JP2020028923A - Control device of articulated robot - Google Patents

Abstract

To provide a control device of an articulated robot enabling exact determination of a movable shaft capable of sensitively detecting external force applied to an arm of a plurality of movable shafts.SOLUTION: A control device 20 of an articulated robot 10 includes: a storage section which stores a correction coefficient or a correction function determined on the basis of a detection value of torque around each movable shaft J1 to J6 when applying sample external force F to a tip of an arm 10a or a motor current value; and torque sensitivity arithmetic means which calculates torque detection sensitivity in each movable shaft J1 to J6 changed according to the direction of the external force F applied to the tip of the arm 10a on the basis of at least a formula element indicating the relation between a rotary shaft direction of each movable shaft J1 to J6 and a direction of the external force F and the correction coefficient or the correction function. The torque detection sensitivity indicates sensitivity of a current detection value of a motor or a detection value of a torque sensor to the external force F in each movable shaft J1 to J6.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an articulated robot.

  2. Description of the Related Art Conventionally, a spot welding robot using a logical formula using an outer product and an inner product in order to accurately calculate a torque generated on each movable axis of the robot, which is generated by an external force applied to the robot from a welding point, is known. (For example, see Patent Document 1).

JP 2001-105152 A

  Even in the spot welding robot, the torque generated in each movable shaft is calculated in consideration of the relationship between the direction of the external force and the direction in which each movable shaft extends in the rotation axis direction. However, each movable axis is connected to a servomotor via a speed reducer, and the rotational resistance in the reducer, the rotational resistance in the servomotor, etc. actually exist. Is often different from the torque actually generated. In particular, the larger the angle between the direction of the external force moment and the direction of the rotation axis of each movable shaft is, the larger the difference from the result obtained from the theoretical formula becomes. In many cases.

  On the other hand, there is a case in which control is typically performed such that one selected movable axis of the plurality of movable axes of the robot follows the movement of the work, the force generated by the operation of the tool, and the like. This follow-up control is performed by limiting the current value of the motor or reducing the position / speed loop gain for the selected movable axis. If torque is limited by a movable shaft that is easily affected by torque due to an external force, the followability is improved. Therefore, it is desirable to be able to accurately estimate the torque generated in each movable shaft motor by the external force.

  The present invention has been made in view of the above circumstances. An object of the present invention is to provide a control apparatus for an articulated robot that enables accurate determination of a movable axis capable of detecting an external force applied to an arm with high sensitivity among a plurality of movable axes.

In order to solve the above problems, the present invention employs the following solutions.
One aspect of the present invention is a control device for an articulated robot in which a plurality of arm members constituting a robot arm move around a plurality of movable axes, wherein each of the plurality of arm members when a sample external force is applied to a tip portion of the arm. A storage unit in which a correction coefficient or a correction function obtained based on a detected value of a torque or a motor current value around a movable axis is stored, and each of the storage units that changes according to a direction of an external force applied to the distal end of the arm. A torque detection sensitivity of the movable shaft, a mathematical element indicating a relationship between the rotation axis direction of each of the movable shafts and the direction of the external force, and a torque sensitivity calculating unit that calculates based on at least the correction coefficient or the correction function. The torque detection sensitivity indicates the sensitivity of the motor current detection value or the torque sensor detection value of each of the movable shafts to the external force.

  In the above aspect, the correction coefficient or the correction function is obtained based on the sample external force whose magnitude and direction are known, and in addition to the mathematical elements indicating the relationship between the rotation axis direction of each movable shaft and the direction of the external force, the correction coefficient or The torque detection sensitivity of each movable shaft is calculated using the correction function. For this reason, it is possible to accurately select a movable shaft that can detect the external force applied to the arm with high sensitivity among the plurality of movable shafts.

In the above aspect, preferably, the torque sensitivity calculation means uses at least the distance between each of the movable shafts and the point of action of the external force, the mathematical element, and the correction coefficient or the correction function to each of the movable shafts. Calculate the torque detection sensitivity at.
In this aspect, the torque detection sensitivity of each movable shaft is calculated using the distance between each movable shaft and the point of action of the external force. For this reason, it is possible to accurately determine the movable shaft that can detect the external force applied to the arm with high sensitivity among the plurality of movable shafts.

In the above aspect, preferably, there is provided an axis determining means for selecting at least one of the plurality of movable axes, in which the torque detection sensitivity is superior, as a movable axis that follows the external force.
In this aspect, at least one of the plurality of movable axes that is superior is determined as the movable axis that follows the external force, using the torque detection sensitivity accurately calculated as described above. This is advantageous in accurately controlling the robot to follow the movement of the work, the force generated by the operation of the tool, and the like.

In the above aspect, preferably, the arm further includes an external force position acquisition unit that detects or estimates a position where the external force is applied to the arm, wherein the external force position acquisition unit is superior in the torque detection sensitivity among the plurality of movable shafts. A detected value of a torque or a motor current value around at least one of the movable axes is used for the detection or the estimation.
In this aspect, since the detected value of the torque or the motor current value around the movable axis where the torque detection sensitivity is superior is used for detecting or estimating the position where the external force is applied, it is possible to more accurately know the position where the external force is applied. .

  ADVANTAGE OF THE INVENTION According to this invention, the exact determination of the movable shaft which can detect the external force applied to the arm with high sensitivity among several movable shafts is attained.

FIG. 1 is a schematic configuration diagram of a robot and a control device according to an embodiment of the present invention. FIG. 5 is an explanatory diagram of the operation of the robot according to the embodiment. It is a block diagram of a control device of this embodiment.

A control device 20 of a robot 10 that 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 the present 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, 16 and the plurality of arm members 11, 12, 13, 14, 15, 16 are respectively movable axes J1, J2, J3, J4, J5. , Move around 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 includes a plurality of servomotors 11a, 12a, 13a, 14a, which drive arm members 11, 12, 13, 14, 15, 16 around the plurality of movable axes J1, J2, J3, J4, J5, J6, respectively. 15a and 16a (FIG. 3). The reduction gears 11b, 12b, 13b, 14b, 15b, 16b (FIG. 3) are connected to the servo motors 11a, 12a, 13a, 14a, 15a, 16a, respectively. The driving force is reduced by the reduction gears 11b, 12b, 13b, 14b, 15b, and 16b and transmitted to the arm members 11, 12, 13, 14, 15, and 16. Each of the servomotors 11a, 12a, 13a, 14a, 15a, 16a has an operating position detecting device (not shown) for detecting its operating position, and the operating position detecting device is, for example, an encoder. The detection result of the operating position detecting device is transmitted to the control device 20.

  As shown in FIG. 3, the control device 20 includes a processor 21 such as a CPU, a display device 22, a storage unit 23 having a nonvolatile storage, a ROM, a RAM, and the like, an input device 24 such as a keyboard, The robot 10 includes a unit 25 and servo controllers 26 corresponding to the servo motors 11a to 16a, respectively, and controls the servo motors 11a to 16a of the robot 10. The storage unit 23 stores a system program 23a, and the system program 23a has a basic function of the control device 20.

  The storage unit 23 stores an operation program 23b, a correction coefficient acquisition program 23c, a sensitivity calculation program (torque sensitivity calculation means) 23d, and an axis determination program (axis determination means) 23e. The processor 21 controls the servomotors 11a to 16a based on the operation program 23b, whereby the robot 10 performs a predetermined operation using the tool T provided at the tip of the arm 10a.

  Further, when a predetermined start signal is input from the input device 24 or when a predetermined start signal is received by the transmission / reception unit 25, the processor 21 determines whether each of the movable axes J1 and J2 is based on the correction coefficient acquisition program 23c. , J3, J4, J5, and J6 are determined, and the determined correction coefficients are stored in the storage unit 23.

  For example, the processor 21 controls the servomotors 11a to 16a to bring the arm 10a to the first posture. At this time, a sample external force F is applied to the tool T. The tool T may be pressed against a predetermined member by the control of the servomotors 11a to 16a by the processor 21, whereby a sample external force F may be applied to the tool T. Pressing the tool T by a predetermined device, The sample external force F may be applied to the tool T by holding the object.

  At this time, the direction and magnitude of the sample external force F are known, and the direction and magnitude of the sample external force F are input to the control device 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. May be detected by the force sensor D, 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 control device 20. In one example, the sample external force F is applied to a part of the tool T in a direction along the movable axis J6 or in a perpendicular direction, and the direction of the sample external force F changes according to a change in the posture of the arm 10a.

The processor 21, based on the correction coefficient acquiring program 23c, for each of the movable axes J1, J2, J3, J4, J5, J6, the correction factor _{R 1, R 2, R 3} , obtaining the · · · _{R n.} In order to obtain the correction coefficients R ₁ , R ₂ , R ₃ ,... R _n , as an example, the processor 21 determines the attitude information of the arm 10 a or the operating positions of the servomotors 11 a, 12 a, 13 a, 14 a, 15 a, 16 a. The theoretical torque is obtained by applying the position vector P _i and the unit vector A _{Ui in the} rotation axis vector direction, which are known from the information of the detection device, and the direction and magnitude of the sample external force F to the following equation (1).

位置ベクトルＰ_ｉ、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である。

The position vector P _i , the unit vector A _Ui , the length of the perpendicular (the distance between each movable axis J1 to J6 and the point of action of the external force F) r _{i, and the} like correspond to the movable axes J1 to J6. numbers entered, for example, _{P 1} is the position vector about movable axis J1, _{P 2} is the position vector about the movable shaft J2, · · · _{P 6} is the position vector for the movable axis J6.

P _i, each movable axis from the point of sample external force F J1, J2, J3, J4, J5, a perpendicular intersection of the rotation axis down to J6 as a point O, the position vector connecting the point of action of F from the point O A _Ui is a unit vector extending in a direction along each of the movable axes J1, J2, J3, J4, J5, and J6, and φ is an angle formed by the rotation axis vector and P _i × F (outer product). is there. A vector obtained by P _i × F (cross product) is orthogonal to both the vector P _i and the vector F.
P _i × F (outer product) and cos φ are mathematical elements indicating the relationship between the rotation axis directions of the movable axes 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 calculates, for each of the movable axes J1, J2, J3, J4, J5, and J6, a theoretical torque (moment) that is theoretically obtained by the equation (1) with respect to the sample external force F. M _ai ), and a correction coefficient is obtained based on the motor current value or the torque value actually measured by the servomotors 11a, 12a, 13a, 14a, 15a, 16a when the sample external force F is applied, and the obtained correction coefficient is obtained. Is stored in the storage unit 23 together with the corresponding numbers of the movable axes J1, J2, J3, J4, J5, and J6. When a torque sensor is provided for each of the servomotors 11a to 16a, the detection value of the torque sensor of each of the servomotors 11a to 16a may be used for calculating the correction coefficient.

Here, preferably, the correction coefficient is obtained so as to correspond to φ and stored in the storage unit 23. For example, in the first position, the outer product of the position vector P _i and sample the external force F represented by formula (1), the angle φ formed between the direction of the rotation axis of the movable shaft J1 (unit vector A _Ui of the movable shaft _J1) If it is 10 °, the storage unit 23, the correction coefficient R ₁ of the movable shaft J1 when the first orientation and sample the external force F is stored in correspondence with the angle phi. Similarly, correction coefficients R ₂ , R ₃ ,..., R _n are stored corresponding to the angle φ in the second posture, the third posture,. FIG. 1 shows a position vector P _i relating to the movable axis J1, a unit vector A _Ui of the movable axis J1, and the like. For each of the movable axes J2, J3, J4, J5, and J6, similarly, the correction coefficient R ₁ , R ₂ , R ₃ ,..., R _n are stored corresponding to the angle φ.

The correction coefficients R ₁ , R ₂ , R ₃ ,..., R _n stored in the storage unit 23 may be obtained by changing the angle φ at every predetermined angle. It may be obtained by changing.

The processor 21 operates by the sensitivity calculating program 23d, the correction coefficient is stored in the storage unit _{23 R 1, R 2, R} 3, ··· obtained based on _{R n} correction function _{f i} (phi) the following formula ( by applying the 2), calculates the torque detection sensitivity S _i against an external force F acting on the actual arm 10a.

The torque detection sensitivity S _i , the rotation axis vector A _Ui , the length of the perpendicular (the distance between each of the movable axes J1 to J6 and the point of application of the external force F) r _i , and the gear ratio G _{i and} other movable axes J1 to J6 Contains the 1-6 digits corresponding to, for example, _{S 1} is the torque sensitivity of the movable shaft J1, _{S 2} is the torque sensitivity of the movable shaft J2, · · · _{S 6} is a torque sensitivity of the movable shaft J6. r _i is the length of a perpendicular line from the point of action of the external force F to each rotation axis vector A _Ui , and G _i is the gear ratio of each of the reduction gears 11b, 12b, 13b, 14b, 15b, 16b.

The 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 of the movable axis J1, and f ₂ (φ) is the correction function of the movable axis J2. The correction function,... F ₆ (φ) is a correction function of the movable axis J6.
The correction function f _i (φ) is an expression obtained from the relationship between the correction coefficients R ₁ , R ₂ , R ₃ ,... R _n and the angle φ at that time for each of the movable axes J1 to J6. Instead of the correction function f _i (φ), a correction table is used in which the correction coefficients R ₁ , R ₂ , R ₃ ,... R _n and the angle φ at that time are associated with each of the movable axes J1 to J6. It is also possible.

As an example, the torque detection sensitivity S ₁ of the movable shaft J1, will be described with reference to FIGS. 1 and 2, the rotational positions of the arm member 14 around the movable axis J4 are different from each other, but the rotational positions of the other movable axes J1, J2, J3, J5, and J6 are the same. In this case, FIGS. 1 and 2 are different from each other in the angle φ between the rotation axis vector A _U1 of the movable axis J1 and P ₁ × F (outer product), and the angle φ is larger in FIG. 2 than in FIG. .

On the other hand, as described above, the correction coefficients R ₁ , R ₂ ,..., R _n of the movable axis J2 are stored corresponding to the angle φ, and for example, when the angle φ is 10 °, 20 °, and 30 °. When the correction coefficients R ₁ , R ₂ , and R ₃ are 0.85, 0.65, and 0.4, the correction function f ₁ (φ) of the movable axis J1 Approximate function of the curve. The approximate function may be another n-order function, logarithmic function, exponential function, or the like.

For example, when φ is 10 ° in FIG. 1 and φ is 20 ° in FIG. 2, the correction coefficient R of the movable axis J1 becomes 0.85 in the state of FIG. 1, and the correction coefficient R of the movable axis J1 in the state of FIG. The correction coefficient R becomes 0.65. In this way, a correction function f _i (φ) of each movable axis J1, J2, J3, J4, J5, J6 is created such that the angle φ corresponds to the correction coefficient R.

As shown in equation (2), the torque detection sensitivity _{S i} of each of the movable axes J1, J2, J3, J4, J5, J6 are as length _{r i} perpendiculars is large, or the correction function _{f i} (phi ) Increases (increases) as the correction coefficient increases, but decreases as the angle φ increases. The correction coefficient tends to increase as φ decreases.
Further, as shown in equation (2), towards the gear ratio is small and the torque detection sensitivity S _i increases.

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 unit 25, or the like, or when the detection value of the force sensor D which is the external force F actually acting on the tool T is received. when the processor 21 obtains the torque detection sensitivity _{S i} of each of the movable axes J1~J6 using equation (2).
Instead of creating the correction function f _i (φ), a correction table in which the angles φ correspond 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 for the position of f _i (φ) in Expression (2), and determines the torque detection sensitivity of each of the movable axes J1 to J6. _Find Si.
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, the correction coefficients stored in the storage unit 23 substitutes the position of the _{f i} (phi) of the formula (2), determining each of the torque detection sensitivity _{S i} of the movable shaft J1 to J6.

Then, the processor 21, one movable shaft is typically the torque detection sensitivity S _i of the movable shaft J1~J6 predominates, as a movable axis to follow the working party during predetermined work based on the operation program 23b Set. To be superior, for example, the most numerically of torque detection sensitivity S _i of the movable shaft J1~J6 is large or numerical Second denotes larger.

Incidentally, the processor 21 may display each of the torque detection sensitivity S _i of the movable shaft J1~J6 on a predetermined display device 22, one torque detection sensitivity S _i is dominant, two, or more The movable axis may be displayed on the display device 22. The processor 21 may be transmitted to another device for display of each of the torque detection sensitivity S _i of the movable shaft J1 to J6, one torque detection sensitivity S _i is dominant, two, or Multiple movable axes may be sent to other devices for display.

If the movable shaft torque detection sensitivity S _i is dominant is displayed, the operator, at least one of a dominant movable shaft, the movable shaft to follow the working party during predetermined work based on the operation program 23b Set as

  Further, the higher-level control device 30 receives the obtained correction coefficient from the control device 20 together with the number of the corresponding movable axis J1 to J6, and stores the received correction coefficient in the memory 31 together with the number of the movable axis J1 to J6. You may. Alternatively, the upper control device 30 receives the obtained correction function or correction table from the control device 20 together with the numbers of the movable axes J1 to J6, and stores the received correction function or correction table together with the numbers of the movable axes J1 to J6 in the memory. 31 may be stored.

  At this time, the host controller 30 preferably includes information on the model of the robot 10, information on the size of the robot 10, information on work of the robot 10, information on the type of the operation program 23b, information on the type of the servomotor, and Application information including at least one of the information of the type T is also received from the control device 20, and the received correction coefficient, correction function, or correction table is stored in the memory 31 in association with the application information. The upper control device 30 receives similar information from the control devices of the other robots, and stores the received information in the memory 31.

The upper control device 30 receives a request and information from, for example, a newly installed robot control device. The information to be received includes the model of the newly installed robot, the size of the robot, the type of operation program, the operation of the robot, the type of servomotor, the type of tool, and the like.
In this case, the higher-level control device 30 determines application information that is close to or coincides with the received information among the application information stored in the memory 31, and determines a correction coefficient, a correction function, or a correction function corresponding to the determined application information. The table is transmitted to the newly installed robot controller, and the newly installed robot controller uses the received correction coefficient, correction function, or correction table.

[Example 1]
The above embodiment can be used when the moving workpiece is supported by the robot 10. In this case, the work is sequentially formed by, for example, roll forming, extrusion forming, or the like, and is supported by the tool T at the tip of the robot 10, and the robot 10 causes the tool T to follow the work. The robot 10 is arranged at a predetermined position with respect to the molding machine and the work, and supports the work at the position. Based on the posture of the robot 10 at that time, the direction of the force applied to the tool T from the work in the posture, and the correction coefficient, the correction function, or the correction table stored in the storage unit 23, the processor 21 determining each of the torque detection sensitivity _{S i} of J6.

Then, the processor 21 or the operator, at least one movable shaft torque detection sensitivity S _i of the movable shaft J1~J6 predominates, as a movable axis to follow the workpiece in the support work of the work based on the operation program 23b select. The processor 21 performs control for causing the selected movable axis to follow the force applied to the tool T from the workpiece. For example, the servomotor is controlled based on the detected current value detected by the servomotor of the selected movable shaft, and other servomotors are controlled based on the detected current value as needed.

[Example 2]
The above embodiment can be used when a workpiece is gripped by the tool T at the tip of the robot 10, when a welding point is sandwiched by the tool T which is a spot welding gun at the tip of the robot, and the like.
For example, when the welding point of the workpiece is sandwiched by the tool T, which is a spot welding gun, if the movable axes J1 to J6 of the robot 10 are completely fixed, the workpiece may be deformed by the clamping force of the tool T. is there. Therefore, at least one of the movable axes J1 to J6 is brought into a state in which it can follow the force from the tool T side.

When selecting the movable axis to be followed, the posture of the robot 10 when sandwiching the welding point with the tool T, the direction of the force applied to the tool T from the welding point in the posture, the correction coefficient stored in the storage unit 23, correction function, or based on the correction table, the processor 21 obtains the torque detection sensitivity _{S i} of each of the movable axes J1 to J6. Then, the processor 21 or the operator selects at least one movable shaft torque detection sensitivity S _i of the movable shaft J1~J6 predominates, as a movable axis to follow the force from the tool T side. The processor 21 performs control to cause the selected movable axis to follow the force applied to the tool T from the welding point. For example, the servomotor is controlled based on the detected current value detected by the servomotor of the selected movable shaft, and other servomotors are controlled based on the detected current value as needed.

Incidentally, after the processor 21 as described above was determined torque detection sensitivity S _i of each of the movable axes J1 to J6, at least one torque of the movable shaft processor 21 dominates the torque detection sensitivity S _i (motor current value ) Is monitored, and when the monitored torque exceeds a predetermined value due to contact between the welding point, the workpiece, etc. and the tool T, the servo motors 11a to 16a control the arm 10a of the robot 10 in a direction in which the monitored torque becomes a predetermined value or less. It is also possible to control the position and attitude.

In the above embodiment, in equations (1) and (2), P _i × F (outer product) and cos φ are used as mathematical elements indicating the relationship between the direction of the rotation axis of each movable axis J1 to J6 and the direction of the external force F. However, it is also possible to use mathematical elements such as a linear function, a quadratic function, etc., which become smaller as the angle formed between the direction of the external force F and the rotation axis direction of each of the movable shafts J1 to J6 becomes larger. .

  In the above embodiment, the correction coefficient or the correction function is obtained based on the sample external force F whose magnitude and direction are known. In addition, the torque detection sensitivity of each of the movable axes J1 to J6 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 of the movable axes J1 to J6 and the direction of the external force F. . Therefore, it is possible to accurately select a movable shaft that can detect the external force F applied to the arm 10a with high sensitivity among the plurality of movable shafts J1 to J6.

In the above embodiment, the formula element indicating the distance r _i between the point of action of the movable axes J1 to J6 and the external force F, the relationship between the direction of the rotation axis and the external force F of the movable axes J1 to J6, The torque detection sensitivity in each of the movable axes J1 to J6 is calculated using at least the correction coefficient or the correction function.
In this configuration, also used the distance r _i between the point of action of the movable axes J1~J6 and the external force F, the torque detection sensitivity of the movable shaft J1~J6 is calculated. Therefore, it is possible to accurately determine the movable axes J1 to J6 which can detect the external force F applied to the arm 10a with high sensitivity among the plurality of movable axes J1 to J6.

In the above-described embodiment, at least one of the plurality of movable axes J1 to J6 having superior torque detection sensitivity is determined as the movable axis that follows the external force F.
In this configuration, at least one of the plurality of movable axes J1 to J6 that is superior is determined as the movable axis that follows the external force F using the torque detection sensitivity accurately calculated as described above. This is advantageous in accurately controlling the robot 10 to follow the movement of the work, the force generated by the operation of the tool, and the like.

Note that the processor 21 can also detect or estimate the position where the external force is applied to the arm 10a based on the external force position acquisition program (external force position acquisition means) 23f stored in the storage unit 23. In this case, after the processor 21 has determined the respective torque detection sensitivity S _i of the movable shaft J1~J6 As described above, the detected torque (motor current value) of the at least one movable shaft is torque detection sensitivity S _i is dominant Is used to detect or estimate the position of the arm 10a where an external force is applied. The processor 21 recognizes the position and the posture of the arm 10a based on the operating position detecting devices of the servo motors 11a, 12a, 13a, 14a, 15a, 16a. In one example, the position and attitude of the arm 10a that is recognized, using the detected torque of the movable shaft (motor current value) is superior torque detection sensitivity S _i, the position processor 21 an external force is applied in the arm 10a Perform detection or estimation. Other, it is also possible to detect or estimate the external force is applied position by using the detected torque (motor current) with known methods of the movable shaft torque detection sensitivity S _i is dominant.

Reference Signs List 10 robot 10a arms 11 to 16 arm members 11a to 16a servo motors 11b to 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 sensitivity calculation program (torque sensitivity calculation means )
23e Axis determination program (axis determination means)
23f External force position acquisition program (External force position acquisition means)
24 Input device 25 Transmitter / receiver 26 Servo controller 30 Host controller 31 Memory J1-J6 Movable axis B Base T Tool D Force sensor

Claims (4)

A control device for an articulated robot in which a plurality of arm members constituting a robot arm move around a plurality of movable axes,
A storage unit that stores a correction coefficient or a correction function obtained based on a torque around each movable axis or a detected value of a motor current value when a sample external force is applied to the tip of the arm,
The torque detection sensitivity of each of the movable shafts, which varies in accordance with the direction of the external force applied to the distal end of the arm, is defined by a mathematical element indicating the relationship between the rotation axis direction of each of the movable shafts and the direction of the external force; And a torque sensitivity calculating means for calculating based on at least the coefficient or the correction function,
The control device for an articulated robot, wherein the torque detection sensitivity indicates a sensitivity of the detected current value of the motor or the detected value of the torque sensor in each of the movable shafts to the external force.   The torque sensitivity calculating means calculates the torque detection sensitivity of each movable shaft using at least the distance between each movable shaft and the point of action of the external force, the mathematical element, the correction coefficient or the correction function. The control device for an articulated robot according to claim 1, wherein   3. The control device for an articulated robot according to claim 1, further comprising an axis determining unit that selects at least one of the plurality of movable axes, in which the torque detection sensitivity is superior, as a movable axis that follows the external force. 4. The apparatus further includes an external force position acquisition unit that detects or estimates a position where the external force is applied to the arm,
The said external force position acquisition means uses the detected value of the torque or the motor current value around at least one of the plurality of movable shafts around which the torque detection sensitivity is superior, for the detection or the estimation. The control device for an articulated robot according to any one of claims 1 to 3.

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