JP7227012B2 - Control device for articulated robot - Google Patents

Description

The present invention relates to a controller for an articulated robot.

Conventionally, when controlling a robot that performs work while pressing a tool held at the end of a robot arm against a workpiece, the counterforce acting on the tool compensates for the amount of slippage between the tool and the workpiece. A control device for an articulated robot is known (see Patent Document 1, for example).

JP 2016-36858 A

When an external force acts on the robot, the arm, speed reducer, etc. are deformed, and the tip position of the robot changes. The control device uses a spring model to calculate the tip displacement of the robot caused by an external force, and corrects the position of the robot using the result to suppress slippage between the tool and the workpiece. In the spring model used in the control device, a spring constant independent of posture is defined for each movable axis. This spring constant is experimentally determined, for example, from the relationship between external force and tip displacement in a specific robot posture. However, with such a simple spring model, it is not possible to accurately obtain the tip displacement in all postures. In other words, depending on the posture, a deviation occurs between the estimated tip displacement and the actual tip displacement.

It is experimentally known that the difference between the tip displacement obtained by the spring model and the actual tip displacement changes depending on the angle formed by the external moment and the rotation axis vector of each movable shaft. For example, when using a spring constant that reduces the deviation from the theoretical value when the corresponding angle is 0°, the larger the corresponding angle, the more the actual tip displacement is than the tip displacement obtained by the spring model. become smaller. Conversely, when using a spring constant that reduces the deviation from the theoretical value when the matching angle deviates from 0°, the closer the matching angle approaches 0°, the more the actual tip displacement is It becomes larger than the tip displacement amount obtained.

The present invention has been made in view of the circumstances described above. One of the objects of the present invention is to provide a controller for an articulated robot that can accurately calculate the displacement of an arm.

In order to solve the above problems, the present invention employs the following means.
One aspect of the present invention is a control device for an articulated robot in which a plurality of arm members constituting an arm of the robot move around a plurality of movable axes, wherein the tip of the arm moves when a sample external force is applied to the tip of the arm. a storage unit storing a correction coefficient or a correction function obtained based on the detected value of the displacement of the arm or the displacement around each movable axis; The calculation of the displacement of each arm member around each movable shaft that changes according to the direction includes a mathematical element representing the relationship between the rotation axis direction of each movable shaft and the direction of the force, and the correction coefficient or the correction. and a displacement calculation means that uses at least a function.
In one embodiment of the above aspect, the storage unit stores a plurality of angles φ and a plurality of correction coefficients corresponding to each of the plurality of arm members, or , the correction function that obtains the correction coefficient with the angle φ as a variable is stored. The angle φ is an angle formed by an external force moment acting on each movable shaft due to the sample external force and the rotation axis direction of each movable shaft.

In the above aspect, a correction factor or correction function is determined based on a sample external force of known magnitude and direction. Further, the displacement of each arm member around each movable axis is calculated using a correction coefficient or a correction function in addition to a mathematical element indicating the relationship between the rotation axis direction of each movable axis and the direction of force. Therefore, it is possible to accurately calculate the displacement of the arm of the robot according to the magnitude and direction of the force acting on the robot.

Preferably, in the control device of the above aspect, the displacement of each arm member due to gravity is calculated by the displacement calculating means, and the position of each arm member is corrected using the result obtained by the calculation.
With this configuration, the displacement of each arm member due to gravity is accurately recognized by the controller. This is useful for improving the accuracy of arm motion.

In another embodiment of the above aspect, the control device is configured such that when the article held at the distal end of the arm is pressed against the work to apply a force to the work, the displacement calculation means causes the displacement from the work to be The relationship between the rotation axis direction of each movable shaft and the direction of the reaction force is defined as: and the correction coefficient or the correction function, and the control device calculates the result obtained by the calculation in order to reduce the amount of slippage occurring between the article and the work. and an operation program correcting means for correcting the operation command of the arm based on the above.

With this configuration, the displacement of each arm member around each movable axis is accurately obtained, and the arm motion command is corrected based on the accurately obtained displacement of each arm member. Therefore, the motion command is corrected by accurately considering the displacement of the arm caused by pressing the article held at the tip of the arm against the work. This is advantageous for improving the accuracy of work, improving workability, and improving the quality of products obtained by the work.

According to the present invention, it is possible to accurately calculate the displacement of the arm.

1 is a schematic configuration diagram of a robot and a control device according to one embodiment of the present invention; FIG. 4A and 4B are operation explanatory diagrams of the robot of the present embodiment; FIG. 4A and 4B are operation explanatory diagrams of the robot of the present embodiment; FIG. It is a block diagram of the control device of this embodiment.

A controller 20 for a robot 10, which is an articulated robot, according to an embodiment of the present invention will be described below with reference to the drawings.
The robot 10 of this embodiment has a base B and an arm 10a, as shown in FIG. The arm 10a has a plurality of arm members 11, 12, 13, 14, 15 and 16, and the plurality of arm members 11, 12, 13, 14, 15 and 16 are movable axes J1, J2, J3, J4 and J5, respectively. , J6. Although the robot 10 shown in FIG. 1 is a vertical articulated robot, it may be a horizontal articulated robot, and is not limited to a specific type of robot.

The robot 10 has a plurality of servomotors 11a, 12a, 13a, 14a, 14a, 14a, 14a, 14a, 14a, 14a, 14a, 14a, 14a, 14a, 14a, 14a, 14a, 11a, 11a, 11a, 11a, 11a, 11, 14a, 11a, 11a, 11a, 11a, 11a, and 11b, respectively. 15a, 16a (Fig. 4). Reduction gears 11b, 12b, 13b, 14b, 15b and 16b (Fig. 4) are connected to the servomotors 11a, 12a, 13a, 14a, 15a and 16a, respectively. Driving force is transmitted to the arm members 11, 12, 13, 14, 15, 16 via the speed reducers 11b, 12b, 13b, 14b, 15b, 16b. Each of the servomotors 11a, 12a, 13a, 14a, 15a, and 16a has an operating position detector (not shown) for detecting its operating position, and the operating position detector is an encoder as an example. A detection result of the operating position detection device is transmitted to the control device 20 .

As shown in FIG. 4, the control device 20 includes a processor 21 such as a CPU, a display device 22, a storage unit 23 having non-volatile storage, ROM, RAM, etc., an input device 24 such as a keyboard, and a transmission/reception device. It includes a section 25 and a servo controller 26 corresponding to each of the servomotors 11a to 16a, and controls the servomotors 11a to 16a of the robot 10. FIG. A system program 23 a is stored in the storage unit 23 , and the system program 23 a performs the basic functions of the control device 20 .

The storage unit 23 stores an operation program 23b, a correction coefficient acquisition program 23c, a displacement calculation program (displacement calculation means) 23d, and an operation correction program (operation program correction means) 23e. The processor 21 controls the servo motors 11a to 16a based on the operation program 23b, whereby the robot 10 uses the tool T provided at the tip of the arm 10a to perform a predetermined work. The operation program 23b is a series of operation commands for controlling the servo motors 11a to 16a.

Further, when a predetermined start signal is input from the input device 24, or when the transmitter/receiver 25 receives a predetermined start signal, the processor 21 sets each movable axis J1, J2 based on the correction coefficient acquisition program 23c. , J3, J4, J5, and J6 are obtained, and the obtained correction coefficients are stored in the storage unit 23. FIG.

For example, the processor 21 places the arm 10a in the first posture by controlling the servomotors 11a-16a. At this time, a sample external force F is applied to the tool T. By controlling the servo motors 11a to 16a by the processor 21, the tool T may be pressed against a predetermined member, whereby the sample external force F may be applied to the tool T. A sample external force F may be applied to the tool T, such as by holding an object of .

The direction and magnitude of the sample external force F at this time are known, and the direction and magnitude of the sample external force F are input to the controller 20 . The direction and magnitude of the sample external force F may be input to the control device 20 via the input device 24 or the transmission/reception unit 25, and the direction and magnitude of the sample external force F are provided at the tip of the arm 10a, the tool T, or the like. It may be detected by a force sensor D ( FIG. 1 ), which is an example of the acquisition means, and the detection result may be transmitted to the control device 20 .

The direction and magnitude of the sample external force F correspond to the reference coordinate system of the arm 10a recognized by the controller 20. FIG. In one example, the sample external force F is applied to a part of the tool T in a direction perpendicular to or along the movable axis J6, and the direction of the sample external force F changes according to changes in the posture of the arm 10a.

The processor 21 obtains correction coefficients R ₁ , R ₂ , R _{3 ,} . In order to obtain the correction coefficients R ₁ , R ₂ , R ₃ , _. Applying the position vector P _i and the unit vector A _Ui in the direction of the rotation axis vector known from the information of the detection device, and the direction and magnitude of the sample external force F to the following formula (1) or (1) and (2), A theoretical moment M _ai and displacement (displacement angle) Δθ _i of each of the movable axes J1, J2, J3, J4, J5, and J6 are obtained. In this embodiment, the displacement _Δθi of each movable axis J1, J2, J3, J4, J5, and J6 is calculated by each arm member 11, 12, 13, 14, 15, 16 displacements.

モーメントＭ_ａｉ、変位Δθ_ｉ、バネ定数Ｋ_ａｉ、位置ベクトルＰ_ｉ、各可動軸Ｊ１～Ｊ６の回転軸方向を示す単位ベクトルＡ_Ｕｉ、垂線の長さ（各可動軸Ｊ１～Ｊ６と外力Ｆの作用点との距離）ｒ_ｉ等のｉには可動軸Ｊ１～Ｊ６に対応する１～６の数字が入り、例えば、Ｐ_１は可動軸Ｊ１に関する位置ベクトル、Ｐ_２は可動軸Ｊ２に関する位置ベクトル、・・・Ｐ_６は可動軸Ｊ６に関する位置ベクトル、Ｍ_ａ１は可動軸Ｊ１に働くモーメントの理論値である。また、×と・はそれぞれ、ベクトルの外積、内積を表す。

Moment M _ai , displacement Δθ _i , spring constant K _ai , position vector P _i , unit vector A _Ui indicating the rotation axis direction of each movable axis J1 to J6, length of perpendicular (between each movable axis J1 to J6 and external force F Distance from point of action) r In _i, etc., numbers 1 to 6 corresponding to movable axes J1 to J6 are entered, for example, _P1 is a position vector related to movable axis J1, and _P2 is a position vector related to movable axis J2. , . . . _P6 is a position vector relating to the movable axis J6, and M _a1 is the theoretical value of the moment acting on the movable axis J1. Also, x and · represent the cross product and inner product of vectors, respectively.

P _i is a position vector connecting points of action of F from point O, where point O is the intersection of the rotation axis and the perpendicular drawn from the point of action of sample external force F to each of the movable axes J1, J2, J3, J4, J5, and J6. , where A _Ui is a unit vector extending in a direction along each movable axis J1, J2, J3, J4, J5, J6, and φ _i is a rotation axis vector (unit vector A _Ui ) and an external force moment P _i It is the angle formed by ×F.
P _i ×F and cos φ are mathematical elements representing the relationship between the direction of the rotation axis of each movable axis J1, J2, J3, J4, J5, and J6 and the direction of the external force F.

Then, based on the correction coefficient acquisition program 23c, the processor 21 determines the displacement _Δθi obtained by the formula (2) and the measured value A correction coefficient is obtained from the ratio of the displacement (displacement angle) _Δθmi based on the above, and the obtained correction coefficient is stored in the storage unit 23 together with the numbers of the corresponding movable axes J1, J2, J3, J4, J5, and J6.

For example, by detecting a reflector RD attached to the tip of the tool T with a laser tracker LT, the position and orientation of the tip before and after applying the sample external force F are measured. By inversely transforming the measured positions and orientations, it is possible to obtain the positions of each movable axis before and after application of the sample external force F, and obtain the displacement _Δθmi of each movable axis from the difference.

An angle detector is attached to each of the movable axes J1, J2, J3, J4, J5, and J6, and the displacement (displacement angle) of each of the movable axes J1, J2, J3, J4, J5, and J6 is measured using the angle detector. Actual measurement is also possible.
Alternatively, the displacement angles of the arm members 11, 12, 13, 14, 15, 16 or the movable axes J1, J2, J3, J4, J5, J6 may be measured using other methods.

The theoretical torque (moment M _ai ) applied to each movable axis J1, J2, J3, J4, J5, and J6 and the actual torque (measured value) applied to each movable axis J1, J2, J3, J4, J5, and J6 It is also possible to obtain the displacement Δθm _i based on the measured value based on the difference between . In this case, the processor 21 calculates the theoretical torque ( moment M _ai ) and the displacement Δθm _i based on the motor current value or torque value actually measured by each of the servo motors 11a, 12a, 13a, 14a, 15a, and _16a when the sample external force F is applied. are used to determine the correction coefficients, and the determined correction coefficients are stored in the storage unit 23 together with the numbers of the corresponding movable axes J1, J2, J3, J4, J5, and J6. When each servo motor 11a-16a is provided with a torque sensor, the detected value of the torque sensor of each servo motor 11a-16a may be used to calculate the correction coefficient.

Here, the correction coefficient is preferably obtained so as to correspond to φ and stored in the storage unit 23 . For example, in the first posture, the angle φ formed by the cross product of the position vector P _i shown in Equation (1) and the sample external force F and the rotation axis direction of the movable axis J1 (the unit vector A _U1 of the movable axis J1) is When the angle is 10°, the storage unit 23 stores the correction coefficient _R1 of the movable axis J1 at the time of the first posture and the sample external force F corresponding to the angle φ. Similarly, correction coefficients R ₂ , R _{3 ,} . FIG. 1 shows the position vector P ₅ related to the movable axis J5, the unit vector _AU5 of the movable axis J5, etc. Similarly, the correction coefficients R ₁ , R ₂ , R ₃ , . . . R _n are stored corresponding to the angle φ.

The correction coefficients R ₁ , R ₂ , R ₃ , _. It may be obtained by changing.

The processor 21 operates by the displacement calculation program 23d, and calculates the correction function f _i ( _φ ) obtained based on the correction coefficients R ₁ , R ₂ , R ₃ , . 3) to calculate the corrected displacement Δθ _i ' of each movable axis J2, J3, J4, J5, J6. In this embodiment, the corrected displacement Δθ _i ' of each movable axis J1, J2, J3, J4, J5, J6 is calculated by each arm member 11, J2, J3, J4, J5, J6 around each movable axis J1, J2, J3, J4, J5, J6. 12, 13, 14, 15, 16 corrected displacements.

The i of the corrected displacement Δθ _i ' is _{a number from 1 to 6 corresponding to the movable axes J1 to J6. For example, Δθ 1 '} is the corrected displacement of the movable axis J1, The corrected displacement, . . . Δθ ₆ ′ is the corrected displacement of movable axis J6.

Numbers 1 to 6 corresponding to the movable axes J1 to J6 are entered in i of the correction function f _i (φ), f ₁ (φ) is the correction function for the movable axis J1, and f ₂ (φ) is for the movable axis J2. A correction function, . . . f ₆ (φ) is a correction function for the movable axis J6.
The _correction function f _i (φ) is a formula obtained from the relationship between the correction coefficients R ₁ , R ₂ , R ₃ , . Instead of the correction _function f _i (φ), a correction table is used in which the correction coefficients R ₁ , R ₂ , R ₃ , . is also possible.

In general, the correction function f _i (φ) takes the maximum value when φ is 0°, and the correction function f _i (φ) tends to decrease as φ moves away from 0°.

Here is an example. 2 and 3, the rotational positions of the arm member 14 around the movable axis J4 are different, but the rotational positions of the other movable axes J1, J2, J3, J5, and J6 are the same. In this case, FIGS. 2 and 3 differ from each other in the angle φ formed by the rotation axis vector _AU2 of the movable axis J2 and P ₂ ×F (cross product), and the angle φ is larger in FIG. 3 than in FIG. .

_On the other hand, as described above, the correction coefficients R ₁ , R ₂ , . are 0.85, _0.65 , and _0.4 , the correction function f ₂ (φ ₎ for the movable axis J2 is, for example, quadratic It becomes an approximation function of the curve. The approximation function may be other n-order functions, logarithmic functions, exponential functions, and the like.

For example, if φ is 10° in FIG. 2 and φ is 20° in FIG. The correction coefficient R becomes 0.65. Correction functions f _i (φ) for the movable axes J1, J2, J3, J4, J5, and J6 are created such that the angles φ and the correction coefficients R correspond to each other.

When the magnitude and direction of the external force F actually acting on the tool T are input via the input device 24, the transmitting/receiving section 25, etc., or the detection value of the force sensor D, which is the external force F actually acting on the tool T, is received. Then, the processor 21 uses equation (3) to determine the corrected displacement θ _i ' of each of the movable axes J1-J6. Instead of the force sensor D, the external force F may be obtained based on the current values of the servomotors 11a to 16a.
The processor 21 then uses forward kinematics to obtain the displacements Δx, Δy, and Δz of the tip of the arm 10a or the predetermined position of the tool T from the corrected displacements θ _i ' of the movable axes J1 to J6.

Instead of creating the correction function f _i (φ), a correction table in which the angle φ corresponds to the correction coefficients R ₁ , R ₂ , . . . R _n may be created. In this case, the processor 21 determines a correction coefficient based on the correction table, substitutes the determined correction coefficient into the position of f _i (φ) in the equation (3), and corrects each of the movable axes J1 to J6. Find the displacement θ _i '.
Also, one correction coefficient is determined for each of the movable axes J1 to J6, and the correction coefficient may be stored in the storage unit 23 instead of the correction function f _i (φ) and the correction table. In this case, the processor 21 substitutes the correction coefficient stored in the storage unit 23 for the position of f _i (φ) in the equation (3), and calculates the corrected displacement θ _i ' of each of the movable axes J1 to J6 as demand.

Then, the processor 21 changes the motion command included in the motion program 23b as necessary based on the motion correction program 23e. For example, when the detected value of the force sensor D, which is the external force F actually acting on the tool T, is received, the displacements Δx, Δy, and Δz of the predetermined position of the tool T are obtained. , change the motion command to cancel that displacement.
For example, when the tool T is pressed against the workpiece during operation by the robot 10 and an undesirable amount of slippage occurs between the tool T and the workpiece, the change in the operation command reduces the slippage between the tool T and the workpiece. or disappear.

Note that the processor 21 may display the corrected displacement θ _i ' of each of the movable axes J1 to J6 on a predetermined display device, and one, two, or a plurality of large corrected displacements θ _i ' may be displayed on the display device. Further, the processor 21 may display the corrected displacement θ _i ' of each of the movable axes J1 to J6, transmit it to another device for simulation or the like, and the one with the larger corrected displacement θ _i ' , two or more movable axes may be sent to other devices for display.

In addition, the upper control device 30, the simulation device, etc. receive the correction coefficients together with the numbers of the corresponding movable axes J1 to J6 from the control device 20, and store the received correction coefficients together with the numbers of the movable axes J1 to J6 in the memory 31. You may The upper control device 30 or the simulation device receives the correction function or the correction table together with the numbers of the movable axes J1 to J6 from the control device 20, and stores the received correction functions or correction tables together with the numbers of the movable axes J1 to J6 in the memory 31. may be stored.

At this time, the upper control device 30, the simulation device, etc. preferably provide information on the model of the robot 10, information on the size of the robot 10, information on the work of the robot 10, information on the type of the operation program 23b, information on the type of the servo motor, and so on. Information and application information including at least one of information about the type of tool T is also received from the control device 20, and the received correction coefficients, correction functions, or correction tables are stored in the memory 31 in association with the application information. The host controller 30 , the simulation device, or the like may receive similar information from the controllers of other robots and store the received information in the memory 31 .

The host controller 30 receives requests and information, for example from the controller of a newly installed robot. The information to be received includes the model of the newly installed robot, the size of the robot, the type of operation program, the work of the robot, the type of servo motor, the type of tool, and the like.
In this case, the host controller 30 determines application information that is close to or matches the received information from among the application information stored in the memory 31, and determines a correction coefficient, a correction function, or a correction function according to the determined application information. The table is sent to the controller of the newly installed robot where the received correction factor, function or table is used.
Further, the simulation device calculates the displacement amount of the arm 10a using the correction coefficient, the correction function, or the correction table stored in the memory 31 when simulating the robot 10, for example.

A correction coefficient or a correction function predetermined for each model may be used instead of performing measurement for each individual.

[Example]
The above-described embodiment is used to suppress or eliminate displacement of the tool T with respect to the work caused by the pressing when the robot 10 presses the tool T against the work. Such operations include FDS (flow drill screw), roller hemming, and the like.
In FDS, a screw (article) held by a tool T is rotated at high speed, and a robot 10 drives the rotating screw into superimposed metal members, thereby welding these metal members together. be. Accurately obtaining the displacement of the tip of the tool T when a screw rotating at high speed is pressed against a metal member improves the accuracy of FDS work, improves workability, and improves the quality of the product obtained by the work. It is advantageous for improving the

Roller hemming is a work in which a roller (article) provided at the tip of a tool T is pressed against a plate-like work, and the roller is moved along the work in this state to bend a part of the work. Accurately obtaining the displacement of the tip of the tool T when the roller is pressed against the work improves the accuracy of the roller hemming work, improves the workability, and improves the quality of the product obtained by the work. Advantageous.

In the above embodiment, in equations (1) and (2), P _i ×F (outer product), cosφ etc. are used, it is also possible to use other mathematical elements such as linear functions and quadratic functions that decrease as the angle formed by the direction of the rotation axis of each movable axis J1 to J6 and the direction of the external force F increases. is.

In the above embodiments, a correction factor or correction function is determined based on a sample external force F whose magnitude and direction are known. Further, the displacement of each of the movable axes J1 to J6 is calculated using a correction coefficient or a correction function in addition to the mathematical elements representing the relationship between the rotation axis direction of each of the movable axes J1 to J6 and the direction of the external force F. Therefore, it is possible to accurately calculate the displacement of the arm 10a of the robot 10 according to the magnitude and direction of the force acting on the robot 10. FIG.

Further, in the above embodiment, when the external force F is only gravity, or when the external force F includes gravity, the processor 21 calculates the displacement of each of the arm members 11 to 16 due to gravity based on the displacement calculation program. The position of each arm member 11 to 16 may be corrected by the processor 21 using the result obtained by the calculation based on the motion correction program 23e.
In this case, the displacement of each arm member 11-16 due to gravity is accurately recognized by the controller 20. FIG. This is useful for improving the accuracy of motion of the arm 10a.

In the above-described embodiment, the force sensor detects the magnitude and direction of the reaction force from the work when a force is applied to the work by pressing the article held at the tip of the arm 10a against the work. D is provided. Based on the displacement calculation program, the processor 21 calculates the displacements of the arm members 11-16 around the movable axes J1-J6, which change according to the magnitude and direction of the reaction force. A calculation is performed using at least a mathematical element indicating the relationship between the rotation axis direction of J6 and the direction of the reaction force, and a correction coefficient or a correction function. Then, the processor 21 corrects the motion command for the arm 10a based on the result obtained by the above calculation, in order to reduce the amount of slippage between the article and the work based on the motion correction program 23e.

In this configuration, the displacements of the arm members 11 to 16 around the movable axes J1 to J6 are accurately determined, and the motion command for the arm 10a is corrected based on the accurately determined displacements of the arm members 11 to 16. . Therefore, the motion command is corrected by accurately considering the displacement of the arm 10a caused by pressing the article held at the tip of the arm 10a against the work. This is advantageous for improving the accuracy of work, improving workability, and improving the quality of products obtained by the work.

10 Robot 10a Arms 11-16 Arm members 11a-16a Servo motors 11b-16b Reduction gear 20 Control device 21 Processor 22 Display device 23 Storage unit 23a System program 23b Operation program 23c Correction coefficient acquisition program 23d Displacement calculation program (displacement calculation means)
23e motion correction program (motion program correction means)
24 Input device 25 Transmitter/receiver 26 Servo controller 30 Upper controller J1 to J6 Movable axis B Base T Tool D Force sensor

Claims (3)

A control device for an articulated robot in which a plurality of arm members constituting an arm of the robot move around a plurality of movable axes,
a storage unit storing a correction coefficient or a correction function obtained based on the detected value of the displacement of the tip portion when a sample external force is applied to the tip portion of the arm or the displacement around each movable axis;
For calculation of the displacement of each arm member around each movable shaft that changes according to the magnitude and direction of the force applied to the distal end portion of the arm, the rotation axis direction of each movable shaft and the force a displacement calculation means that uses at least the correction coefficient or the correction function ;
When a force is applied to the work by pressing the article held at the tip of the arm against the work, the displacement calculation means calculates a At least the correction coefficient or the correction function is used to express the changing displacement of each arm member around each movable axis, a mathematical element indicating the relationship between the direction of the rotation axis of each movable axis and the direction of the reaction force. and
The control device further comprises operation program correction means for correcting the operation command of the arm based on the result obtained by the calculation in order to reduce the amount of slippage between the article and the work. Control device for articulated robots. A control device for an articulated robot in which a plurality of arm members constituting an arm of the robot move around a plurality of movable axes,
a storage unit storing a correction coefficient or a correction function obtained based on the detected value of the displacement of the tip portion when a sample external force is applied to the tip portion of the arm or the displacement around each movable axis;
For calculation of the displacement of each arm member around each movable shaft that changes according to the magnitude and direction of the force applied to the distal end portion of the arm, the rotation axis direction of each movable shaft and the force a displacement calculation means that uses at least the correction coefficient or the correction function ;
The storage unit stores a plurality of angles φ and a plurality of correction coefficients corresponding to each of the plurality of arm members, or the angle φ is used as a variable for each of the plurality of arm members. the correction function for obtaining the correction factor is stored;
The angle φ is an angle formed by an external force moment acting on each movable shaft due to the sample external force and a rotation axis direction of each movable shaft. 3. The control of the articulated robot according to claim 1, wherein the displacement of each arm member due to gravity is calculated by the displacement calculating means, and the position of each arm member is corrected using the result obtained by the calculation. Device.

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