Robot controller for mastering by torque or force control

Abstract

A control device for a robot according to the present invention controls a drive motor for one specific drive shaft of the robot such that the torque output by a torque detector matches a torque setting value when rotation of a component member is inhibited by a rotation inhibiting unit. The control device acquires a rotational position output by a rotational position detector of the specific drive shaft once the torque matches the torque setting value. The control device generates mastering data in response to output by the rotational position detector on the basis of the rotational position of the drive motor output by the rotational position detector and predetermined mastering data design values.

Description

[Technical Field]

[0001] The present invention relates to a control device for a robot that performs mastering by controlling torque or force. [Background technology]

[0002] A robot device equipped with a robot having joints can perform work using a work tool while changing the position and posture of the robot. The position and posture of the robot are related to the joint angles at each joint. The joint angles at each joint are related to the output of an encoder attached to a drive motor.

[0003] In conventional technology, it is known to perform mastering to accurately correlate the output values ​​of the encoders attached to the drive motors that drive each joint with the design values ​​(theoretical values). Mastering involves generating mastering data that converts the encoder output values ​​into machine pulse values ​​used to control the robot. The mastering data corresponds to the origin position of the robot's drive axis, for example, the position where the encoder output is 0°.

[0004] A known method for mastering a robot involves obtaining the output of an encoder when the robot's position and orientation are set to a specific position and orientation for mastering. For example, it is known to use a dedicated device for determining the robot's position and orientation to adjust the robot to the position and orientation for mastering. The robot's position and orientation are precisely adjusted. For example, a dedicated device with a dial gauge is attached to the robot's components. It is also known that an operator manually operates the robot to generate the position and orientation for mastering.

[0005] Alternatively, the robot can be set to a predetermined position and posture using images from a camera attached to the robot. For example, a jig with a target is attached to a predetermined component of the robot. A camera is attached to the wrist of the robot. It is known that the position and posture of the robot can be set to a position and posture for mastering by precisely adjusting the positional relationship between the camera and the target based on images acquired by the camera.

[0006] In recent years, it has become known to attach a force sensor to the wrist of a robot to detect the force applied to a work tool and control the position and posture of the robot (e.g., JP 2016-221642 A). Also, a device and control that adjusts the position and posture of a robot based on the output of a force sensor to achieve the position and posture of the robot for mastering is known (e.g., JP 8-171410 A). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-221642 [Patent Document 2] Japanese Patent Application Publication No. 8-171410 Summary of the Invention [Problem to be solved by the invention]

[0008] In conventional technology, to achieve the robot's position and orientation for mastering, an operator manually drives the robot using a teaching console. The operator must finely adjust the robot's three-dimensional position and orientation. For this reason, the accuracy of mastering depends on the operator's skill level. Operators with low skill levels often have difficulty making fine adjustments to the robot's position and orientation, resulting in poor mastering accuracy. Operators may also make errors when setting the mastering data. Furthermore, when using measuring devices such as cameras, the accuracy of mastering can be adversely affected by ambient light. Thus, conventional technology has the drawback of making it difficult to perform accurate mastering with simple control. [Means for solving the problem]

[0009] A control device according to a first aspect of the present disclosure is a robot control device that generates mastering data for the output of a rotational position detector attached to a drive motor of one specific drive axis that rotates a component of the robot. The control device includes a torque detector that detects torque around the specific drive axis. Robot rotating The control device includes a torque control unit that controls the drive motor of the specific drive shaft so that the torque output from the torque detector becomes a predetermined torque set value when the rotation of the component is prevented by the rotation preventing unit. The control device includes a rotational position acquisition unit that acquires the rotational position output from the rotational position detector of the specific drive shaft when the torque output from the torque detector becomes the torque set value. The control device includes a data generation unit that generates mastering data for the output of the rotational position detector arranged on the specific drive shaft based on the rotational position of the drive motor output by the rotational position detector and a predetermined design value of the mastering data.

[0010] A control device according to a second aspect of the present disclosure is a robot control device that generates mastering data for the output of a rotational position detector attached to a drive motor of one specific drive axis that rotates a component of the robot. Robot rotating The control device includes a jig that prevents rotation of the component and includes a force detector. Robot rotating The control device includes a force control unit that controls the drive motor of the specific drive shaft so that the force output from the force detector becomes a predetermined force set value when rotation of the component is prevented by the jig. The control device includes a rotational position acquisition unit that acquires the rotational position output by the rotational position detector of the specific drive shaft when the force output from the force detector becomes the force set value. The control device includes a data generation unit that generates mastering data for the output of the rotational position detector arranged on the specific drive shaft based on the rotational position of the drive motor output by the rotational position detector and a predetermined design value of the mastering data. [Effects of the Invention]

[0011] According to an aspect of the present disclosure, it is possible to provide a robot control device that performs mastering with simple control and high accuracy. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a side view of the first robot device according to the embodiment. [Figure 2] FIG. 2 is a block diagram of a first robotic device. [Figure 3] FIG. 10 is a side view of the robot illustrating a first control of the first robot device. [Figure 4] FIG. 2 is a schematic plan view of a robot illustrating a first control of a first robot device. [Figure 5] FIG. 10 is another schematic plan view of the robot illustrating the first control of the first robot device. [Figure 6] FIG. 1 is a first enlarged cross-sectional view of the gear meshing portion. [Figure 7] FIG. 10 is a second enlarged cross-sectional view of the gear meshing portion. [Figure 8] FIG. 10 is a third enlarged cross-sectional view of the gear meshing portion. [Figure 9] FIG. 10 is a side view of the robot illustrating a second control of the first robot device. [Figure 10] FIG. 10 is a schematic plan view of the robot illustrating a second control of the first robot device. [Figure 11] FIG. 10 is another schematic plan view of the robot illustrating the second control of the first robot device. [Figure 12] FIG. 10 is a side view of the robot illustrating a third control of the first robot device. [Figure 13] FIG. 10 is a side view of the robot illustrating a fourth control of the first robot device. [Figure 14] FIG. 10 is a side view of the robot illustrating a fifth control of the first robot device. [Figure 15] FIG. 10 is another side view of the robot illustrating the fifth control of the first robot device. [Figure 16] FIG. 10 is a side view of the robot illustrating a sixth control of the first robot device. [Figure 17] FIG. 4 is a side view of a second robot device according to the embodiment. [Figure 18] FIG. 10 is a block diagram of a second robotic device. [Figure 19] FIG. 10 is a schematic plan view of a robot illustrating control of a second robot device. [Figure 20] FIG. 10 is another schematic plan view of the robot illustrating the control of the second robot device. DETAILED DESCRIPTION OF THE INVENTION

[0013] A robot control device according to an embodiment will be described with reference to Fig. 1 to Fig. 20. The robot control device according to this embodiment drives the robot for each drive axis and generates mastering data for each drive axis. The robot control device generates mastering data for the output of a rotational position detector attached to a drive motor arranged on one drive axis.

[0014] FIG. 1 is a schematic diagram of a first robot device in this embodiment. FIG. 1 shows a state before a work tool is attached. FIG. 2 shows a block diagram of the robot device in this embodiment. With reference to FIGS. 1 and 2, the first robot device 5 includes a robot 1 that moves a work tool 2. The robot 1 in this embodiment is a multi-joint robot including multiple joints. In particular, the robot 1 in this embodiment is a vertical multi-joint robot. The robot 1 includes multiple movable components. The components of the robot 1 are configured to rotate around their respective drive axes.

[0015] The robot 1 includes a base unit 14 fixed to an installation surface and a swivel base 13 supported by the base unit 14. The swivel base 13 rotates relative to the base unit 14 about a first drive axis J1. The robot 1 includes an upper arm 11 and a lower arm 12. The lower arm 12 rotates relative to the swivel base 13 about a second drive axis J2. The upper arm 11 rotates relative to the lower arm 12 about a third drive axis J3. Furthermore, the upper arm 11 rotates about a fourth drive axis J4 parallel to the direction in which the upper arm 11 extends.

[0016] The robot 1 includes a wrist 15 supported by an upper arm 11. The wrist 15 rotates around a fifth drive shaft J5. The wrist 15 also includes a flange 16 that rotates around a sixth drive shaft J6. A work tool 2 is fixed to the flange 16. In this embodiment, the base 14, swivel base 13, lower arm 12, upper arm 11, wrist 15, and work tool 2 correspond to the components of a robot device 5.

[0017] The robot 1 in this embodiment has six drive axes, J1 to J6, but is not limited to this. Any robot that can change its position and posture using any mechanism can be used. The work tool 2 is a device that corresponds to the work to be performed by the robot device.

[0018] A robot coordinate system is set in the robot device 5, which is a coordinate system in which the position is fixed and the orientation of the coordinate axes is also fixed. The robot coordinate system is also called a world coordinate system. A flange coordinate system having its origin at the flange 16 of the wrist 15 is set in the robot device 5. The flange coordinate system is a coordinate system that moves and rotates together with the surface of the flange 16. A tool coordinate system is set in the robot device 5, which has its origin set at an arbitrary position on the work tool. The tool coordinate system is a coordinate system that moves and rotates together with the work tool. The relative position and orientation of the tool coordinate system with respect to the flange coordinate system are constant and predetermined. The position of the robot 1 corresponds, for example, to the position of the origin of the tool coordinate system in the robot coordinate system. The orientation of the robot 1 corresponds to the orientation of the tool coordinate system with respect to the robot coordinate system.

[0019] The robot 1 includes a robot drive device that changes the position and posture of the robot 1. The robot drive device includes drive motors 22a-22f that drive components such as the arm and wrist. In this embodiment, multiple drive motors 22a-22f are arranged corresponding to multiple drive axes J1-J6. One drive motor is arranged for each drive axis. The robot device 5 is equipped with a work tool drive device 21 that drives the work tool 2. The work tool drive device 21 includes, for example, a motor, a cylinder, and a solenoid valve that drive the work tool.

[0020] The robot device 5 is equipped with a control device 4 that controls the robot 1 and the work tool 2. The control device 4 includes a control device main body 40 that performs control, and a teaching operation panel 37 that allows the worker to operate the control device main body 40. The control device main body 40 includes an arithmetic processing device (computer) that has a CPU (Central Processing Unit) as a processor. The arithmetic processing device has RAM (Random Access Memory), ROM (Read Only Memory), etc. connected to the CPU via a bus.

[0021] The teaching operation panel 37 is connected to the control device main body 40 via a communication device. The teaching operation panel 37 includes an input unit 38 for inputting information about the robot 1 and the work tool 2. The input unit 38 is made up of input members such as a keyboard and a dial. The teaching operation panel 37 also includes a display unit 39 for displaying information about the robot 1 and the work tool 2. The display unit 39 can be made up of any display panel, such as a liquid crystal display panel or an organic EL (Electro Luminescence) display panel.

[0022] An operation program 46 created in advance for operating the robot 1 and the work tool 2 is input to the control device 4. Alternatively, a worker can set teaching points for the robot 1 by operating the teaching operation panel 37 to drive the robot 1. The control device 4 can generate the operation program 46 for the robot 1 and the work tool 2 based on the teaching points.

[0023] The control device main body 40 includes an operation control unit 43 that controls the operations of the robot 1 and the work tool 2. The operation control unit 43 sends operation commands to the robot drive unit 45 for driving the robot 1 based on an operation program 46. The robot drive unit 45 includes an electrical circuit that drives the drive motors 22a to 22f. The robot drive unit 45 supplies electricity to the drive motors 22a to 22f based on the operation commands. The operation control unit 43 also sends operation commands to the work tool drive unit 44 for driving the work tool 2 based on the operation program 46. The work tool drive unit 44 includes an electrical circuit that drives the work tool drive device 21. The work tool drive unit 44 supplies electricity to the work tool drive device 21 based on the operation commands.

[0024] The control device main body 40 includes a memory unit 42 that stores information related to the control of the robot 1 and the work tool 2. The memory unit 42 can be configured with a non-transitory storage medium capable of storing information. For example, the memory unit 42 can be configured with a storage medium such as a volatile memory, a non-volatile memory, a magnetic storage medium, or an optical storage medium. An operation program 46 is stored in the memory unit 42.

[0025] The operation control unit 43 corresponds to a processor that operates in accordance with the operation program 46. The operation control unit 43 is configured to be able to read information stored in the storage unit 42. The processor reads the operation program 46 and performs the control defined in the operation program 46, thereby functioning as the operation control unit 43.

[0026] The robot 1 includes rotational position detectors 19a to 19f for detecting the position and posture of the robot 1. In this embodiment, the rotational position detectors 19a to 19f are attached to the drive motors 22a to 22f of the respective drive shafts. One rotational position detector is attached to each drive motor. Each rotational position detector 19a to 19f can be configured by an encoder that detects the rotation angle of the output shaft of the drive motor 22a to 22f. The position and posture of the robot 1 are detected based on the outputs of the multiple rotational position detectors 19a to 19f.

[0027] The control device 4 of the first robot device 5 includes torque sensors 25a to 25f as torque detectors that detect torque around the drive axes J1 to J6 at the joints. In this embodiment, torque sensors 25a to 25f are provided for all six drive axes J1 to J6. One torque sensor is provided for each drive axis. Any sensor capable of detecting torque, such as a sensor equipped with a strain gauge, can be used as the torque sensors 25a to 25f. The torque sensors are provided between one robot component and another component that rotates while being supported by the other robot component. For example, the torque sensor is provided between the output shaft of a reducer attached to a drive motor and a component driven by the reducer.

[0028] In this way, in the robot 1 of the first robot device 5, a drive motor, a rotational position detector, and a torque sensor are arranged for each drive axis. For example, a rotational position detector 19a that detects the rotational position is attached to the drive motor 22a that rotates the swivel base 13 around the drive axis J1. In addition, a torque sensor 25a that detects the torque around the drive axis J1 is arranged.

[0029] In this embodiment, mastering data of the robot is generated for each drive axis. That is, mastering data is generated for the output of a rotational position detector attached to a drive motor arranged in one joint. In this embodiment, the drive axis for which mastering data is generated is called a specific drive axis. The specific drive axis is predetermined by the operator.

[0030] The control device main body 40 includes a calculation unit 51 that performs force control of the robot 1 based on the output of a torque sensor arranged on a specific drive axis. The calculation unit 51 also generates mastering data based on the output of a rotational position detector attached to the drive motor of the specific drive axis. The calculation unit 51 also includes a torque control unit 52 that controls the drive motor so that the torque output from the torque sensor becomes a predetermined torque set value 47. In particular, the torque control unit 52 controls the torque when rotation of a component of the robot around the specific drive axis is prevented by a rotation prevention unit.

[0031] The calculation unit 51 includes a rotational position acquisition unit 53 that acquires the rotational position output by the rotational position detector of the specific drive shaft when the torque reaches the torque setting value 47. The calculation unit 51 includes a data generation unit 54 that generates mastering data for the output of the rotational position detector arranged on the specific drive shaft. The data generation unit 54 generates the mastering data based on the rotational position of the drive motor output by the rotational position detector and a predetermined design value 49 of the mastering data.

[0032] Mastering design values ​​49, which are theoretical values ​​of the rotation angles of the respective drive shafts for mastering, are determined in advance. The mastering design values ​​49 for the outputs of the rotation position detectors attached to the respective drive motors are stored in the storage unit 42. The mastering design values ​​49 are generated for each of the rotation position detectors 19a to 19f.

[0033] The calculation unit 51, torque control unit 52, rotational position acquisition unit 53, and data generation unit 54 correspond to a processor that operates in accordance with the operation program 46. The processor reads the operation program 46 and performs the control defined in the operation program 46, thereby functioning as each unit.

[0034] In this embodiment, rotational position detectors 19a to 19f are provided on the drive axes J1 to J6 of the robot 1 to detect the rotational positions of the output shafts of the drive motors 22a to 22f. For each of the drive axes J1 to J6, the machine pulse value, which is the rotational position of the drive motor used to control the robot, is determined by the following equation (1).

[0035] (machine pulse value) = (output value of rotational position detector) - (mastering data) ... (1)

[0036] In the mastering process, mastering data is calculated. The mastering data indicates the rotational position corresponding to the robot's origin position. When the output value of the rotational position detector becomes the same as the mastering data, the machine pulse value becomes zero. By subtracting the mastering data from the output value of the rotational position detector, the machine pulse value used to control the robot can be calculated.

[0037] For example, the joint angle of each drive shaft (joint) can be calculated based on the machine pulse value and the gear ratio of the reducer. Then, based on the joint angle of each joint, coordinate values ​​of the position and orientation of the robot in the robot coordinate system can be calculated by forward kinematics transformation. Alternatively, the joint angle of each joint can be calculated by inverse kinematics transformation based on the position and orientation of the robot defined in the operation program. Then, the machine pulse value can be calculated based on the joint angle and the gear ratio of the reducer. The control device can control the rotational position of the drive motor so that this machine pulse value is obtained.

[0038] In this embodiment, the robot is driven around one specific drive axis of the robot. Rotation of the robot is then prevented by a rotation prevention unit such as a stopper or jig. Torque control unit 52 performs control to press the component member at a predetermined torque setting value 47. A mastering design value 49, which is the theoretical value of the output of the rotation position detector at this time, is predetermined. The mastering data can be calculated using the following equation (2).

[0039] (Mastering data) = (output value of the rotational position detector when the robot component is pressed) - (theoretical value of the output of the rotational position detector) ... (2)

[0040] The control of this embodiment allows for highly accurate mastering. In the mastering process of this embodiment, the drive motors of drive axes other than the specific drive axis are not driven, maintaining a predetermined rotational position. The joint angles of the drive axes other than the specific drive axis are maintained at a predetermined angle. Then, the drive motor of the specific drive axis is driven. For this reason, it is preferable to perform low-precision mastering before performing the mastering of this embodiment. For example, when precision mastering was performed in the past, linear scribing lines that span the boundaries between adjacent robot components can be formed. The linear scribing lines can be formed so that the rotational position of one component relative to the other component can be determined. The scribing lines can be formed for each joint.

[0041] The operator manually manipulates the robot's position and orientation using the teaching console so that the scribe lines on one component and the scribe lines on the other component are aligned. When the scribe lines at all joints are aligned, the position and orientation for mastering are achieved. At this point, coarse-grained mastering can be performed based on the output of the rotational position detector and the design value (theoretical value) of the rotational position. After that, high-precision mastering according to this embodiment can be performed.

[0042] FIG. 3 shows a side view of the robot illustrating the first control of the first robot device in this embodiment. In the first control, the drive axis J1 is selected as the specific drive axis. In the first control, mastering of the drive axis J1 is performed. That is, mastering data is generated for the output of the rotational position detector 19a arranged on the drive axis J1.

[0043] The base unit 14 corresponds to a first component of the robot 1, and the swivel base 13 corresponds to a second component that rotates relative to the first component around a specific drive axis as indicated by arrow 85. The stopper portion 13a of the swivel base 13 and the stopper portion 14a of the base unit 14 are formed to prevent the swivel base 13 from rotating excessively around the drive axis J1. In other words, they are formed to restrict the angle at which the swivel base 13 rotates (the range of joint angles of the drive axis J1).

[0044] In the first control, the rotation prevention portion that prevents rotation of the swivel base 13 includes a stopper portion 14a as a contact portion arranged on the base portion 14, and a stopper portion 13a as a contact portion arranged on the swivel base 13. The rotation prevention portion is formed so that when the swivel base 13 rotates as indicated by the arrow 85, the stopper portion 13a comes into contact with the stopper portion 14a, thereby preventing the rotation of the swivel base 13.

[0045] FIG. 4 shows a schematic plan view of the robot illustrating the first control of the first robot device. With reference to FIGS. 2 to 4, to perform mastering, torque control unit 52 drives drive motor 22a to rotate swivel base 13 in one direction as indicated by arrow 85a. When rotating swivel base 13, the other drive motors 22b to 22f are stopped. That is, the joint angles of the other drive axes J2 to J6 are maintained at predetermined angles.

[0046] When stopper portion 13a comes into contact with stopper portion 14a, rotation of swivel base 13 is prevented. Torque control portion 52 acquires torque from torque sensor 25a. Torque control portion 52 controls drive motor 22a so that the torque output from torque sensor 25a when rotation of swivel base 13 is prevented becomes a predetermined torque set value 47. Torque set value 47 at this time is predetermined and stored in memory portion 42.

[0047] Any method can be adopted as the method by which the torque control unit 52 controls the torque applied to the component members. It is preferable to implement control that reduces the rotational speed of the drive motor as the torque detected by the torque sensor 25a approaches the target torque value. For example, the torque control unit 52 can implement damping control as force control. In damping control, a speed command v is calculated by dividing the difference between the current force F and a predetermined target force Fd by a predetermined damper coefficient D. The damping control formula can be expressed as the following formula (3).

[0048] v = (F - Fd) / D … (3)

[0049] The torque control unit 52 can calculate the force by dividing the torque acquired from the torque sensor 25a by a predetermined radius of rotation from the center of rotation to the contact point. For example, the torque control unit 52 can calculate the force F applied to the stopper portion 13a by dividing the output of the torque sensor 25a by the distance from the drive shaft J1 to the stopper portion 13a. Then, the damping control of the above equation (3) can be performed based on the force F calculated from the torque acquired from the torque sensor 25a.

[0050] The torque control unit 52 sends a speed command v for the drive motor 22a to the operation control unit 43. The operation control unit 43 can control the drive motor 22a of the drive shaft J1 based on the command from the torque control unit 52.

[0051] Note that the speed command v may be calculated using an equation in which the target force Fd in equation (3) is changed to the target torque and the current force F is changed to the current torque. Alternatively, in this embodiment, torque sensors 25a to 25f are provided on all of the drive axes J1 to J6. For this reason, the forces at the contact points of the stoppers may be calculated based on the outputs of all of the torque sensors 25a to 25f. The speed command for the drive motor 22a may then be calculated based on the forces at the contact points.

[0052] Next, when the torque output by the torque sensor 25a reaches the torque setting value 47, the rotational position acquisition unit 53 acquires the rotational position output by the rotational position detector 19a of the drive shaft J1. The data generation unit 54 generates mastering data for the output of the rotational position detector 19a arranged on the drive shaft J1 based on the above equation (2). The data generation unit 54 generates the mastering data based on the rotational position of the drive motor 22a output by the rotational position detector 19a and a predetermined design value 49 of the mastering data. The storage unit 42 stores the mastering data for the drive shaft J1 generated by the data generation unit 54.

[0053] When controlling the position and posture of the robot 1 in an actual operation of the robot device, the machine pulse value calculated from the mastering data is used as shown in equation (1). As a result, the robot can be driven so as to correspond precisely to the design values ​​of the robot. In other words, the position and posture of the robot can be controlled precisely so as to correspond to the position and posture of the robot in the design.

[0054] The control device of this embodiment can perform mastering using torque sensors arranged on each drive shaft. In this embodiment, one component of the robot is rotated and its rotation is prevented by a rotation prevention unit. At this time, the torque control unit controls the torque so that a predetermined component is pressed against it at a torque setting value. This control ensures that the components that prevent rotation are tightly attached to each other, achieving precise robot position and posture. In this embodiment, mastering data is generated based on the rotational position when a predetermined force is applied to the pressing point of the predetermined component. This allows for precise mastering.

[0055] The robot control device in this embodiment can generate mastering data with high accuracy through simple control. High-accuracy mastering can be performed regardless of the skill level of the worker. In particular, by having the calculation unit 51 automatically perform the mastering work, mastering can be performed easily and operator operation errors can be reduced.

[0056] Furthermore, the control device of this embodiment can perform mastering for each drive axis. It is possible to perform mastering on the output of the rotational position detector of the drive motor of some of the drive axes, without having to perform mastering on all of the drive axes. For example, when some of the drive motors or rotational position detectors are replaced, mastering can be performed on the drive axes of the replaced parts. Alternatively, after performing low-precision mastering, such as mastering using scribed lines, the control of this embodiment can be performed on drive axes for which high mastering precision is desired.

[0057] In the first control of the first robot device, mastering of the drive axis J1 has been described, but this is not limited to this. For the other drive axes J2 to J6, if stoppers that restrict the rotation range are provided, the same control as the first control can be performed. Alternatively, stoppers may be provided for each robot so as to limit the rotation angle at which the robot is driven.

[0058] When driving the robot 1, the outputs of the drive motors 22a to 22f are transmitted to the respective components after being reduced in speed by the reducers. In the reducers, multiple gears mesh with each other. This causes the influence of backlash at the meshing portions of the gears. Next, a control for correcting the influence of backlash in the first control will be described.

[0059] 4, torque control unit 52 rotates swivel base 13 in a direction indicated by arrow 85a as a first direction. Rotational position acquisition unit 53 detects the first rotational position when rotation of swivel base 13 in the first direction is prevented. Rotational position acquisition unit 53 detects the first rotational position when stopper portion 13a is pressed against one stopper portion 14a of base portion 14.

[0060] FIG. 5 shows another schematic plan view of the first robot device during the first control. Next, the torque control unit 52 rotates the swivel base 13 in the direction indicated by the arrow 85b, which is the second direction opposite to the first direction. The stopper portion 13a contacts the other stopper portion 14a, preventing rotation. Again, the torque control unit 52 controls the stopper portion 13a to press against the other stopper portion 14a so that the torque reaches the torque setting value 47. The rotation position acquisition unit 53 detects the second rotation position when the rotation of the swivel base 13 in the second direction is prevented. The rotation position acquisition unit 53 detects the second rotation position when the stopper portion 13a is pressed against the stopper portion 14a. Next, the data generation unit 54 calculates a correction value for the mastering data based on the first rotation position and the second rotation position.

[0061] FIG. 6 shows a schematic cross-sectional view of the meshing portion of the gears of the reducer. FIG. 6 shows the meshing portion of one gear 81 and another gear 82 of the reducer. In this example, teeth 81a of gear 81 engage with teeth 82a and 82b of gear 82. Arrow 89a corresponds to the first direction in which the base unit 14 is rotated. Arrow 89b corresponds to the second direction in which the base unit 14 is rotated.

[0062] Fig. 7 shows an enlarged cross-sectional view of the gear when rotated in a first direction. Fig. 8 shows an enlarged schematic cross-sectional view of the gear when rotated in a second direction. With reference to Figs. 6 to 8, by rotating gear 81 in the direction indicated by arrow 89a, tooth portion 81a comes into contact with tooth portion 82b. By rotating gear 81 in the direction indicated by arrow 89b, tooth portion 81a comes into contact with tooth portion 82a. Even though gear 81 is rotating, gear 82 may not be rotating due to the influence of backlash.

[0063] 4 and 5, in this embodiment, calculation unit 51 detects a first rotation position when swivel base 13 is rotated in a first direction indicated by arrow 85a. Calculation unit 51 detects a second rotation position when swivel base 13 is rotated in a second direction indicated by arrow 85b.

[0064] The data generating unit 54 calculates the rotation angle when the swivel base 13 is rotated from the first rotation position to the second rotation position, as indicated by arrow 90. The angle obtained by subtracting the design value of the rotation angle from the rotation angle when the swivel base 13 is actually rotated corresponds to the backlash rotation angle δ. The difference between the rotation angles shown in FIGS. 7 and 8 corresponds to the backlash rotation angle δ.

[0065] When the rotational position output from the rotational position detector rotates in the negative direction, a small rotational position is output due to backlash, so δ / 2 can be added to the machine pulse value. The data generation unit 54 can subtract δ / 2 from the mastering data. On the other hand, when the rotational position of the rotational position detector rotates in the positive direction, a large rotational position is output, so δ / 2 can be subtracted from the machine pulse value. That is, the data generation unit 54 can add δ / 2 to the mastering data. In this way, the calculation unit 51 can calculate a correction value for the output pulse value of the above equation (1). That is, the calculation unit 51 can calculate a correction value for the mastering data.

[0066] In this way, by pressing twice in opposite directions, it is possible to calculate a correction value for the mastering data related to backlash. Note that the pressing of a component of the robot or the pressing of a jig supported by the robot can be performed by rotating twice in the positive direction and then in the negative direction, but it may be repeated three or more times.

[0067] FIG. 9 shows a side view of the robot illustrating the second control of the first robot device in this embodiment. In the second to sixth controls of the first robot device described below, a jig for preventing rotation of the components of the robot 1 is arranged as a rotation prevention unit. In the second control, the drive axis J1 is selected as the specific drive axis. The torque control unit 52 rotates the swivel base 13, which serves as the second component, relative to the base unit 14, which serves as the first component. The swivel base 13 is rotated around the drive axis J1 in the direction indicated by the arrow 85.

[0068] FIG. 10 shows a schematic plan view of the robot illustrating the second control of the first robot device. Referring to FIGS. 9 and 10, the rotation prevention unit includes a jig 71 fixed to the base unit 14 as a first component. The jig 71 is fixed to a member that remains stationary when the robot is driven. The jig 71 is formed in a rod shape. For example, the jig 71 is formed in a cylindrical shape. The jig 71 is arranged so as to come into contact with the wrist unit 15 when the swivel base 13 rotates. The contact of the jig 71 with the wrist unit 15 prevents the rotation of the swivel base 13. It is preferable that the position where the jig 71 is fixed and the attitude of the jig 71 are precisely adjusted.

[0069] The torque control unit 52 rotates the swivel base 13 together with the lower arm 12, upper arm 11, and wrist unit 15 in the direction indicated by arrow 85a, which is the first rotation direction. The rotation positions of the drive motors 22b to 22f for the other drive axes J2 to J6 when rotating the swivel base 13 are predetermined. The joint angles for the drive axes J2 to J6 other than the specific drive axis J1 are fixed.

[0070] The torque control unit 52 controls the drive motor 22a so that the torque detected by the torque sensor 25a becomes equal to the torque set value 47 when the wrist 15 comes into contact with the jig 71. When the torque detected by the torque sensor 25a becomes equal to the torque set value, the rotational position acquisition unit 53 acquires the first rotational position from the rotational position detector 19a. The data generation unit 54 can then generate mastering data based on the first rotational position of the drive motor 22a and the design value 49 of the mastering data.

[0071] FIG. 11 shows another schematic plan view of the robot illustrating the second control of the first robot device. The second control also allows for calculation of a correction value for the mastering data that takes into account the effects of backlash. The torque control unit 52 rotates the swivel base 13 in a second direction opposite to the first direction. The torque control unit 52 rotates the swivel base 13 in the direction of arrow 85b, which is the second direction, and presses the wrist 15 against the jig 71 at the torque setting value 47. The rotational position acquisition unit 53 acquires the second rotational position from the rotational position detector 19a.

[0072] The rotational position acquisition unit 53 acquires a first rotational position when rotation in a first direction shown in FIG. 10 is blocked, and a second rotational position when rotation in a second direction shown in FIG. 11 is blocked. As with the first control, the data generation unit 54 calculates a correction value for the mastering data based on the first rotational position and the second rotational position. The data generation unit 54 can calculate a correction value for backlash in the mastering data based on the difference between the rotation angle from the first rotational position to the second rotational position shown by arrow 91 and the theoretical value of the rotational angle. Other controls, actions, and effects are the same as those of the first control.

[0073] FIG. 12 shows a side view of the robot illustrating the third control of the first robot device. In the third control, the second drive axis J2 is selected as the specific drive axis. In the third control, mastering data is generated for the output of the rotational position detector 19b attached to the drive motor 22b arranged on the drive axis J2. In the third control, the jig 71 is fixed to the base unit 14, as in the second control.

[0074] In the third control, the torque control unit 52 changes the position and posture of the robot 1 so that the upper arm 11 and the wrist 15 face upward relative to the lower arm 12. The joint angles of the drive axes J1, J3 to J6 are determined in advance. The torque control unit 52 does not drive the drive motors 22a, 22c to 22f of the drive axes J1, J3 to J6, maintaining them in a stopped state. The torque control unit 52 drives the drive motor 22b of the drive axis J2. The torque control unit 52 brings the lower arm 12 into contact with the jig 71, as indicated by the arrow 86. Then, the torque control unit 52 controls the drive motor 22b so that the torque output from the torque sensor 25b becomes the predetermined torque set value 47.

[0075] Next, the rotational position detector 19b detects the rotational position when the lower arm 12 is pressed against the jig 71. Then, the data generator 54 can generate mastering data based on this rotational position and the mastering design value 49. Other controls, actions, and effects are the same as those of the first control.

[0076] Figure 13 shows a side view of the robot, illustrating the fourth control of the first robot device. The jig that prevents a component from rotating around one specific drive axis does not have to be stationary, but may move along with the drive of the robot. In the fourth control, the second drive axis J2 is selected as the specific drive axis.

[0077] In the fourth control, a jig 73 is fixed to the swivel base 13. The position and orientation of the jig 73 are precisely adjusted. The jig 73 moves together with the swivel base 13. The jig 73 is rod-shaped. The torque control unit 52 rotates the lower arm 12 by driving the drive motor 22b disposed on the drive axis J2, as indicated by the arrow 87. At this time, the joint angles of the other drive axes J1, J3 to J6 are maintained constant. While the torque control unit 52 presses the lower arm 12 against the jig 73 at a predetermined torque setting value 47, the rotational position acquisition unit 53 acquires the rotational position output from the rotational position detector 19b. The data generation unit 54 generates mastering data for the output of the rotational position detector 19b disposed on the drive axis J2. In this way, the jig that prevents the rotation of a robot component on a specific drive axis may move together with the robot component. Other controls, actions, and effects are the same as those of the first control.

[0078] 14 shows a side view of the robot illustrating the fifth control of the first robot device. In the fifth control, the fifth drive axis J5 is selected as the specific drive axis. In the fifth control, mastering data is generated for the output of the rotational position detector 19e of the drive motor 22e arranged on the drive axis J5.

[0079] In the fifth control, a jig 74 including a first member 74a and a second member 74b is used. The first member 74a is a plate-like member with a rectangular planar shape. The first member 74a is fixed to the flange 16 of the wrist 15. The maximum area surface of the first member 74a, which has the largest area, is fixed to the flange 16. The position and posture of the first member 74a can be changed by the robot 1.

[0080] In contrast, the second member 74b is a stationary member. The second member 74b is fixed to the base 14. The position and orientation of the second member 74b are precisely adjusted. Alternatively, the second member 74b may be fixed to the installation surface of the robot 1. A recess 74bx having a rectangular planar shape is formed on the upper surface of the second member 74b. The first member 74a is sized to be placed inside the recess 74bx.

[0081] In the fifth control, the torque control unit 52 rotates the wrist 15 around the drive axis J5 in the direction of the arrow 88a, which is a first direction. The joint angles of the other drive axes J1 to J4, J6 are maintained constant. The torque control unit 52 brings the end surface 74aa of the first member 74a into contact with the side surface 74ba of the recess 74bx of the second member 74b. The torque control unit 52 presses the first member 74a at a predetermined torque setting value 47 based on the output of the torque sensor 25e. At this time, the rotational position acquisition unit 53 acquires the first rotational position from the rotational position detector 19e. The data generation unit 54 can then generate mastering data for the output of the rotational position detector 19e based on the output of the rotational position detector 19e and the mastering design value 49.

[0082] 15 shows another side view of the robot illustrating the fifth control of the first robot device. The planar shape of the recess 74bx of the second member 74b is formed slightly larger than the planar shape of the first member 74a. Even in the fifth control, it is possible to calculate a correction value for the mastering data that takes into account the influence of backlash.

[0083] The torque control unit 52 rotates the wrist 15 in the direction indicated by arrow 88b, which is a second direction opposite to the first direction. The end surface 74ab of the first member 74a contacts the side surface 74bb of the recess 74bx of the second member 74b. With the first member 74a pressed at the torque setting value 47, the rotational position acquisition unit 53 acquires the second rotational position of the rotational position detector 19e. The data generation unit 54 calculates the rotation angle from the first rotational position to the second rotational position, as indicated by arrow 92. Based on the difference between the measured value of this rotational angle and the design value (theoretical value), the data generation unit 54 can calculate the rotational angle (δ / 2), which is a correction value for the rotational angle related to backlash.

[0084] In this way, in the fifth control, too, a correction value for backlash can be calculated by rotating the wrist 15 in the first direction and the second direction opposite to the first direction. Other controls, actions, and effects are the same as those in the first control.

[0085] In the fifth control, mastering data for the fifth drive axis J5 is generated. However, mastering data for the third drive axis J3 can be generated using similar control. That is, the joint angles of the drive axes J1, J2, J4 to J6 other than the drive axis J3 are maintained constant, and the drive motor 22c is driven to press the first member 74a of the jig 74 against the recess 74bx of the second member 74b. Then, by detecting the rotational position of the rotational position detector 19c attached to the drive motor 22c, mastering data for the output of the rotational position detector 19c can be generated.

[0086] FIG. 16 shows a side view of the robot illustrating the sixth control of the first robot device. The sixth control also uses a jig 74 including a first member 74a and a second member 74b. In the sixth control, the sixth drive axis J6 is selected as the specific drive axis. In the sixth control, mastering data is generated for the output of the rotational position detector 19f of the drive motor 22f arranged on the drive axis J6.

[0087] In the sixth control, the first member 74a is positioned so that the largest surface extends horizontally. A side surface 74ba of the recess 74bx of the second member 74b and an end surface 74aa of the first member 74a are formed flat. The torque control unit 52 brings the end surface 74aa into surface contact with the side surface 74ba. Alternatively, the first member 74a may be positioned in a predetermined position and orientation so that a gap is formed between the side surface 74ba and the end surface 74aa.

[0088] The torque control unit 52 rotates the first member 74a in a first direction, which is one of the directions of the arrow 93. The joint angles of the other drive axes J1 to J5 are maintained constant. The torque control unit 52 performs control to press the first member 74a against the second member 74b at a torque setting value 47. The torque control unit 52 controls the drive motor 22f so that the torque detected by the torque sensor 25f becomes the predetermined torque setting value 47. The rotational position acquisition unit 53 acquires the first rotational position, and the data generation unit 54 can generate mastering data for the output of the rotational position detector 19f based on the first rotational position.

[0089] Furthermore, torque control unit 52 rotates first member 74a in a second direction, which is the other of the directions of arrow 93. While torque control unit 52 is controlling the pressing of first member 74a at torque setting value 47, rotational position acquisition unit 53 acquires a second rotational position. Data generation unit 54 can calculate a correction value for backlash based on the rotation angle from the first rotational position to the second rotational position. Other controls, actions, and effects are the same as those of the first control.

[0090] In the sixth control, mastering data for the sixth drive axis J6 is generated, but this is not limited to this. Mastering data for the J4 axis can also be generated using a similar control. The calculation unit 51 drives the drive motor 22d to press the end surface 74aa of the first member 74a against the side surface 74ba of the recess 74bx of the second member 74b. Then, the calculation unit 51 can generate mastering data for the rotational position detector 19d based on the output of the rotational position detector 19d.

[0091] As described above, in the fifth and sixth controls, the jig 74 is used to generate mastering data for the drive axes J3 to J5. The first member of the jig 74 can have any shape. The recess of the second member can have any shape. Here, a spherical first member can be used instead of the first member 74a having a rectangular planar shape. Furthermore, a hemispherical recess can be formed instead of the recess 74bx having a rectangular planar shape in the second member 74b. By adopting this configuration, mastering data for the drive axes J1 and J2 can be generated. With the first member pressed against the recess of the second member, the rotational positions output by the respective drive motors 22a and 22b can be obtained. Mastering data can be generated based on the rotational positions.

[0092] Fig. 17 shows a side view of the second robot device in this embodiment. Fig. 18 shows a block diagram of the second robot device in this embodiment. With reference to Figs. 17 and 18, the second robot device 6 includes a robot 3 and a control device 7. In the second robot device 6, the torque sensor of the first robot device 5 does not need to be disposed at the joint of the robot 3.

[0093] The control device 7 of the second robot device 6 is equipped with a jig 76 that prevents rotation of a component member around a specific drive axis. The jig 76 includes a force sensor 24 as a force detector that detects force in a predetermined direction. The force sensor 24 of this embodiment can detect forces applied in the positive and negative directions of three mutually orthogonal axes (X-axis, Y-axis, and Z-axis). Any force sensor, such as a sensor including a strain sensor or a capacitance sensor, can be used as the force sensor 24.

[0094] The jig 76 has a fixed part 76a attached to one surface of the force sensor 24 and a movable part 76b attached to the other surface of the force sensor 24. In this embodiment, the fixed part 76a and the movable part 76b are each formed in a rod shape. The fixed part 76a is fixed to a member that remains stationary when the robot 3 is driven. In this example, the fixed part 76a is fixed to the base part 14 of the robot 3. The position and orientation of the jig 76 are precisely adjusted.

[0095] The control device 7 of the second robot device 6 controls the force applied to the component or jig based on the output of the force sensor 24 instead of the torque sensor output. The second robot device also performs mastering for each drive axis. In this example, drive axis J1 is selected as the specific drive axis.

[0096] The control device 7 includes a calculation unit 61 that performs force control and generates mastering data. The calculation unit 61 includes a force control unit 62 that controls the drive motor of a specific drive axis so that the force output from the force sensor 24 becomes equal to the force set value 48. The force control unit 62 performs this control when the rotation of a component of the robot 3 is prevented by a jig 76. The force set value 48 is determined in advance and stored in the memory unit 42.

[0097] A rotational position acquisition unit 53 acquires the rotational position output by the rotational position detector of the specific drive shaft when the force output from the force sensor 24 reaches the force setting value 48. A data generation unit 54 generates mastering data for the output of the rotational position detector arranged on the specific drive shaft based on the rotational position of the drive motor output by the rotational position detector and a predetermined design value 49 of the mastering data.

[0098] Fig. 19 is a schematic plan view of the robot illustrating the control of the second robot device. Referring to Fig. 17 to Fig. 19, in the second robot device 6, the force control unit 62 performs control to press the wrist 15, which is a component of the robot 3, against the movable part 76b of the jig 76. In the second robot device as well, control is performed to maintain constant joint angles in the drive axes other than the specific drive axis.

[0099] The force control unit 62 drives the first drive motor 22a to rotate the wrist 15 in the direction indicated by the arrow 85a, which is the first direction. The wrist 15 comes into contact with the movable unit 76b. Based on the output of the force sensor 24, the force control unit 62 controls the drive motor 22a so that the force with which the wrist 15 presses the movable unit 76b becomes the force setting value 48.

[0100] The rotational position acquisition unit 53 acquires the first rotational position output by the rotational position detector 19a when the force output from the force sensor 24 reaches the force setting value 48. The data generation unit 54 can generate mastering data for the output of the rotational position detector 19a based on the first rotational position of the drive motor 22a output by the rotational position detector 19a and the design value 49 of the mastering data.

[0101] In the second robot device 6, a force sensor 24 is arranged on the jig 76 instead of the torque sensor of the first robot device. Force control is performed based on the output of the force sensor 24 to generate mastering data. In the second robot device as well, mastering can be performed with high accuracy using simple control.

[0102] FIG. 20 shows another schematic plan view of the robot illustrating the control of the second robot device. In the second robot device, a backlash correction value can be calculated, similar to the second control of the first robot device. The force control unit 62 drives the first drive motor 22a so that the wrist 15 moves in a second direction indicated by an arrow 85b, which is opposite to the first direction. The wrist 15 of the robot 3 can be pressed against the movable part 76b of the jig 76. The force control unit 62 controls the wrist 15 to rotate in the second direction, which is opposite to the first direction.

[0103] The force control unit 62 controls the first drive motor 22a so that the movable part 76b is pressed with a predetermined force setting value 48. The rotational position acquisition unit 53 acquires the second rotational position at this time. In this manner, control is performed to rotate the component in a first direction and control to rotate the component in a second direction opposite to the first direction. The rotational position acquisition unit 53 detects the first rotational position when rotation in the first direction is blocked and the second rotational position when rotation in the second direction is blocked.

[0104] Then, based on the first rotational position and the second rotational position, the data generating unit 54 calculates the rotation angle from the first rotational position to the second rotational position indicated by arrow 91. Based on this rotational angle and the theoretical value of the rotational angle, the data generating unit 54 can calculate the rotational angle (δ / 2), which is the backlash correction value.

[0105] In this way, by arranging a force detector on a jig that presses a component of a robot or a workpiece, mastering data can be generated. For example, a force detector can be attached to jig 71 shown in FIG. 12. A force sensor can also be attached to jig 73 shown in FIG. 13. A force sensor can also be attached to second member 74b of jig 74 shown in FIG. 14. Then, mastering data can be generated based on the output value of the force detector when a component of a robot or a jig supported by the robot is pressed against the fixed jig and the design value of the force.

[0106] Although the jig including the force detector in this embodiment is formed in a rod shape, it is not limited to this form and a jig of any shape can be used. The configuration, operation, and effects of the second robot device other than those described above are the same as those of the first robot device, so description thereof will not be repeated here.

[0107] In each of the above-described controls, the order of steps can be changed as appropriate within the scope that does not change the functions and actions.

[0108] The above-described embodiments can be combined as appropriate. In each of the above-described drawings, the same or equivalent parts are designated by the same reference numerals. Note that the above-described embodiments are merely examples and do not limit the invention. Furthermore, the embodiments include modifications of the embodiments as set forth in the claims. [Explanation of symbols]

[0109] 1,3 Robot 4,7 Control device 5,6 Robotic devices 11 Upper arm 12 Lower Arm 13 Swivel Base 13a Stopper part 14 Base 14a Stopper part 15 Wrist part 16 flange 19a~19f Rotational position detector 22a~22f Drive motor 24 Force sensor 25a~25f Torque sensor 37 Teaching control panel 38 Input section 39 Display section 40 Control device main body 42 Storage section 47 Torque setting value 48 Force setting value 49 Mastering Design Value 52 Torque control section 53 Rotation position acquisition unit 54 Data Generation Unit 62 Force control section 71, 73, 74, 75 Jig 74a First member 74b Second member 76 Jig

Claims

1. A robot control device that generates mastering data for an output of a rotational position detector attached to a drive motor of one specific drive shaft that rotates a component of the robot, a torque detector for detecting torque around a specific drive shaft; a torque control unit that controls the drive motor of the specific drive shaft so that the torque output from the torque detector becomes a predetermined torque set value when the rotation of a component of the robot that rotates around the specific drive shaft is prevented by the rotation prevention unit; a rotational position acquisition unit that acquires the rotational position output by the rotational position detector of the specific drive shaft when the torque output from the torque detector reaches a torque setting value; A control device comprising: a data generation unit that generates mastering data for the output of a rotational position detector arranged on a specific drive shaft based on the rotational position of the drive motor output by the rotational position detector and a predetermined design value of the mastering data.

2. the robot includes a second component that rotates relative to the first component about a particular drive axis; the rotation preventing portion includes a contact portion disposed on the first component and a contact portion disposed on the second component, and is configured such that rotation of the second component is prevented by the contact portion of the first component coming into contact with the contact portion of the second component; 2. The control device according to claim 1, wherein the torque control unit controls the torque of the drive motor that drives the second component member so that the torque when rotation of the second component member is prevented becomes a predetermined torque set value.

3. the robot includes a second component that rotates relative to the first component about a particular drive axis; The control device according to claim 1 , wherein the rotation prevention portion includes a jig that prevents rotation of the second component member.

4. The control device according to claim 3 , wherein the jig is fixed to the first component member.

5. The control device according to claim 3 , wherein the jig is fixed to a member that remains stationary when the robot is driven.

6. the torque control unit performs control to rotate the component in a first direction and control to rotate the component in a second direction opposite to the first direction; the rotational position acquisition unit detects a first rotational position when rotation in a first direction is blocked and a second rotational position when rotation in a second direction is blocked; The control device according to claim 1 , wherein the data generating unit calculates a correction value for the mastering data based on the first rotational position and the second rotational position.

7. A robot control device that generates mastering data for an output of a rotational position detector attached to a drive motor of one specific drive shaft that rotates a component of the robot, a jig that prevents rotation of a component of the robot that rotates around a specific drive axis and includes a force detector; a force control unit that controls the drive motor of the specific drive shaft so that the force output from the force detector becomes a predetermined force set value when the rotation of a component of the robot that rotates around the specific drive shaft is prevented by a jig; a rotational position acquisition unit that acquires the rotational position output by the rotational position detector of the specific drive shaft when the force output from the force detector reaches a force setting value; A control device comprising: a data generation unit that generates mastering data for the output of a rotational position detector arranged on a specific drive shaft based on the rotational position of the drive motor output by the rotational position detector and a predetermined design value of the mastering data.

8. the force control unit performs control to rotate the component in a first direction and control to rotate the component in a second direction opposite to the first direction; the rotational position acquisition unit detects a first rotational position when rotation in a first direction is blocked and a second rotational position when rotation in a second direction is blocked; The control device according to claim 7 , wherein the data generating unit calculates a correction value for the mastering data based on the first rotational position and the second rotational position.

Images