FORCE DETECTING DEVICE, ROBOT, ELECTRONIC COMPONENT CONVEYING APPARATUS

• US 20150127159A1
• Filed: 11/04/2014
• Published: 05/07/2015
• Est. Priority Date: 11/05/2013
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: KAMIYA, Toshiyuki, KAWAI, Hiroki
• Granted Patent: US 9,770,826 B2
• Time in Patent Office: Days
• US Class Current: 700/258
• CPC Class Codes: B25J 13/085 Force or torque sensors B25J13/082, B25J13/084 take precedence
• CPC Class Codes: B25J 9/1633 compliant, force, torque control, e.g. combined with position control
• CPC Class Codes: B25J 9/1694 characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
• CPC Class Codes: G01L 1/16 using properties of piezoelectric devices
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
• CPC Class Codes: G01L 5/00 Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
• CPC Class Codes: G01L 5/009 Force sensors associated with material gripping devices
• CPC Class Codes: G01L 5/167 using piezoelectric means
• CPC Class Codes: G01L 5/226 to manipulators, e.g. the force due to gripping
• CPC Class Codes: G01P 15/09 by piezoelectric pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: H02N 2/0095 producing combined linear and rotary motion, e.g. multi-direction positioners
• CPC Class Codes: H10N 30/302 Sensors
• CPC Class Codes: H10N 30/50 having a stacked or multilayer structure
• CPC Class Codes: H10N 30/802 Drive or control circuitry or methods for piezoelectric or electrostrictive devices not otherwise provided for
• CPC Class Codes: Y10S 901/46 Sensing device

Abstract

A force detecting device includes a first base section, a second base section, and a charge output element arranged between the first base section and the second base section. The charge output element includes a first board formed by a Y-cut quartz plate and a second board formed by a Y-cut quartz plate. The boards are laminated in a direction orthogonal to the normal an attachment surface of the second base section. The force detecting device detects an external force on the basis of a first output corresponding to a shearing force in a first detection direction orthogonal to the laminating direction of the first board and a second output corresponding to a shearing force in a second detection direction orthogonal to the laminating direction of the second board and crossing the first detection direction.

Claims

1. A force detecting device comprising:

a first base section;

a second base section; and

a plurality of piezoelectric elements sandwiched by the first base section and the second base section and configured to detect external forces applied to the first base section and the second base section, wherein

the first base section includes a first attachment surface fixed to a measurement target and the second base section includes a second attachment surface fixed to the measurement target,

the piezoelectric element includes a first board formed by a Y-cut quartz plate and a second board formed by a Y-cut quartz plate, the first board and the second board are laminated in parallel, and, in a laminating direction of the first board and the second board, an x axis of the first board and an x axis of the second board cross each other and a z axis of the first board and a z axis of the second board cross each other, and

the piezoelectric element is set such that a normal of the first attachment surface or the second attachment surface and the laminating direction are orthogonal to each other.

2. The force detecting device according to claim 1, wherein the piezoelectric element detects external forces in three directions in total including orthogonal two directions in planes of the first board and the second board and one direction orthogonal to the two directions.

3. The force detecting device according to claim 1, wherein

at least one base section of the first base section and the second base section is formed by a member formed in a tabular shape, and

when orthogonal two directions in a plane of the member are represented as A axis and B axis, a direction orthogonal to the A axis and the B axis is represented as C axis, an inclination angle of the piezoelectric element with respect to the A axis is represented as ε

, an angle formed by the x axis of the first board of the piezoelectric element and the member is represented as η

, a force applied in the x-axis direction of the first board of one piezoelectric element in two piezoelectric elements among the plurality of piezoelectric elements is represented as fx1-1, a force applied in the x-axis direction of the second board is represented as fx1-2, a force applied in the x-axis direction of the first board of the other piezoelectric element is represented as fx2-1, and a force applied in the x-axis direction of the second board is represented as fx2-2, a force FA in the A-axis direction, a force FB in the B-axis direction, and a force FC in the C-axis direction are respectively represented by the following expressions (1), (2), and (3);

FA=fx1-1·

cos η

·

cos ε

−

fx1-2·

sin η

·

cos ε

−

fx2-1·

cos η

·

cos ε

+fx2-2·

sin η

·

cos ε

 

 

(1)

FB=−

fx1-1·

cos η

·

sin ε

+fx1-2·

sin η

·

sin ε

−

fx2-1·

cos η

·

sin ε

+fx2-2·

sin η

·

sin ε

 

 

(2)

FC=−

fx1-1·

sin η

−

fx1-2·

cos η

−

fx2-1·

sin η

−

fx2-2·

cos η

 

 

(3).

4. The force detecting device according to claim 1, wherein

the force detecting device includes a plurality of pressurizing screws provided around the piezoelectric element and configured to apply pressurization to the piezoelectric element, and

a pressurization direction of the pressurizing screw is a direction parallel to the laminating direction of the first board and the second board.

5. The force detecting device according to claim 1, wherein the plurality of piezoelectric elements include the piezoelectric elements not arranged on the same plane and not arranged in parallel to each other.

6. The force detecting device according to claim 1, wherein

at least one base section of the first base section and the second base section is formed in a tabular shape, and

in the plurality of piezoelectric elements, the first board and the second board are arranged perpendicularly to the one base section.

7. The force detecting device according to claim 1, wherein

at least one base section of the first base section and the second base section is formed in a tabular shape, and

a quartet or more of the piezoelectric elements are respectively arranged in positions apart from a center section of the one base section when viewed from the attachment surface on which the one base section is fixed to the measurement target.

8. The force detecting device according to claim 1, wherein the piezoelectric element includes a third board formed by an X-cut quartz plate.

9. A robot comprising:

an arm;

an end effector provided in the arm; and

the force detecting device of claim 1 provided between the arm and the end effector and configured to detect an external force applied to the end effector.

10. An electronic component conveying apparatus comprising:

a gripping section configured to grip an electronic component; and

the force detecting device of claim 1 configured to detect an external force applied to the gripping section.

11. A force detecting device comprising:

a first base section;

a second base section; and

a plurality of piezoelectric elements sandwiched by the first base section and the second base section and configured to detect external forces applied to the first base section and the second base section, wherein

the first base section includes a first attachment surface fixed to a measurement target and the second base section includes a second attachment surface fixed to the measurement target, and

the piezoelectric element includes a first board and a second board having a laminating direction orthogonal to a normal direction of the first attachment surface or the second attachment surface and detects the external forces applied to the first base section and the second base section from detection of a shearing force in a first detection direction same as the normal direction by the first board and detection of a shearing force in a second detection direction crossing the first detection direction by the second board.

12. The force detecting device according to claim 11, wherein

the first board and the second board are Y-cut quartz plates, and

an x axis of a quartz crystal of the first board and an x axis of a quartz crystal of the second board are orthogonal to each other.

13. The force detecting device according to claim 11, wherein

an A axis, a B axis, and a C axis, which are orthogonal coordinate axes, are set as coordinate axes in which the C axis is in a direction parallel to an intersection line of a first plane orthogonal to a first sandwiching direction and a second plane orthogonal to a second sandwiching direction, and

the external forces applied to the first base section and the second base section are detected as components of external forces in the three axis directions.

14. The force detecting device according to claim 12, wherein

the force detecting device includes a plurality of pressurizing screws provided around the piezoelectric element and configured to apply pressurization to the piezoelectric element, and

a pressurization direction of the pressurizing screw is a direction parallel to the laminating direction of the first board and the second board.

15. A force detecting device comprising:

a first base section;

a second base section; and

a plurality of piezoelectric elements sandwiched by the first base section and the second base section and configured to detect external forces applied to the first base section and the second base section, wherein

the first base section includes a first attachment surface fixed to a measurement target and the second base section includes a second attachment surface fixed to the measurement target,

the piezoelectric element is set such that a normal of the first attachment surface or the second attachment surface and a laminating direction of a first board and a second board of the piezoelectric element are orthogonal to each other, and

total weight of the force detecting device is smaller than 1 kg.

17. The force detecting device according to claim 15, wherein the conversion circuit or the arithmetic circuit includes at least any one of a semiconductor switch and an MEMS switch.

19. The force detecting device according to claim 15, wherein

the first base section and the second base section form a housing space having a circular or corner-rounded square sectional shape, and

distances between the respective piezoelectric elements and the center of the first attachment surface or the second attachment surface corresponding to the piezoelectric elements are equal.

16. A force detecting device comprising:

a first base section;

a second base section; and

a plurality of piezoelectric elements sandwiched by the first base section and the second base section and configured to detect external forces applied to the first base section and the second base section, wherein

the first base section includes a first attachment surface fixed to a measurement target and the second base section includes a second attachment surface fixed to the measurement target,

the piezoelectric element is set such that a normal of the first attachment surface or the second attachment surface and a laminating direction of a first board and a second board of the piezoelectric element are orthogonal to each other, and

a conversion circuit configured to convert charges output by the plurality of piezoelectric elements into a voltage and an arithmetic circuit configured to calculate an external force from the voltage are housed in a space between the first base section and the second base section.

18. The force detecting device according to claim 16, wherein the conversion circuit or the arithmetic circuit includes at least any one of a semiconductor switch and an MEMS switch.

20. A robot comprising:

a force detecting device including a plurality of piezoelectric elements configured to detect an external force; and

a robot arm, wherein

weight of the force detecting device is smaller than 20% of maximum weight that the robot arm can convey.