JP2018119823A - Hardness measurement device, system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hardness measurement device and the like that can correctly measure hardness of an object even if force pinching the object fluctuates.SOLUTION: A finger-like structure body 100 has a contact face 105 in which a hole 106 is formed. An elastic body 102 has an indenter point 104 that protrudes from the hole 106. A finger without sensor 11 has a contact face 107 that opposes the contact face 105. A finger-like structure body-purposed strain sensor 101 is configured to measure strain εof the finger-like structure body 100. An elastic body-purposed strain sensor 103 is configured to measure strain εof the elastic body 102. A CPU of a hardness measurement device is configured to determine hardness H of an object 13 on the basis of the strain εand the strain εmeasured during a period in which the contact face 105 and the contact face 107 pinches the object 13 with force F1.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a hardness measurement apparatus, system, and method.

  As a sensor for detecting hardness as an electrical signal, a softness sensor that can measure the softness of a substance having rheological properties by pressing is disclosed (for example, see Patent Document 1). This sensor has one elastic film provided at one end of a box that is open at both ends and pressed against the object to be measured, and another elastic film provided at the other end of the box and provided with a strain gauge on the surface. An incompressible fluid is sealed in the box so as to transmit the pressure received by the one elastic membrane from the object to be measured to the other elastic membrane, and the strain gauge is connected to the pressure gauge via the pressure measuring device. When connected to an inference device that infers the elasto-plastic softness of the object to be measured from the size and its time relaxation rate or relaxation time, the object to be measured is pressed against one elastic membrane. The pressure is detected by the strain gauge through the incompressible fluid, and the softness of the object to be measured is measured from the detected pressure signal.

  Moreover, a living body hardness measurement apparatus that can measure the hardness of a measurement object simply by statically pressing the measurement object is disclosed (for example, see Patent Document 2). This sensor has a sensor base composed of a soft solid material and a thin plate inserted in a non-flexible hollow material of appropriate hardness and a soft solid material and a thin plate. Is a hardness measurement sensor having a structure fixed by a non-flexible hollow material, and each of the forces applied to the non-flexible hollow material and the sensor base at the sensor tip is measured, and the ratio of these forces is used to measure the sensor. From the characteristic curve, the hardness of the measurement object is quantitatively estimated by Young's modulus.

JP-A-1-213546 JP 2009-273777 A

  With the progress of automation at the manufacturing site, the needs for industrial robot hands are expected to increase in the future. In a manufacturing site that handles a plurality of parts, there is a demand for a robot hand that can be gripped with an optimum force for each type of part. The reason is that if the gripping force is too weak, there is a risk of dropping when carrying the target component, and if the gripping force is too strong, the target component may be destroyed.

  As a method for eliminating these dangers, a force for gripping the robot hand can be set according to a predetermined process. This method is effective when the type of the object and the order of carrying are determined. However, in a manufacturing site where a large amount of objects are supposed to be handled in one day, there is a possibility that process changes may be required according to the occurrence of large and small troubles. Therefore, in this method, it is necessary to reset the gripping force of the robot hand by changing the process, and as a result, manufacturing delay can be a problem.

  Therefore, there is a need for a robot hand that does not set the gripping force in advance but can measure the hardness of the object when it is gripped and control the gripping force. In order to realize this robot hand, a sensor for measuring the hardness of an object that can be incorporated into the fingertip of the robot hand is required.

  When the object is rubber or plastic, a durometer is generally used as an instrument for measuring its hardness. The durometer is an instrument that displays the pushing amount of the push needle when the push force is pushed into the object with the force of the spring and the repulsive force of the object and the force of the spring are balanced as a hardness of 0 to 100. . Although the hardness of the object can be measured very easily, it is structurally difficult to incorporate it into the finger of the robot hand.

  On the other hand, the softness sensor described in Patent Document 1 can measure the deformation of the shape depending on the hardness of the object as an electrical signal simply by pressing the sensor. Therefore, when it is necessary to adjust the pressing force like a robot hand, the hardness cannot be measured accurately. In addition, because of the structure in which the incompressible fluid is confined with an elastic film inside the sensor, advanced technology is required to manufacture the sensor so as to prevent leakage of the incompressible fluid. Because of the structure in contact with the sensor, there is a problem with the durability of the sensor.

  Furthermore, the living body hardness measuring device described in Patent Document 2 can measure the deformation of the shape and the pressing force depending on the hardness of the object by simply pressing the device. It is considered that there is a problem in the durability of the sensor because of the structure in which the soft flexible solid material is in contact with the object. In addition, since the pressing force of the sensor is measured through a soft flexible solid material, transmission of the pressing force is insufficient due to deformation of the flexible solid material, and it is considered that the measurement of the pressing force is inaccurate.

  An object of the present invention is to provide a hardness measuring device or the like that can accurately measure the hardness of an object even if the force sandwiching the object fluctuates.

  In order to achieve the above object, the present invention provides a first member having a first surface in which a hole is formed, a second member having a protruding portion protruding from the hole, and a second member facing the first surface. A third member having a surface; a first sensor for measuring a first strain of the first member; a second sensor for measuring a second strain of the second member; and the first surface and the second surface. And a processor for determining the hardness of the object based on the first strain and the second strain measured during a period in which the object is sandwiched between the first forces.

  According to the present invention, it is possible to accurately measure the hardness of an object even if the force sandwiching the object fluctuates. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a figure which shows the structure of the robot hand by embodiment of this invention. It is a figure which shows the structure of the robot hand by embodiment of this invention. It is a figure which shows the structure of the finger with a sensor of the robot hand by embodiment of this invention. It is a figure which shows the structure of the finger with a sensor of the robot hand by embodiment of this invention. It is a system diagram which controls a robot hand by an embodiment of the present invention. It is a figure which shows an example of ((epsilon) _a , (epsilon) _b ) -H database. It is a figure which shows an example of the ((epsilon) _a / (epsilon) _b ) -H database. It is a flowchart which shows another example of operation | movement of a system. is a diagram illustrating an example of epsilon _a -F database. It is a figure which shows an example of a (F, (epsilon) _b ) -H database. It is a figure which shows an example of HF database.

  Hereinafter, the configuration and operation of a system including a hardness measurement device according to an embodiment of the present invention will be described with reference to the drawings. In each figure, the same numerals indicate the same parts. In addition to the object of the present invention described above, an object of the present embodiment is to provide, for example, a hardness measuring device that can be easily manufactured and can improve durability.

  First, the basic configuration of the robot hand 1 according to the present invention will be described with reference to FIG. FIG. 1 is an external view of the robot hand 1 holding the object 13. The robot hand 1 includes a finger 10 with a sensor, a finger 11 without a sensor, and an arm 12. The sensored finger 10 and the sensorless finger 11 can grip the object 13 by moving in the direction of the arrow 190.

  Next, the structure of the surface on which the sensor-equipped finger 10 contacts the object 13 will be described with reference to FIG. FIG. 2 is an external view of the robot hand 1 in a state where the object 13 is not grasped. The sensor-equipped finger 10 and the sensorless finger 11 sandwich the object 13 between the circular contact surface 105 and the contact surface 107. In the figure, the contact surface 105 and the contact surface 107 are circular, but there is no problem even if they are polygonal. Further, the contact surface 105 of the sensor-equipped finger 10 has a hole 106 at the center thereof, and has a structure in which a part of the push needle 104 connected to the elastic body 102 described later protrudes from the hole 106.

  In other words, the finger-like structure 100 (first member) has the contact surface 105 (first surface) on which the hole 106 is formed. The elastic body 102 (second member) has a push needle 104 (projection) that projects from the hole 106. The sensorless finger 11 (third member) has a contact surface 107 (second surface) facing the contact surface 105 (first surface). Since the number of parts is small, for example, manufacturing is easy.

  Next, a mechanism for measuring the hardness of the object 13 when the object 13 is grasped by the robot hand 1 will be described with reference to FIG. FIG. 3 is a cross-sectional view of the robot hand 1. The robot hand 1 is composed of the sensor-equipped finger 10, the sensorless finger 11, and the arm 12 as described above, and sandwiches the object 13 by moving the sensorized finger 10 and the sensorless finger 11 in the direction of the arrow 190. The sensor-equipped finger 10 measures the hardness of the finger-like structure 100, the finger-like structure strain sensor 101 for measuring the strain generated in the arm 109 of the finger-like structure 100, and the hardness of the object 13. An elastic body 102, an elastic body strain sensor 103 for measuring strain generated in the arm 110 of the elastic body 102, and a push needle 104 for connecting the tip 13 of the elastic body 102 to push the object 13. Composed.

In other words, the finger-shaped structure strain sensor 101 (first sensor) measures the strain ε _a (first strain) of the finger-shaped structure 100 (first member). The elastic body strain sensor 103 (second sensor) measures the strain ε _b (second strain) of the elastic body 102 (second member).

  The finger-like structure 100 includes a head portion 108 and an arm 109, and the head portion 108 has a shape extending from the contact surface 105 toward the arm 109, and has a structure in which the elastic body 102 is accommodated inside the head portion 108.

  The elastic body 102 has a cantilever structure including a distal end portion 111 having a push needle 104 and an arm 110, and a distal end 112 of the arm 110 fixed to the distal end of the head portion 108 of the finger-like structure 100.

In other words, the elastic body 102 (second member) has a cantilever structure. By the cantilever structure, the thickness in the direction Dir1 can be reduced, and the size can be reduced. The finger-like structure 100 (first member) has a head portion 108 (support portion) that supports the base of the elastic body 102 (second member). The head portion 108 includes a portion 108a extending in the upward direction in FIG. 3 (direction Dir1 from the contact surface 107 toward the contact surface 105) and a left direction in FIG. 3 (direction Dir2 from the tip of the finger 10 with sensor toward the root). 108b. The head portion 108 can reduce, for example, the influence of the elastic force of the elastic body 102 on the strain ε _a measured by the finger-like structure strain sensor 101.

When the object 13 is sandwiched between the sensor-equipped finger 10 and the sensorless finger 11, the contact surface 105 of the finger-like structure 100 receives a normal force equal to the pinched force from the object 13, and the finger-like structure 100 is caused by the force. A strain ε _a is generated in the arm 109. The strain ε _a can be measured by the finger-shaped structure strain sensor 101 attached to the arm 109 of the finger-shaped structure 100. Since the measured strain amount is proportional to the normal force, the strain ε _a is used for the finger-shaped structure. The force with which the object 13 is sandwiched between the sensor-equipped finger 10 and the sensorless finger 11 can be measured by the output value of the strain sensor 101.

  At this time, the push needle 104 of the elastic body 102 also pushes the object 13. When the push needle 104 is pushed, the object 13 is deformed and a dent 131 is generated. The object 13 generates a restoring force to return to the original and pushes back the push needle 104. The softer the object 13, the smaller the restoring force, and the push needle 104 is pushed deeper into the object 13.

As a result, the distance between the tip of the push needle 104 and the contact surface 105 when the restoring force of the object 13 and the pushing force of the push needle 104 are balanced is a value depending on the hardness of the object 13. Further, since this value has a correlation with the strain ε _b generated in the arm 110 of the elastic body 102, the strain ε _b is measured by the elastic strain sensor 103 attached to the arm 110 of the elastic body 102, and the output value is obtained. Thus, the hardness of the object 13 can be measured.

The force with which the push needle 104 pushes the object 13 and the strain ε _b generated on the arm 110 of the elastic body 102 change depending on the magnitude of the force that sandwiches the object 13 between the sensor-equipped finger 10 and the sensorless finger 11. In the configuration of the embodiment, since the force with which the robot hand 1 pinches the object 13 can be measured from the strain ε _a of the arm 109 of the finger-like structure 100, it occurs in the arm 110 of the elastic body 102 according to the pinching force. By creating a database related to the strain ε _b to be made for each object, it is possible to measure the hardness of the object 13 even if the pinching force changes. Further, if the object 13 is an elastic body, the ratio ε _b / ε _a of the strain ε _a of the arm 109 of the finger-like structure 100 and the strain ε _b generated in the arm 110 of the elastic body 102 is fixed. It becomes a value depending on the thickness, and it can be determined that the larger the value, the harder the substance.

Next, conditions for selecting materials for the finger-like structure 100, the elastic body 102, and the push needle 104 in this embodiment will be described. Since the elastic body 102 needs to bend more easily than the finger-like structure 100, the Young's modulus e _e of the elastic body 102 has a finger-like structure 100 as a condition for selecting the material of the finger-like structure 100 and the elastic body 102. it is preferable smaller than the Young's modulus e _f. In other words, the elastic body 102 (second member) is more flexible than the finger-like structure 100 (first member). Accordingly, when the contact surface 105 and the contact surface 107 are in contact with the object 13, the push needle 104 and the tip end portion 111 of the elastic body 102 are easily pushed into the direction Dir1.

  In use, since the push needle 104 is pressed directly against the object 13 and is required to have a property that is difficult to bend and deteriorate even in a thin structure, it is preferable to select a material having high rigidity. While maintaining this relationship, the robot hand 1 can be made from metals such as iron, stainless steel and aluminum, engineering plastics such as polycarbonate and polyamide, plastics such as polypropylene and acrylic, rubbers such as silicone rubber and chloroprene rubber. The material of the finger-like structure 100, the elastic body 102, and the push needle 104 is selected according to the usage. Thereby, durability can be improved.

  FIG. 4 is an example in which the push needle 104 is not used. In this modification, since the strain of the finger-like structure 100 and the elastic body 102 is used, a part (protrusion) of the tip portion 111 of the elastic body 102 is a hole in the contact surface 105 of the finger-like structure 100. If it protrudes from 106, it is not necessary to provide the push needle 104 as shown in FIG. When there is a problem in durability in the tip portion 111 by not using the push needle 104, it is preferable to perform a process such as partially curing only the tip portion 111.

(Operation example 1)
Next, a control method of the robot hand 1 according to the hardness of the object 13 will be described with reference to FIG. FIG. 5 is a system diagram of the robot hand 1. The robot hand 1 is used by being connected to a hardness measuring device 150 for measuring the hardness of the object 13 and a robot hand control device 151. For example, the hardness measurement device 150 and the robot hand control device 151 are each configured by a separate microcomputer, but may be configured by one microcomputer. The microcomputer includes a CPU (Central Processing Unit), a memory, an input / output device, and the like.

First, when the robot hand control device 151 instructs the robot hand 1 to hold the object 13 with a constant force F1 (arrow 154), when the robot hand 1 holds the object 13 with a constant force F1, the robot hand 1 From the hand 1 to the hardness measuring device 150, the strain ε _a of the arm 109 (FIG. 3) of the finger structure 100 (FIG. 3) and the strain ε generated in the arm 110 (FIG. 3) of the elastic body 102 (FIG. 3). Information _b is transmitted (arrow 152). The hardness measuring device 150 determines the hardness of the object 13 from ε _a and ε _b and sends the hardness information to the robot hand control device 151 (arrow 153). The robot hand control device 151 holds a database on the optimum magnitude of the force with respect to the hardness of the object 13, and the gripping force is set to an optimum value according to the hardness of the object 13 by collating with the database. It can be adjusted (arrow 154).

In other words, in the CPU (processor) of the hardness measuring device 150, the contact surface 105 (first surface) and the contact surface 107 (second surface) sandwich the object 13 with the force F1 (first force). Based on the strain ε _a (first strain) and strain ε _b (second strain) measured during the period, the hardness H of the object 13 is determined.

Specifically, the memory of the hardness measuring device 150 includes the (ε _a , ε _b ) -H database 201 shown in FIG. Here, the (ε _a , ε _b ) -H database 201 (first database) includes a combination of strain ε _a (first strain) and strain ε _b (second strain), and the hardness H of the object 13. Are stored in association with each other. The CPU (processor) of the hardness measuring device 150 includes a strain ε _a measured by the finger-shaped structure strain sensor 101 (first sensor) and a strain ε measured by the elastic body strain sensor 103 (second sensor). By reading the hardness H of the object 13 corresponding to the combination of _{b from} the (ε _a , ε _b ) -H database 201, the hardness H of the object 13 is determined.

On the other hand, instead of the (ε _a , ε _b ) -H database 201 shown in FIG. 6, the (ε _a / ε _b ) -H database 202 shown in FIG. 7 may be used. Here, the (ε _a / ε _b ) -H database 202 (second database) includes the ratio of strain ε _a (first strain) and strain ε _b (second strain), and the hardness H of the object 13. Are stored in association with each other. The CPU (processor) of the hardness measuring device 150 determines the hardness H of the object 13 based on the ratio of the strain ε _a and the strain ε _b . By using the ratio of the strain epsilon _a strain epsilon _b, for example, the size of the database is reduced, the calculation amount of CPU is also reduced.

Specifically, the CPU (processor) of the hardness measuring device 150 corresponds to the ratio of the strain ε _a measured by the finger-shaped structure strain sensor 101 and the strain ε _b measured by the elastic body strain sensor 103. The hardness H of the object 13 is determined by reading the hardness H of the object 13 from the (ε _a / ε _b ) -H database 202.

  As described above, according to the present embodiment, it is possible to accurately measure the hardness of an object even if the force sandwiching the object fluctuates.

(Operation example 2)
Next, another operation example of the system will be described with reference to FIG. The flowchart shown in FIG. 8 is an example showing an operation when it is assumed that the object 13 is an elastic body.

The robot hand control device 151 transmits a command F1 ^* for sandwiching the object 13 with a force F1 to an actuator (not shown) that drives at least one of the sensor-equipped finger 10 and the sensorless finger 11. Upon receiving the command F1 ^* , the actuator drives at least one of the sensor-equipped finger 10 and the sensorless finger 11. Thereby, the sensor-equipped finger 10 and the sensorless finger 11 start an operation of sandwiching the object 13 with the force F1 (S10).

The hardness measuring device 150 determines whether or not the strain ε _b of the elastic body 102 indicated by the output value of the elastic body strain sensor 103 is greater than 0 (S15). When the strain ε _b is 0 or less (S15: No), the hardness measuring device 150 repeats the determination of S15. On the other hand, if the strain ε _b is greater than 0 (S15: Yes), the hardness measuring device 150 proceeds to S20.

Hardness measurement device 150 stores the timing t1 it is determined that the strain epsilon _b is greater than 0 in the memory. That is, the hardness measuring device 150 identifies the timing t1 when the push needle 104 as the protruding portion or the tip portion 111 of the elastic body 102 contacts the object 13 (S20).

The hardness measuring device 150 determines whether or not the strain ε _a of the finger-like structure 100 indicated by the output value of the finger-like structure strain sensor 101 is greater than 0 (S25). When the strain ε _a is 0 or less (S25: No), the hardness measuring device 150 repeats the determination of S25. On the other hand, when the strain ε _a is greater than 0 (S25: Yes), the hardness measuring device 150 advances the process to S30.

Hardness measurement device 150 stores the timing t2 where it is determined that the strain epsilon _a is larger than 0 in the memory. That is, the hardness measuring device 150 specifies the timing t2 when the contact surfaces 105 and 107 contact the target 13 (S30).

Hardness measuring device 150 determines whether the strain epsilon _a is constant (S35). When the strain ε _a is not constant (S35: No), the hardness measuring device 150 repeats the determination of S35. On the other hand, if the strain epsilon _a is constant (S35: Yes), firmness measuring device 150 advances the processing to S40.

The hardness measuring device 150 reads the pinching force Fg corresponding to the strain ε _a (constant value) measured in S35 from the ε _a -F database 203 shown in FIG. 9 (S40). Here, the ε _a -F database 203 stores the strain ε _a and the force F sandwiching the object 13 in association with each other. Thereby, the hardness measuring apparatus 150 measures force Fg which pinches | interposes the target object 13 (S45).

The hardness measuring device 150 determines whether or not the strain ε _b is constant (S50). When the strain ε _b is not constant (S50: No), the hardness measuring device 150 repeats the determination of S50. On the other hand, when the strain ε _b is constant (S50: Yes), the hardness measuring device 150 advances the process to S55.

Hardness measuring device 150, shown in FIG. 10 (F, ε _b) of -H database 204, corresponding to the combination of the measured sandwich force Fg and strain measured at S50 epsilon _b (constant value) at S45 target The hardness H of the object is read (S55). Here, the (F, ε _b ) -H database 204 stores the combination of the sandwiching force F and the strain ε _b and the hardness H (an index indicating the hardness) of the object 13 in association with each other. Thereby, the hardness measuring device 150 determines (measures) the hardness H of the object 13 (S60). The hardness measuring device 150 transmits the hardness H (measured value) of the object 13 to the robot hand control device 151.

  When the robot hand control device 151 receives the hardness H of the object 13 from the hardness measurement device 150, the robot hand control device 151 obtains a pinching force F2 (optimum) corresponding to the hardness H of the object 13 from the HF database 205 shown in FIG. The second force indicating a strong force is read (S65). Here, the HF database 205 (third database) stores the hardness H of the object 13 and the optimum clamping force F (second force) corresponding to the hardness H of the object 13 in association with each other. To do. Thereby, the robot hand control device 151 determines an optimum clamping force F2 according to the hardness H of the object 13.

The robot hand control device 151 transmits a command F2 ^* for sandwiching the object 13 with a force F2 to an actuator that drives at least one of the sensor-equipped finger 10 and the sensorless finger 11. Upon receiving the command F2 ^* , the actuator drives at least one of the sensor-equipped finger 10 and the sensorless finger 11. Thereby, the sensor-equipped finger 10 and the sensorless finger 11 pinch the object 13 with the force F2 (S70).

  In other words, the CPU (processor) of the robot hand control device 151 uses a pinching force F2 (second force) corresponding to the hardness H of the object 13 determined by the CPU (processor) of the hardness measurement device 150. Read out from the HF database 205 (third database), the force F1 (first force) caused by the contact surface 105 (first surface) and the contact surface 107 (second surface) is changed to force F2 (second force). It functions as a force control unit that executes switching control. Thereby, the force grasped according to the hardness of the object 13 can be controlled. Specifically, for example, dropping or destroying the target 13 can be suppressed. Note that the optimum pinching force F of the H-F database 205 can be set based on results of experiments, simulations, and the like, for example.

  In addition, this invention is not limited to above-described embodiment, Various modifications are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to the one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Further, each of the above-described configurations, functions, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by a processor (microcomputer). Information such as programs, tables, and files for realizing each function can be stored in a recording device such as a memory, a hard disk, or an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

  In addition, the following aspects may be sufficient as embodiment of this invention.

  (1) A finger-like structure having an elastic body provided with a needle-like part partially protruding from a frame on a contact surface with an object or an elastic body partially protruding, the elastic body and The finger-like structure includes a sensor for measuring strain generated in each of the finger-like structures, and is generated in the elastic body and the finger-like structure when the object and the frame are in contact with each other. A sensor capable of measuring the hardness of the object by measuring strain.

  (2) The sensor according to (1), wherein the elastic body is more flexible than the finger-like structure, and can measure the hardness of the object.

  (3) The sensor according to (2), wherein the elastic body has a cantilever shape, and the hardness of the object can be measured.

  (4) In the sensor according to (3), the finger-like structure includes a protrusion shape at a tip, and the elastic body is included in the protrusion shape, and measures the hardness of the object. Sensor that can.

  (5) From the ratio of the strain generated in the finger-like structure and the strain generated in the elastic body when the contact surface of the finger-like structure is pressed against the object using the sensor described in (4). Deriving the hardness of the object.

  (6) In the hardness measurement method according to (5), the strain generated in the finger-like structure and the strain generated in the elastic body when the contact surface of the finger-like structure is pressed against the object. A method for determining the hardness of an object from a database in which data is recorded for each object having a different hardness.

  (7) A robot hand including any one of the sensors according to (1) to (4), a determination system for determining the hardness of the object by the method according to (5) or (6), and a robot A system consisting of a control system that controls the movement of the hand.

  (8) In the system according to (7), an optimal value database of gripping force depending on the hardness of the object is provided, and the robot hand is extracted from the database according to the hardness of the object determined by the determination system. A system that can control the gripping force to the optimum value.

  According to the above (1) to (8), by providing a robot hand provided with a sensor-equipped finger that can measure the hardness of an object, the object to be grasped can be fixed even if the grasping force varies. Demonstrate the extremely excellent effect that can be measured.

1: Robot hand 10: Sensored finger 11: Sensorless finger 12: Arm 13: Object 100: Finger-like structure 101: Strain sensor 102 for finger-like structure 102: Elastic body 103: Strain sensor 104 for elastic body: Push Needle 105: Contact surface 106: Hole 107: Contact surface 108: Head portion 109: Arm 110: Arm 111: Tip portion 112: End 150: Hardness measuring device 151: Robot hand control device

Claims (9)

A first member having a first surface in which a hole is formed;
A second member having a protrusion protruding from the hole;
A third member having a second surface facing the first surface;
A first sensor for measuring a first strain of the first member;
A second sensor for measuring a second strain of the second member;
A processor for determining the hardness of the object based on the first strain and the second strain measured during a period in which the first surface and the second surface sandwich the object with a first force; ,
A hardness measuring device comprising: The hardness measuring device according to claim 1,
The second member is
The hardness measuring device is more flexible than the first member. The hardness measuring device according to claim 2,
The second member is
Hardness measuring device characterized by a cantilever structure. The hardness measuring device according to claim 3,
The first member is
It has a support part which supports the base of the 2nd member. A hardness measuring device characterized by things. The hardness measuring device according to claim 1,
The processor is
The hardness measuring device, wherein the hardness of the object is determined based on a ratio between the first strain and the second strain. The hardness measuring device according to claim 1,
A first database for storing the combination of the first strain and the second strain and the hardness of the object in association with each other;
The processor is
By reading from the first database the hardness of the object corresponding to the combination of the first strain measured by the first sensor and the second strain measured by the second sensor, Hardness measuring device characterized by determining hardness. The hardness measuring device according to claim 1,
A second database for storing the ratio of the first strain and the second strain and the hardness of the object in association with each other;
The processor is
By reading out the hardness of the object corresponding to the ratio of the first strain measured by the first sensor and the second strain measured by the second sensor from the second database, Hardness measuring device characterized by determining hardness. A system including the hardness measuring device according to claim 1,
A third database for storing the hardness of the object in association with a second force indicating an optimum force according to the hardness of the object;
The second force corresponding to the stiffness of the object determined by the processor is read from the third database, and the first force by the first surface and the second surface is converted to the second force. A force control unit for executing control to switch to,
A system comprising: A first step of sandwiching an object between a first surface of a first member in which a hole from which a protruding portion of the second member protrudes and a second surface of a third member facing the first surface;
A second step of measuring a first strain of the first member;
A third step of measuring a second strain of the second member;
4th which determines the hardness of the said object based on the said 1st distortion | strain and the said 2nd distortion | strain measured in the period when the said 1st surface and the said 2nd surface pinch | interpose the target object with 1st force. Process,
Having a method.

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