rod 36 Second Bearing Fixing Screw 41 Holder Step 42 Female Screw 43 Arm Press 44 Substrate pressing protrusion 51 Substrate receiving step 52 c De mounting screw hole 53 substrate support projections 61 bottom part 62 central convex portion 63 side wall portion 64 sensor attachment holes

Claims (10)

  A base, a table having six degrees of freedom with respect to the base, and arranged to face the base; six connecting portions arranged in parallel to connect the base and the table; the base and the In a sensor comprising a plurality of detection elements for detecting displacement and / or deformation between the table and an arithmetic unit for comprehensively calculating the displacement and / or deformation amount of each detection element, The table-side first bearing is configured to be fitted from the back side of the table, and is held and fixed by a pressing plate fixed to the table and the table.   Each of the connecting portions includes a first bearing connected to the table, a rod connected to the first bearing, a second bearing provided at an end of the rod opposite to the first bearing, The force sense according to claim 1, comprising an arm fixed to the base and connected to the second bearing, wherein the arm is formed of a plate-like member that can be connected to the six connecting portions. Or motion sensor.   The first bearing of the connecting portion is installed perpendicular to the table, the second bearing is installed perpendicular to the arm, and the first bearing and the second bearing are rod-connected. The force or motion sensor according to claim 1 or 2, wherein the force sensor or the motion sensor is connected by a plate.   The said arm consists of an elastic member, The said base was provided with the overload protection part which prevents destruction of the said arm when the said arm is over-displaced and / or over-deformed. Force or motion sensor.   5. The force according to claim 1, wherein the first bearing and / or the second bearing of the connecting portion is a ball joint, and at least the ball portion and the bearing portion are integrally formed. Sense or motion sensor.   6. The force or motion sensor according to claim 5, wherein the ball portion and the bearing portion are integrally formed by metal sintering or resin molding.   The force sensor or motion sensor according to claim 5 or 6, wherein the bearing part is divided into two parts.   The holder part of the said 1st bearing and / or a 2nd bearing was provided with the clearance adjustment function which adjusts the play of the said ball | bowl part and the said bearing part, The Claim 5 thru | or 7 characterized by the above-mentioned. Force or motion sensor.   The force sensor or motion sensor according to any one of claims 1 to 8, wherein the outside of the base and the table is covered with an extendable cover.   A rod connected to a table with respect to a base including a calculation unit that comprehensively calculates the displacement and / or deformation amount of the detection element; and a first bearing provided at the table side end of the rod; After fixing a plurality of connecting portions composed of a second bearing provided on the opposite end of the rod to the first bearing and an arm connected to the second bearing, a pressing plate is arranged, After the first bearing of the portion is fitted and assembled at a predetermined position of the table, the connecting portion is fixed to the table by connecting the table and the pressing plate by a connecting means. A method of manufacturing a sense or motion sensor.

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