JP2020142324A - Robot device and automatic correction method - Google Patents

Abstract

To achieve a robot device configured so that a deviation of a shaft core of a component can be corrected regardless of presence or absence of chamfering of the component.SOLUTION: The robot device comprises: a robot 1; a force sensor 101 attached to a tip of the robot 1; a holding part 104, attached to the force sensor 101, which can hold a first component; a robot controller 2 that controls the robot 1 so that loads can be generated on the first component in the opposite direction of a direction in which the first component is inserted into a second component, using a measured result by the force sensor 101, when the robot 1 performs work for inserting the first component into the second component; and a calculator 3 that controls operation of the robot 1 on the basis of an operation angle, a rotation angle of the tip of the robot 1 having an in-plane shaft orthogonal to the insertion direction as a rotation shaft. The calculator 3 stops the robot 1 and rotates the tip of the robot 1 in the opposite direction of the first direction, if the operation angle in the first direction as a rotation direction exceeds an allowable rotation angle.SELECTED DRAWING: Figure 1

Description

The present invention relates to a robot device that performs assembly work and an automatic correction method.

In recent years, the production form at production sites has shifted from high-mix low-volume production to variable-variable production that can respond to changes in production models and production volumes. In response to such changes in production forms, highly versatile equipment is required. Robots are often used to realize highly versatile equipment. The robot referred to here refers to a teaching playback type robot that operates by reproducing a motion taught in advance, an orthogonal robot composed of orthogonal slide axes, and the like.

Such robots are used in the assembly work of the parts assembly process at the production site. In the part assembly process, for example, an insertion part, which is a part to be inserted, is inserted into a mating part, which is an insertion destination. In such a robot, the operation position is taught by programming the operation order in advance, and the determined operation is repeatedly performed. However, in the parts assembly work by the robot, there is a variation in the reproducibility of the position in the work repeatedly performed by the robot, and the thermal expansion of the robot and equipment due to the temperature change affects the distance between the axis of the inserted part and the axis of the mating part. The position of the inserted part may shift and the inserted part may interfere with the mating part. Hereinafter, the deviation that occurs between the axis of the inserted component and the axis of the mating component is also simply referred to as the deviation of the axis of the component.

Two techniques, interference detection and interference avoidance, are used to solve the problem that the inserted component interferes with the mating component. Interference detection is generally performed by attaching a force sensor to the tip of the robot and detecting the presence or absence of interference using the reaction force detected by the force sensor. As a method of avoiding interference, generally, a chamfering process is performed on the corners of the inserted part, a reaction force at the time of interference is generated in a direction oblique to the insertion direction, and the reaction force is generated in a direction orthogonal to the insertion direction. A method of detecting the component force of the reaction force with a force sensor is adopted. In this method, a control program for moving the robot is mounted on the robot controller so that the component force detected by the force sensor is reduced, and the robot controller controls the operation of the robot based on the control program. Alternatively, a compliance mechanism that corrects the movement of the robot so as to reduce the component force detected by the force sensor is used.

For example, Patent Document 1 discloses a technique for correcting a misalignment of the axial core between an inserted part and a mating part by moving the inserted part in parallel. In the technique described in Patent Document 1, a force sensor is attached to the tip of a horizontal articulated robot, and a remote center compliance mechanism capable of translating an insertion part gripped by the robot is attached to the lower part of the force sensor. ing. In the technique described in Patent Document 1, the corners of the inserted part or the mating part are chamfered, the reaction force is detected by the force sensor, and the component force of the reaction force in the direction orthogonal to the insertion method is reduced. By moving the inserted parts in parallel by the remote center compliance mechanism, the deviation of the axis of the parts is corrected.

Japanese Unexamined Patent Publication No. 7-241733

However, in the technique of Patent Document 1, since the deviation of the axis of the component is corrected by using the component force of the reaction force, the contact angle portion of at least one of the inserted component and the mating component is chamfered. Must be. Therefore, if neither the inserted part nor the mating part is chamfered, there is a problem that the deviation of the axis of the part cannot be corrected.

The present invention has been made in view of the above, and an object of the present invention is to obtain a robot device capable of correcting a deviation of the axis of a component regardless of the presence or absence of chamfering of the component.

In order to solve the above-mentioned problems and achieve the object, the robot device according to the present invention is attached to a robot, a force sensor attached to the tip of the robot, and a force sensor, and can grip the first component. It is provided with a grip portion. Further, when the robot performs the work of inserting the first component into the second component, the robot device uses the measurement result measured by the force sensor to reverse the direction of inserting the first component into the second component. A robot controller that controls the robot so that a load is generated on the first component in the direction of Further, the robot device includes an arithmetic unit that controls the operation of the robot based on the operation angle which is the rotation angle of the tip of the robot whose rotation axis is an axis in a plane orthogonal to the insertion direction. When the operating angle with the first direction as the rotation direction exceeds the allowable rotation angle, the calculator stops the robot, stops the robot, and then turns the tip of the robot in the direction opposite to the first direction. Control the robot to rotate to.

According to the present invention, there is an effect that the deviation of the axis of the component can be corrected regardless of the presence or absence of the chamfering process of the component.

The figure which shows the functional structure example of the robot apparatus which concerns on Embodiment 1. The figure which shows typically the appearance of the robot apparatus of Embodiment 1. The figure which shows the structural example of the processing circuit of Embodiment 1. A flowchart showing an example of a procedure for automatic correction processing of the axis of a component in the robot device of the first embodiment. The figure which shows an example of the automatic correction operation of the robot apparatus of Embodiment 1 when the axis is shifted in parallel. The figure which shows an example of the automatic correction operation of the robot apparatus of Embodiment 1 when the axis is shifted in parallel. The figure which shows an example of the automatic correction operation of the robot apparatus of Embodiment 1 when the axis is shifted in parallel. The figure which shows an example of the automatic correction operation of the robot apparatus of Embodiment 1 when the axis is shifted in parallel. The figure which shows an example of the automatic correction operation of the robot apparatus of Embodiment 1 when the axis is tilted. The figure which shows typically the appearance of the robot apparatus of Embodiment 2.

The robot apparatus and the automatic correction method according to the embodiment of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to this embodiment.

Embodiment 1.
FIG. 1 is a diagram showing a functional configuration example of the robot device 100 according to the first embodiment of the present invention. FIG. 2 is a diagram schematically showing the appearance of the robot device 100. As shown in FIGS. 1 and 2, the robot device 100 includes a robot 1 which is a vertical articulated robot, a force sensor 101 attached to the tip of the robot 1, and a chuck attached to the lower surface of the force sensor 101. The drive unit 102 and the chuck 103 attached to the lower part of the chuck drive unit 102 and forming a set of the two are provided. Although one chuck 103 is coded in FIG. 2, two chucks 103 are provided below the chuck drive unit 102. The two chucks 103 can sandwich and grip the insertion component 501, which is the first component. The chuck drive unit 102 and the two chucks 103 form a grip portion 104 that sandwiches the insertion component 501 and can rotate in the sandwiched state. The robot device 100 further includes a robot controller 2 that controls the operation of the robot 1 and a calculator 3 that is connected to the robot controller 2.

The robot device 100 can perform assembly work. Specifically, the robot device 100 can insert the insertion component 501 into the mating component 502, which is a second component having an insertion portion corresponding to the insertion component 501. The mating component 502 is fixed by the mating component mounting base 503. Here, an example in which the mating component 502 is placed and fixed on the mating component mounting base 503 will be described, but if the mating component 502 is difficult to move, the mating component mounting base 503 may not be provided. ..

As shown in FIG. 2, the robot 1 and the robot controller 2 are connected by a connection cable 301, the force sensor 101 and the robot controller 2 are connected by a connection cable 302, and the robot controller 2 and the arithmetic unit 3 are connected by a connection cable 303. It is connected. In the examples shown in FIGS. 1 and 2, the arithmetic unit 3 is a component of the robot device 100, but the arithmetic unit 3 may be connected to the robot controller 2 and is external to the robot device 100. It may be a device.

Further, in the embodiment, as shown in FIG. 2, the XYZ coordinate system, which is a Cartesian coordinate system, has the direction from the back to the front of the paper surface as the plus direction of the X axis, orthogonal to the X axis, and from the left side of the paper surface. The direction to the right is defined as the positive direction of the Y axis, and the direction from the bottom to the top of the paper is defined as the positive direction of the Z axis. Further, as shown in FIG. 2, it is assumed that the negative direction of the Z axis is vertically downward.

Next, the details of each component constituting the robot device 100 will be described. First, the robot 1 which is a vertical articulated robot will be described. As shown in FIG. 1, the robot 1 includes servomotors 11-1 to 11-6 corresponding to each axis. FIG. 1 shows an example in which the robot 1 has 6-axis joints. The robot 1 can freely change the position and posture of the tip of the robot 1 by rotating each joint by the servomotors 11-1 to 11-6 corresponding to each axis.

Here, the robot 1 not only inserts parts whose insertion direction is the minus Z direction, which is the downward direction shown in FIG. 2, but also inserts parts whose insertion direction is the horizontal direction such as the minus Y direction. To make it possible, that is, to increase versatility, a 6-axis vertical articulated robot is taken as an example. However, the robot 1 is not limited to a 6-axis vertical articulated robot, and the number of axes included in the robot 1 is not limited to 6, and may be 5 or 7 or more. Further, when the insertion direction of the parts is limited, the number of axes included in the robot 1 may be 4 or less. The robot 1 can grip the insertion component 501 conveyed in the previous process with the chuck 103, move the gripped insertion component 501 upward of the mating component 502, and lower it, centering on the X-axis and the Y-axis. It suffices if there is a rotating mechanism.

Next, the force sensor 101 will be described. The force sensor 101 is a sensor capable of measuring the load acting on the tip of the robot 1, that is, the reaction force and the moment of the tip of the robot 1. As for the reaction force, the force sensor 101 may measure the force generated in the direction opposite to the insertion direction of the insertion component 501. For example, as shown in FIG. 2, when the insertion component 501 is inserted from above the mating component 502, the insertion direction is the minus Z direction, so that the force sensor 101 applies a force generated in the plus Z direction as a reaction force. It is good if it can be detected. As for the moment, the force sensor 101 may detect the moment generated around the axis in the plane orthogonal to the direction in which the insertion component 501 is displaced in the plane orthogonal to the insertion direction. For example, as shown in FIG. 2, when the insertion direction is the minus Z direction and the insertion part 501 shifts in the X-axis direction (± X direction) due to the insertion operation, the moment My generated around the Y-axis direction is detected. I hope I can. The force sensor 101 periodically transmits the measured load and moment to the robot controller 2 via the connection cable 302 as the measurement result.

Next, the chuck drive unit 102 will be described. The chuck drive unit 102 is attached to the lower surface of the force sensor 101, and is a drive component capable of operating the two chucks 103 in the plus Y direction and the minus Y direction, respectively. The mechanism of the chuck drive unit 102 is not particularly limited as long as the chuck 103 can be driven. For example, in an environment where compressed air can be supplied, an air chuck that operates with air or an electric chuck that operates with a motor is used. Can be done. The housing of the chuck drive unit 102 is preferably made of a metal material such as aluminum. The reason is that the reaction force received by the insertion part 501 when it comes into contact with the mating part 502, which will be described later, is transmitted to the force sensor 101 via the chuck 103 and the chuck drive unit 102, so that a material such as a resin part having a large amount of elastic deformation This is because it becomes difficult for the force sensor 101 to accurately detect the reaction force actually acting on the insertion component 501 when the above is used for the housing.

Next, the chuck 103 will be described. The chuck 103 is a component for gripping the insertion component 501. Specifically, in the example shown in FIG. 2, the two chucks 103 approach the insertion component 501 from the plus Y direction and the minus Y direction, respectively, thereby sandwiching and gripping the insertion component 501. The material of the chuck 103 is preferably a material such as aluminum, which has a smaller amount of elastic deformation than resin parts. The reason is that, like the chuck drive unit 102, the reaction force received by the insertion component 501 when it comes into contact with the mating component 502 is transmitted to the force sensor 101 that detects the load via the chuck 103 and the chuck drive unit 102, and thus is elastic. This is because if the material has a large amount of deformation, it becomes difficult for the force sensor 101 to accurately detect the reaction force actually acting on the insertion part 501.

The contact area between the chuck 103 and the insertion component 501 will be described. When the chuck 103 is gripping the insertion part 501, gravity exerts a force downward on the insertion part 501 in the vertical direction. Further, when the insertion part 501 interferes with the mating part 502 in the inserting operation, the inserting part 501 receives a reaction force due to the contact with the mating part 502. As in these cases, when the insertion part 501 receives a force, the insertion part 501 may slide on the surface of the chuck 103. When the insertion part 501 slides on the surface of the chuck 103, the insertion part 501 may rotate around the X-axis, the Y-axis, or the Z-axis, or may fall off from the chuck 103. It is desirable that the contact area between the chuck 103 and the insertion component 501 is determined so that the above-mentioned rotation and dropout do not occur. Further, an elastic body such as urethane rubber (not shown) may be attached to the contact surface of the chuck 103 that comes into contact with the insertion component 501 in order to prevent slipping. By attaching an elastic body such as urethane rubber, the insertion part 501 can be prevented from being scratched. However, if the elastic body is too thick, as described above, the reaction force may not be accurately transmitted to the force sensor 101 due to the elastic deformation of the elastic body. Therefore, it is necessary to adjust the thickness of the elastic body according to the situation of slippage and scratches of the insertion component 501 within a range in which the accuracy of reaction force detection by the force sensor 101 does not cause a problem.

Next, the insertion component 501 will be described. The material of the insertion component 501 is not particularly limited as long as the reaction force received by the insertion component 501 when it comes into contact with the mating component 502 can be transmitted to the force sensor 101. The shape of the insertion part 501 is not particularly limited, but may be, for example, a cylindrical shape or a quadrangular prism shape. If the shape of the insertion part 501 is a cylinder, it is desirable that the insertion part 501 be gripped by the chuck 103 with the upper and lower surfaces of the circular shape facing the plus Z direction and the minus Z direction, respectively. If the shape of the insertion part 501 is a square columnar shape, the orientation is not particularly limited, but if possible, the lower surface may be gripped by the chuck 103 so as to be parallel to the upper surface of the mating part 502. The corners of the lower surface of the insertion part 501 may have no chamfering and no copying surface, but may be chamfered.

Next, the mating component 502 will be described. The mating component 502 is a component having an insertion portion into which the insertion component 501 is inserted. The insertion portion of the mating part 502 may be a hole in the shape of the insertion part 501 provided so that the insertion part 501 fits, or the insertion part 501 fits around the insertion part 501. It may be a portion provided with a protrusion as described above. The material of the mating component 502 is not particularly limited as long as it generates a reaction force on the insertion component 501 during the insertion operation. The upper corner of the insertion portion of the mating component 502 that comes into contact with the insertion component 501 may have a shape without chamfering and no copying surface, but may be chamfered. It is desirable that the mating component 502 is fixed by a mating component mounting base 503 or the like so as not to move or tilt due to a reaction force or the like during the insertion operation of the inserting component 501.

Next, the mating component mounting base 503 will be described. The mating component mounting base 503 is a component for fixing the mating component 502 so as not to move. The material is not particularly limited as long as it can generate a reaction force on the insertion component 501 during the insertion operation.

Next, the robot controller 2 will be described. As shown in FIG. 1, the robot controller 2 includes an operation control unit 21, a transmission / reception unit 22, and a setting reception unit 23. The transmission / reception unit 22 receives the measurement result from the force sensor 101 via the connection cable 302, and outputs the received measurement result to the operation control unit 21. The transmission / reception unit 22 transmits the received measurement result to the arithmetic unit 3 via the connection cable 303. The transmission / reception unit 22 transmits an operation command to be described later, which is output from the operation control unit 21, to the robot 1 via the connection cable 301. The transmission / reception unit 22 outputs a command to be described later received from the arithmetic unit 3 via the connection cable 303 to the operation control unit 21.

The setting reception unit 23 receives input of setting information for setting the operation of the robot 1 from the operator. The setting information that can be received as input from the operator can exemplify the information that can be set in the general motion control of the robot 1. However, in the present embodiment, as will be described later, the insertion operation is performed. Includes set values that are target values for the load and moment in the insert part 501 when performing. The setting reception unit 23 outputs the received setting information to the operation control unit 21. The setting reception unit 23 is an input means such as a keyboard, a mouse, a touch panel, and a button. Further, the robot controller 2 may include a display unit (not shown) for presenting information to the operator. The display unit and the setting reception unit 23 may be integrated and realized by a touch panel.

The motion control unit 21 sets the target position and angle of the tip of the robot 1 based on the robot program for controlling the robot 1 and the setting information input from the setting reception unit 23. An operation command for controlling the servomotors 11-1 to 11-6 built in each joint is generated. The motion control unit 21 transmits the generated motion command to the robot 1 via the transmission / reception unit 22. In this way, the motion control unit 21 controls the motion of the robot 1. As for the motion control of the robot 1 for setting the target position and angle of the tip of the robot 1, a general technique can be used, and therefore detailed description thereof will be omitted. The motion control unit 21 has a function of feedback control based on the measurement result of the force sensor 101 so that the load and the moment in the insertion component 501 become the above-mentioned set values input by the operator. Further, the operation control unit 21 receives the detection result by the encoder (not shown) that detects the rotation angle of the servomotors 11-1 to 11-6 from the encoder via the transmission / reception unit 22, and determines the rotation angle detected by the encoder. Use to perform feedback control. In this case, the transmission / reception unit 22 may transmit the detection result by the encoder to the arithmetic unit 3. The motion control unit 21 also has a function of operating the robot 1 based on a command received from the arithmetic unit 3 via the transmission / reception unit 22.

Next, the arithmetic unit 3 will be described. The arithmetic unit 3 controls the operation of the robot 1 via the robot controller 2 based on the operation angle which is the rotation angle of the tip of the robot 1. As shown in FIG. 1, the arithmetic unit 3 includes a transmission / reception unit 31, an operation angle determination unit 32, and a rotation control unit 33. The transmission / reception unit 31 receives the measurement result of the force sensor 101 from the robot controller 2 via the connection cable 303, and outputs the received measurement result to the operation angle determination unit 32. Further, the transmission / reception unit 31 may receive the detection result by the encoder from the robot controller 2 via the connection cable 303 and output the received detection result to the operation angle determination unit 32. The transmission / reception unit 31 transmits a command output from the rotation control unit 33 to the robot controller 2 via the connection cable 303.

The operation angle determination unit 32 compares the operation angle of the robot 1 with the allowable rotation angle, and when the operation angle of the robot 1 exceeds the allowable rotation angle, notifies the rotation control unit 33 to that effect. In the present embodiment, the operating angle is the rotation angle of the tip of the robot 1 whose rotation axis is an in-plane axis orthogonal to the insertion direction. The operating angle is calculated, for example, as follows. The robot controller 2 calculates the angle of the tip of the robot 1 based on the detection result by the encoder of each joint of the robot 1. The robot controller 2 repeats this calculation at regular intervals, and the calculation result is transmitted to the arithmetic unit 3. The calculator 3 stores the calculation result at the start of rotation as the rotation start angle, and when a new calculation result is received from the robot controller 2, calculates the difference between the received calculation result and the rotation start angle as the operation angle. Then, the arithmetic unit 3 compares the operating angle and the allowable rotation angle. The method of calculating the operating angle is not limited to this example. The permissible rotation angle may be predetermined or may be set by the operator. When set by the operator, the robot controller 2 may receive the input from the operator and transmit it to the arithmetic unit 3, or the arithmetic unit 3 has the input means and the input from the operator is input by the input means. May be accepted.

When the rotation control unit 33 is notified by the operation angle determination unit 32 that the operation angle of the robot 1 exceeds the allowable rotation angle, the rotation control unit 33 executes the rotation control described later.

Here, the hardware configuration of the robot controller 2 and the arithmetic unit 3 will be described. The transmitter / receiver 22 of the robot controller 2 and the transmitter / receiver 31 of the arithmetic unit 3 are a transmitter and a receiver, and are realized by a communication circuit. The setting reception unit 23 of the robot controller 2 is realized by an input means such as a keyboard as described above.

The operation control unit 21 of the robot controller 2, the operation angle determination unit 32 of the arithmetic unit 3, and the rotation control unit 33 are realized by a processing circuit. The processing circuit may be a circuit including a processor or dedicated hardware.

When the processing circuit is a circuit including a processor, the processing circuit is, for example, a processing circuit having the configuration shown in FIG. FIG. 3 is a diagram showing a configuration example of the processing circuit of the present embodiment. The processing circuit 400 shown in FIG. 3 includes a processor 401 and a memory 402. When the operation control unit 21, the operation angle determination unit 32, and the rotation control unit 33 are realized by the processing circuit 400 shown in FIG. 3, the processor 401 reads and executes the program stored in the memory 402. These are realized. That is, when the operation control unit 21, the operation angle determination unit 32, and the rotation control unit 33 are realized by the processing circuit 400 shown in FIG. 3, these functions are realized by using a program which is software. The memory 402 is also used as a work area for the processor 401. The processor 401 is a CPU (Central Processing Unit) or the like. The memory 402 corresponds to, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, a magnetic disk, or the like.

When the processing circuit that realizes the operation control unit 21, the operation angle determination unit 32, and the rotation control unit 33 is dedicated hardware, the processing circuit may be, for example, an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). is there. The operation control unit 21, the operation angle determination unit 32, and the rotation control unit 33 may be realized by combining a processing circuit including a processor and dedicated hardware. The operation control unit 21, the operation angle determination unit 32, and the rotation control unit 33 may each be realized by a plurality of processing circuits.

Next, a method of automatically correcting the shaft cores of the parts in the robot device 100 of the present embodiment will be described. FIG. 4 is a flowchart showing an example of a procedure for automatic correction processing of the shaft cores of parts in the robot device 100 of the present embodiment. The automatic correction process shown in FIG. 4 is started when the chuck 103 sandwiches the insertion component 501 and the chuck 103 moves so that the insertion component 501 is located above the mating component 502 in the assembly work of the robot device 100. .. The operation started when the chuck 103 moves so that the insertion component 501 is located above the mating component 502 is also hereinafter referred to as an operation of inserting the inserting component 501 into the mating component 502. In the assembly work of the robot device 100, the operation of the robot device 100 until the chuck 103 sandwiches the insertion part 501 and the chuck 103 moves so that the insertion part 501 is located above the mating part 502 is a general robot device. Since it is the same as the operation in the above, detailed description thereof will be omitted.

The automatic correction process of the present embodiment is executed in the work of inserting the insertion component 501 into the mating component 502. During the execution of the automatic correction process, the load acting on the force sensor 101 is set to be generated in the plus Z direction, and the moment generated on the force sensor 101 is set to be 0 (zero) Nm. As described above, the robot controller 2 receives the settings related to these loads and moments as setting information from the operator, for example. Further, the load and moment generated in the force sensor 101 due to gravity are canceled in advance in consideration of the weight and the position of the center of gravity of the parts mounted below the force sensor 101, that is, the chuck drive unit 102, the chuck 103, and the insertion part 501. I will do it. This cancellation can be realized, for example, by a calibration function which is a general function of the robot 1 using the force sensor 101. The calibration function is performed by swinging the chuck 103 at various angles by the robot 1 with the chuck drive unit 102 and the chuck 103 attached to the robot 1, and based on the load and moment generated in the force sensor 101 at that time, the chuck drive unit. The robot controller estimates the weight and the position of the center of gravity of the 102 and the chuck 103. By using this function, the load and the moment generated in the force sensor 101 due to gravity can be canceled in advance. The method of canceling the load and the moment generated in the force sensor 101 by gravity is not limited to this example.

As shown in FIG. 4, in the robot device 100, first, the operation angle determination unit 32 calculates the operation angle of the robot 1 (step S1). Next, the operation angle determination unit 32 determines whether or not the operation angle of the robot 1 exceeds the allowable rotation angle (step S2).

When the operating angle of the robot 1 does not exceed the allowable rotation angle (step S2 No), the process returns to step S1. When the operating angle of the robot 1 exceeds the allowable rotation angle (step S2 Yes), the robot device 100 stops the rotation of the robot 1 (step S3). Specifically, the operation angle determination unit 32 of the arithmetic unit 3 notifies the rotation control unit 33 that the operation angle of the robot 1 exceeds the allowable rotation angle, and the rotation control unit 33 stops the operation of the robot 1. The operation stop command, which is a command for the robot, is generated and transmitted to the robot controller 2 via the transmission / reception unit 31. When the robot controller 2 receives the operation stop command, the robot controller 2 stops the operation of the robot 1. As a result, the rotation of the robot 1 is stopped.

As described above, in the robot 1, the load acting on the force sensor 101 is set to be generated in the plus Z direction, and the moment generated on the force sensor 101 is set to be 0 Nm. Therefore, based on the measurement result measured by the force sensor 101, the robot 1 so that the load acting on the force sensor 101 is generated in the plus Z direction while the load acting on the force sensor 101 is 0N. In addition, the tip of the robot 1 is continuously moved in the minus Z direction. That is, when the robot 1 inserts the insertion component 501 into the mating component 502, the robot controller 2 inserts the inserting component 501 into the mating component 502 using the measurement result measured by the force sensor 101. The robot 1 is controlled so that a load is generated on the insertion component 501 and a moment is not generated on the insertion component 501 in the direction opposite to the direction. The robot controller 2 may control the insertion component 501 so that a load is generated in the direction opposite to the insertion direction of the insertion component 501 into the mating component 502, and the robot 1 is operated so that a moment is not generated in the insertion component 501. Control is not essential. The robot controller 2 may allow, for example, a certain moment to be generated in the insertion component 501. If there is no deviation of the axis of the component, that is, the axis of the insertion component 501 and the axis of the mating component 502, the insertion component 501 is directly inserted into the mating component 502 from above.

On the other hand, as will be described later, when the axis of the component is displaced, the insertion component 501 interferes with the mating component 502, so that a moment acts on the insertion component 501 and the moment is measured by the force sensor 101. The robot 1 controls to rotate the tip of the robot 1 so that the moment measured by the force sensor 101 is 0 Nm according to the setting, but the control to move the tip of the robot 1 in the minus Z direction is also continued. Therefore, the tip of the robot 1 keeps rotating. In the present embodiment, the arithmetic unit 3 transmits an operation stop command to the robot 1 when the operation angle of the robot 1 exceeds the allowable rotation angle so that the robot 1 does not continue to rotate beyond the allowable rotation angle. As a result, the robot 1 is stopped.

After step S3, the robot device 100 rotates the robot 1 in a direction opposite to the direction in which the robot 1 has been rotating (step S4). Specifically, the rotation control unit 33 generates a rotation command instructing the robot 1 to rotate in a direction opposite to the direction in which the robot 1 has been rotating so far, and sends the robot 1 to the robot controller 2 via the transmission / reception unit 31. Send. As a result, the robot controller 2 controls the robot 1 to rotate in the opposite direction.

The robot device 100 determines whether or not the work of inserting the insertion component 501 is completed (step S5), and when the work is completed (step S5 Yes), the automatic correction process ends. When the work is not completed (step S5 No), the robot device 100 repeats the process of step S4. That is, the robot device 100 keeps rotating the robot 1 in the opposite direction. The robot controller 2 determines whether or not the work of inserting the insertion component 501 has been completed. The specific method of determination is the same as the determination of the end in a general component insertion operation using a robot. For example, the robot controller 2 has the insertion component 501 when the load and the moment measured by the force sensor 101 do not change for a certain period of time or more and the load measured by the force sensor 101 is in the plus Z direction. It is judged that the work of inserting is completed. Although not shown in FIG. 4, the same applies when the robot controller 2 determines that the work of inserting the insertion component 501 is completed while the result is No in step S2 and step S1 is repeated. At the end of the automatic correction process. In this case, the work is completed without the correction by the automatic correction process, that is, without the displacement of the axis of the component.

As described above, in the automatic correction method of the present embodiment, when the robot 1 inserts the insertion part 501 into the mating part 502, the insertion is performed by using the measurement result measured by the force sensor 101. It includes a first step of controlling the robot 1 so that a load is generated on the inserted component 501 in a direction opposite to the direction in which the component 501 is inserted into the mating component 502. Further, the automatic correction method of the present embodiment includes a second step of controlling the operation of the robot 1 based on the operation angle of the robot 1.

It is desirable that the operating origin of the robot 1 in the height direction, that is, the Z direction is set near the lower surface of the insertion component 501, that is, the surface of the insertion component 501 in contact with the mating component 502. As a result, the robot 1 can rotate around each of the X-axis, the Y-axis, and the X-axis around the lower surface of the insertion part 501.

Next, the above-mentioned automatic correction process will be described with reference to specific examples of misalignment of the shaft cores of the parts. There are various causes of misalignment of the axis of the parts, such as processing variation of each part, an error of the position of the robot 1, an error of the angle of the robot 1, and a thermal expansion of the mating component mounting base 503 due to a change in room temperature. However, the misalignment of the shaft cores of the parts caused by these causes is classified into the following two types.
(1) When the shaft core is displaced in parallel (2) When the shaft core is tilted

In the example shown in FIG. 2, the above (1) corresponds to the case where the center of the bottom surface of the insertion component 501 and the center of the hole of the mating component 502 deviate from each other. In the example shown in FIG. 2, the insertion component 501 is inserted into the hole which is the insertion portion of the mating component 502. The line extending in the height direction of the insertion part 501 passing through the center of the bottom surface of the insertion part 501 is the axis of the insertion part 501, and the line extending in the height direction of the mating part 502 passing through the center of the hole of the mating part 502 is the mating part 502. As the axis of. Here, it is assumed that the height direction of each component is the insertion direction in an ideal state where each component is inserted correctly and there is no error in each component.

In the example shown in FIG. 2, the above (2) corresponds to the rotation of the insertion component 501 around the X-axis causing the axis of the insertion component 501 to deviate from the axis of the mating component 502.

First, the case where the axis of the above (1) is displaced in parallel will be described with reference to the drawings. 5 to 8 are diagrams showing an example of the automatic correction operation of the robot device 100 of the present embodiment when the axes are displaced in parallel. First, as shown in the left figure of FIG. 5, the robot 1 descends, that is, minus Z, in a state where the insertion part 501 is located above the mating part 502 and the inserting part 501 is not in contact with the mating part 502. Start moving in the direction. As described above, this is set to control the robot 1 so as to act on the force sensor 101 in the plus Z direction, and the load measured by the force sensor 101 is 0N, so that the robot controller This is because 2 controls the robot 1 to move in the minus Z direction.

When the robot 1 continues the descending operation as it is, the axis is displaced in parallel, so that the robot 1 comes into contact with the mating component 502 as shown in the right figure of FIG. In the example shown in FIG. 5, since the insertion part 501 is displaced to the right side of the hole of the mating part 502, that is, in the plus Y direction, the insertion part 501 comes into contact with the right corner of the hole of the mating part 502. When such contact 602 occurs, the insertion part 501 receives a reaction force at the contact point on the right side of the center, so that a moment around the X axis + Mx is generated. The moment around the X-axis is positive counterclockwise. As a result, the robot 1 rotates in the counterclockwise rotation direction 601. That is, in this example, the insertion direction is the minus Z direction, and the tip of the robot 1 rotates around the X axis, which is an in-plane axis orthogonal to the insertion direction.

By rotating counterclockwise, the robot 1 tilts as shown in the left figure of FIG. At this time, the insertion component 501 slides in the sliding direction 603, which is the same direction as the tilted direction, at the contact point of the mating component 502. As the insertion part 501 slides in the sliding direction 603, the left corner of the insertion part 501 comes into contact with the left side surface of the hole of the mating part 502, as shown in the right figure of FIG. In the state where such contact 604 occurs, the right corner of the insertion part 501 rests on the right corner of the hole of the mating part 502, and the left corner of the insertion part 501 is the mating part. It is in contact with the left side of the hole in 502. Therefore, at this time as well, a moment of + Mx is generated. Therefore, the robot 1 performs an operation of setting the moment to 0 Nm, but also performs a descending operation, so that the robot 1 continues to rotate counterclockwise as shown in the left figure of FIG.

On the other hand, as described with reference to FIG. 4, the arithmetic unit 3 determines whether or not the operating angle of the robot 1 exceeds the allowable rotation angle, so that the robot 1 continues to rotate counterclockwise and the operating angle. When exceeds the permissible rotation angle, it is determined to be Yes in step S2 of FIG. 4, and the robot device 100 stops the rotation of the robot 1. After that, as shown in the right figure of FIG. 7, the robot 1 rotates in the rotation direction 605, which is the direction opposite to the rotation direction 601 by the operation described in step S4 of FIG.

These operations, that is, the operation of pressing the insertion component 501 against the mating component 502 to rotate the robot 1 by continuing to lower it and rotating it to the opposite side when the allowable rotation angle is exceeded, as shown in the left figure of FIG. As described above, the axis of the insertion component 501 and the axis of the mating component 502 coincide with each other. Since the axes are aligned, the insertion component 501 can be inserted into the mating component 502 by lowering the robot 1 as shown in the right figure of FIG.

Next, the case where the shaft core of the above (2) is tilted will be described with reference to the drawings. FIG. 9 is a diagram showing an example of an automatic correction operation of the robot device 100 according to the present embodiment when the axis is tilted. As shown in the left figure of FIG. 9, FIG. 9 shows an example in which the axis of the insertion component 501 is tilted in the counterclockwise direction. Similar to the case where the axes of (1) are displaced in parallel, the robot 1 is in a state where the insertion part 501 is located above the mating part 502 and the inserting part 501 is not in contact with the mating part 502. Start descending. After that, as shown in the right figure of FIG. 9, the right corner portion of the lower surface of the insertion component 501 comes into contact with the right corner portion of the mating component 502. When such contact 606 occurs, the insertion part 501 receives a reaction force at the contact point on the right side of the center, so that a moment around the X axis + Mx is generated. As a result, the robot 1 rotates in the counterclockwise rotation direction 601. Subsequent operations are similar to those shown in FIGS. 6, 7, and 8.

As described above, in both cases (1) when the shaft cores are displaced in parallel and (2) when the shaft cores are tilted, the deviation of the shaft cores is corrected by the automatic correction process shown in FIG. The insertion component 501 can be inserted into the mating component 502. In the examples shown in FIGS. 5 to 9, the axis of the insertion component 501 is displaced parallel to the axis of the mating component 502 in the X direction and is tilted in the direction of rotation around the X axis. explained. Depending on the configuration of the robot device 100, instead of the deviation parallel to the X direction and the inclination in the direction of rotation around the X axis, the deviation parallel to the Y direction and the inclination in the direction of rotation around the Y axis may occur. In such a case, the X-axis described above is read as the Y-axis, and similarly, the arithmetic unit 3 stops the robot 1 when the operating angle around the Y-axis exceeds the allowable rotation angle. Later, control may be performed to rotate the robot in the opposite direction.

Further, when a vertical articulated robot is used as the robot 1, the degree of freedom of movement of the robot 1 is high. Therefore, in addition to the deviation parallel to the axis of the mating component 502 and the inclination in the direction of rotation around the X axis, the axis of the inserted component 501 may be further displaced parallel to the Y axis, or Y. It is also conceivable to tilt in the direction of rotation around the axis. In such a case, the allowable rotation angle is also set for the operation angle around the Y-axis, and when the operation angle around the Y-axis exceeds the allowable rotation angle of the arithmetic unit 3 as in the X-axis, the robot Control may be performed to rotate 1 in the opposite direction after stopping it. In this case, the above-mentioned control may be independently performed for each of the X-axis and the Y-axis. If only the operating angle around the X-axis exceeds the allowable rotation angle, the above-mentioned operation is performed with respect to the X-axis, and if only the operating angle around the Y-axis exceeds the allowable rotation angle, the above-mentioned operation is performed with respect to the Y-axis. When the operating angles both around the X-axis and around the Y-axis exceed the permissible rotation angle, the above-mentioned operations are performed for both the X-axis and the Y-axis.

In the above description, an example in which the arithmetic unit 3 is provided separately from the robot controller 2 has been described, but the robot controller 2 may have the function of the arithmetic unit 3 of the present embodiment.

As described above, in the present embodiment, the robot controller 2 controls the robot 1 so as to cancel the moment while moving the robot 1 in the insertion direction. Then, the arithmetic unit 3 controls the robot 1 to stop and then rotate in the opposite direction when the operating angle of the robot 1 exceeds the allowable rotation angle. Therefore, it is possible to correct the deviation of the axis of the component regardless of the presence or absence of the chamfering process of the component. Further, in the present embodiment, since the deviation of the shaft core is corrected by the above-described operation, the shaft core of the component is not only when the shaft core of the component is displaced in parallel but also when the shaft core is tilted. It is possible to correct the deviation of.

Embodiment 2.
Next, the operation of the robot device 100 according to the second embodiment of the present invention will be described. The configuration of the robot device 100 of the present embodiment is the same as that of the first embodiment. Hereinafter, the points different from those of the first embodiment will be mainly described, and the description overlapping with the first embodiment will be omitted.

FIG. 10 is a diagram schematically showing the appearance of the robot device 100 of the second embodiment. In the first embodiment, the insertion part 501 is inserted into the mating part 502 by moving from top to bottom while being sandwiched between the chucks 103. That is, in the first embodiment, the insertion direction of the insertion component 501 was the vertical direction. On the other hand, in the present embodiment, the insertion part 501 is inserted into the mating part 502 by moving in the horizontal direction as shown in FIG. That is, in the second embodiment, the insertion direction of the insertion component 501 is the horizontal direction.

As in the example shown in FIG. 10, even when the insertion direction of the insertion component 501 is the horizontal direction, the deviation of the axis of the component can be prevented by performing the same automatic correction process as in the first embodiment. It can be corrected. Specifically, the robot controller 2 is set to control the robot 1 so that the load measured by the force sensor 101 becomes a value in the plus Y direction and the moment measured by the force sensor 101 becomes 0 Nm. I will do it. The robot controller 2 performs the same operation as when the Z-axis of the first embodiment is read as the Y-axis. As a result, the robot controller 2 moves the robot 1 in the minus Y direction when the automatic correction process is started. When the insertion component 501 and the mating component 502 come into contact with each other due to the displacement of the axis of the component, the robot 1 starts rotating. When the operating angle of the robot 1 exceeds the allowable rotation angle, the arithmetic unit 3 controls the robot 1 via the robot controller 2 so as to stop the robot 1 and then rotate it in the opposite direction, as in the first embodiment. To do.

As a result, even if the insertion direction of the insertion component 501 is the horizontal direction, the deviation of the axis of the component can be corrected regardless of the presence or absence of the chamfering process of the component, as in the first embodiment.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1 Robot, 2 Robot controller, 3 Computer, 11-1 to 11-6 Servo motor, 21 Motion control unit, 22, 31 Transmission / reception unit, 23 Setting reception unit, 32 Operation angle determination unit, 33 Rotation control unit, 100 Robot Device, 101 force sensor, 102 chuck drive unit, 103 chuck, 104 grip unit, 301-303 connection cable, 501 insertion part, 502 mating part, 503 mating part mounting base.

Claims (3)

With a robot
A force sensor attached to the tip of the robot and
A grip portion that is attached to the force sensor and can grip the first component,
When the robot inserts the first component into the second component, the measurement result measured by the force sensor is used to reverse the direction in which the first component is inserted into the second component. A robot controller that controls the robot so that a load is generated on the first component in the direction,
An arithmetic unit that controls the operation of the robot based on the operation angle, which is the rotation angle of the tip of the robot, whose rotation axis is an axis in a plane orthogonal to the insertion direction.
With
When the operating angle with the first direction as the rotation direction exceeds the allowable rotation angle, the arithmetic unit stops the robot, stops the robot, and then sets the tip of the robot in the first direction. A robot device characterized in that the robot is controlled so as to rotate in the direction opposite to that of the robot. The robot controller is characterized in that the robot is controlled so that a load is generated on the first component and a moment is not generated on the first component in a direction opposite to the direction in which the first component is inserted into the second component. The robot device according to claim 1. The axis and the first of the first component in a robot device including a robot, a force sensor attached to the tip of the robot, and a grip portion attached to the force sensor and capable of gripping the first component. It is an automatic correction method that corrects the deviation from the axis of the second part into which the part is inserted.
When the robot inserts the first component into the second component, the measurement result measured by the force sensor is used to reverse the direction in which the first component is inserted into the second component. A first step of controlling the robot so that a load is generated on the first component in the direction,
A second step of controlling the operation of the robot based on an operation angle which is a rotation angle of the tip of the robot whose rotation axis is an axis in a plane orthogonal to the insertion direction.
Including
In the second step, when the operating angle with the first direction as the rotation direction exceeds the allowable rotation angle, the robot is stopped, the robot is stopped, and then the tip of the robot is first. An automatic correction method characterized in that the robot is controlled so as to rotate in a direction opposite to that of.

Images