JPH0639068B2 - Robot controller - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a robot control device capable of accurately self-checking an object position and then shifting to a predetermined motion without teaching the object position itself. .

[Description of Prior Art] A conventional operation method of, for example, an industrial robot is to perform a predetermined operation while faithfully restoring the position based on position data given in advance. Therefore,
If accurate position movement is desired, accurate position data must be given. Here, the teaching method of the position data includes an indirect teaching method in which the position data is given by a numerical value, a robot is actually moved, and the position after the movement is compensated by a position detecting device. There is a direct teaching method in which it is directly stored.

However, regardless of which method is used, the teaching work of the position data requires a lot of time and meticulous attention and is a laborious work. In particular, when the laminated materials are sequentially taken out or sequentially placed, the number of teachings increases in proportion to the number of laminated layers, and the position teaching work is extremely laborious work.

That is, in direct teaching, the robot must be moved to the actual material position, but in order to improve the work accuracy or avoid the collision between the robot and the material, it is necessary to accurately position the robot. (For example, the accuracy is +0.05 mm in the + direction and 0.3 mm in the one direction), which requires the careful attention, the great amount of time, and the labor as described above. Further, even if the position data determined in this way is accurate at the time of teaching, it cannot always be adapted to the variation in the material dimensions, and there is a possibility that trouble may occur due to the variation in the material dimensions.

On the other hand, in the case of indirect teaching, the material position must be programmed as numerical data, but in order to create this numerical data, the position must be measured using, for example, a three-dimensional measuring device, and this is the reason for this. It took a lot of work. Incidentally, even in the indirect teaching, as in the case of the direct teaching, it was not possible to adapt to variations in material dimensions.

[Object of the Invention] An object of the present invention is to provide a robot control device capable of causing the robot itself to determine an accurate object position and automatically shifting to the next predetermined work. .

Another object of the present invention is to provide a robot controller capable of judging the positions of various objects regardless of the material and shape of the objects and automatically shifting to the next predetermined work. To do.

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides X,
A mounting plate mounted on a base mounted on the tip of an arm movable in the Y and Z directions is provided so as to be movable in the X and Z directions and biased and held at an intermediate position in the X and Z directions. A sensor for detecting movement of the mounting plate in the X direction and the Z direction with respect to the base is provided, and a gripper having a finger capable of gripping a material is attached to the mounting plate, and each detected value of each sensor is From the state management unit, a comparison unit that compares a plurality of set values set in the setting unit, a state storage unit that stores the comparison result of the comparison unit, an axis control unit that feedback-controls each control axis of the robot, and a state management unit. An operating state control unit that sends an axis control signal to the axis control unit according to a state to be communicated, and the state management unit that manages the state of the state storage unit.

[Explanation of Examples] FIG. 1 shows a working state of a Cartesian coordinate system robot. The robot 1 can move in the X direction along the table 3 and can extend its support column 5 in the vertical direction (Z). The arm 7 can be moved in the front-rear direction (Y direction) via a rack and pinion mechanism (not shown) by rotating the motor M fixedly provided with respect to the column 5. Therefore, the hand unit 9 via the pitching axis P can freely move the three-dimensional coordinates on the table 3. These movements are instructed by the numerical control device NC and are performed via a servo motor.

The hand portion 9 has a pitching shaft P and a gripper 1.
A pressure detection device FS, which will be described in detail later, is provided between the pressure detection device 1 and The gripper 11 has a pair of fingers 13 and 13 that can be rotated counterclockwise (R +) and clockwise (R-) when viewed from the front of the robot 1 and can perform a gripping operation. Therefore, the gripper 11 grips the materials W ₄ , W ₅ , ... Placed at a predetermined height position (Z = Z ₁ ) on the table 3 and moves to another predetermined height position Z = Z ₂ , for example. It is possible to perform work such as separating the gripping material.

2 to 6 show a detailed view of the pressure detection device FS and an explanatory view thereof. 2 is a plan view of the pressure detection device FS seen from the gripper 11 side shown in FIG. 1, and FIG. 3 is a plan view of FIG.
III-III view sectional view, FIG. 4 is a sectional view taken along the line IV-IV in FIG. The pressure detection device FS has a pressure detection unit FSX that detects the pressure from the X direction and a pressure detection unit FSZ that detects the pressure from the Z direction, and the external force from the X and Z directions received by the gripper 11 during movement. It is the structure which can detect each. However, when the pitching axis P is moved up and down 90 °, it is of course possible to detect the external force in the X-axis and Y-axis directions.

2 to 4, the mounting plate 15 has taps 17,1.
A screw member (not shown) from the gripper 11 side is screwed into 7 and attached to the gripper 11 side. Intermediate member 19
Is fixed to the mounting plate 15 via bolts 21 and 21. The base 25 is attached to the pitching shaft P side via a bolt (not shown). A slide plate 27 is provided between the base 25 and the intermediate member 19, and the base 2
A plurality of spheres 2 capable of moving in the X direction between
A plurality of spherical bodies 31, 31 are provided between the intermediate body 19 and the movable members 9, 29 so as to be movable in the Z direction.

On the other hand, a frame 33 is fixedly provided on the base 25 outside the outer periphery of the intermediate member 19. Then, the pin 35 is fitted and inserted into the hole provided in the frame 33, and the pin 35 is pressed toward the center by the spring 39 in the housing 37. I am trying to position it. The pressing force of the spring 37 can be adjusted by rotating a nut screwed into the bolt 41.

The two pressure detection units FSX and FSZ are the mounting plate 1
Magnets MgX and MgZ are provided on the back surface of the frame 5, and the frame 3 is opposed to the magnets MgX and MgZ.
Magnetic force sensors SX and SZ are provided on the third side, respectively. The magnetism generator MgX of the pressure detection unit FSX is attached to the mounting plate 15
The sensor SX senses the movement in the X direction, and the sensor SX does not sense the movement in the Z direction.
The width of the magnetic body MgX is configured to be long in the Z direction. For the same reason, the magnetism generator MgZ of the pressure detection unit FSZ is made to have a width longer in the X direction so as not to detect movement in the X direction.

With the above configuration, the mounting plate 15 is X
When moving in the direction, the intermediate member 19 and the sliding plate 27 move together, and the spring 39 in the housing 37 on the right side or the left side in FIG. 2 is pressed. The moving distance is determined by the balance between the pressing force and the spring 39. The maximum moving distance is designed to be, for example, about ± 3 mm in the X direction shown in FIG. 4, and the pressing force of the spring at the maximum moving position is designed to be about several Kgw.

On the other hand, when a force in the Z direction acts on the mounting plate 15, the sliding plate 27 is fixed with respect to the base 25, and the intermediate member 19 moves in the vertical direction of FIG. Spring 39
Press. In this case, similarly to the above, ± 3 mm in the Z direction
It can be operated in balance with the pressure within several Kgw within the range of.

FIG. 5 shows the sensor SX (SZ) and the magnetizer MgX (Mg
The mutual relationship of Z) is expanded and shown. Magnetizer MgX
By shifting the center axis of the sensor SX (SZ) in the left-right direction in the figure with respect to (MgZ), a voltage substantially proportional to the shifted distance can be obtained from the sensors SX and SZ.

FIG. 6 is a distance-voltage characteristic diagram in that case. The horizontal axis shows the moving distance (mm) and the vertical axis shows the generated voltage (volt). If the gripper 11 receives an external force in FIG. 1, the mounting plate 15 shown in FIG. 3 moves in the direction in which the external force is received, and the sensors SX and SZ respectively obtain voltages corresponding to the amount of movement. It will be. For example, when moving by +2 mm in the X direction, it seems that the sensor SX outputs +2.5 volts.

In FIG. 7 and FIG. 8, the pressure detecting device F is moved by moving the robot.
The explanatory view in the case of operating S is shown. Both of the figures correspond to the right side of FIG. 1, and show only the arm and hand of the robot 1.

Now, as shown in FIG. 7, the fingers 13, 13 of the robot are
Is positioned directly above the laminated material W ₄ ... (Z = Z ₁ ) and then the uppermost material W ₄ (Z = Z ₂ ) is to be gripped. First, the operation until reaching the position of Z = Z ₁ just above the material W ₄ may be taught by either direct teaching or indirect teaching. Then, a predetermined function is used from the position of Z = Z ₁ . This predetermined function is, for example, Z
= The position P ₁ of Z _1, it is sufficient that the position of the material W ₄ desired to be gripped can be passed. In this example,
A virtual target position P ₀ (Z = Z ₀ ) is standardized just below the material W ₄ , and linear interpolation is performed from the position P ₁ of Z = Z ₁ toward the virtual target position P ₀ .

At this time, as shown in FIG. 7, an example is shown in which the fingers 13 are formed by suction pads. The suction pad 13 is made to face the material W ₄ , and if the suction pad 13 is advanced as it is, the suction pad 13 abuts on the upper surface of the material. this is,
This is because the pressure detection unit FSZ detects the force pressing from below through the suction pad 13. After that, the robot hand unit 9 is lowered toward the material W ₄ at a predetermined speed.

FIG. 8 shows a state in which the suction pad 13 is in contact with the material W ₄ . Since the sensor SZ detects the pressure value in such a state, the movement of the robot is stopped after confirming that the detected pressure is a predetermined value. At this time, the pitching shaft P side of the hand portion 9 and the suction pad mounting portion 11 are
It is in a state of being displaced by Δlmm (within 3 mm).

FIG. 9 is a block diagram of the robot controller. A / D converter 4 receives voltage signals from the plurality of sensors 1, 2, ... (Pressure detection units SX, SZ ...) Through a multiplexer 43.
5, and sends the digital value obtained from the A / D converter 45 to the comparison unit 47.

On the other hand, in the pressure setting unit 49, preset setting values are set in advance corresponding to the sensors 1, 2, .... As an example, 0.
2 volt, 0.4 volt ....
Set a large number of setting values in units of 2 volts. The reason for providing a large number of set values in this way is, for example, from 0.8 volt to 2.0
If a voltage up to a volt is detected, the material position is confirmed, and at the same time, the detected voltage value is analyzed to find out how many mm overrun is currently occurring (Fig. 8, Δl
(See) can be known. Another reason is that, for example, when a voltage of 2.2 V or higher is detected by the sensor, alarm processing can be performed together.

Such a large number of set values are provided for each sensor. Here, it is understood that the plurality of sensors 1, 2, ... Are properly provided at appropriate positions of the robot in addition to the sensors SX, SZ and can be used for appropriate work (position confirmation, rear-end collision prevention, etc.). Will be done.

The comparison unit 47 compares the set value of the pressure setting unit 49 with the voltage value from the A / D converter 45. This comparison period is performed at least while the robot is moving toward the virtual target position P ₀ shown in FIG. 7 and FIG.
Then, for example, it is repeated about 10 times per second.
The result compared by the comparison unit 47 is stored in the state storage unit 51.

The state storage unit 51 can temporarily store a plurality of states for each sensor. The plurality of states means to detect how much voltage the pressure detector is currently outputting in a plurality of stages. FIG. 10 is a memory map corresponding to the i-th sensor in the state storage unit 51. A flag of Ni ₁ , Ni ₂ , ... Nin is provided for every 0.2 volt, and a flag corresponding to the detected voltage is set.

The state management unit 53, the operation state control unit 55 shown in FIG.
The axis control unit 57 is a control unit under the operating system, and is the same as that used in a normal operating system. That is, the axis control unit 5
Reference numeral 7 feedback-controls each control axis of the robot. The operation state control unit 55 sends an appropriate axis control signal to the axis control unit according to the state notified from the state management unit 53. Therefore, the state management unit 53 can manage the state of the 51. At this time, since it is possible to know at which position the flag stands in the calculation unit 59, it is possible to perform processing such as movement stop, transition to the next processing, and alarm generation. In addition, by knowing Δl shown in FIG. 8, proper position correction for the next processing can be performed.

FIG. 11 is a flow chart for explaining the operation status of the robot shown in FIGS. 7 and 8. Step 111
Move toward the virtual target position P ₀ set in advance. This movement is performed until a predetermined voltage (for example, 0.6 V or more) is output from the pressure detection device FS in step 113. In order to prevent the pressure detecting device from exceeding the maximum permissible range of 3 mm and causing equipment damage, for example, when the detected voltage of 2.6 V is detected, the robot detects the detected voltage in step 115. This is a signal for performing alarm processing such as stop and alarm generation. When the predetermined voltage value is detected in step 113, the process proceeds to step 116. Step 1
At 16, the robot is stopped immediately.

The processing after step 117 is for shifting to the next processing. In step 117, the stop position is set as the target position, that is, the reference position for the next work, and in step 118, the follow-up process until reaching the target position is completed. At this time, it should be noted that the reference position can be corrected from the flag position of the state storage unit.

Step 119 shows the next work. In the next work, for example, a gripping operation such as activating a vacuum device (not shown) in the state shown in FIG.

In this way, the robot holding the material W ₄ shown in FIG. 1 operates at a predetermined position (for example, Z = Z ₁ shown in FIG. 7).
Position), and after performing a predetermined processing operation, place the material W ₄ in a predetermined place. The first drawing for convenience shown on the same table for location, already material W _1, W
₂ and W ₃ are shown mounted. It is obvious that the gripping material can be separated by the same processing as the gripping method.

In this example, the virtual target position P ₀ immediately below the material is input by programming or the like to perform linear interpolation, but it is not always necessary to actually specify the position. For example, the first
In the figure, a method of advancing an infinite distance from the point P _{1 in the} direction of P ₀ by a predetermined amount, a method that can use circular arc interpolation, or another method may be used. In short, it is sufficient to proceed toward the material W _4. It is a thing. The tolerance at that time is the area of W ₄ ,
And a member that comes into contact with the material W ₄ (in this example, the suction pad 1
Since it suffices if there is a portion that intersects with the area of 3), an extremely large tolerance is allowed, and the teaching work becomes easier.

Although the above embodiment has shown the Cartesian coordinate type robot, the present invention is not limited to this, and the present invention can be applied to polar coordinate type robots, articulated type robots, and other types of robots. Further, in the above-mentioned embodiment, the pressure detecting device is used as the position confirming means of the object, but in this case, as compared with the case where the proximity sensor (for example, magnetic or optical type) is used, The position can be accurately detected directly, and the position can be detected accurately without being affected by materials such as aluminum and iron, and by being not affected by the surface condition of the detection material and other shapes. This is advantageous because

[Effects of the Invention] As can be understood from the above description of the embodiments, the present invention is, in short, the mounting plate mounted on the base 25 mounted on the distal end portion of the arm 7 movable in the X, Y, and Z directions. Fifteen, x
Sensors SX and SZ that are movable in the Z direction and the Z direction and are biased to and held at intermediate positions in the X direction and the Z direction, and that detect the movement of the mounting plate 15 with respect to the base 25 in the X and Z directions. A gripper 11 provided with a finger 13 capable of gripping a material is mounted on the mounting plate 15, and each detection value of each of the sensors SX and SZ and a setting unit 49 are provided.
Comparing unit 4 for comparing a plurality of setting values set in
7, a state storage unit 51 that stores the comparison result of the comparison unit 47, an axis control unit 57 that feedback-controls each control axis of the robot, and the axis control unit according to the state communicated from the state management unit 53. The operation state control unit 55 that sends an axis control signal to the control unit 57 and the state management unit 53 that manages the state of the state storage unit 51 are provided.

As is apparent from the above configuration, in the present invention, the mounting plate 15 mounted on the base 25 mounted on the tip of the arm 7
A gripper with fingers 13 is attached to the. The movement of the mounting plate 15 in the X and Z directions with respect to the base 25 is detected by the sensors SX and SZ, and the detection values of the sensors SX and SZ are set in advance by the setting unit 49. The configuration is compared with the set value in the comparison unit 47.

Therefore, for example, when the finger 13 comes into contact with the work during movement in the Z direction, the movement is stopped by the Z direction sensor SZ, and the stop position is the detection value of the sensor SZ. Is compared with the set value, it can be easily known with reference to the contact position of the work.

Therefore, the operation based on the contact position with the work can be easily performed.

[Brief description of drawings]

The drawings all show examples, and FIG. 1 is a perspective explanatory view showing a working state of a robot. FIG. 2 is a plan view of the pressure detecting device, and FIG. 3 is III of FIG.
-III arrow sectional drawing, FIG. 4 is IV-IV arrow sectional drawing of FIG. FIG. 5 is an explanatory view showing the mutual relationship between the magnetized body and the sensor, and FIG. 6 is a relationship characteristic diagram between the moving distance of the sensor and the generated voltage. FIG. 7 and FIG. 8 are explanatory views showing the moving state of the robot and enlarging the arm and the hand portion. FIG. 9 is a block diagram of the robot controller, FIG. 10 is an explanatory diagram of a memory map of the state storage unit, and FIG. 11 is a processing flowchart showing follow-up control. 1 ... Robot, 3 ... Table, 5 ... Strut, 7 ... Arm, 9 ... Hand part, 11 ... Gripper, 13 ... Finger (suction pad) FS ... Pressure detection device FSX, FSZ ... Pressure detection unit MgX, MgZ ...... onset magnetized body SX, SZ ...... sensor P ₀ ...... virtual target position

Claims (1)

[Claims] 1. An arm (7) movable in X, Y and Z directions.
The mounting plate (1) attached to the base (25) attached to the tip of the
5) is provided so as to be movable in the X and Z directions and biased and held to an intermediate position in the X and Z directions, and the mounting plate (15) with respect to the base (25) in the X and Z directions.
A gripper (1) provided with a sensor (SX, SZ) for detecting movement in a direction and provided with a finger (13) capable of grasping a material.
1) mounted on the mounting plate (15), and comparing each detected value of each sensor (SX, SZ) with a plurality of set values set by the setting unit (49) (47)
A state storage unit (51) for storing the comparison result of the comparison unit (47), an axis control unit (57) for feedback controlling each control axis of the robot, and a state communicated from the state management unit (53). An operation state control unit (55) that sends an axis control signal to the axis control unit (57), and a state management unit (53) that manages the state of the state storage unit (51).
A robot control device comprising: