JP2015066610A - Force correction value detection method and robot - Google Patents

Abstract

Provided is a force correction value detection method and a robot capable of always detecting a correct force and applying a correct force without excess or deficiency to a workpiece.
A force correction value detection method detects a first force applied to a force sensor in a first posture by controlling the posture of an arm and setting the posture of an end effector as a first posture. Detecting the second force applied to the force sensor 10 in the second posture by controlling the posture of the arm 16 so that the posture of the end effector 12 is a second posture different from the first posture; and a control unit Includes calculating a drift value of the force sensor 10 by taking a difference between the first force and the second force, and the first point of the end effector 12 is different from the first point. In a straight line passing through the second point of the effector 12, the first direction from the first point in the first posture toward the second point is from the second point in the second posture to the first point. It is the same as the 2nd direction to go.
[Selection] Figure 6

Description

  The present invention relates to a force correction value detection method and a robot.

  In general, the force sensor generates an output drift due to the influence of a temperature change. This output drift is not preferable because it lowers the detection resolution and detection accuracy of the force sensor. For this reason, in assembly work that requires high accuracy, it is necessary to correct the temperature of the sensor.

  For the temperature correction of the force sensor, there is a method in which the temperature coefficient and DC component at each temperature in the operating environment of the force sensor are measured in advance and calculated from the measured values. For example, the difference between the force value (measured value including the drift value) applied by the force caused only by gravity in a specific posture and the value (theoretical value that does not include drift) calculated in advance based on the robot structure. Discloses a method of calculating and correcting a drift value (see, for example, Patent Document 1).

Japanese Patent Publication No.62-114892

  However, in Patent Document 1, if it is a value obtained by calculation on the assumption of the structure of the robot, an unexpected error (encoder error, error due to arm deflection, backlash of the reducer or sliding part error (backlash), part processing) Tolerances, unexpected modifications by users, etc.) are not taken into account and are far from actual values.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A force correction value detection method according to this application example is provided between an arm capable of taking a plurality of postures, an end effector, and the arm and the end effector. A force sensor for detecting a force between the end effector and a control unit for controlling the arm to set an arbitrary posture and calculating a difference between each of a plurality of force signals detected by the force sensor; The controller controls the posture of the arm to detect the first force applied to the force sensor with the posture of the end effector as the first posture, and the controller controls the posture of the arm. Detecting the second force applied to the force sensor in the second posture, and controlling the posture of the end effector as a second posture different from the first posture; and Calculating a drift value of the force sensor by taking a difference between the first force and the second force, and the first point of the end effector is different from the first point In a straight line passing through the second point of the end effector, the first direction from the first point in the first posture toward the second point is the second point in the second posture. It is the same as the 2nd direction which goes to said 1st point from.

  According to this application example, using the first force and the second force, which are two actually measured values in a 180 ° different (inverted) posture of the end effector, the force sensor drift value is obtained by the difference between them. be able to. Thereby, a correct drift value can be obtained in real time by obtaining the above two actually measured values at an arbitrary timing during work. During robot operation, the ambient temperature during actual operation and the heat generated by the motor change slowly. By correcting the force sensor in the immediately preceding state, the correct force can always be detected, and the correct force without excess or deficiency can be applied to the object.

  Application Example 2 In the force correction value detection method according to the application example described above, the detection axis direction of the force sensor in the first posture is parallel to the gravity direction.

  According to this application example, since the detection axis direction (for example, the positive direction) of the force sensor in the first posture is parallel to the gravity direction (that is, vertically downward), the force sensor direction in the second posture which is the 180 ° inversion direction. (In this case, the negative direction) is parallel to the direction of gravity. Thereby, the sensor value which changed the positive / negative of the axial direction (180 degrees) using the dead weight concerning a hand can be acquired, and a sensor value can be corrected. As a result, the detection accuracy can be increased.

  Application Example 3 In the force correction value detection method according to the application example described above, the force sensor includes a plurality of force detection elements whose detection axis directions are orthogonal to each other.

  According to this application example, it is possible to obtain the drift values of the force detection elements in a plurality of directions orthogonal to each other.

  Application Example 4 In the force correction value detection method described in the application example, the end effector is a hand that can grip an object.

  According to this application example, the object can be stably held.

  Application Example 5 A robot according to this application example is arranged between an arm capable of taking a plurality of postures, an end effector, the arm and the end effector, and the arm and the end effector. A force sensor capable of detecting a force between, and a control unit configured to control the arm to set an arbitrary posture and calculate a difference between each of the plurality of force signals detected by the force sensor, The control unit controls the posture of the end effector to control the posture of the end effector to a first posture, and the control unit controls the posture of the arm to change the posture of the end effector after the first posture. The second posture is such that the arbitrary surface faces in a direction opposite to the normal direction of the arbitrary surface predetermined for the end effector in the first posture by 180 °.

  According to this application example, the same effect as the force correction value detection method described above can be obtained. Then, it is possible to feed back the force detected by the force correction value detection method and execute the operation more precisely. Further, the contact of the end effector with the obstacle can be detected by the force detected by the force correction value detection method. Therefore, an obstacle avoidance operation, an object damage avoidance operation, and the like, which are difficult with conventional position control, can be easily performed, and the work can be executed more safely.

The figure which shows an example of the single arm robot using the force detection apparatus which concerns on this embodiment. The figure which shows the force detection apparatus and hand which concern on this embodiment. The figure which shows the force detection apparatus which concerns on this embodiment. 3A is a cross-sectional view taken along line AA in FIG. 3B, and FIG. 3B is a plan view. FIG. 4 is a circuit diagram schematically showing the force detection device shown in FIG. 3. Sectional drawing which shows schematically the electric charge output element of the force detection apparatus shown in FIG. The figure which shows the correction value acquisition state of the force detection apparatus which concerns on this embodiment. FIG. 6A shows the first posture. FIG. 6B shows the second posture. The figure which shows an example of the multi-arm robot using the force detection apparatus which concerns on this embodiment.

  Hereinafter, a force correction value detection method and a robot according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

<Embodiment of single arm robot>
A single arm robot 2 as a robot according to this embodiment will be described.
FIG. 1 is a diagram illustrating an example of a single-arm robot 2 using a force detection device 10 according to the present embodiment. FIG. 2 is a diagram illustrating the force detection device 10 and the hand 12 according to the present embodiment. As shown in FIG. 1, the single-arm robot 2 according to the present embodiment includes a base 14, an arm 16 capable of taking a plurality of postures, and a hand as an end effector provided on the distal end side of the arm 16. 12, a force detection device 10 as a force sensor that is disposed between the arm 16 and the hand 12 and can detect the force between the arm 16 and the hand 12, and controls the arm to set an arbitrary posture. And a control unit 18 that calculates a difference between each of the plurality of force signals detected by the force detection device 10.

  The base 14 has a function of accommodating an actuator (not shown) that generates power for rotating the arm 16, a control unit 18 that controls the actuator, and the like. The base 14 is fixed on, for example, a floor, a wall, a ceiling, or a movable carriage.

  The arm 16 includes a first arm element 20, a second arm element 22, a third arm element 24, a fourth arm element 26, and a fifth arm element 28. It is comprised by connecting so that rotation is possible. The arm 16 is driven by being complexly rotated or bent around the connecting portion of each arm element under the control of the control unit 18.

  The arm 16 causes the hand 12 to take the first posture. After the first posture, the arm 16 causes the hand 12 in the first posture to take a second posture in which the arbitrary surface faces in a direction opposite to the normal direction of the predetermined surface by 180 °.

  The hand 12 has a function of gripping an object as an object. According to this, the object can be gripped stably. The hand 12 has a first finger 30 and a second finger 32. After the hand 12 reaches a predetermined operating position by driving the arm 16, the object can be gripped by adjusting the distance between the first finger 30 and the second finger 32.

  The force detection device 10 has a function of detecting a force applied to the hand 12. By feeding back the force detected by the force detection device 10 to the control unit 18 of the base 14, the single-arm robot 2 can perform more precise work. Further, the single arm robot 2 can detect contact of the hand 12 with an obstacle or the like by the force detected by the force detection device 10. Therefore, an obstacle avoidance operation, an object damage avoidance operation, and the like that are difficult with the conventional position control can be easily performed, and the single-arm robot 2 can perform the work more safely. As shown in FIG. 2, the force detection device 10 is configured to have a hand 12 attached to each X, Y, Z axis, a sensor capable of measuring moments Mx, My, Mz around the XYZ axis.

  The control unit 18 controls an actuator (not shown) that generates power for rotating the arm 16. The control unit 18 drives the arm 16 by complexly rotating or bending around the connecting portion of each arm element. The control unit 18 feeds back the force detected by the force detection device 10. The control unit 18 performs control such as posture control, vibration control, and acceleration control by controlling an actuator or the like according to the force transmitted from the force detection device 10.

  The control unit 18 controls the posture of the arm 16 to cause the hand 12 to take the first posture. Then, the first force applied to the force detection device 10 in the first posture is detected. The control unit 18 controls the posture of the arm 16 to cause the hand 12 to take a second posture different from the first posture. Then, the second force applied to the force detection device 10 in the second posture is detected. The control unit 18 calculates the drift value of the force detection device 10 by taking the difference between the first force and the second force. Here, in a straight line passing through the first point of the hand 12 and the second point of the hand 12 that is different from the first point, the first point from the first point to the second point in the first posture. The direction is the same as the second direction from the second point toward the first point in the second posture.

  The detection axis direction (for example, positive direction) of the force detection device 10 in the first posture is parallel to the gravity direction (that is, vertically downward). According to this, the direction of the force detection device 10 in the second posture which is the 180 ° inversion direction (in this case, the negative direction) is parallel to the direction of gravity. Thereby, the sensor value which changed the positive / negative of an axial direction (180 degrees) can be acquired using the dead weight concerning the hand 12, and a sensor value can be corrected. As a result, the detection accuracy can be increased.

  In the illustrated configuration, the arm 16 includes a total of five arm elements, but the present embodiment is not limited to this. Within the scope of the present embodiment, the arm 16 is constituted by one arm element, is constituted by 2 to 4 arm elements, and is constituted by 6 or more arm elements. is there.

  3A and 3B are diagrams showing the force detection device 10 according to the present embodiment, in which FIG. 3A is a cross-sectional view taken along line AA in FIG. 3B, and FIG. 3B is a plan view. is there. FIG. 4 is a circuit diagram schematically showing the force detection device 10 shown in FIG.

  As shown in FIG. 3, the force detection device 10 includes a first substrate 38, a second substrate 40 that is disposed at a predetermined interval from the first substrate 38 and faces the first substrate 38, An analog circuit board 42 provided with four charge output elements (force detection elements) 36 provided between the first board 38 and the second board 40 and outputting a signal in accordance with the applied force. A digital circuit board 44 electrically connected to the analog circuit board 42, and eight pressurizing bolts 46 for fixing the first board 38 and the second board 40. The force detection device 10 has a function of detecting a force (including a moment), that is, a six-axis force (translation force component (shearing force, compression and tensile force) in the X, Y, and Z axis directions) and an X, Y, and Z axis It has a function of detecting the surrounding rotational force component (moment)). The force detection device 10 includes a plurality of charge output elements 36 whose detection axis directions are orthogonal to each other. According to this, the respective drift values of the charge output elements 36 in a plurality of orthogonal directions can be obtained.

  Each charge output element 36 is an element for acquiring a charge (signal) used for detecting force. Each charge output element 36 is disposed on the surface of the analog circuit board 42 on the second board 40 side, and the analog circuit board 42 is sandwiched between the first board 38 and the second board 40. Note that either the first substrate 38 or the second substrate 40 may be a substrate on which a force is applied, but in the present embodiment, the second substrate 40 will be described as a substrate on which a force is applied.

  In addition, each charge output element 36 may be arranged on the surface of the analog circuit board 42 on the first board 38 side. Further, the number of charge output elements 36 is not limited to four, and may be one, two, three, five or more, for example. However, the number of charge output elements 36 is preferably plural, and more preferably three or more. For example, the force detection device 10 includes three charge output elements 36 whose detection axis directions are orthogonal to each other (X, Y, Z). According to this, force detection in a three-dimensional direction becomes possible.

  If the force detection device 10 has at least three charge output elements 36, it can detect a six-axis force. When the number of charge output elements 36 is three, the number of charge output elements 36 is small, so that the force detection device 10 can be reduced in weight. Further, when the number of charge output elements 36 is four as shown in the drawing, the six-axis force can be obtained by a very simple calculation described later, so that the calculation unit 48 shown in FIG. 4 can be simplified.

  The shapes of the first substrate 38, the second substrate 40, the analog circuit substrate 42, and the digital circuit substrate 44 are not particularly limited, but in the present embodiment, the first substrate 38, the second substrate 40, and the analog The external shape of the circuit board 42 and the digital circuit board 44 is circular in plan view. Examples of the other outer shape of the first substrate 38, the second substrate 40, the analog circuit substrate 42, and the digital circuit substrate 44 in a plan view include, for example, a polygon such as a quadrangle and a pentagon, an ellipse, and the like. Is mentioned.

  Further, as the constituent materials of the first substrate 38, the second substrate 40, the parts other than the respective elements and wirings of the analog circuit board 42, and the components of the respective parts of the digital circuit board 44 other than the respective wirings, For example, various resin materials, various metal materials, and the like can be used.

  Further, the position of each charge output element 36 is not particularly limited, but in this embodiment, each charge output element 36 is arranged along the circumferential direction of the first substrate 38, the second substrate 40, and the analog circuit substrate 42. Are arranged at equiangular intervals (90 ° intervals). Thereby, force can be detected without deviation. And a six-axis force can be detected. In the present embodiment, the charge output elements 36 are all mounted on the analog circuit board 42 in the same direction. However, the present invention is not limited to this.

  As shown in FIG. 4, the analog circuit board 42 includes a conversion output circuit 50a that converts the charge Qx output from the charge output element 36 into a voltage Vx, a conversion output circuit 50b that converts the charge Qz into a voltage Vz, Four sets of conversion output circuits 50c for converting Qy into voltage Vy are provided. The digital circuit board 44 also includes a force detection circuit 52 that detects the applied force. The digital circuit board 44 is disposed closer to the first board 38 than the analog circuit board 42.

  The first substrate 38 and the second substrate 40 are fixed by eight pressurizing bolts 46. The head of each pressurizing bolt 46 is disposed on the first substrate 38 side, and is screwed into the second substrate 40. The “fixing” by the pressurizing bolt 46 is performed while allowing a predetermined amount of movement of the two fixed objects. Specifically, the first substrate 38 and the second substrate 40 are moved in the plane direction of the predetermined amount of the first substrate 38 and the second substrate 40 by eight pressurizing bolts 46. It is fixed while being allowed. The pressurizing bolt 46 applies a predetermined amount of pressure in the Z-axis direction, that is, pressurization, to each charge output element 36. In addition, the magnitude | size of the said pressurization is not specifically limited, It sets suitably. The number of pressurizing bolts 46 is not limited to eight, and may be two, three, four, five, six, seven, nine, or more, for example.

  Further, the position of each pressurizing bolt 46 is not particularly limited, but in the present embodiment, each pressurizing bolt 46 is arranged along the circumferential direction of the first board 38, the second board 40, and the analog circuit board 42. Has been placed. In addition, each pressurizing bolt 46 has a pair of pressurizing bolts 46 disposed on both sides of the charge output element 36 with respect to each charge output element 36 with the charge output element 36 interposed therebetween. As a result, the first substrate 38 and the second substrate 40 can be fixed in a balanced manner, and pressure can be applied to each charge output element 36 in a balanced manner.

<Charge output element>
FIG. 5 is a cross-sectional view schematically showing the charge output element 36 of the force detection device 10 shown in FIG. Each of the charge output elements 36 has three powers according to each of the forces applied (received) along three axes (α (X) axis, β (Y) axis, γ (Z) axis) orthogonal to each other. It has a function of outputting charges Qx, Qy, Qz.

  Although the shape of the charge output element 36 is not particularly limited, in the present embodiment, the charge output element 36 has a quadrangular shape in a plan view of the first substrate 38. Examples of the other external shape of the charge output element 36 in plan view include other polygons such as a pentagon, a circle, and an ellipse.

  As shown in FIG. 5, the charge output element 36 outputs four charges Qy according to four ground electrode layers 54 grounded to the ground (reference potential point) and a force (shearing force) parallel to the β axis. 1 sensor 56, a second sensor 58 that outputs a charge Qz according to a force (compression / tensile force) parallel to the γ-axis, and a charge Qx according to a force (shearing force) parallel to the α-axis The ground electrode layer 54 and the sensors 56, 58, 60 are alternately stacked. In FIG. 5, the stacking direction of the ground electrode layer 54 and the sensors 56, 58, 60 is the γ-axis direction, and the directions orthogonal to the γ-axis direction and orthogonal to each other are the α-axis direction and β-axis direction, respectively.

  In the configuration shown in the drawing, the first sensor 56, the second sensor 58, and the third sensor 60 are stacked in this order from the lower side in FIG. 5, but the present embodiment is not limited to this. The stacking order of the sensors 56, 58 and 60 is arbitrary.

  The ground electrode layer 54 is an electrode grounded to the ground (reference potential point). Although the material which comprises the ground electrode layer 54 is not specifically limited, For example, gold | metal | money, platinum, chromium, titanium, aluminum, copper, iron, or an alloy containing these is preferable. Among these, it is particularly preferable to use stainless steel which is an iron alloy. The ground electrode layer 54 made of stainless steel has excellent durability and corrosion resistance.

  The first sensor 56 has a function of outputting a charge Qy according to a force (shearing force) applied (received) along the β axis. The first sensor 56 is configured to output a positive charge according to a force applied along the positive direction of the β axis and to output a negative charge according to a force applied along the negative direction of the β axis. Has been. The first sensor 56 is provided so as to face the first piezoelectric layer 62 having the first crystal axis CA1 and the second piezoelectric axis having the second crystal axis CA2. A body layer 64 and an output electrode layer 66 that outputs a charge Q are provided between the first piezoelectric layer 62 and the second piezoelectric layer 64.

  The first piezoelectric layer 62 is composed of a piezoelectric body having a first crystal axis CA1 oriented in the negative direction of the β axis. When a force along the positive direction of the β axis is applied to the surface of the first piezoelectric layer 62, electric charges are induced in the first piezoelectric layer 62 due to the piezoelectric effect. As a result, positive charges are collected in the vicinity of the surface of the first piezoelectric layer 62 on the output electrode layer 66 side, and negative charges are collected in the vicinity of the surface of the first piezoelectric layer 62 on the ground electrode layer 54 side. Similarly, when a force along the negative direction of the β axis is applied to the surface of the first piezoelectric layer 62, negative charges are generated near the surface of the first piezoelectric layer 62 on the output electrode layer 66 side. The positive charges are collected near the surface of the first piezoelectric layer 62 on the ground electrode layer 54 side.

  The second piezoelectric layer 64 is made of a piezoelectric body having a second crystal axis CA2 oriented in the positive direction of the β axis. When a force along the positive direction of the β axis is applied to the surface of the second piezoelectric layer 64, electric charges are induced in the second piezoelectric layer 64 due to the piezoelectric effect. As a result, positive charges are collected near the surface of the second piezoelectric layer 64 on the output electrode layer 66 side, and negative charges are collected near the surface of the second piezoelectric layer 64 on the ground electrode layer 54 side. Similarly, when a force along the negative direction of the β axis is applied to the surface of the second piezoelectric layer 64, negative charges are generated in the vicinity of the surface of the second piezoelectric layer 64 on the output electrode layer 66 side. The positive charges are collected near the surface of the second piezoelectric layer 64 on the ground electrode layer 54 side.

  Thus, the first crystal axis CA1 of the first piezoelectric layer 62 is directed in the opposite direction to the direction of the second crystal axis CA2 of the second piezoelectric layer 64. As a result, in comparison with the case where the first sensor 56 is configured by only one of the first piezoelectric layer 62 and the second piezoelectric layer 64 and the output electrode layer 66, the output electrode layer 66 is closer to the vicinity. The collected positive or negative charge can be increased. As a result, the charge Q output from the output electrode layer 66 can be increased.

The constituent materials of the first piezoelectric layer 62 and the second piezoelectric layer 64 are quartz, topaz, barium titanate, lead titanate, lead zirconate titanate (PZT: Pb (Zr, Ti) O). ₃ ), lithium niobate, lithium tantalate and the like. Of these, quartz is particularly preferable. This is because the piezoelectric layer made of quartz has excellent characteristics such as a wide dynamic range, high rigidity, high natural frequency, and high load resistance. Further, like the first piezoelectric layer 62 and the second piezoelectric layer 64, a piezoelectric layer that generates an electric charge with respect to a force (shearing force) along the surface direction of the layer is constituted by a Y-cut crystal. be able to.

  The output electrode layer 66 has a function of outputting positive charges or negative charges generated in the first piezoelectric layer 62 and the second piezoelectric layer 64 as charges Qy. As described above, when a force along the positive direction of the β axis is applied to the surface of the first piezoelectric layer 62 or the surface of the second piezoelectric layer 64, a positive charge is present in the vicinity of the output electrode layer 66. Gather. As a result, positive charge Qy is output from the output electrode layer 66. On the other hand, when a force along the negative direction of the β axis is applied to the surface of the first piezoelectric layer 62 or the surface of the second piezoelectric layer 64, negative charges are collected in the vicinity of the output electrode layer 66. As a result, the negative charge Qy is output from the output electrode layer 66.

  The width of the output electrode layer 66 is preferably equal to or greater than the width of the first piezoelectric layer 62 and the second piezoelectric layer 64. When the width of the output electrode layer 66 is narrower than that of the first piezoelectric layer 62 or the second piezoelectric layer 64, a part of the first piezoelectric layer 62 or the second piezoelectric layer 64 is the output electrode layer. No contact with 66. Therefore, in some cases, a part of the charge generated in the first piezoelectric layer 62 or the second piezoelectric layer 64 cannot be output from the output electrode layer 66. As a result, the charge Qy output from the output electrode layer 66 decreases. The same applies to output electrode layers 72 and 78 described later.

  The second sensor 58 has a function of outputting an electric charge Qz according to a force (compression / tensile force) applied (received) along the γ axis. The second sensor 58 is configured to output a positive charge according to a compressive force parallel to the γ axis and to output a negative charge according to a tensile force parallel to the γ axis. The second sensor 58 is provided to face the third piezoelectric layer 68 having the third crystal axis CA3 and the third piezoelectric layer 68, and has a fourth piezoelectric axis having the fourth crystal axis CA4. It has an output electrode layer 72 that is provided between the body layer 70, the third piezoelectric layer 68, and the fourth piezoelectric layer 70 and outputs a charge Qz.

  The third piezoelectric layer 68 is made of a piezoelectric body having a third crystal axis CA3 oriented in the positive direction of the γ axis. When a compressive force parallel to the γ-axis is applied to the surface of the third piezoelectric layer 68, charges are induced in the third piezoelectric layer 68 due to the piezoelectric effect. As a result, positive charges gather near the surface of the third piezoelectric layer 68 on the output electrode layer 72 side, and negative charges gather near the surface of the third piezoelectric layer 68 on the ground electrode layer 54 side. Similarly, when a tensile force parallel to the γ-axis is applied to the surface of the third piezoelectric layer 68, negative charges gather near the surface of the third piezoelectric layer 68 on the output electrode layer 72 side, Positive charges are collected near the surface of the third piezoelectric layer 68 on the ground electrode layer 54 side.

  The fourth piezoelectric layer 70 is configured by a piezoelectric body having a fourth crystal axis CA4 oriented in the negative direction of the γ axis. When a compressive force parallel to the γ-axis is applied to the surface of the fourth piezoelectric layer 70, electric charges are induced in the fourth piezoelectric layer 70 due to the piezoelectric effect. As a result, positive charges gather near the surface of the fourth piezoelectric layer 70 on the output electrode layer 72 side, and negative charges gather near the surface of the fourth piezoelectric layer 70 on the ground electrode layer 54 side. Similarly, when a tensile force parallel to the γ-axis is applied to the surface of the fourth piezoelectric layer 70, negative charges gather near the output electrode layer 72 side surface of the fourth piezoelectric layer 70, Positive charges are collected near the surface of the fourth piezoelectric layer 70 on the ground electrode layer 54 side.

  As the constituent material of the third piezoelectric layer 68 and the fourth piezoelectric layer 70, the same constituent material as that of the first piezoelectric layer 62 and the second piezoelectric layer 64 can be used. Further, like the third piezoelectric layer 68 and the fourth piezoelectric layer 70, a piezoelectric layer that generates an electric charge with respect to a force (compression / tensile force) perpendicular to the surface direction of the layer is made of an X-cut crystal. Can be configured.

  The output electrode layer 72 has a function of outputting positive charges or negative charges generated in the third piezoelectric layer 68 and the fourth piezoelectric layer 70 as charges Qz. As described above, when a compressive force parallel to the γ-axis is applied to the surface of the third piezoelectric layer 68 or the surface of the fourth piezoelectric layer 70, positive charges are collected in the vicinity of the output electrode layer 72. . As a result, a positive charge Qz is output from the output electrode layer 72. On the other hand, when a tensile force parallel to the γ-axis is applied to the surface of the third piezoelectric layer 68 or the surface of the fourth piezoelectric layer 70, negative charges are collected in the vicinity of the output electrode layer 72. As a result, a negative charge Qz is output from the output electrode layer 72.

  The third sensor 60 has a function of outputting a charge Qx according to a force (shearing force) applied (received) along the α axis. The third sensor 60 is configured to output a positive charge according to the force applied along the positive direction of the α axis and to output a negative charge according to the force applied along the negative direction of the α axis. Has been. The third sensor 60 is provided so as to face the fifth piezoelectric layer 74 having the fifth crystal axis CA5 and the fifth piezoelectric layer 74, and the sixth piezoelectric layer having the sixth crystal axis CA6. It has an output electrode layer 78 that is provided between the body layer 76, the fifth piezoelectric layer 74, and the sixth piezoelectric layer 76, and outputs a charge Qx.

  The fifth piezoelectric layer 74 is composed of a piezoelectric body having a fifth crystal axis CA5 oriented in the negative direction of the α axis. When a force along the positive direction of the α-axis is applied to the surface of the fifth piezoelectric layer 74, electric charges are induced in the fifth piezoelectric layer 74 due to the piezoelectric effect. As a result, positive charges collect near the surface of the fifth piezoelectric layer 74 on the output electrode layer 78 side, and negative charges collect near the surface of the fifth piezoelectric layer 74 on the ground electrode layer 54 side. Similarly, when a force along the negative direction of the α-axis is applied to the surface of the fifth piezoelectric layer 74, negative charges are generated in the vicinity of the surface of the fifth piezoelectric layer 74 on the output electrode layer 78 side. The positive charges are collected near the surface of the fifth piezoelectric layer 74 on the ground electrode layer 54 side.

  The sixth piezoelectric layer 76 is composed of a piezoelectric body having a sixth crystal axis CA6 oriented in the positive direction of the α axis. When a force along the positive direction of the α-axis is applied to the surface of the sixth piezoelectric layer 76, an electric charge is induced in the sixth piezoelectric layer 76 due to the piezoelectric effect. As a result, positive charges gather near the surface of the sixth piezoelectric layer 76 on the output electrode layer 78 side, and negative charges gather near the surface of the sixth piezoelectric layer 76 on the ground electrode layer 54 side. Similarly, when a force along the negative direction of the α-axis is applied to the surface of the sixth piezoelectric layer 76, negative charges are generated in the vicinity of the surface of the sixth piezoelectric layer 76 on the output electrode layer 78 side. The positive charges are collected near the surface of the sixth piezoelectric layer 76 on the side of the ground electrode layer 54.

  As the constituent material of the fifth piezoelectric layer 74 and the sixth piezoelectric layer 76, the same constituent material as that of the first piezoelectric layer 62 and the second piezoelectric layer 64 can be used. Further, like the fifth piezoelectric layer 74 and the sixth piezoelectric layer 76, the piezoelectric layer that generates an electric charge with respect to the force (shearing force) along the surface direction of the layer is the first piezoelectric layer. Similar to 62 and the second piezoelectric layer 64, it can be composed of Y-cut quartz.

  The output electrode layer 78 has a function of outputting positive charges or negative charges generated in the fifth piezoelectric layer 74 and the sixth piezoelectric layer 76 as charges Qx. As described above, when a force along the positive direction of the α axis is applied to the surface of the fifth piezoelectric layer 74 or the surface of the sixth piezoelectric layer 76, a positive charge is present in the vicinity of the output electrode layer 78. Gather. As a result, a positive charge Qx is output from the output electrode layer 78. On the other hand, when a force along the negative direction of the α axis is applied to the surface of the fifth piezoelectric layer 74 or the surface of the sixth piezoelectric layer 76, negative charges are collected in the vicinity of the output electrode layer 78. As a result, a negative charge Qx is output from the output electrode layer 78.

  Thus, the first sensor 56, the second sensor 58, and the third sensor 60 are stacked so that the force detection directions of the sensors are orthogonal to each other. Thereby, each sensor can induce an electric charge according to force components orthogonal to each other. Therefore, the charge output element 36 outputs three charges Qx, Qy, and Qz according to each of the forces along the three axes (α (X) axis, β (Y) axis, γ (Z) axis). Can do.

<Conversion output circuit>
Returning to FIG. 4, conversion output circuits 50 a, 50 b, and 50 c are connected to each charge output element 36. Since the respective conversion output circuits 50a, 50b, 50c connected to each charge output element 36 are the same, the conversion output circuits 50a, 50b, 50b connected to one charge output element 36 will typically be described below. 50c will be described.

  The conversion output circuit 50a has a function of converting the charge Qx output from the charge output element 36 into a voltage Vx. The conversion output circuit 50b has a function of converting the charge Qz output from the charge output element 36 into a voltage Vz. The conversion output circuit 50c has a function of converting the charge Qy output from the charge output element 36 into a voltage Vy. Since the conversion output circuits 50a, 50b, and 50c are the same, the conversion output circuit 50c will be typically described below.

  The conversion output circuit 50c has a function of converting the charge Qy output from the charge output element 36 into a voltage Vy and outputting the voltage Vy. The conversion output circuit 50 c includes an operational amplifier 80, a capacitor 82, and a switching element 84. The first input terminal (minus input) of the operational amplifier 80 is connected to the output electrode layer 66 (see FIG. 5) of the charge output element 36, and the second input terminal (plus input) of the operational amplifier 80 is ground (reference potential). Is grounded. The output terminal of the operational amplifier 80 is connected to the force detection circuit 52. The capacitor 82 is connected between the first input terminal and the output terminal of the operational amplifier 80. The switching element 84 is connected between the first input terminal and the output terminal of the operational amplifier 80 and is connected in parallel with the capacitor 82. The switching element 84 is connected to a drive circuit (not shown), and the switching element 84 performs a switching operation in accordance with an on / off signal from the drive circuit.

  When the switching element 84 is off, the charge Qy output from the charge output element 36 is stored in the capacitor 82 having the capacitance C1, and is output to the force detection circuit 52 as the voltage Vy. Next, when the switching element 84 is turned on, both terminals of the capacitor 82 are short-circuited. As a result, the electric charge Qy stored in the capacitor 82 is discharged to 0 coulomb, and the voltage V output to the force detection circuit 52 is 0 volt. When the switching element 84 is turned on, the conversion output circuit 50c is reset. The voltage Vy output from the ideal conversion output circuit 50 c is proportional to the amount of charge Qy output from the charge output element 36.

  The switching element 84 is a semiconductor switching element such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). Since the semiconductor switching element is smaller and lighter than the mechanical switch, it is advantageous for reducing the size and weight of the force detection device 10. Hereinafter, a case where a MOSFET is used as the switching element 84 will be described as a representative example.

  The switching element 84 has a drain electrode, a source electrode, and a gate electrode. One of the drain electrode and the source electrode of the switching element 84 is connected to the first input terminal of the operational amplifier 80, and the other of the drain electrode and the source electrode is connected to the output terminal of the operational amplifier 80. The gate electrode of the switching element 84 is connected to a drive circuit (not shown).

  The same drive circuit may be connected to the switching element 84 of each conversion output circuit 50a, 50b, 50c, and a different drive circuit may be connected to each. Each switching element 84 receives an on / off signal that is all synchronized from the drive circuit. Thereby, the operation of the switching element 84 of each of the conversion output circuits 50a, 50b, 50c is synchronized. That is, the on / off timings of the switching elements 84 of the conversion output circuits 50a, 50b, and 50c are the same.

<Force detection circuit>
The force detection circuit 52 outputs voltages Vx1, Vx2, Vx3, and Vx4 output from the conversion output circuits 50a, voltages Vz1, Vz2, Vz3, and Vz4 output from the conversion output circuits 50b, and outputs from the conversion output circuit 50c. Based on the applied voltages Vy1, Vy2, Vy3, and Vy4, and has a function of detecting the applied force. The force detection circuit 52 includes an AD converter 86 connected to the conversion output circuits 50 a, 50 b, and 50 c, and an arithmetic unit 48 connected to the AD converter 86.

  The AD converter 86 has a function of converting the voltages Vx1, Vy1, Vz1, Vx2, Vy2, Vz2, Vx3, Vy3, Vz3, Vx4, Vy4, and Vz4 from analog signals to digital signals. The voltages Vx 1, Vy 1, Vz 1, Vx 2, Vy 2, Vz 2, Vx 3, Vy 3, Vz 3, Vx 4, Vy 4, Vz 4 that are digitally converted by the AD converter 86 are input to the arithmetic unit 48.

  That is, when a force that shifts the relative positions of the first substrate 38 and the second substrate 40 in the α (X) axis direction is applied, the AD converter 86 outputs the voltages Vx1, Vx2, Vx3, and Vx4. Similarly, when a force that shifts the relative positions of the first substrate 38 and the second substrate 40 in the β (Y) axis direction is applied, the AD converter 86 outputs voltages Vy1, Vy2, Vy3, and Vy4. . In addition, when a force that shifts the relative positions of the first substrate 38 and the second substrate 40 to each other in the γ (Z) axis direction is applied, the AD converter 86 outputs voltages Vz1, Vz2, Vz3, and Vz4.

  The first substrate 38 and the second substrate 40 are capable of relative displacement rotating around the X axis, relative displacement rotating around the Y axis, and relative displacement rotating around the Z axis. Can be transmitted to the charge output element 36.

  The computing unit 48 translates the translational force component Fx in the X-axis direction and the translation in the Y-axis direction based on the digitally converted voltages Vx1, Vy1, Vz1, Vx2, Vy2, Vz2, Vx3, Vy3, Vz3, Vx4, Vy4, and Vz4. It has a function of calculating a force component Fy, a translational force component Fz in the Z-axis direction, a rotational force component Mx around the X axis, a rotational force component My around the Y axis, and a rotational force component Mz around the Z axis. Each force component can be obtained by the following equation.

Fx = Vx1 + Vx2 + Vx3 + Vx4
Fy = Vy1 + Vy2 + Vy3 + Vy4
Fz = Vz1 + Vz2 + Vz3 + Vz4
Mx = b × (Vz4-Vz2)
My = a × (Vz3−Vz1)
Mz = b * (Vx2-Vx4) + a * (Vy1-Vy3)
Here, a and b are constants.
As described above, the force detection device 10 can detect six-axis forces.

  The calculation unit 48 performs correction based on the digitally converted voltages Vx1, Vy1, Vz1, Vx2, Vy2, Vz2, Vx3, Vy3, Vz3, Vx4, Vy4, and Vz4 to obtain a translational force component Fx in the X-axis direction, It has a function of calculating a translational force component Fy in the Y-axis direction, a translational force component Fz in the Z-axis direction, a rotational force component Mx around the X-axis, a rotational force component My around the Y-axis, and a rotational force component Mz around the Z-axis. .

  Here, when each force component is obtained, the translational force is calculated by taking the difference (drift value fx (T)) between the translational force component (first force) Fx1 and the translational force component (second force) Fx2. The component Fx is corrected (the translational force component Fx is compensated). Thereby, all or a part of the noise component caused by the structure of the force detection device 10 such as the noise component caused by thermal expansion included in the translational force component Fx and the noise component caused by the circuit are removed from the translational force component Fx. .

  Similarly, the translational force component Fy is corrected by taking the difference between the translational force component Fy1 and the translational force component Fy2. Further, the translational force component Fz is corrected by taking the difference between the translational force component Fz1 and the translational force component Fz2. The correction includes not only the case where the noise component is completely removed but also the case where the noise component is reduced.

  Specifically, the translational force component Fz1 is represented by the following formula (1), and the translational force component Fz2 is represented by the following formula (2). The drift value fz (T) is calculated from Expression (1) -Expression (2) shown by the following Expression (3). FZ is the weight of the hand 12 in the Z-axis direction.

Fz1 = FZ + fz (T) (1)
Fz2 = −FZ + fz (T) (2)
fz (T) = (Fz1 + Fz2) / 2 (3)

Next, an example of an implementation method will be described.
FIG. 6 is a diagram illustrating a correction value acquisition state of the force detection device 10 according to the present embodiment. FIG. 6A is a diagram showing the first posture, and FIG. 6B is a diagram showing the second posture. A state in which the direction of gravity and the Z axis of the force detection device 10 are in parallel is shown.

  First, the control unit 18 controls the posture of the arm 16 to cause the hand 12 to take the first posture. Then, the first force applied to the force detection device 10 in the first posture is detected. In other words, in a state where the force detection device 10 is arranged between the arm 16 and the hand (end effector) 12, the arm 16 is moved to change the posture of the hand 12 to the first posture (for example, the palm of the hand 12 is moved to gravity). On the other hand, the first force applied to the force detection device 10 at that time due to gravity is detected. At this time, the measurement value of the force detection device 10 is the sum of the measurement value based on the weight of the hand 12 and the temperature characteristic function. The detection axis direction (for example, positive direction) of the force detection device 10 in the first posture is parallel to the gravity direction (that is, vertically downward).

  Next, the control unit 18 controls the posture of the arm 16 to cause the hand 12 to take a second posture different from the first posture. Specifically, in a straight line passing through the first point of the hand 12 and the second point of the hand 12 different from the first point, the first point in the first posture is directed to the second point. The first direction is the same as the second direction from the second point toward the first point in the second posture. In other words, after that, the arm 16 is moved to cause the hand 12 to take the second posture (for example, the palm of the hand 12 is vertically downward with respect to the gravity) reversed 180 ° from the first posture. FIG. 6B shows a state where the force detection device 10 is rotated + 180 ° or −180 ° around the Y axis.

  Next, the second force applied to the force detection device 10 in the second posture is detected. The measurement value of the force detection device 10 in this state is expressed by Expression (2), and the measurement value due to the weight of the hand 12 is reversed in sign.

  Next, the control unit 18 calculates the drift value of the force detection device 10 by taking the difference between the first force and the second force. When the temperature change is sufficiently small, the temperature characteristic value can be obtained from the equations (1) and (2) (equation (3)). In other words. The difference between the first force and the second force is taken. The difference is used as a drift value, and is used as information for obtaining a correct detection value necessary for subsequent force control of the arm 16.

As for the torque around the X axis, the temperature characteristic value can be obtained from the equations (4) and (5) in the same manner as described above (equation (6)). FM _X is a torque around the X axis of the hand 12.

Mx1 = −FM _X + fmx (T) (4)
_{Mx2 = FM X + fmx (T} ) ... (5)
fmx (T) = (Mx1 + Mx2) / 2 (6)

  As described above, the temperature of the charge output element 36 can be similarly corrected for the 5-axis output other than the torque My around the Y-axis.

  As described above, according to the force detection device 10, it depends on the noise component due to the variation factor and temperature dependency due to the circuit of the force detection device 10, and the variation factor and temperature dependency due to the structure of the force detection device 10. The noise component can be removed or reduced, and thereby the measurement accuracy can be improved. Further, it is not necessary to individually perform temperature correction on the force detection device 10. Furthermore, it is possible to correct the temporally changing component.

  According to the force correction value detection method of the present embodiment, the first force and the second force, which are two actually measured values in a posture in which the posture of the hand 12 is 180 ° different (inverted), are used, and the force is determined by the difference between them. The drift value of the detection device 10 can be obtained. Thereby, a correct drift value can be obtained in real time by obtaining the above two actually measured values at an arbitrary timing during work. When the single-arm robot 2 is in motion, the ambient temperature during actual operation, the heat generated by the motor, etc. change slowly. By correcting the force detection device 10 in the immediately preceding state, the correct force can always be detected, and the correct force without excess or deficiency can be applied to the object.

  Further, according to the single-arm robot 2 of the present embodiment, the same effects as those of the force correction value detection method described above can be obtained. Then, it is possible to feed back the force detected by the force correction value detection method and execute the operation more precisely. Further, the contact of the hand 12 with the obstacle can be detected by the force detected by the force correction value detection method. Therefore, an obstacle avoidance operation, an object damage avoidance operation, and the like, which are difficult with conventional position control, can be easily performed, and the work can be executed more safely.

<Embodiment of double-arm robot>
Next, the multi-arm robot 4 as a robot according to the present embodiment will be described. Hereinafter, the present embodiment will be described focusing on the differences from the above-described embodiment of the single-arm robot 2, and the description of the same matters will be omitted.

FIG. 7 is a diagram illustrating an example of the multi-arm robot 4 using the force detection device 10 according to the present embodiment. As shown in FIG. 7, the multi-arm robot 4 according to this embodiment includes a base 90, a first arm 92, a second arm 94, and a first arm 92 provided on the distal end side of the first arm 92. One hand 96a, a second hand 96b provided on the distal end side of the second arm 94, between the first arm 92 and the first hand 96a, and between the second arm 94 and the second hand 96b, The force detection device 10 is provided between the two. In addition, as the force detection apparatus 10, the thing similar to embodiment mentioned above is used.
In the present embodiment, the posture in which the first and second hands 96a and 96b are lowered is the above-described first posture (indicated by a solid line), and the first and second hands 96a and 96b are raised. The posture is the above-described second posture (indicated by a broken line).

  The base 90 has a function of accommodating an actuator (not shown) that generates power for rotating the first arm 92 and the second arm 94, a control unit 18 that controls the actuator, and the like. The base 90 is fixed on, for example, a floor, a wall, a ceiling, or a movable carriage.

  The 1st arm 92 is comprised by connecting the 1st arm element 98 and the 2nd arm element 100 so that rotation is possible. The 2nd arm 94 is comprised by connecting the 1st arm element 102 and the 2nd arm element 104 so that rotation is possible. The first arm 92 and the second arm 94 are driven by being rotated or bent in a compound manner around the connecting portion of each arm element under the control of the control unit 18.

  The first and second hands 96a and 96b have a function of gripping an object. The first hand 96a has a first finger 106a and a second finger 108a. The second hand 96b has a first finger 106b and a second finger 108b. After the first hand 96a reaches the predetermined operating position by driving the first arm 92, the object can be grasped by adjusting the distance between the first finger 106a and the second finger 108a. it can. Similarly, after the second hand 96b reaches the predetermined operating position by driving the second arm 94, the distance between the first finger 106b and the second finger 108b is adjusted to hold the object. can do.

  The force detection device 10 has a function of detecting the force applied to the first and second hands 96a and 96b. By feeding back the force detected by the force detection device 10 to the control unit 18 of the base 90, the multi-arm robot 4 can execute the work more precisely. Further, the multi-arm robot 4 can detect contact of the first and second hands 96a and 96b with an obstacle by the force detected by the force detection device 10. Therefore, an obstacle avoidance operation, an object damage avoidance operation, and the like that have been difficult with conventional position control can be easily performed, and the multi-arm robot 4 can perform the work more safely.

  In the illustrated configuration, there are a total of two arms, but the present embodiment is not limited to this. The case where the multi-arm robot 4 has three or more arms is also within the scope of the present embodiment.

(Modification)
In the multi-axis robot having the force detection device 10, failure detection of the force detection device 10 is performed during the work. That is, sensor failure detection is performed by controlling the posture of the arm 16 and comparing sensor values between specific posture states.

(Example)
When performing failure verification of the force detection device 10, the failure of the sensor can be confirmed by evaluating the difference between Fz1 and Fz2 obtained from Equations (1) and (2) (Equation (7)).

FZ ₁ −FZ ₂ <δ _Z (7)

  As for the torque around the X-axis, the sensor failure can be confirmed by comparing the states shown in FIGS. 6A and 6B (Formula (8)).

FM _X1 −FM _X2 <δM _X (8)

  As described above, an abnormality can be detected by evaluating the difference in sensor value between postures with respect to the 5-axis output other than the torque My around the Y-axis. Thereby, it is possible to detect an abnormality of the force detection device 10. It is possible to detect a failure even when the robots 2 and 4 are in operation.

  As described above, the force correction value detection method and the robot according to the present embodiment have been described based on the illustrated embodiment. However, the present embodiment is not limited to this, and the configuration of each unit is an arbitrary function having the same function. It can be replaced with the configuration of In addition, other arbitrary components may be added to the present embodiment. In addition, the present invention may be a combination of any two or more configurations (features) of the embodiment.

  In the present embodiment, the analog circuit board 42 and the digital circuit board 44 may be configured as a single circuit board.

  In the present embodiment, some of the functions of the circuit board, for example, the AD converter 86 of the digital circuit board 44, the arithmetic unit 48, and the like may be provided outside. Further, for example, either one or both of the analog circuit board 42 and the digital circuit board 44 may be provided outside.

  Further, the robots 2 and 4 of this embodiment are not limited to arm type robots (robot arms), but may be other types of robots such as scalar robots, legged walking (running) robots, and the like.

  In addition, the force detection device 10 of the present embodiment is applied to various sensors, in particular, various sensors in which the influence of gravity depending on the thermal deformation of the sensor structure or the posture of the sensor affects the sensor characteristics. The temperature characteristic table can be created simultaneously with the above correction. Specific examples include, for example, a piezoelectric force sensor, a piezoelectric force sensor, a piezoelectric acceleration sensor, a piezoelectric angular velocity sensor, a strain gauge type, a capacitive type, an optical type force sensor, a force sensor, Examples include an acceleration sensor and an angular velocity sensor.

  Further, the force detection device 10 of the present embodiment is not limited to a robot, an electronic component transport device, an electronic component inspection device, a component processing device, and a moving body, but other devices such as a transport device, an inspection device, a vibrometer, an acceleration It can also be applied to measuring devices such as gauges, gravimeters, dynamometers, seismometers, inclinometers, and input devices.

  DESCRIPTION OF SYMBOLS 2 ... Single arm robot 4 ... Multi-arm robot 10 ... Force detection apparatus (force sensor) 12 ... Hand (end effector) 14 ... Base 16 ... Arm 18 ... Control part 20 ... 1st arm element 22 ... 2nd arm Element 24 ... Third arm element 26 ... Fourth arm element 28 ... Fifth arm element 30 ... First finger 32 ... Second finger 36 ... Charge output element (force detection element) 38 ... First substrate DESCRIPTION OF SYMBOLS 40 ... 2nd board | substrate 42 ... Analog circuit board 44 ... Digital circuit board 46 ... Pressurizing volt | bolt 48 ... Operation part 50a, 50b, 50c ... Conversion output circuit 52 ... Force detection circuit 54 ... Ground electrode layer 56 ... 1st sensor 58 ... second sensor 60 ... third sensor 62 ... first piezoelectric layer 64 ... second piezoelectric layer 66 ... output electrode layer 68 ... third piezoelectric layer 70 ... fourth Electrical layer 72 ... Output electrode layer 74 ... Fifth piezoelectric layer 76 ... Sixth piezoelectric layer 78 ... Output electrode layer 80 ... Operational amplifier 82 ... Capacitor 84 ... Switching element 86 ... AD converter 90 ... Base 92 ... First 1 arm 94 ... 2nd arm 96a ... 1st hand 96b ... 2nd hand 98 ... 1st arm element 100 ... 2nd arm element 102 ... 1st arm element 104 ... 2nd arm element 106a 1st finger 106b 1st finger 108a 2nd finger 108b 2nd finger CA1 1st crystal axis CA2 2nd crystal axis CA3 3rd crystal axis CA4 4th crystal Axis CA5 ... Fifth crystal axis CA6 ... Sixth crystal axis.

Claims (5)

An arm that can take multiple postures,
An end effector,
A force sensor provided between the arm and the end effector for detecting a force between the arm and the end effector;
A control unit that controls the arm to set an arbitrary posture, and calculates a difference between each of a plurality of force signals detected by the force sensor;
With
The control unit detects the first force applied to the force sensor by controlling the posture of the arm and setting the posture of the end effector as the first posture.
The control unit detects the second force applied to the force sensor by controlling the posture of the arm so that the posture of the end effector is a second posture different from the first posture; and
The control unit calculates a drift value of the force sensor by taking a difference between the first force and the second force;
Including
In a straight line passing through the first point of the end effector and the second point of the end effector different from the first point,
The first direction from the first point to the second point in the first posture is the same as the second direction from the second point to the first point in the second posture. The force correction value detection method characterized by the above-mentioned. The force correction value detection method according to claim 1,
The force correction value detection method according to claim 1, wherein a detection axis direction of the force sensor in the first posture is parallel to a gravity direction. In the force correction value detection method according to claim 1 or 2,
The force correction value detecting method, wherein the force sensor includes a plurality of force detecting elements whose detection axis directions are orthogonal to each other. In the force correction value detection method as described in any one of Claims 1-3,
The force correction value detection method, wherein the end effector is a hand capable of gripping an object. An arm that can take multiple postures,
An end effector,
A force sensor disposed between the arm and the end effector and capable of detecting a force between the arm and the end effector;
A control unit that controls the arm to set an arbitrary posture, and calculates a difference between each of a plurality of force signals detected by the force sensor;
Including
The control unit controls the posture of the arm to set the posture of the end effector to the first posture,
The control unit controls the posture of the arm and, after the first posture, changes the posture of the end effector to the normal direction of an arbitrary surface predetermined for the end effector in the first posture. A robot having a second posture in which the arbitrary surface faces in a direction opposite to 180 °.

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