Robot system

Abstract

The robot system includes: a robot having a plurality of operating axes; a robot control device for operating each of the plurality of operating shafts to adjust the orientation of the operating shafts; an acceleration sensor which is provided at the tip of the robot and measures the gravitational acceleration of the tip; and a terminal device capable of communicating between the acceleration sensor and the robot control device. The robot control device moves the posture of the first operation axis to at least three different postures, and the terminal device stores three or more pieces of first gravitational acceleration data detected by the acceleration sensor in each of the three or more postures, and controls the robot based on the three or more pieces of first gravitational acceleration data. A first rotation axis vector of a first operation axis in a three-dimensional space is calculated, and a correction parameter for correcting a posture shift of the robot is calculated on the basis of the calculated first rotation axis vector.

Description

Technical Field

[0001] The present disclosure relates to robotic systems. Background Art

[0002] Patent document 1 discloses a calibration method for a robot having an arm with more than 6 degrees of freedom, which enables the front end of the arm to be positioned at an arbitrary position / posture by applying force to the front end of the arm to move it. The calibration method for the robot is performed by providing a position detector at each axis of the joint of the arm, using a three-dimensional measuring instrument that can measure the position / posture of the front end based on the signal of the position detector of each axis, coupling the front end of the three-dimensional measuring instrument to the fingertip located at the front end of the multi-joint robot to be calibrated, measuring the position / posture of the front end of the robot, and measuring a plurality of teaching points by changing the position / posture of the robot.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2001-50741 Summary of the invention

[0006] The present disclosure provides a robot system that can adjust the posture of each joint of the robot with higher accuracy.

[0007] The present disclosure provides a robot system, which comprises: a robot having multiple motion axes; a robot control device, which moves the multiple motion axes respectively to adjust the postures of the motion axes; an acceleration sensor, which is arranged at the front end of the robot, to measure the gravitational acceleration of the front end; and a terminal device, which can communicate between the acceleration sensor and the robot control device, the robot control device moves the posture of any first motion axis among the multiple motion axes to at least three different postures, and the terminal device performs the following processing: storing three or more first gravitational acceleration data detected by the acceleration sensor in the three or more postures respectively; calculating the first rotation axis vector of the first motion axis in three-dimensional space based on the stored three or more first gravitational acceleration data; and calculating a correction parameter for correcting the posture deviation of the robot based on the calculated first rotation axis vector.

[0008] According to the present disclosure, the posture of each joint of the robot can be adjusted with higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a block diagram showing a system configuration example of a robot system according to an embodiment.

[0010] Figure 2 This is a diagram showing an example of six joint axes of the robot in the embodiment.

[0011] Figure 3 This is a diagram for explaining the six rotation axis vectors of the robot and the coordinate system of the three-dimensional acceleration sensor in the embodiment.

[0012] Figure 4 This is a flowchart for explaining an example of the operation procedure of the robot system according to the embodiment.

[0013] Figure 5 This is a flowchart for explaining an example of a procedure for measuring gravitational acceleration of the robot system according to the embodiment.

[0014] Figure 6 This is a flowchart for explaining an example of a procedure for measuring gravitational acceleration of the robot system according to the embodiment.

[0015] Figure 7 This is a flowchart for explaining an example of a procedure for calculating the rotational axial amount of the terminal device in the embodiment.

[0016] Figure 8 This is a diagram for explaining an example of a plane and a circle.

[0017] Fig. 9 This is a diagram for explaining an example of a circle estimation process procedure.

[0018] Fig.10 This is a diagram for explaining setting example 1 of the rotation axis direction amount.

[0019] Fig.11 This is a diagram for explaining setting example 2 of the rotation axis direction amount.

[0020] Fig.12 This is a diagram for explaining setting example 3 of the rotation axis direction amount.

[0021] Fig.13 This is a diagram for explaining an example of detecting the inclination of the surface on which the robot is installed.

[0022] Fig.14 This is a diagram for explaining an example of detecting an axis misalignment of a joint axis.

[0023] Fig.15 This figure explains an example of adjusting the origin of the wrist axis.

[0024] Fig.16 is the angle difference Φ RW , Φ TW An example is shown in FIG. DETAILED DESCRIPTION

[0025] (The process of realizing this disclosure)

[0026] The robot is shipped from the factory with each joint axis calibrated. However, due to collision of the front end of the robot with obstacles, replacement of robot parts, etc., position / posture deviation occurs in the joint axis. For this reason, as in Patent Document 1, a robot calibration method using a three-dimensional position measuring device that can measure joint angles with high precision is disclosed, but the three-dimensional position measuring device is expensive and requires a working space for measurement. In addition, the operator must set a position detector at each joint of the robot and couple the fingertips of the multi-joint robot and the front end of the three-dimensional measuring device to a predetermined position, which is very troublesome.

[0027] In addition, as another robot calibration method, there is a method of calibrating the robot by attaching a pin for position alignment to the front end of the robot and aligning the pin with the position alignment point on the fixture. However, such a calibration method has a problem that the calibration accuracy is affected by the proficiency of the operator who performs the position alignment.

[0028] Hereinafter, each embodiment of the robot system involved in the present disclosure will be described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions are sometimes omitted. For example, detailed descriptions of matters that are already widely known and repeated descriptions of substantially the same structures are sometimes omitted. This is to avoid the following description from becoming unnecessarily lengthy and to make it easy for those skilled in the art to understand. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0029] First, refer to Figure 1 as well as Figure 2 , the overall structure of the robot system 100 involved in the embodiment is explained. Figure 1 1 is a block diagram showing a system configuration example of the robot system 100 according to the embodiment. Figure 2 This is a diagram showing an example of six joint axes (RT joint axis J1 , UA joint axis J2 , FA joint axis J3 , RW joint axis J4 , BW joint axis J5 , and TW joint axis J6 as examples of motion axes) of the robot M1 in the embodiment.

[0030] The robot system 100 according to the embodiment includes a terminal device P1 , a robot control device R1 , and a robot M1 .

[0031] The terminal device P1 is implemented by, for example, a PC (Personal Computer), a notebook PC, a tablet terminal, etc. The terminal device P1 can accept an operator's operation for performing calibration work on the robot M1, and calculate a correction parameter of at least one joint axis of the robot M1 based on a measured value of gravitational acceleration of at least one joint axis of the robot M1. The terminal device P1 includes a first communication unit 10, a first processor 11, a first memory 12, an input unit 13, and a display unit 14.

[0032] The first communication unit 10 is connected to the three-dimensional acceleration sensor 31 installed in the robot M1 by wireless or wired communication, and performs data transmission and reception. In addition, the wireless communication mentioned here is, for example, communication via a wireless LAN (Local Area Network) such as Wi-Fi (registered trademark). The first communication unit 10 outputs the information of the gravitational acceleration sent from the three-dimensional acceleration sensor 31 to the first processor 11.

[0033] The first processor 11 is configured using, for example, a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array), and performs various processing and control in cooperation with the first memory 12. Specifically, the first processor 11 implements the functions of each unit by referring to a program stored in the first memory 12 and executing the program. In addition, the units mentioned here are a rotation axis vector calculation unit 111, a correction parameter calculation unit 112, a posture measurement command unit 113, etc. The first processor 11 calculates a correction parameter for correcting (adjusting) the posture of at least one joint axis based on the posture (gravitational acceleration) of the robot M1 measured by the three-dimensional acceleration sensor 31.

[0034] The rotation axis vector calculation unit 111 calculates the rotation axis vector of the joint axis based on the measured values ​​of the gravitational acceleration measured for one joint axis in three or more different postures. In addition, the rotation axis vector calculation unit 111 can also calculate the gravity vector indicating the magnitude and direction of the gravity applied to the three-dimensional acceleration sensor 31 based on the measured value of the gravitational acceleration.

[0035] Here, the rotation axis vector is explained. The rotation axis vector is a so-called rotation vector of a joint axis and is a normal vector perpendicular to a plane defined by a trajectory of a measured value of gravitational acceleration obtained when a given joint axis is driven (rotated) uniaxially. The rotation axis vector calculation unit 111 outputs information on the calculated rotation axis vector to the correction parameter calculation unit 112.

[0036] The correction parameter calculation unit 112 calculates the correction parameter of the joint axis specified by the operator based on the rotation axis vector of at least one joint axis obtained from the rotation axis vector calculation unit 111. The correction parameter calculation unit 112 outputs the calculated correction parameter of each joint axis to the display unit 14 for display. In addition, the correction parameter calculation unit 112 sends the calculated correction parameter of each joint axis to the robot control device R1 for recording.

[0037] The posture measurement command unit 113 generates a control command for changing the posture (rotation angle) of the joint axis currently measuring the gravity acceleration to a given posture in order to obtain three or more different gravity accelerations for one joint axis. The posture measurement command unit 113 sends the generated control command to the robot control device R1. In addition, the control command transmission process can also be performed via the first communication unit 10 of the terminal device P1.

[0038] The first memory 12 includes, for example, a RAM (Random Access Memory) as a working memory used when executing the processing of the first processor 11, and a ROM (Read Only Memory) storing a program that defines the processing of the first processor 11. The RAM temporarily stores data generated or acquired by the first processor 11. The ROM stores a program that defines the processing of the first processor 11. The first memory 12 records the first posture data 121.

[0039] The first posture data 121 is data in which information on the posture (rotation angle) designated by the posture measurement command unit 113 is associated with three or more different gravitational acceleration values ​​measured by the three-dimensional acceleration sensor 31. The first processor 11 records the first posture data 121 for each joint axis.

[0040] The input unit 13 is a user interface such as a touch panel, a button, a keyboard, a mouse, etc. The input unit 13 receives an operation by an operator, converts it into an electrical signal (control command), and outputs it to the first processor 11. In addition, when a touch panel is used, the input unit 13 and the display unit 14 may be integrally formed.

[0041] The display unit 14 is, for example, a display such as an LCD (Liquid Crystal Display) or an organic EL (Electroluminescence) The display unit 14 displays calculation results of correction parameters of each joint axis and the like.

[0042] The robot control device R1 controls the six joint axes of the robot M1 based on the control command transmitted from the terminal device P1 . The robot control device R1 includes a second communication unit 20 , a second processor 21 , and a second memory 22 .

[0043] The second communication unit 20 is connected to the terminal device P1 and the robot M1 so as to be able to transmit and receive data. The second communication unit 20 outputs control commands, correction parameters for each joint axis, and the like transmitted from the terminal device P1 to the second processor 21 .

[0044] The second processor 21 is configured using, for example, a CPU or an FPGA, and performs various processing and control in cooperation with the second memory 22. Specifically, the second processor 21 implements the functions of each part by referring to a program stored in the second memory 22 and executing the program. The second processor 21 drives and controls each joint axis of the robot M1 based on a control instruction sent from the terminal device P1, or performs posture correction (adjustment) of each joint axis of the robot M1 based on an angle difference between a correction parameter of each joint axis sent from the terminal device P1 and the current posture of the joint axis.

[0045] The second memory 22 includes, for example, a RAM as a working memory used when executing the processing of the second processor 21, and a ROM storing a program that defines the processing of the second processor 21. The RAM temporarily stores data generated or acquired by the second processor 21. The ROM stores a program that defines the processing of the second processor 21. The second memory 22 records the second posture data 221.

[0046] The second posture data 221 respectively records the postures (angles) of the six joint axes (RT joint axis J1, UA joint axis J2, FA joint axis J3, RW joint axis J4, BW joint axis J5, TW joint axis J6) of the robot M1. When a correction parameter for correcting (adjusting) the posture of the joint axis is sent from the terminal device P1, the second posture data 221 is rewritten to the posture (angle) represented by the correction parameter acquired by the second processor 21.

[0047] The robot M1 is connected to the robot control device R1 so as to be able to transmit and receive data. In addition, in the present embodiment, an example of a robot having six joint axes capable of driving six arms is shown, but it goes without saying that the number of joint axes is not limited thereto.

[0048] The robot M1 has an RT joint axis J1 that rotates freely around the RT axis, a UA joint axis J2 that rotates freely around the UA axis, an FA joint axis J3 that rotates freely around the FA axis, an RW joint axis J4 that rotates freely around the RW axis, a BW joint axis J5 that rotates freely around the BW axis, and a TW joint axis J6 that rotates freely around the TW axis. The robot M1 has a three-dimensional acceleration sensor 31 installed on the front end portion 33 of the arm by an operator.

[0049] The robot M1 includes a control unit 32. The control unit 32 is controlled by the robot control device R1. Based on the control command sent from the robot control device R1, the control unit 32 drives the motors (not shown) respectively provided on the six joint axes (RT joint axis J1, UA joint axis J2, FA joint axis J3, RW joint axis J4, BW joint axis J5, TW joint axis J6) to rotate the six joint axes, thereby realizing the drive control of each of the six arms. In addition, when the gravitational acceleration of the joint axis is measured, the control unit 32 uniaxially drives (rotates) only the joint axis that is the measurement object of the gravitational acceleration.

[0050] A three-dimensional acceleration sensor 31 as an example of an acceleration sensor is mounted on the arm front end portion 33 (an example of the front end portion) of the robot M1 to measure the gravity acceleration of the joint axis based on the sensor coordinate system. The sensor coordinate system referred to here is a coordinate system set in the three-dimensional acceleration sensor 31, and is respectively determined by, for example Figure 3 The coordinate system is defined by the X-axis, Y-axis, and Z-axis shown in FIG. The three-dimensional acceleration sensor 31 transmits information on the measured gravitational acceleration to the terminal device P1.

[0051] Next, refer to Figure 3 , the rotation axis vector of each joint axis is described. Figure 3 is the six rotation axis vectors V of the robot in the embodiment RT 、V UA 、V FA 、V RW 、V BW 、V TW and a coordinate system of the three-dimensional acceleration sensor 31. Figure 3 It goes without saying that the sensor coordinate system of the three-dimensional acceleration sensor 31 shown is an example and is not limited to this.

[0052] The rotation axis vector V calculated by the rotation axis vector calculation unit 111 RT 、V UA 、V FA 、V RW 、V BW 、V TWThe respective starting points coincide with the origin O of the sensor coordinates. Thus, the correction parameter calculation unit 112 can calculate the value of the sensor coordinates based on the rotation axis vector and the installation surface H0 (see Fig.13 ) comparison, comparison of multiple rotation axis quantities, etc., calculate the correction parameters that can correct (adjust) the posture of the joint axis.

[0053] Next, refer to Figure 4 , an example of the operation steps of the robot system 100 is described. Figure 4 This is a flowchart for explaining an example of the operation procedure of the robot system 100 according to the embodiment.

[0054] The terminal device P1 in the robot system 100 receives the selection (designation) operation of one or more joint axes by the operator, generates a control command to request the start of measurement of the gravitational acceleration of the selected (designated) joint axis, and sends it to the robot control device R1. The robot control device R1 adjusts the posture of the robot M1 to the basic measurement posture based on the control command sent from the terminal device P1. The terminal device P1 obtains three or more gravitational accelerations sent from the three-dimensional acceleration sensor 31 for each joint axis, thereby measuring the gravitational acceleration of each joint axis (St11).

[0055] The terminal device P1 calculates the rotation axis vector of each joint axis using the three or more gravitational accelerations acquired for each joint axis ( St12 ).

[0056] Based on the calculated rotation axis vector, the terminal device P1 calculates the angle difference between the joint axes, the angle difference between the joint axes and the installation surface H0 of the robot M1, or the angle difference between the joint axes and the gravity direction represented by the gravity vector, etc. (St13). In addition, in step St13, the terminal device P1 can receive the selection of the object (joint axis, installation surface H0, gravity direction, etc.) used in the calculation of the angle difference by the operator, and calculate the angle difference between any two selected objects. In this way, the terminal device P1 can calculate the correction parameters of the joint axis desired by the operator.

[0057] Here, the angle difference calculated in the process of step St13 is described. When calculating the angle difference between two rotation axis vectors, or the angle difference between the rotation axis vector and the gravity vector, the terminal device P1 may also calculate the internal angle between the two vectors as the angle difference between the two vectors. In addition, the terminal device P1 may also calculate the orthographic projection vectors of each of the two vectors, and calculate the internal angle of the two orthographic projection vectors as the angle difference between the two vectors.

[0058] The terminal device P1 calculates a correction parameter (angle) of a joint axis to be corrected (adjusted) in posture based on the calculated angle difference ( St14 ).

[0059] The terminal device P1 associates the calculated correction parameter for each joint axis with a control command for rewriting the existing posture data of the robot M1 to new posture data based on the correction parameter and transmits it to the robot control device R1 , thereby executing rewriting of the second posture data 221 ( St15 ).

[0060] The terminal device P1 displays the calculation result of the correction parameter for each joint axis on the display unit 14 , and notifies the operator of the calculation result of the correction parameter calculated for each joint axis ( St16 ).

[0061] As described above, the robot system 100 according to the embodiment can more easily calculate the correction parameters of the joint axis postures of the robot M1 . In addition, the robot system 100 can more effectively assist the operator in the posture correction (adjustment) work of the robot M1 by displaying the calculation results of the correction parameters on the display unit 14 .

[0062] In addition, the posture correction (adjustment) operation of the robot M1 may also be performed by the robot control device R1. In this case, the robot control device R1 may also correct (adjust) the posture of each joint axis based on the angle (posture) difference between the second posture data 221 before rewriting and the correction parameter sent from the terminal device P1.

[0063] Next, refer to Figure 5 as well as Figure 6 , come on Figure 4 The step St11 (the method of measuring the gravitational acceleration) shown in FIG. Figure 5 This is a flowchart for explaining an example of a procedure for measuring gravitational acceleration in the robot system 100 according to the embodiment. Figure 6 2 is a flowchart for explaining an example of a measurement procedure of the gravitational acceleration of the robot system 100 according to the embodiment. Figure 5 as well as Figure 6 In the description, in order to make the description easier to understand, an example of measuring the gravitational acceleration when the posture (rotation angle) of the joint axis represented by the “joint axis A” is changed will be described as an example.

[0064] The operator attaches the three-dimensional acceleration sensor 31 to a predetermined position of the arm tip 33 of the robot M1 ( St111 ). If the three-dimensional acceleration sensor 31 is always attached, the process of step St111 may be omitted.

[0065] The terminal device P1 receives a selection (designation) operation of any joint axis A whose gravity acceleration has not been measured as a measurement target of gravity acceleration by the operator ( St112 ). The terminal device P1 generates a control command requesting the start of measurement of gravity acceleration corresponding to the posture change of the selected joint axis A, and transmits it to the robot control device R1 .

[0066] In addition, the number of joint axes selected (specified) in step St112 may be plural. When the terminal device P1 receives the operation of selecting (specifying) a plurality of joint axes as the measurement targets of gravitational acceleration, it selects a joint axis A for which gravitational acceleration is not measured among the plurality of selected (specified) joint axes.

[0067] In addition, in step St112, the terminal device P1 may also accept the selection (designation) operation of the adjustment purpose or detection purpose related to the posture of the joint axis of the robot M1, such as the tilt adjustment of the robot M1 relative to the installation surface, the origin adjustment, and the axis offset detection. In this case, the terminal device P1 records the information of one or more joint axes that will be the measurement object of the gravitational acceleration for each adjustment purpose or each detection purpose in the first memory 12. The terminal device P1 refers to the first memory 12 and determines at least one joint axis that will be the measurement object of the gravitational acceleration based on the information of the joint axis corresponding to the adjustment purpose or detection purpose selected (designated) by the operator.

[0068] The robot control device R1 controls the motors that can drive the joint axes of the robot M1 based on the control command sent from the terminal device P1, and adjusts the posture of the robot M1 to the basic measurement posture (St13). When the robot M1 has completed the adjustment to the basic measurement posture, the robot control device R1 generates a control command (electrical signal) notifying the completion of the adjustment to the basic measurement posture, and sends it to the terminal device P1.

[0069] In addition, the basic posture for measurement mentioned here is the posture (rotation angle) of the basic posture when adjusting to the measurement of gravity acceleration, and the information of the posture (rotation angle) is recorded in the first memory 12 for each joint axis. The basic posture for measurement is, for example, RT joint axis J1 = 0 (zero) °, UA joint axis J2 = -50 °, FA joint axis J3 = -50 °, RW joint axis J4 = 0 (zero) °, BW joint axis J5 = -10 °, TW joint axis J6 = 0 (zero) °. In addition, it goes without saying that the above-mentioned basic posture for measurement is an example and is not limited to this.

[0070] The terminal device P1 sets the number of measurements of the gravitational acceleration corresponding to the posture change of the joint axis A (i: an integer greater than or equal to 0) to i=1 (St114) based on the control command notifying the completion of the adjustment to the measured basic posture sent from the robot control device R1. The terminal device P1 obtains (receives) the current posture (rotation angle) information of the joint axis A from the robot control device R1, and obtains (receives) the gravitational acceleration from the three-dimensional acceleration sensor 31 installed on the front end portion 33 of the robot M1 (St115).

[0071] The terminal device P1 compares the posture (rotation angle) information of the joint axis A with the measured value of gravity acceleration (x i ,y i , z i ) is associated with the joint axis A and recorded in the first memory 12 as posture data of the joint axis A (St116).

[0072] The terminal device P1 determines whether the number of times i of measuring the gravitational acceleration corresponding to the posture change of the joint axis A is greater than or equal to a given number m (m: an integer greater than or equal to 3) ( St117 ). The given number m can be set to any number by the operator.

[0073] When it is determined in the process of step St117 that the number of times i of measuring the gravitational acceleration corresponding to the posture change of the joint axis A is greater than or equal to a given number m (i ≥ m) (St117, yes), the terminal device P1 determines whether the measurement of the gravitational acceleration corresponding to the posture change of all joint axes has been completed (St118). In addition, all joint axes mentioned here refer to all joint axes selected (specified) in the process of step St112.

[0074] On the other hand, when it is determined in the processing of step St117 that the number of measurements i of the gravitational acceleration corresponding to the posture change of the joint axis A is not greater than the given number m (i<m) (St117, No), the terminal device P1 generates a control instruction to change the posture (rotation angle) of the joint axis A, and sends it to the robot control device R1.

[0075] Based on the control command sent from the terminal device P1, the robot control device R1 drives (rotates) a single axis of the joint axis A among the six joint axes of the robot M1, and changes the posture of the joint axis A to a different posture (St119). When the posture change of the joint axis A is completed, the robot control device R1 associates the posture (rotation angle) information of the changed joint axis A with the control command notifying the completion of the posture change and sends it to the terminal device P1.

[0076] In addition, the change to a different posture can be achieved, for example, by rotating only the joint axis A (i.e., a single axis) by a given rotation angle (e.g., 15°, 30°, 60°, etc.) each time, or by rotating only the joint axis A to three or more pre-set rotation angles (e.g., 0 (zero)°, 120°, 270°, etc.).

[0077] The terminal device P1 obtains the posture (rotation angle) information and control command of the changed joint axis A sent from the robot control device R1. Based on the control command, the terminal device P1 increments the number of gravitational acceleration measurements i (i=i+1) (St120), and obtains (receives) the gravitational acceleration measurement value from the three-dimensional acceleration sensor 31 installed on the arm front end 33 of the robot M1 (St115).

[0078] When it is determined in the process of step St118 that the measurement of the gravitational acceleration corresponding to the posture change of all joint axes is completed (St118, Yes), the terminal device P1 generates a notification indicating that the measurement of the gravitational acceleration is completed, and displays it on the display unit 14. The operator ends the gravitational acceleration measurement operation by removing the three-dimensional acceleration sensor 31 from the arm front end portion 33 of the robot M1 (St121). In addition, when it is not necessary to remove the three-dimensional acceleration sensor 31, the process of step St121 can be omitted.

[0079] On the other hand, when the terminal device P1 determines that the measurement of the gravitational acceleration corresponding to the posture change of all joint axes has not been completed in the process of step St118 (St118, No), the terminal device P1 accepts a selection (designation) operation of any joint axis A for which the gravitational acceleration has not been measured as a measurement target of the gravitational acceleration based on the operator (St112). In addition, the terminal device P1 may automatically select any joint axis for which the gravitational acceleration has not been measured without a selection operation by the operator.

[0080] Next, refer to Figure 7 ,right Figure 4 The process of step St12 (the process of calculating the rotation axis amount) will be described below. Figure 7 This is a flowchart for explaining an example of a procedure for calculating the rotation axis amount of the terminal device P1 in the embodiment. Figure 7 In the description, in order to make the description easier to understand, an example of measuring the gravitational acceleration when the posture (rotation angle) of the joint axis represented by the “joint axis A” is changed will be described as an example.

[0081] The terminal device P1 determines the joint axis A for calculating the rotation axis vector ( St211 ). The operator may determine the joint axis A. In this case, the terminal device P1 determines the joint axis A selected by the operator as the joint axis to be calculated for the rotation axis vector.

[0082] The terminal device P1 refers to the first memory 12 to obtain the posture data corresponding to the joint axis A (St212). The terminal device P1 calculates the difference value of each of the m gravitational acceleration measurement values ​​measured at each posture (rotation angle) (St213), and determines whether each calculated difference value is greater than or equal to the threshold value ThA (St214). In addition, the threshold value ThA is a value indicating the measurement noise (measurement error) of the three-dimensional acceleration sensor, and can be set to an arbitrary value by the operator.

[0083] When the terminal device P1 determines in the process of step St214 that the calculated difference value is greater than or equal to the threshold value ThA (St214, Yes), it is determined that there is a significant difference in each of the m gravitational acceleration measurement values ​​that is not the measurement noise of the three-dimensional acceleration sensor. The terminal device P1 calculates the m gravitational acceleration measurement values ​​(x i ,y i , z i ),…,(x m ,y m , z m ), to estimate the plane obtained by plotting the m measured values ​​of gravitational acceleration (for example, Figure 8 The plane P shown TW ) (St215). In addition, the plane estimation can be performed using SVD (Singular Value Decomposition) or other plane estimation methods.

[0084] On the other hand, when the terminal device P1 determines in the process of step St214 that the calculated difference value is not greater than the threshold value ThA (St214, No), the gravity vector represented by the measured value of the gravitational acceleration is determined as the rotation axis vector of the joint axis A (St216). In addition, the process of step St216 is described later. Fig.10 A specific example is used in the description of the invention.

[0085] The terminal device P1 projects the m measured values ​​of gravitational acceleration onto the estimated plane. The terminal device P1 estimates a circle (for example, Figure 8 The circle C shown TW) (St217). The terminal device P1 determines whether the estimated radius of the circle is less than or equal to a threshold value ThB (St218).

[0086] When the terminal device P1 determines in the process of step St218 that the radius of the estimated circle is less than or equal to the threshold value ThB (St218, Yes), the center coordinates of the estimated circle (for example, Figure 8 The center coordinates CO shown in FIG. 2 are determined as the rotation axis vector (St219) of the joint axis A. In addition, the processing of step St219 is described later. Fig.11 A specific example is used in the description of the invention.

[0087] On the other hand, when the terminal device P1 determines in the process of step St218 that the radius of the estimated circle is not less than the threshold value ThB (St218, No), the normal vector with respect to the estimated plane is determined as the rotation axis vector of the joint axis A (St220). In addition, regarding the process of step St220, in the following Fig.12 A specific example is used in the description of the invention.

[0088] The terminal device P1 determines the sign (that is, the direction) of the set rotation axis direction quantity based on the rotation direction of the joint axis A in the positive direction ( St221 ).

[0089] For example, the terminal device P1 determines the direction along the positive rotation direction of the motor driving the joint axis A as the direction of the rotation axis direction in each of step St216, step St219, and step St220.

[0090] In addition, for example, the terminal device P1 calculates the angular difference between the determined direction of the rotation axis quantity and the direction of the rotation axis quantity calculated based on the measured value of the gravitational acceleration. The terminal device P1 may determine the direction of the rotation axis quantity calculated based on the measured value of the gravitational acceleration when the calculated angular difference is an acute angle, and may determine the direction to be the direction after the direction of the rotation axis quantity calculated based on the measured value of the gravitational acceleration is reversed when the calculated angular difference is an obtuse angle.

[0091] The terminal device P1 determines whether calculation of the rotation axis amounts of all joint axes measured in the process of step St11 has been completed ( St222 ).

[0092] When the terminal device P1 determines in the process of step St222 that the calculation of the rotation axis amounts of all the joint axes has been completed ( St222 , Yes), the calculation process of the rotation axis amounts is terminated.

[0093] On the other hand, when the terminal device P1 determines in the process of step St222 that the calculation of the rotation axis amounts of all joint axes has not been completed ( St222 , No), the process returns to the process of step St211 and selects any joint axis whose rotation axis amount has not been calculated ( St211 ).

[0094] Reference Figure 8 as well as Fig. 9 Each of them is described separately Figure 7 The processing of step St215 (plane estimation processing) and the processing of step St217 (circle estimation processing) are shown. Figure 8 is the plane P TW and circle C TW An example is shown in FIG. Fig. 9 It is the circle C TW A diagram illustrating an example of the estimation processing steps.

[0095] In addition, Figure 8 As an example, the plane P estimated based on each of the m gravitational acceleration measurement values ​​obtained when the posture (rotation angle) of the TW joint axis J6 is changed is shown. TW and circle C TW In addition, Fig. 9 In order to make the plane P TW and circle C TW The description of each estimation process step is easy to understand. Figure 8 The sensor coordinate system and plane P are shown TW and circle C TW Examples of different positional relationships.

[0096] Figure 8 as well as Fig. 9 The X-axis, Y-axis, and Z-axis shown in each diagram represent a sensor coordinate system set in the three-dimensional acceleration sensor 31 .

[0097] Plane P TW The terminal device P1 uses m measured values ​​of gravitational acceleration (x i ,y i , z i ),…,(x m ,y m , z m ), to calculate each of the coefficients a, b, c, d of (Formula 1) representing the plane, thereby executing the plane P TW presumptive treatment.

[0098] [Mathematical formula 1]

[0099]

[0100] Circle C TW is the circle estimated by the processing of step St217. Fig. 9 , for circle C TW The inference processing is described in detail.

[0101] The terminal device P1 calculates the plane P estimated using (Formula 1) in the sensor coordinate system. TW The unit normal vector of the calculated plane P TW The rotation matrix R that makes the unit normal vector of the Z axis consistent with the unit vector in the Z axis direction TW (St217-1). In addition, for the rotation matrix R TW The calculation method of can use any known method, for example, the rotation formula of Rodriguez can be used.

[0102] [Mathematical formula 2]

[0103]

[0104] As shown in (Equation 2), the terminal device P1 calculates the rotation matrix R TW , respectively, let the measured values ​​of m gravitational acceleration (x i ,y i , z i ),…,(x m ,y m , z m ) rotates, thereby making the plane P TW Rotation (St217-2). In addition, plane P TW ´ is to use the rotation matrix R TW The plane P after rotation TW . Convert value (x i ´,y i ´, z i ´)、…、(x m ´,y m ´, z m ´) are respectively using the rotation matrix R TW The m measured values ​​of gravitational acceleration after rotational movement are performed.

[0105] The terminal device P1 is based on the m conversion values ​​(x i ´,y i ´, z i ´)、…、(x m ´,y m ´, z m ´) in the XY plane (x i ´,y i´)、…、(x m ´,y m ´), execute circle C TW The terminal device P1 calculates the estimated circle C TW The center coordinates CO of ´(c x ´,c y ´) and circle C TW ´ has a radius r (St217-3). In addition, circle C TW The estimation of ' is performed using any known method such as the least squares method.

[0106] Terminal device P1 is a circle C TW The center coordinates CO of ´(c x ´,c y ´) and calculate the origin of the sensor coordinate system and the plane P TW ´The distance D between them (St217-4).

[0107] Terminal device P1 calculates the rotation matrix R TW The inverse matrix R TW -1 As shown in (Equation 3), the terminal device P1 uses the calculated inverse matrix R TW -1 , to calculate the circle C in the sensor coordinate system TW The center coordinates CO (c x , c y , c z )(St217-5).

[0108] [Mathematical formula 3]

[0109]

[0110] Through the above, the terminal device P1 can estimate the circle C TW The center coordinates CO (c x , c y , c z ).

[0111] Reference Fig.10 ,right Figure 7 The processing of step St216 shown (processing for determining the rotation axis vector) will be described. Fig.10 This is a diagram for explaining example 1 of setting the rotation axis amount. Fig.10 As an example, the rotation axis vector V when the object of measurement of gravity acceleration is the RT joint axis J1 is RT An example of decision processing is described below.

[0112] Example 1 of setting the rotation axis vector is that, as in the case where the robot M1 is placed on a horizontal plane, the rotation axis of the joint axis is aligned with the gravity vector G indicated by the gravity direction measured by the three-dimensional acceleration sensor 31. RT An example of a process for determining a rotation axis vector in a case where the two axes coincide with each other.

[0113] In this case, each difference value of the m gravitational acceleration measurement values ​​will not be greater than the threshold value ThA. Therefore, the terminal device P1 determines that the calculated difference value is not greater than the threshold value ThA in the processing of step St214, and transfers to the processing of step St216 to convert the gravity vector G RT Determine the rotation axis vector V of the RT joint axis J1 RT .

[0114] Reference Fig.11 ,right Figure 7 The processing of step St219 shown (processing for determining the rotation axis vector) is explained. Fig.11 This is a diagram for explaining example 2 of setting the rotation axis amount. Fig.11 As an example, the rotation axis vector V when the object of measurement of gravity acceleration is the TW joint axis J6 is TW An example of decision processing is described below.

[0115] Example 2 of setting the rotation axis amount is as follows Figure 2 The angle (for example, the angle difference θ) between the rotation axis of the joint axis and the gravity direction measured by the three-dimensional acceleration sensor 31 is as shown in FIG. TW An example of determining the rotation axis vector when ) is small.

[0116] In this case, according to the m measured values ​​of gravitational acceleration (x i ,y i ),…,(x m ,y m ) The estimated circle C TW At a location far from the origin of the sensor coordinate system (that is, Fig. 9 The distance D shown is larger), with a radius r below a threshold ThB.

[0117] In addition, in such a case, Fig.11 As shown, when there is a measurement error ER11, when comparing the measurement error ER12 and the measurement error ER13, the measurement error ER12 is smaller. The measurement error ER12 is the measurement error of the estimated circle C. TW The center coordinates CO TW The rotation axis vector V TWWhen the rotation axis vector of the TW joint axis J6 is determined, the ideal rotation axis vector V´ TW The measurement error ER13 is the error of the estimated plane P TW The normal vector of is determined as the rotation axis vector of the TW joint axis J6 and the ideal rotation axis vector V´ TW In addition, Fig.11 The center coordinates CO´ are shown TW The center coordinates of the circle estimated based on the ideal measured values. Plane P´ TW It is a plane estimated based on an ideal measurement result. Note that the term “ideal” here refers to an ideal measurement result of the three-dimensional acceleration sensor 31 without measurement error.

[0118] Therefore, the terminal device P1 will pass through the circle C estimated by the processing of step St217. TW The center coordinates CO TW and the rotation axis vector V of the origin O of the sensor coordinate system TW The rotation axis vector of the TW joint axis J6 is determined instead of the normal vector of the plane estimated by the processing of step St215.

[0119] Therefore, the terminal device P1 can determine the rotation axis vector in which the measurement error of the joint axis posture obtained by the three-dimensional acceleration sensor 31 becomes smaller, that is, the measurement accuracy of the joint axis posture is higher, based on the relationship between the value of the threshold value ThB set corresponding to the size of the measurement error of the three-dimensional acceleration sensor 31 and the radius of the circle.

[0120] Reference Fig.12 ,right Figure 7 The step St220 (determination process of the rotation axis vector) shown in FIG. 2 will be described. Fig.12 This is a diagram for explaining example 3 of setting the rotation axis amount. Fig.12 As an example, the rotation axis vector V when the object of measurement of gravitational acceleration is the UA rotation axis is UA An example of decision processing is described below.

[0121] Example 3 of setting the rotation axis amount is as follows Figure 2 This is an example of determining a rotation axis vector when the rotation axis of the joint axis, such as the UA joint axis J2 and the FA joint axis J3 shown in FIG. 1 , is at a right angle or a nearly right angle to the gravity direction measured by the three-dimensional acceleration sensor 31 .

[0122] In this case, according to the m measured values ​​of gravitational acceleration (x i ,y i ),…,(x m ,ym ) and the estimated circle C UA The vicinity of the origin O of the sensor coordinate system has a radius r greater than or equal to the threshold value ThB. In addition, the rotation axis of the UA joint axis J2 and the gravity vector G indicating the gravity direction measured by the three-dimensional acceleration sensor 31 are located at the same angle as the rotation axis of the UA joint axis J2. UA When the angle formed is a right angle, the estimated circle C UA The radius is the largest.

[0123] In addition, in such a case, Fig.12 As shown in FIG. 1 , when the measurement value of the three-dimensional acceleration sensor 31 includes the measurement error ER23, compared with the circle C determined based on the estimation, UA The center coordinates CO UA The measurement error ER21 in the case of the rotation axis vector is the estimated plane P UA The normal vector of is determined as the rotation axis vector V of the UA joint axis J2 UA The measurement error ER22 in the case of the ideal rotation axis vector V´ UA The measurement error is smaller. In addition, Fig.12 The center coordinates CO´ are shown UA The center coordinates of the circle estimated based on the ideal measured values. Plane P´ UA This is a plane estimated based on ideal measurement results.

[0124] Therefore, the terminal device P1 determines the normal vector of the plane (not shown) estimated by the process of step St215 as the rotation axis vector V of the UA joint axis J2. UA , instead of passing through the circle C estimated by the processing of step St217 TW The center coordinates of and the rotation axis vector of the origin O (not shown) of the sensor coordinate system.

[0125] Next, refer to Fig.13 , explains how to use the rotation axis quantity. Fig.13 This is a diagram for explaining an example of detecting the inclination of the installation surface H1 of the robot M1.

[0126] The terminal device P1 can determine the rotation axis vector V based on the determined rotation axis vector V. RT The gravity vector G based on the measurement value of the gravitational acceleration by the three-dimensional acceleration sensor 31 RT The angle formed (= angle difference θ RT ), to calculate the inclination of the installation surface H1 where the robot M1 is installed (= angle difference θ RT The terminal device P1 calculates the angle difference θ based on the calculated angle difference θ. RT , and calculates the correction parameters of each joint axis. In this way, the operator can perform the inclination correction for the installation surface H1 of the robot M1.

[0127] In addition, the terminal device P1 may also calculate the inclination of the installation surface H1 (= the angle difference θ RT ), calculate the gravity compensation parameters in the motor control of each joint axis and send them to the robot control device R1.

[0128] Next, refer to Fig.14 , explains how to use the rotation axis quantity. Fig.14 This is a diagram for explaining an example of detecting an axis misalignment of a joint axis. Here, an example of detecting an axis misalignment of the FA joint axis J3 when no axis misalignment occurs in the UA joint axis J2 will be explained.

[0129] exist Fig.14 In the robot M1 shown, a component M11 that rotates about the FA axis is assembled in an installation posture PT1 that is different from a normal installation posture PT0 due to foreign matter that enters during assembly.

[0130] The terminal device P1 calculates the rotation axis vector V of the FA joint axis J3 which is parallel to each other when no axis deviation occurs. FA The rotation axis vector V with respect to the UA joint axis J2 UA The angle difference θ FA The terminal device P1 calculates the angle difference θ based on the calculated FA To determine whether there is an axis offset in the FA joint axis J3 or the UA joint axis J2, or based on the angle difference θ FA The sign (direction) of the axis deviation is used to determine the axis deviation direction. In addition, the terminal device P1 can also calculate the angle difference θ FA The value is compared with a given threshold value to determine whether axis deviation occurs in the FA joint axis J3 or the UA joint axis J2.

[0131] Thus, the terminal device P1 can calculate the angle difference θ based on the calculated angle difference θ. FA , abnormalities of the component M11 itself (for example, degradation, defects, etc. of the component M11 ), assembly abnormalities of the component M11 , etc. are detected.

[0132] In addition, when there is no abnormality in the component M11 itself (for example, deterioration or defect of the component M11) or abnormality in assembly of the component M11, but only axis deviation of the FA joint axis occurs, the terminal device P1 can calculate the angle difference θ based on the calculated angle difference θ. FA , to calculate the correction parameter for correcting the inclination of the posture of the FA joint axis.

[0133] Next, refer to Fig.15 as well as Fig.16 The following explains how to use the rotation axis quantity. Fig.15This diagram explains an example of adjusting the origin of the wrist axes (RW joint axis J4, BW joint axis J5, and TW joint axis J6). Fig.16 is the angle difference Φ RW , Φ TW The wrist axis mentioned here refers to three joint axes near the front end portion 33 of the arm, namely, the RW joint axis J4, the BW joint axis J5, and the TW joint axis J6.

[0134] In addition, Fig.15 In the origin adjustment example shown, an example in which the measurement basic posture of the robot M1 is set so that the angle difference between the TW axis and the RW axis is 10° will be specifically described.

[0135] The terminal device P1 measures the gravitational acceleration obtained when the postures (rotation angles) of the RW joint axis J4 , the TW joint axis J6 , and the BW joint axis J5 are changed in this order.

[0136] The terminal device P1 estimates the plane P corresponding to each joint axis based on the measured values ​​of the gravitational acceleration of each of the RW joint axis J4, the TW joint axis J6, and the BW joint axis J5. RW , P TW , P BW Each of the circles C RW (not shown), C TW (not shown), C BW The terminal device P1 is based on the estimated plane P RW , P TW , P BW Each of the circles C RW (not shown), C TW (not shown), C BW Each of them determines the rotation axis vector V corresponding to each joint axis. RW 、V TW 、V BW .

[0137] The terminal device P1 calculates the rotation axis vector V of the BW joint axis J5. BW The rotation axis vector V of the RW joint axis J4 when it rotates RW and the rotation axis vector V of the TW joint axis J6 TW The angle difference θ BW , and the rotation axis vector V BW The angle difference of the tilt (posture) direction Φ RW , Φ TW In addition, the angle difference θ calculated here BWis a value that changes according to the operating angle of the BW joint axis J5. That is, the terminal device P1 can calculate the correction parameter so that the angle difference θ BW The origin adjustment of the robot M1 is performed in accordance with the measured basic posture.

[0138] For example, in Fig.15 In the example shown, the terminal device P1 calculates the angle difference θ based on the calculated angle difference θ. BW =10.5° and the angle difference = 10° set as the measured basic posture of the robot M1, the angle difference = 0.5° is used to calculate the correction parameter for performing the origin adjustment of the BW joint axis J5. The terminal device P1 displays the calculated correction parameter on the display unit 14 and sends it to the robot control device R1. As a result, the operator can perform a higher-precision origin adjustment of the BW joint axis J5.

[0139] In addition, the angle difference Φ RW , Φ TW are angles that are independent of the operating angle of the robot M1. Therefore, the terminal device P1 can calculate the angle difference Φ based on the calculated angle difference Φ. RW , Φ TW , to detect assembly abnormalities of the wrist axis (RW joint axis J4, BW joint axis J5, TW joint axis J6), etc.

[0140] Through the above, the robot system 100 involved in the embodiment includes: a robot M1 having a plurality of joint axes (an example of an action axis, such as RT joint axis J1, UA joint axis J2, FA joint axis J3, RW joint axis J4, BW joint axis J5, and TW joint axis J6); a robot control device R1 that moves the plurality of joint axes to adjust the postures of the joint axes; a three-dimensional acceleration sensor 31 (an example of an acceleration sensor) that is provided at the front end portion 33 (an example of the front end portion) of the arm of the robot M1 to measure the gravitational acceleration of the front end portion 33 of the arm; and a terminal device P1 that can communicate between the three-dimensional acceleration sensor 31 and the robot control device R1. The robot control device R1 moves the posture of any first joint axis among the plurality of joint axes to at least three different postures. The terminal device P1 stores three or more first gravity acceleration data detected by the three-dimensional acceleration sensor 31 in each of the three or more postures, calculates the first rotation axis vector of the first joint axis in the three-dimensional space based on the stored three or more first gravity acceleration data, and calculates the correction parameter for correcting the posture deviation of the robot M1 based on the calculated first rotation axis vector.

[0141] Thus, the robot system 100 according to the embodiment can calculate the correction parameter capable of correcting the posture deviation of each joint axis with higher accuracy. Therefore, the operator can correct the posture deviation of the robot M1 more easily based on the calculated correction parameter.

[0142] In addition, the terminal device P1 in the robot system 100 according to the embodiment calculates the first rotation axis vector and the gravity vector along the gravity direction measured by the three-dimensional acceleration sensor 31, and calculates a correction parameter based on the angle difference between the first rotation axis vector and the gravity vector. Thus, the robot system 100 according to the embodiment can calculate a correction parameter that can perform a more accurate tilt correction on the installation surface H1 of the robot M1.

[0143] In addition, the robot control device R1 in the robot system 100 involved in the embodiment causes the posture of any second joint axis different from the first joint axis among the multiple joint axes to move to at least three different postures. The terminal device P1 stores three or more second gravity acceleration data detected by the three-dimensional acceleration sensor 31 in the three or more postures of the second joint axis, calculates the second rotation axis vector of the second joint axis in the three-dimensional space based on the stored three or more second gravity acceleration data, and calculates the correction parameter based on the angle difference between the calculated first rotation axis vector and the second rotation axis vector. Thus, the robot system 100 involved in the embodiment can adjust the posture of the second joint axis based on the calculated angle difference (for example, Fig.14 The angle difference θ shown FA ), and calculates correction parameters for performing higher-precision axis offset adjustment (correction) of the joint axes of the robot M1.

[0144] In addition, the robot control device R1 in the robot system 100 according to the embodiment moves the posture of any one of the plurality of joint axes, which is different from the first joint axis and the second joint axis, to at least three different postures. The terminal device P1 stores three or more third gravity acceleration data detected by the three-dimensional acceleration sensor 31 at three or more postures of the third joint axis, calculates the third rotation axis vector of the third joint axis in the three-dimensional space based on the stored three or more third gravity acceleration data, and calculates the correction parameter based on the angle difference between the calculated first rotation axis vector, the second rotation axis vector and the third rotation axis vector. Thus, the robot system 100 according to the embodiment can calculate the correction parameter for performing higher-precision origin adjustment of the joint axis.

[0145] In the above, various embodiments are described with reference to the accompanying drawings, but it is self-evident that the present disclosure is not limited to the examples involved. If it is a person skilled in the art, it is obvious that various changes, corrections, substitutions, additions, deletions, and equivalents can be thought of within the scope of the claims, and it is understood that these certainly also belong to the technical scope of the present disclosure. In addition, the various structural elements in the above-mentioned various embodiments can be arbitrarily combined without departing from the scope of the main purpose of the present invention.

[0146] Industrial Applicability

[0147] The present disclosure is useful as a robot system that can adjust the posture of each joint of the robot with higher accuracy.

[0148] -Explanation of symbols-

[0149] 10 1st Communications Department

[0150] 20 2nd Communications Department

[0151] 11.1 Processor

[0152] 21 Second Processor

[0153] 12 1st memory

[0154] 22 2nd memory

[0155] 13 Input section

[0156] 14 Display

[0157] 31 3D Acceleration Sensor

[0158] 32 Control Unit

[0159] 33 Arm front end

[0160] 100 Robotic Systems

[0161] 111 Rotation axis vector calculation unit

[0162] 112 Correction parameter calculation unit

[0163] 113 Posture measurement command unit

[0164] 121 1st posture data

[0165] 221 Second posture data

[0166] J1RT Joint Axis

[0167] J2UA Joint Axis

[0168] J3FA Joint Axis

[0169] J4RW Joint Axis

[0170] J5BW Joint Axis

[0171] J6TW Joint shaft

[0172] M1 Robot

[0173] P1 Terminal Device

[0174] R1 Robot Control Unit.

Claims

1. A robot system comprising: Robots, with multiple axes of motion; A robot control device that respectively moves the plurality of motion axes to adjust the postures of the motion axes; An acceleration sensor is provided at the front end of the robot to measure the gravitational acceleration of the front end; and a terminal device capable of communicating between the acceleration sensor and the robot control device, The robot control device causes the posture of any first motion axis among the plurality of motion axes to move to at least three different postures. The terminal device performs the following processing: storing three or more first gravity acceleration data detected by the acceleration sensor in the three or more postures respectively; calculating a first rotation axis vector of the first motion axis in a three-dimensional space based on the three or more stored first gravitational acceleration data; Based on the calculated first rotation axis vector, a correction parameter for correcting the posture deviation of the robot is calculated.

2. The robot system according to claim 1, wherein: The terminal device performs the following processing: calculating the first rotation axis vector and a gravity vector along the gravity direction measured by the acceleration sensor; A correction parameter based on an angle difference between the first rotation axis vector and the gravity vector is calculated.

3. The robot system according to claim 1, wherein: The robot control device performs the following processing: The posture of any one of the plurality of motion axes, which is different from the first motion axis, is moved to at least three different postures. The terminal device performs the following processing: storing three or more second gravity acceleration data detected by the acceleration sensor in the three or more postures of the second motion axis; calculating a second rotation axis vector of the second motion axis in the three-dimensional space based on the three or more stored second gravitational acceleration data; A correction parameter based on the calculated angular difference between the first rotation axis vector and the second rotation axis vector is calculated.

4. The robot system according to claim 3, wherein: The robot control device performs the following processing: The posture of any one of the plurality of motion axes, which is a third motion axis different from the first motion axis and the second motion axis, is moved to at least three different postures. The terminal device performs the following processing: storing three or more third gravity acceleration data detected by the acceleration sensor in the three or more postures of the third motion axis respectively; calculating a third rotation axis vector of the third motion axis in the three-dimensional space based on the three or more third gravitational acceleration data stored; A correction parameter based on the calculated angle difference between the first rotation axis vector, the second rotation axis vector, and the third rotation axis vector is calculated.

5. A robot system comprising: Robots, with multiple axes of motion; The robot control device causes two or more of the plurality of motion axes to operate to adjust the postures of the two or more operated motion axes; An acceleration sensor is provided at the front end of the robot to measure the gravitational acceleration of the front end; and a terminal device capable of communicating between the acceleration sensor and the robot control device, The robot control device causes the posture of each of the two or more operating axes to move to at least three different postures. The terminal device performs the following processing: storing three or more first gravity acceleration data detected by the acceleration sensor in the three or more postures respectively; calculating, based on the three or more first gravitational acceleration data stored, a rotation axis vector of each of the two or more motion axes that have moved in the three-dimensional space; Based on the calculated rotation axis vectors, correction parameters for correcting the posture deviation of the robot are calculated.

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