Calibration system and calibration method

Abstract

To provide a calibration system and a calibration method capable of performing accurate calibration more simply.SOLUTION: A calibration system comprises a stage, a weighting jig, a parallel linkage mechanism, and a controller. A weighted body has a force sensor that outputs a value based on a load value including at least one of six axial components of a load applied to the weighted body, and a master sensor that is calibrated to output a load value according to a load. The weighting jig holds the weighted body between itself and the stage, and the weighted body is thus fixed. The parallel link mechanism is composed of six rods. The parallel linkage has an output unit corresponding to each of the six rods. The six rods are connected in parallel to the weighting jig. The controller controls the output of each output unit, displaces the weighting jig relative to the stage, and calibrates the force sensor based on the value output from the force sensor and the load value output from the master sensor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a calibration system and method. [Background technology]

[0002] Patent Document 1 discloses a calibration device that applies a load in six axial directions to a weighted body. This calibration device includes a stage on which the weighted body is placed, a drive unit that controls the position and attitude of the weighted body via the stage, and a load unit that applies a load to the weighted body. The load unit includes a jig attached to the top of the weighted body, a wire drawn horizontally from the jig, a pulley that converts the wire from the horizontal direction to the vertical direction, and a weight attached to the tip of the wire. The load applied to the weighted body by the load unit changes in six axial directions according to changes in the position and attitude of the weighted body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-112414 A Summary of the Invention [Problem to be solved by the invention]

[0004] The calibration device disclosed in Patent Document 1 converts gravity acting on the weight into loads in six axial directions that are applied to the weighted body via wires and pulleys. For this reason, it is necessary to change the device configuration, such as the number or type of weights, depending on the magnitude of the load to be applied to the weighted body. Furthermore, in the device disclosed in Patent Document 1, sliding resistance occurs between the wire and pulley, which may cause errors in the load applied to the weighted body. The present disclosure provides a calibration system and calibration method that allows for easier and more accurate calibration. [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided a calibration system including a stage, a load jig, a parallel link mechanism, and a control device. A weighted body is fixed to the stage. The weighted body has a force sensor that outputs a value based on a load value including at least one axial component of six axial components of a load applied to the weighted body, and a master sensor calibrated to output a load value according to the load. The load jig holds the weighted body between the stage and the load jig, and the weighted body is fixed to the load jig. The parallel link mechanism is composed of six rods. The parallel link mechanism has output units corresponding to each of the six rods. The six rods are connected in parallel to the load jig. The control device controls the output of each output unit to displace the load jig relative to the stage, and calibrates the force sensor based on the value output from the force sensor and the load value output from the master sensor.

[0006] In this calibration system, the weighted body is fixed to and clamped by the stage and the load jig. Six rods constituting a parallel link mechanism are connected in parallel to the load jig. The six rods are driven by output units corresponding to the respective rods. The output of each output unit is controlled by the control device to displace the load jig relative to the stage. This allows a load in six axial directions to be applied to the weighted body. Then, a value based on a load value including at least one axial component of the six axial components of the load applied to the weighted body is output from the force sensor, and a load value according to the load is output from the calibrated master sensor. The control device calibrates the force sensor based on the value output from the force sensor and the load value output from the master sensor. In this way, this calibration system does not need to change the device configuration such as the number or type of weights depending on the magnitude of the load applied to the weighted body, so that calibration can be performed more easily. In addition, this calibration system does not need to consider the sliding resistance generated between the wire and the pulley, so that calibration can be performed more accurately.

[0007] According to another aspect of the present invention, there is provided a calibration method, which includes the steps of fixing a weighted body to a stage, sandwiching the weighted body between the stage and a loading jig and fixing the sandwiched weighted body to the loading jig, controlling outputs of output units corresponding to six rods constituting a parallel link mechanism connected to the loading jig to displace the loading jig relatively to the stage, a force sensor included in the weighted body outputting a value based on a load value including at least one axial component of six axial components of a load applied to the weighted body, a calibrated master sensor included in the weighted body outputting a load value in response to the load, and calibrating the force sensor based on the value output from the force sensor and the load value output from the master sensor.

[0008] According to this calibration method, similar to the above-mentioned calibration system, calibration can be performed more easily and accurately. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a calibration system and a calibration method that can perform accurate calibration more easily. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a configuration diagram of a calibration system according to an embodiment. [Diagram 2] FIG. 1 is a block diagram illustrating a calibration system according to an embodiment. [Diagram 3] 4 is a flow chart illustrating an example of a calibration method using the calibration system. [Figure 4] FIG. 13 is a side view for explaining a calibration system according to the first modified example. [Diagram 5] FIG. 11 is a side view for explaining a calibration system according to a second modified example. [Figure 6] FIG. 13 is a side view for explaining a calibration system according to a third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following description, the same or equivalent elements are given the same reference numerals, and redundant description will not be repeated. The dimensional ratios of the drawings do not necessarily match those in the description. The terms "upper", "lower", "left" and "right" are based on the illustrated state and are for convenience.

[0012] [Calibration system] FIG. 1 is a configuration diagram of a calibration system according to an embodiment. As shown in FIG. 1, the calibration system 1 is an apparatus that applies a load to a weighted body 2 having a force sensor 21 and a master sensor 22 to calibrate the force sensor 21. A load is applied to the weighted body 2 by the calibration system 1. The force sensor 21 is a sensor that outputs a value corresponding to an applied load value. The master sensor 22 is a force sensor that is calibrated to output a load value corresponding to the load. The force sensor 21 and the master sensor 22 will be described in detail later. Below, a test for calibrating the force sensor 21 so that it functions as a sensor that outputs a load value will be described.

[0013] The calibration system 1 includes a base 4, a stage 10, a loading jig 20, a parallel link mechanism 30, and a control device 40. The control device 40 includes a measurement unit 41 and a control unit .

[0014] The stage 10 is a pedestal provided on the base 4. The stage 10 is made of metal, for example. The stage 10 may be formed integrally with the base 4. A weighted body 2 is fixed to the stage 10. In the example shown in FIG. 1, the weighted body 2 is fixed so that the master sensor 22 side faces the upper surface of the stage 10.

[0015] The weighted body 2 and the stage 10 are fixed by, for example, screwing. As a more specific example, a female screw is provided on the top surface of the stage 10, and a bolt is inserted into a through hole provided in the master sensor 22, and the master sensor 22 is screwed to the stage 10. The force sensor 21 is connected to the master sensor 22 via a jig or the like. The force sensor 21 may be directly connected to the master sensor 22. By connecting the force sensor 21 and the master sensor 22, a load equal to the load applied to the force sensor 21 is applied to the master sensor 22. Note that the method of fixing the stage 10 and the master sensor 22 is not limited to screwing. When the stage 10 and the base 4 are formed integrally, the stage 10 may be the same as the base 4. That is, the weighted body 2 may be fixed to the base 4.

[0016] The load jig 20 holds the weighted body 2 between itself and the stage 10. The load jig 20 is a plate-shaped member having an upper surface and a lower surface. The load jig 20 is formed of metal, for example. The load jig 20 is fixed to the lower surface of the load jig 20, and is held between the upper surface of the stage 10 and the lower surface of the load jig 20. As a more specific example, a female thread is provided on the upper surface of the force sensor 21, and a bolt is inserted into a through hole provided in the load jig, and the force sensor 21 is screwed to the load jig 20. The method of fixing the load jig 20 and the force sensor 21 is not limited to screwing.

[0017] The parallel link mechanism 30 is composed of six ball screw mechanisms 31 and rods 35 connected to the ball screw mechanisms 31, respectively. As an example, the ball screw mechanism 31 is composed of a ball screw and a linear guide connected to an output unit 32 such as a motor. The six ball screw mechanisms 31 are arranged in a circular ring shape so as to surround the stage 10. The ends of each of the six ball screw mechanisms 31 are fixed to the base 4. This fixes the relative positional relationship between the stage 10 and the parallel link mechanism 30. The six ball screw mechanisms 31 are arranged as three sets of ball screw mechanisms 31, each set consisting of two ball screw mechanisms 31 arranged at equal intervals. The three sets of ball screw mechanisms 31 are arranged so as to be symmetrical about 120 degrees with the stage 10 as the center.

[0018] Parallel link mechanisms are broadly classified into three types: “telescopic type,” “rotary type,” and “linear type.” In the parallel link mechanism 30 of this embodiment, as an example, a linear type parallel link mechanism is configured by six ball screw mechanisms 31 and rods 35.

[0019] As an example, the linear-type parallel link mechanism has a ball screw mechanism 31, an output unit 32, a first bearing 33, and a second bearing 34 corresponding to each of six rods 35. The output unit 32 linearly moves the first bearing 33 in the ball screw mechanism 31 along the Z direction. The first bearing 33 and the second bearing 34 are connecting members that connect two members with three degrees of freedom in the X rotation direction, the Y rotation direction, and the Z rotation direction. The first bearing 33 is fixed to the ball screw mechanism 31. The second bearing 34 is fixed to the upper surface of the load jig 20. The rod 35 is a structural member that connects the first bearing 33 and the second bearing 34. In other words, the first bearing 33 is connected to the end of the rod 35, and the second bearing 34 is connected to the tip of the rod 35. The six rods 35 are connected in parallel to the upper surface of the load jig 20 via the respective second bearings 34. Connected in parallel means that each of the rods 35 is connected to a predetermined position of the load jig 20. The six rods 35 are connected to the respective ball screw mechanisms 31 via the first bearings 33.

[0020] Even in the case of a telescopic parallel link mechanism, which is another example, there is an output section corresponding to each of the six rods. Each output section is incorporated in each rod and extends or contracts the rod itself to apply a load to the load jig to which each rod is connected. And even in the case of a rotating parallel link mechanism, there is an output section corresponding to each of the six rods. Each output section is provided at the end of each rod. Each output section rotates each rod to apply a load to the load jig to which each rod is connected. In this way, the parallel link mechanism only needs to have a configuration that allows each of the six rods to operate independently, and the output section may be attached externally to the rod or may be incorporated in the rod.

[0021] The parallel link mechanism 30 applies a load in at least one of six axial directions to the load-bearing body 2 sandwiched between the stage 10 and the loading jig 20. The six axial directions are three mutually orthogonal axial directions and three rotation directions about each of the three axes as a rotation axis. In the following description, the three axial directions are referred to as the X direction, the Y direction, and the Z direction, respectively. In this embodiment, the X direction is the first horizontal direction, the Y direction is the second horizontal direction perpendicular to the first horizontal direction, and the Z direction is the vertical direction. In addition, the three rotation directions around the axes corresponding to the X direction, the Y direction, and the Z direction are referred to as the X rotation direction, the Y rotation direction, and the Z rotation direction, respectively. If a load value including components in these six axial directions is F, the load value F can be expressed by the following mathematical formula (1). F = [Fx, Fy, Fz, Mx, My, Mz] … (1)

[0022] Here, Fx is the load in the X direction, Fy is the load in the Y direction, Fz is the load in the Z direction, Mx is the load in the X rotation direction, My is the load in the Y rotation direction, and Mz is the load in the Z rotation direction. The load value F does not need to include all six axial components, but it is sufficient to include a component in at least one axial direction.

[0023] The control device 40 is configured as a PLC (Programmable Logic Controller) having a function of a motor controller, for example. The control device 40 may include a computer system including a processor such as a CPU (Central Processing Unit), a memory such as a RAM (Random Access Memory) and a ROM (Read Only Memory), an input / output device such as a touch panel, a mouse, a keyboard, and a display, and a communication device such as a network card. As shown in FIG. 1, the control device 40 is configured integrally with a measurement unit 41 and a control unit 42, and realizes the functions of the measurement unit 41 and the control unit 42 by operating each piece of hardware under the control of the processor based on a computer program stored in the memory. The control device 40 may include an interface to which the force sensor 21, the master sensor 22, and other sensors are connected.

[0024] The measurement unit 41 measures a load value based on the amount of current and the like. FIG. 2 is a block diagram for explaining the calibration system 1 according to an embodiment. As shown in FIG. 2, the measurement unit 41 is communicably connected to the control unit 42. The measurement unit 41 acquires control values ​​(such as current consumption) of each output unit 32 controlled by the control unit 42. The measurement unit 41 measures a load value applied to the weighted body 2 from the control values ​​of the output units 32.

[0025] The control unit 42 controls the output of each output unit 32 so as to displace the loading jig 20 relative to the stage 10. Specifically, when the output unit 32 is a motor, the control unit 42 controls the current applied to the output unit 32, etc. The control unit 42 may control the output of the output unit 32 based on the load value output by the master sensor 22. The control unit 42 may also control the output of the output unit 32 based on the load value measured by the measurement unit 41.

[0026] In this embodiment, the control device 40 has a function of determining an abnormality in the calibration based on the load value output by the master sensor 22, and a function of calibrating the force sensor 21 based on the load value output by the master sensor 22. Specifically, the control device 40 compares the load value output by the master sensor 22 with the load value measured by the measurement unit 41 to determine an abnormality in the calibration. In addition, the control device 40 calibrates the force sensor 21 based on the load value output from the master sensor 22.

[0027] [Master sensor and force sensor] In this embodiment, a strain gauge type force sensor 21 is used. The strain gauge type force sensor 21 measures the magnitude of the force applied to the force sensor 21 by a strain gauge provided on a structural member of the force sensor 21. Specifically, the load applied to the force sensor 21 is measured by converting the amount of elastic deformation occurring in the structural member of the force sensor 21 into a resistance change of the strain gauge. The load value applied to the force sensor 21 is output as a value. In other words, the load value of the load applied to the force sensor 21 is converted into a value. The value is, for example, an electrical signal such as a voltage.

[0028] In this embodiment, a calibrated strain gauge type force sensor is used as the master sensor 22. The master sensor 22 does not have to be the same sensor as the force sensor 21. The master sensor 22 only needs to output a calibrated load value. For example, the force sensor 21 and the master sensor 22 may be piezoelectric or capacitance type force sensors. The force sensor 21 and the master sensor 22 only need to be force sensors that output at least one axial component of the six axial components of the applied load. The load applied to the master sensor 22 is output as a load value including six axial components. The master sensor 22 may output a value before being converted into a load value. In this case, the value of the master sensor 22 is converted into a load value in the control device 40.

[0029] In this embodiment, the weighted body 2 includes a force sensor 21 and a master sensor 22, and the master sensor 22 is fixed to the force sensor 21. Therefore, the same load as that applied to the force sensor 21 is applied to the master sensor 22. The load value of the master sensor 22 and the value of the force sensor 21 are based on the same load.

[0030] [Calibration method using a calibration system] Fig. 3 is a flowchart showing a calibration method using the calibration system 1. As an example, the flowchart shown in Fig. 3 is started by an operator or the like. First, a step of fixing the weighted body 2 to the stage 10 (step S10) is performed.

[0031] In this embodiment, the master sensor 22 of the weighted body 2 is fixed to face the upper surface of the stage 10. The force sensor 21 is connected to the master sensor 22 via a jig or the like.

[0032] Next, a step (step S11) of fixing the weighted body 2 to the loading jig 20 is performed. As an example, the force sensor 21 is fixed to face the lower surface of the loading jig 20. The weighted body 2 is sandwiched between the upper surface of the stage 10 and the lower surface of the loading jig 20.

[0033] Next, a step (step S12) of controlling the output of each output unit 32 corresponding to the six rods 35 and displacing the load jig 20 relative to the stage 10 is performed. In step S13, the output of the output unit 32 may be controlled based on the master sensor 22. Specifically, the control device 40 controls the output of the output unit 32 so that the load value output by the master sensor 22 approaches a target value. The weighted body 2 is fixed to the upper surface of the stage 10 and is further fixed to the lower surface of the load jig 20. As a result, a load value is applied to the weighted body 2 according to the relative displacement between the stage 10 and the load jig 20. In other words, the output of each output unit 32 generates elastic deformation in the weighted body 2. The load jig 20 displaces relative to the stage 10 according to the amount of elastic deformation of the weighted body 2. In this embodiment, the base 4, the stage 10, the load jig 20, and the parallel link mechanism 30 have a rigidity larger than that of the weighted body 2. Therefore, the amount of displacement of the loading jig 20 relative to the stage 10 approximates the amount of elastic deformation of the load body 2 .

[0034] Next, a step (step S13) is performed in which the force sensor 21 included in the weighted body 2 outputs a value based on a load value including at least one axial component out of six axial components of the load applied to the weighted body 2, and a step (step S14) is performed in which the calibrated master sensor 22 included in the weighted body 2 outputs a load value according to the load applied to the weighted body 2. The order of steps S13 and S14 may be reversed.

[0035] Finally, a step (step S15) of calibrating the force sensor 21 is performed. The calibration of the force sensor 21 is performed by calibrating the value V S (In the following explanation, S ) and the load value F of the master sensor 22 M (In the following explanation, M Specifically, the force sensor 21 outputs a value V when the load value output by the master sensor 22 reaches a predetermined range included in the above-mentioned target value.S and the load value F of the master sensor 22. M The calibration matrix C is calculated based on the above. Details of C will be described later. S is expressed by the following formula (2). Also, F obtained in step S15 M is expressed by the following equation (3). V S =[V S1 ,V S2 ,V S3 ,V S4 ,V S5 ,V S6 ]…(2) F M =[F M1 ,F M2 ,F M3 ,F M4 ,F M5 ,F M6 ]…(3)

[0036] V S and F M is the output based on the same load. Therefore, V S By multiplying by a given matrix, V S and F M That is, as shown in the following formula (4), F M C and V S In other words, C is the product of V S F M C is a calibration matrix that converts the force sensor 21 into the force sensor 21. F M =C×V S …(4)

[0037] The control device 40 calculates C. C is calculated by F M V S Inverse matrix V S -1 Specifically, the force sensor 21 and the master sensor 22 are connected to an interface of the control device 40. The control device 40 multiplies the acquired V S From VS -1 The control device 40 calculates the obtained F M V S -1 Multiply by this to calculate C. F M ×V S -1 =C…(5)

[0038] Based on the above formulas (2), (3), (4), and (5), the control device 40 calculates C. C (the calibration matrix of the force sensor 21) is written, for example, to an internal memory of the force sensor 21. Furthermore, if the force sensor 21 does not have an internal memory, C may be written to an external memory provided outside the force sensor 21. S (The value output by the force sensor 21) is converted based on C stored in the internal memory or the external memory and output. This is the end of the flow chart shown in FIG.

[0039] The control device 40 judges whether there is an abnormality in the calibration based on the load value measured by the master sensor 22. Specifically, as an operation for judging whether there is an abnormality in the calibration, a step of acquiring the load value measured by the measurement unit 41 (step S20), a step of judging whether there is an abnormality in the calibration based on the load value output from the master sensor 22 and the load value measured by the measurement unit 41 (step S21), and a step of canceling the calibration (step S22) are performed.

[0040] The operation of determining whether or not there is a calibration abnormality is started, for example, in a process (step S11) of fixing the weighted body 2 to the loading jig 20. The operation of determining whether or not there is a calibration abnormality is executed simultaneously in parallel with the flowchart shown in Fig. 3, and the operation of determining whether or not there is a calibration abnormality is executed with priority.

[0041] First, a step (step S20) of acquiring the load applied to the weighted body 2 is performed. The control device 40 measures the load values ​​of the loads applied to the force sensor 21 and the master sensor 22. In this embodiment, the measurement unit 41 measures the load values ​​based on the control values ​​(such as current consumption) of the respective output units 32 controlled by the control unit 42.

[0042] For example, the measurement unit 41 stores in advance a correspondence table in which the control values ​​of the respective output units 32 correspond to the load values. The correspondence table is created when a normal calibration is performed. The measurement unit 41 refers to the correspondence table and measures the load values ​​based on the current control values ​​of the respective output units 32. The measurement unit 41 may also measure the load values ​​based on a force conversion matrix that converts the output values ​​of the respective output units 32 into load values. The force conversion matrix is ​​calculated based on the control values ​​of the output units 32 and the load values ​​of the master sensor 22.

[0043] Next, a step (step S21) of determining whether the calibration is abnormal is performed based on the load value output from the master sensor 22 and the load value measured by the measurement unit 41. The control device 40 compares the load value output from the master sensor 22 (hereinafter referred to as the first load value) with the load value measured by the measurement unit 41 (hereinafter referred to as the second load value). If the comparison determines that the relationship between the first load value and the second load value is out of a predetermined relationship, the control device 40 determines that the calibration is abnormal. The predetermined relationship refers to, for example, a relationship in which the second load value is included in a predetermined numerical range based on the first load value. If the second load value is not included in a predetermined numerical range based on the first load value, the first load value and the second load value are determined to be out of the predetermined relationship.

[0044] If the control device 40 does not determine that the calibration is abnormal (step S21: NO), the operation of determining whether the calibration is abnormal ends. In this case, the operation of determining whether the calibration is abnormal resumes and is executed repeatedly from step S20. If the control device 40 determines that the calibration is abnormal (step S21: YES), a step of canceling the calibration (step S22) is performed. In step S22, as an example, output to the output unit 32 is stopped, and an operator or the like is notified that the calibration is abnormal. From this point on, the operation of the flowchart in FIG. 3 becomes invalid. With the above, the operation of determining whether the calibration is abnormal ends.

[0045] [Summary of the embodiment]

[0046] In the calibration system 1 and the calibration method, the weighted body 2 is fixed to and clamped by the stage 10 and the load jig 20. Six rods 35 constituting a parallel link mechanism 30 are connected in parallel to the load jig 20. The six rods 35 are driven by the output units 32 corresponding to the respective rods 35. The output of each output unit 32 is controlled by the control device 40, and the load jig 20 is displaced relative to the stage 10. This allows a load in six axial directions to be applied to the weighted body 2. Then, a value based on a load value including at least one axial component among the six axial components of the load applied to the weighted body 2 is output from the force sensor 21, and a load value according to the load is output from the calibrated master sensor 22. The control device 40 calibrates the force sensor 21 based on the value output from the force sensor 21 and the load value output from the master sensor 22. In this way, the calibration system 1 can perform calibration more easily because it does not need to change the device configuration, such as the number or type of weights, depending on the magnitude of the load applied to the weighted body 2. In addition, the calibration system 1 can perform calibration more accurately because it does not need to take into account the sliding resistance generated between the wire and the pulley.

[0047] The control device may determine whether or not there is a calibration abnormality based on the load value output from the master sensor 22. According to the calibration system 1 and the calibration method, whether or not there is a calibration abnormality can be determined based on the load value output from the master sensor 22.

[0048] This calibration system 1 can be made smaller than a calibration device that uses weights. By replacing the output unit 32, the load range can be changed more easily than a calibration device that uses weights. By replacing the master sensor 22, the calibration range can be changed more easily than a calibration system that uses weights. Since there are no restrictions on the posture during calibration, device design is easier. Since the posture does not change during calibration, errors due to fluctuations in the center of gravity position are suppressed.

[0049] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described embodiments, and various omissions, substitutions, and modifications may be made. In the following, the differences from the above-described embodiments will be mainly described, and descriptions of commonalities will be omitted.

[0050] [Variation 1] Fig. 4 is a side view for explaining the calibration system of Modification 1. In the above embodiment, the weighted body 2 is fixed so that the master sensor 22 side faces the upper surface of the stage 10, but in Modification 1, as shown in Fig. 4, the force sensor 21 side is fixed so that it faces the upper surface of the stage 10. The master sensor 22 is fixed to the loading jig 20. In this way, the overlapping order of the force sensor 21 and the master sensor 22 on the weighted body 2 is not limited, and the same action and effect are achieved regardless of the overlapping order.

[0051] [Variation 2] Fig. 5 is a side view for explaining the calibration system of the modified example 2. In the above embodiment, the calibration abnormality is determined based on the load value output from the master sensor 22 and the load value measured by the measurement unit 41, but it may be based on the master sensor 22 and other measurement means. In the modified example 2, as an example of the other measurement means, a strain gauge 5 is provided on each rod 35 as shown in Fig. 5. The strain gauge 5 outputs the strain of the rod 35. The control device 40 determines the calibration abnormality based on the load value output from the master sensor 22 and the output of the strain gauge 5.

[0052] The other measuring means may be a load cell provided on each rod 35. In this manner, the calibration system 1 may determine a calibration anomaly based on the master sensor 22 and other measuring means (such as a strain gauge and a load cell).

[0053] [Variation 3] FIG. 6 is a side view for explaining the calibration system of the modified example 3. In the above embodiment, the base 4 is one plate-like member, but the base 4 may be composed of a plurality of members. In the modified example 3, as shown in FIG. 6, the stage 10 is fixed to the base 4A, and the six ball screw mechanisms 31 are fixed to the base 4B. The stage 10 may be fixed to the base 4B. The base 4A and the base 4B are two opposing plate-like members whose relative positional relationship is fixed. As an example, the base 4A and the base 4B are connected by a support column (not shown), and their relative positional relationship is fixed. In the present embodiment, the stage 10 and the ball screw mechanism 31 of the parallel link mechanism 30 are fixed on the same plane, but they do not have to be fixed on the same plane. In this way, in the modified example 4, the degree of freedom of the posture of the stage 10 and the six ball screw mechanisms 31 is improved. [Explanation of symbols]

[0054] 1...calibration system, 2...weighted body, 21...force sensor, 22...master sensor, 4, 4A, 4B...base, 10...stage, 20...loading jig, 30...parallel link mechanism, 31...ball screw mechanism, 32...output section, 35...rod, 40...control device, 41...measurement section, 42...control section.

Claims

1. a stage on which a weighted object is fixed; a loading jig that sandwiches the weighted body between itself and the stage and to which the weighted body is fixed; a parallel link mechanism including six rods, the parallel link mechanism having output portions corresponding to the six rods, the six rods being connected in parallel to the load jig; a control device that controls the output of each of the output units to displace the load jig relatively to the stage; Equipped with The weighted body is a force sensor that outputs a value based on a load value including at least one axial component among six axial components of the load applied to the load bearing member; a master sensor calibrated to output the load value in response to the load; having the control device calibrates the force sensor based on a value output from the force sensor and the load value output from the master sensor. Calibration system.

2. a step of fixing a weighted body to a stage; a step of sandwiching the weighted body between the stage and a loading jig and fixing the sandwiched weighted body to the loading jig; a step of controlling outputs of output sections of six rods constituting a parallel link mechanism connected to the load jig, and displacing the load jig relative to the stage; a step of outputting a value based on a load value including at least one axial component among six axial components of a load applied to the weighted body, by a force sensor included in the weighted body; a step of a calibrated master sensor included in the weighted body outputting the load value in response to the load; calibrating the force sensor based on a value output from the force sensor and the load value output from the master sensor; Including, Calibration method.

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