JP4873254B2 - Robot direct teaching device - Google Patents

Description

  The present invention relates to an industrial robot teaching apparatus, and more particularly to a direct teaching apparatus in which an operator directly applies a force to a robot to operate the robot to perform teaching.

Conventionally, direct robot teaching methods based on force control have been proposed. In this direct teaching method, the teaching worker applies a force to the hand effector provided at the tip of the arm of the robot, and the applied force is detected by the force sensor provided in the wrist portion, and the force sensor outputs the force. By controlling the arm of the robot so as to operate according to the applied force by the control means that performs force control by a predetermined arithmetic expression based on the force signal, the moving speed and moving direction of the hand effector are determined, The hand effector is guided to the target position and the teaching data is stored.
In the robot control by this force control, a virtual mass is set in the hand effector on the above calculation formula, and the hand effect is obtained by speed or acceleration proportional to the force applied by the teaching worker to the force sensor, or an algebraic sum thereof. Configured to move the vessel. As a conventional direct teaching apparatus or direct teaching method of a robot configured as described above, there are those disclosed in Patent Document 1, Patent Document 2, and the like.
In addition, operability such as changing only the direction (posture) without changing the position of the control point of the articulated robot tip or changing only the three-dimensional position without changing the direction (posture) of the robot tip. As a robot direct teaching apparatus effective for improvement, there is one disclosed in Patent Document 3.
JP 59-14484 JP 59-157715 A Japanese Patent Laid-Open No. 5-285870

As described above, in the conventional direct teaching apparatus, the direction (posture) of the robot tip is changed while keeping the preset control point position constant, or conversely, the position is changed while the direction (posture) is constant. Improved operability.
However, when teaching the robot in an actual assembly line, the workability may deteriorate unless the control point position of the robot tip is changed during the work.
For example, when teaching the assembling operation of a part that must be assembled by combining two or more key grooves, first, a control point is set at the part inserted into the first key groove for the part gripped by the robot. Adjust the position and orientation of the control point so that it matches the keyway on the object side. After completing the adjustment for the first keyway, adjust the position and orientation of the part inserted into the second keyway. There may be cases where it is necessary.
In the conventional technique in which teaching is performed only by a direct guidance operation by a teaching worker while the control points are fixed, it is very difficult to teach the operation as described above, and there is a problem that the operability is remarkably lowered.
In addition, the control point position determined based on the dimensions of the parts gripped by the robot often required to be changed during teaching work due to assembly errors, processing errors, misalignment of the grip points by the hand, etc. . There has been a problem that the teaching work is temporarily interrupted due to such a change of the control point position, and the teaching work takes time.
The present invention has been made in view of such problems, and an object of the present invention is to make it possible to easily change the control point position during the guidance operation and to improve the operability of the teaching work in each stage. It is another object of the present invention to provide a practical direct teaching apparatus capable of reducing the time required for teaching work.

In order to solve the above problems, the present invention is configured as follows.
The robot direct teaching apparatus according to claim 1, wherein an operation handle provided at a tip portion of an articulated robot via a force sensor and an operation force of a teaching worker applied to the operation handle are detected by the force sensor, A direct teaching device for a robot having a control device including a force control unit that outputs a command to move the robot by force control according to the operating force, wherein the operating handle is set by the teaching worker during teaching. Control point input means for inputting the change amount and direction of the control point of the robot is provided, and the control device updates the control point setting of the robot in accordance with the change amount and direction input by the control point input means. and a control point arithmetic unit for outputting to the power control unit, the control point arithmetic unit, a control point to be compared with the preset value of the change amount input by the control point inputting unit Characterized in that it comprises a囲監vision portion.
The robot direct teaching apparatus according to claim 2 , wherein the control point range monitoring unit sets the change amount when the change amount input by the control point input unit is larger than the preset value. It is limited to the preset value, and an alarm is displayed to the teaching operator.
4. The robot direct teaching apparatus according to claim 3 , wherein the control device records the position of each joint of the robot as a teaching point by the operation of the teaching operator, and records the control point setting at the time of the recording. It comprises a part.
5. The direct teaching device for a robot according to claim 4 , wherein the control device reads the immediately preceding teaching point and the immediately preceding control point setting from the recording unit by the operation of the teaching operator, and instructs the robot to perform the immediately preceding teaching. A return position command generation unit is provided that outputs a command to move to a point and outputs the previous control point setting to the force control unit.
The robot direct teaching apparatus according to claim 5 , wherein the control point setting is expressed based on a gripped object coordinate system set for an object gripped by an end effector of the robot.
7. The robot direct teaching apparatus according to claim 6 , wherein the control point input means inputs a change amount and direction of the posture of the grasped object coordinate system in addition to the change amount and direction of the control point position. And

According to the first aspect of the present invention, since the teaching worker can change the setting of the control point without releasing his hand from the operation handle while performing the guidance operation of the robot, the operability of the teaching work is improved and the teaching work is made efficient. Can be done well.
Further , according to the first and second aspects of the present invention, since an unexpected position and posture are not set for the control point, it is possible to prevent the efficiency of teaching work from being lowered and to secure safety.
According to the third and fourth aspects of the invention, even when the robot is guided and moved after changing the control point setting, the control point setting can be returned to the previous state in addition to the position of the robot. Therefore, it is possible to easily recover from an erroneous operation and to prevent a reduction in teaching work efficiency.
According to the fifth aspect of the present invention, it is easy to set the control point according to the shape of the object gripped by the end effector during the teaching work, and the operability of the teaching work can be improved.
According to the sixth aspect of the present invention, since not only the position of the control point but also the posture can be changed during the teaching work, the teaching of assembling work of an object having a complicated shape can also be efficiently performed. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of the entire robot direct teaching apparatus system according to the first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an articulated robot. Each movable axis is sequentially counted from its reference point, the first axis is taken as the J1 axis, and thereafter the axis up to the J6 axis forms an articulated joint.
An end effector 2 is attached to the tip of the robot 1. A force sensor 3 is disposed between the tip of the robot 1 and the end effector 2, and an operation handle 4 is fixed to the force sensor 3 to be gripped when a teaching worker directly teaches. The force sensor 3 can detect the direction and magnitude of the force applied to the operation handle 4. A control point input means 5 is attached to the operation handle 4.
The control point input means 5 is an input means for changing the setting of the control point of the robot 1, and the operation handle 4 is shown in FIG. 3 together with an example of the control point input means 5. FIG. 3A is a front view of a grip portion of the operation handle 4, and FIG. 3B is a diagram illustrating a state in which the teaching operator grips the operation handle 4. In this embodiment, the control point input means 5 is composed of two types of switches, a direction selection button 5A and a change amount input button 5B.
The operation handle 4 is also provided with an emergency stop switch. When the robot 1 performs an unexpected operation during direct teaching, or when another worker enters the operating range of the robot 1, the teaching worker immediately presses the emergency stop switch, and the robot 1 is immediately urgent. Stop. Since the emergency stop switch is provided on the operation handle 4, the robot 1 can be stopped immediately when the teaching operator determines that it is dangerous, and the safety during direct teaching is ensured.
Reference numeral 60 denotes a control device for controlling the robot 1, in addition to the force control unit 61, the position / speed servo system 62, the servo amplifier 63, the control point calculation unit 64, the recording unit 65, and the return position command generation unit. 66 and switching means 67 and 68. In addition, about the structure in the control apparatus 60, only the part regarding this invention is extracted and drawn, The structure for emergency stop by the above-mentioned emergency stop switch operation etc. are abbreviate | omitted.

An internal configuration of the force control unit 61 is shown in FIG.
In the force control unit 61, first, the sensor coordinate conversion unit 611 converts the operation force detected by the force sensor 3 into an operation force based on the robot coordinate system and outputs the operation force to the impedance model unit 612. In the present embodiment, the reference point of the robot coordinate system is provided on the base of the robot 1, but can be changed as appropriate according to the application and the installation method of the robot.
Here, the impedance model of the impedance model unit 612 is expressed as the following equation (1).

Where F: operating force based on the robot coordinate system x: displacement of the control point position of the robot 1 M: inertia coefficient B: viscosity coefficient K: spring coefficient, both of which are real numbers.
The inertial coefficient M, the viscosity coefficient B, and the spring coefficient K in the equation (1) are adjusted, and the obtained x is output and added to the command to the robot 1, so that the robot 1 with respect to the force detected by the force sensor 3. The operating characteristics during direct operation can be changed. Since impedance control is a known technique, a detailed description thereof is omitted.
A position calculated by forward conversion 614 based on a joint angle (feedback position) detected by a joint angle detector (not shown) provided in each drive unit or each joint unit of the robot 1, and a control point position of the robot 1 to be described later And the output of the impedance model unit 612 obtained by the equation (1) is added to calculate a position command based on the robot coordinate system which is an orthogonal coordinate system. This position command is inversely transformed into the joint coordinate system of the robot 1 by inverse transformation 613 to obtain joint angle commands for the respective joints J1 to J6.

  The position / velocity servo system 62 calculates the torque generated by each servo motor (not shown), which is a driving source of J1 to J6, based on the joint angle command and the feedback position of the robot 1, and the servo amplifier 63 causes the servo motor Is driven.

Next, control by the control device 60 when the teaching operator holds the operation handle 4 to guide the robot 1 and directly teaches will be described with reference to FIGS.
4, the first component 100 is gripped by the end effector 2 at the tip of the robot 1, and the robot 1 is operated appropriately so that the first convex portion 100 </ b> A and the second convex portion 100 </ b> B of the first component 100 are moved. These are inserted into the first hole 101A and the second hole 101B of the second component 101, respectively. In FIG. 4, FT is a coordinate system (hereinafter referred to as a gripped object coordinate system) for the control point C00 set for the first component 100, and the control point C00 is expressed based on the gripped object coordinate system. C00 (0, 0, Lz). Here, Lz is a real number.

  At this time, FIG. 5 shows the teaching procedure of the insertion operation by the teaching worker. The insertion operation is performed in the order of FIG. 5A to FIG. 5B and FIG. FIG. 5A shows the first part 100A of the first part 100 before the first part 100A is inserted into the second part 101. FIG. 5B shows the first part 100A of the first part 100. FIG. 5C shows a state in which the second convex portion 100B of the first component 100 is inserted into the second hole 101B of the second component 101 after the first convex portion 100A. First, the first convex portion 100A is inserted, and then the second convex portion 100B is inserted.

In the state of FIG. 5A, the control point of the first component 100 is set to C01.
C01 may be the same position as C00 described above or a different position, but C01 is assumed to be the same position as C00 for the sake of simplicity. First, the teaching worker grips the operation handle 4 and applies a force as shown in FIG. 3B with the control point C01 as the control point, so that the first component 100 is attached to the second component 101 so that the insertion operation can be easily performed. Guide and perform rough positioning.
When the rough positioning of the first component 100 is completed, the teaching worker presses the recording switch 6 on the operation handle 4. The signal is sent to the recording unit 65 in the control device 60. Similarly to the force control unit 61, the feedback position is input to the recording unit 65, and the recording unit 65 that receives the signal that the recording switch 6 is pressed records the feedback position of the robot 1 at that time as a teaching point. . Further, the recording unit 65 records the control point position C01 generated by the control point calculation unit 64. The control point calculation unit 64 will be described later.
Through the above procedure, teaching of FIG. 5A in the insertion operation is completed.

Subsequently, the control point position is changed from C01 to C02 shown in FIG. The teaching worker selects the X-axis direction as the movement direction of the control point position by operating the direction selection button 5A while holding the operation handle 4 as shown in FIG. The selected direction is input to the control point generator 642 in the control point calculator 64 shown in FIG.
Further, when the teaching worker depresses the minus direction button of the change amount input button 5B, the movement amount of the control point position in the minus direction of the X axis according to the depressing time is converted to an analog signal A / A in the control point calculation unit 64. The digital signal that is input to the D converter 641 and converted is input to the control point generator 642.
The control point generation unit 642 calculates the position of a new control point from the input movement direction and movement amount and outputs it to the control point range monitoring unit 643. As a specific example, if a point moved from the C01 in the X axis minus direction by the movement amount Lx (real number) is C02, the control point position based on the gripped object coordinate system is (−Lx, 0, Lz).

In the control point range monitoring unit 643, a maximum value is set in advance for each axis direction of the control point movement amount, and it is monitored whether the movement amount designated by the change amount input button 5B exceeds the maximum value.
For example, the maximum value of the control point movement amount in the X-axis direction is Mx (positive real number), and the teaching worker changes the control point position (−Lx, 0, Lz) calculated by the control point generation unit 642 by the teaching worker. It is assumed that the input button 5B is pressed for a long time and Mx <| Lx |. In this case, the control point range monitoring unit 643 blinks the LED 8 provided on the operation handle 4 as an alarm presenting means to notify the teaching worker that the movement amount is too large, and to the force control unit 61 and the recording unit 65. (-Mx, 0, Lz) is output. The LED is merely an example of an alarm presenting means, and can be changed as appropriate, for example, an alarm is presented to a teaching worker by emitting a buzzer sound from a speaker.
In the case of Lx ≦ Mx, the control point range monitoring unit 643 outputs the output of the control point generation unit 642 to the force control unit 61 and the recording unit 65 as it is.

  In this way, the control point position is moved to C02 at the tip of the first convex portion 100A. As a result, since the steering operation of the teaching worker subsequently acts on the new control point C02, it becomes easy to adjust the position of the tip of the first convex portion 100A, and an appropriate position for insertion into the first hole 101A. The first component 100 can be moved in a short time. That is, teaching work can be performed efficiently.

On the other hand, in the force control unit 61, the control point update monitoring unit 615 monitors the update of the control point position. When the control point position is updated, the control point update monitoring unit 615 notifies the impedance model unit of the update. When the update of the control point position is detected, the impedance model unit 612 sets the output of the impedance model unit 612 to 0 for a preset time. This time is several times of the control cycle, specifically about several ms.
Thereafter, force control is performed based on the new control point C02 (-Lx, 0, Lz).
Then, as described above, joint angle commands for the respective joints J1 to J6 are calculated and output to the position / speed servo system 62. Based on this joint angle command and a joint angle (feedback position) detected by a joint angle detector (not shown) provided at each drive part or each joint part of the robot 1, the torque generated by the motor in the position / speed servo system 62 is calculated. Then, the servo amplifier 63 drives the servo motor of each joint of the robot 1.

FIG. 5B shows a state in which after the control point position is moved to C02, the tip of the first convex portion 100A is moved downward and partially inserted into the first hole 101A.
After the control point position is moved to the distal end portion of the first convex portion 100A, the teaching operator applies a force to the operation handle 4 to move the distal end portion of the first convex portion 100A downward, as shown in FIG. If the recording switch 6 on the operation handle 4 is pressed again, the feedback position of the robot 1 and the control point position C02 at that time are recorded in the recording unit 65.
Thereafter, the posture of the first component 100 is changed by operating the operation handle 4 while keeping the control point position constant, and the second component 101 is made to approach the second hole 101B while being opposed to the second component 101. This state is shown in FIG.
When the state shown in FIG. 5C is reached, the recording switch 6 on the operation handle 4 is pressed, and the feedback position and control point position C02 of the robot 1 at that time are recorded in the recording unit 65.
As described above, by appropriately changing the control point position during direct teaching according to the work of the robot, the operability is improved and the burden on the teaching worker can be reduced. Furthermore, since the control point position can be changed from the operation handle, the teaching work is not interrupted and the time required for teaching can be shortened.

Although only the change of the control point position has been described above, the position / posture changeover switch 9 is provided on the operation handle 4 as shown in FIG. 3 to directly teach not only the position of the control point but also the posture. It becomes possible to change to.
When the position / posture changeover switch 9 is used to specify a change in posture, the direction selection button 5A is used to specify which axis of the XYZ of the gripped object coordinate system is rotated to change the posture. The rotation amount is designated by the input button 5B.
By changing the posture, the present invention can be applied even when the shape of the first component 100 'is curved as shown in FIG. 7, for example, and the operability of direct teaching can be improved. In FIG. 7, in accordance with the shape of the tip of the first component 100 ′, a coordinate system (FT ′ in the figure) obtained by rotating the gripped object coordinate system around its Y axis is set. In the case of FIG. 7, the operation of the assembly work of inserting the first convex portion 100A ′ and the second convex portion 100B ′ of the first component 100 ′ into the first hole 101A and the second hole 101B of the second component 101, respectively. When teaching, the first component 100 ′ can be moved along the Z-axis direction of the FT ′, so that the operability during direct teaching is improved and the time required for teaching can be shortened.

  The configuration of the control point input means 5 shown in FIG. 3 is merely an example, and the direction selection button 5A is eliminated as shown in FIG. 8, and a change amount input button 5B is provided for each of the X, Y, and Z axes instead. May be.

Next, the function of the return position command generation unit 66 in the control device 60 will be described. As described above, the operation handle 4 is provided with the recording switch 6, and when the teaching operator depresses the recording switch 6, the feedback position and the control point position of the robot 1 at that time are recorded in the recording unit 65.
Here, when the teaching operator changes the control point position and tries to move the robot 1 to the next teaching point, the robot 1 may be greatly deviated from the desired position due to an operation error. In such a case, since the control point position is changed, the operation feeling for the teaching worker also changes, and it may not be possible to return to the original position successfully.
When the teaching worker depresses the return switch 7 of the operation handle 4 in such a case, the return position command generation unit 66 reads the immediately preceding teaching position and the immediately preceding control point position recorded in the recording unit 65 and also switches the switching means. In step 67, the position command from the return position command generation unit 66 is output to the position / speed servo system 62 instead of the force control unit 61. Further, the control unit 68 outputs the immediately preceding control point position to the force control unit 61.
As a result, the servo motors of the joints of the robot 1 are driven to return to the immediately preceding teaching position, which is the return position, and the control point also returns to the immediately preceding setting. In this way, the teaching worker can start teaching again from the immediately preceding teaching position, so the operability of direct teaching can be improved and teaching work can be performed efficiently.

  The present invention can be used not only for a direct teaching device but also for direct guidance operation of a robot manually by force control.

The figure which shows the whole structure of this invention The figure which shows the structure of the force control part of this invention The figure which shows the operation handle of this invention Figure showing an embodiment of the teaching according to the invention Transition diagram of working state for explaining an embodiment of the present invention The figure which shows the structure of the control point calculating part of this invention FIG. 5 shows another embodiment of the teaching according to the present invention. The figure which shows another example of the operation handle of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Robot 2 End effector 3 Force sensor 4 Operation handle 5 Control point input means 5A Direction selection button 5B Change amount input button 6 Recording switch 7 Return switch 8 LED
9 Position / Attitude Changeover Switch 60 Controller 61 Force Control Unit 62 Position / Speed Servo System 63 Servo Amplifier 64 Control Point Calculation Unit 65 Recording Unit 66 Return Position Command Generation Units 67, 68 Switching Means 100, 100 ′ First Parts 100A, 100A '1st convex part 100B, 100B' 2nd convex part 101 2nd component 101A 1st hole 101B 2nd hole 611 Sensor coordinate transformation part 612 Impedance model part 613 Reverse transformation 614 Forward transformation 615 Control point update monitoring part 641 A / D Converter 642 Control point generator 643 Control point range monitor

Claims (6)

An operation handle provided at the tip of the articulated robot via a force sensor;
Directly of a robot having a control device including a force control unit that detects an operation force of a teaching worker applied to the operation handle by the force sensor and outputs a command to move the robot by force control according to the operation force. A teaching device,
The operation handle includes control point input means for a teaching operator to input a change amount and direction of the control point of the robot during teaching,
The control device includes a control point calculation unit that updates the control point setting of the robot and outputs the control point setting to the force control unit according to the change amount and direction input by the control point input unit ,
The robot direct teaching apparatus, wherein the control point calculation unit includes a control point range monitoring unit that compares the amount of change input by the control point input unit with a preset value . The control point range monitoring unit limits the change amount to the preset value when the change amount input by the control point input means is larger than the preset value, 2. The robot direct teaching apparatus according to claim 1 , wherein an alarm is displayed to a teaching operator . 2. The control device according to claim 1 , further comprising: a recording unit that records the position of each joint of the robot as a teaching point by an operation of the teaching operator and records a control point setting at the time of the recording. 3. The robot direct teaching apparatus according to 2. The control device reads the immediately preceding teaching point and the immediately preceding control point setting from the recording unit by an operation of the teaching operator, outputs a command to move the robot to the immediately preceding teaching point, and outputs the force 4. The robot direct teaching apparatus according to claim 3 , further comprising a return position command generation unit that outputs the immediately preceding control point setting to the control unit. The direct control of the robot according to claim 1 , wherein the control point setting is expressed based on a gripped object coordinate system set for an object gripped by an end effector of the robot. Teaching device. 6. The control point input means inputs a change amount and direction of an attitude of the gripped object coordinate system in addition to a change amount and direction of the control point position. The robot direct teaching apparatus as described.