JP2844660B2 - Initial adjustment method of work positioning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention automatically and automatically adjusts the parameters of an operation mechanism of a work positioning device suitable for use in an assembly line in a factory, for example, a car body assembly line. How to do it.

(Prior Art) In recent years, with the development of PA (factory automation), a large number of work positioning devices are used in factories, for example, in automobile body assembly lines.

These work positioning devices generally include an operation mechanism using a servomotor or the like, and perform desired work positioning by controlling the operation mechanism by a control device external to the apparatus.

By the way, after the work positioning device is completed, an operation confirmation test is performed to perform various initial adjustments. In the conventional example, in the conventional example, an operator performs measurement based on various operation conditions for each work positioning device. Then, the obtained measurement results are analyzed, and the adjustment of the parameters to eliminate the malfunction of the operating mechanism and achieve the desired positioning accuracy is repeatedly performed.

(Problems to be Solved by the Invention) When such a method is adopted, since the number of use of the work positioning device is extremely large as described above,
As a whole, a large initial adjustment time is required, which leads to an undesired increase in operation time. In addition, since the initial adjustment is performed by a human, even when a standard value of the adjustment is determined, the adjustment value varies due to individual differences, and it is quite difficult to manage to the desired positioning accuracy.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problem by automatically and initially adjusting parameters of an operation mechanism of a work positioning device so as to eliminate an error generation factor.

(Means for Solving the Problems) For this purpose, the method according to the present invention detects the vibration of the work positioning device by the vibration detecting means and the speed detecting means when initially adjusting the parameters of the operating mechanism of the work positioning device. Based on the detected result, it is determined whether normal operation is possible in the low speed range. If normal operation is possible, undershoot or overshoot of high speed characteristics in the middle speed range and the high speed range According to the presence or absence of the chute or the predetermined high-frequency vibration or low-frequency vibration, at least one of the acceleration / deceleration, the position loop gain, and the speed loop gain as the above parameters is reduced. Judgment is performed to determine if positioning accuracy is achieved.If the specified positioning accuracy cannot be obtained, increase acceleration / deceleration. Reacting in the state where it has been performed, it is determined whether or not the predetermined positioning accuracy is achieved.If the predetermined positioning accuracy cannot be obtained, the state where the acceleration / deceleration is increased is canceled, and then the speed loop is performed. By re-operating with the gain increased, it is determined whether the predetermined positioning accuracy is achieved.If the predetermined positioning accuracy cannot be obtained, the state in which the speed loop gain is increased is changed. In the state of fine adjustment in the direction of loosening the positioning accuracy after cancellation, it is determined whether or not the finely adjusted positioning accuracy is achieved.If the finely adjusted positioning accuracy cannot be obtained, the fine adjustment is performed. Until the positioning accuracy is obtained, the acceleration / deceleration increase or the speed loop gain increase is repeated.

(Operation) When initially adjusting the parameters of the operating mechanism of the work positioning device, if the speed characteristics have undershoot or overshoot, or if predetermined high-frequency vibration or low-frequency vibration occurs, the predetermined positioning accuracy can be achieved. Disappears.

Therefore, the vibration of the work positioning device is detected by the vibration detecting means, and the operating speed is detected by the speed detecting means. Based on the detection result, it is first determined whether or not normal operation is possible in a low speed range.

Here, if the detected operation speed follows a normal operation, for example, a command value in a low speed range, then, in the middle speed range and the high speed range, the acceleration / deceleration, the position loop gain, and the speed loop gain as the above parameters are used. Adjust to reduce at least one of them (note that abnormal operation, for example, when the detected operation speed shows a clear abnormal value with respect to the command value in the low speed range, an alarm is issued and the operation mechanism is reworked). Encouraged). This adjustment is performed so as to eliminate undershoot or overshoot of the speed characteristic and predetermined high-frequency vibration or low-frequency vibration.

Next, in this state, the work positioning device is operated to check whether or not the predetermined positioning accuracy is achieved.If the positioning accuracy cannot be achieved, the acceleration / deceleration is increased. Check whether positioning accuracy is achieved. If the predetermined positioning accuracy cannot be achieved even by the increase in the acceleration / deceleration, the state where the acceleration / deceleration is increased is canceled, and then the operation is performed again with the speed loop gain increased, so that the predetermined positioning accuracy is achieved. Check whether or not. If the predetermined positioning accuracy cannot be achieved even by the increase in the speed loop gain, the state in which the speed loop gain is increased is canceled, and then the finely adjusted positioning accuracy is achieved in a state in which the positioning accuracy is loosened. Check if it is done. When the finely adjusted positioning accuracy cannot be achieved, the acceleration / deceleration increase or the speed loop gain increase is repeated until the finely adjusted positioning accuracy is achieved (the predetermined positioning accuracy is Even if the fine adjustment is performed, it is strictly set so that a desired positioning accuracy can be secured.)

In this way, the above series of initial adjustment steps are automatically processed, so that a desired positioning accuracy can be achieved in any case, and the work time for the initial adjustment of the work positioning device can be greatly reduced. it can.

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

FIG. 1 is a diagram illustrating the configuration of a work positioning device used in an embodiment of the method of the present invention. In the drawing, reference numeral 4 denotes a work positioning device.

The work positioning device (hereinafter referred to as a locator) 4 is provided with an approach axis of a three-dimensional orthogonal coordinate system and various working means (not shown). 2 is provided. When the locator 4 is mounted on the frame 2, for the purpose of making the body assembling apparatus suitable for various types and types of vehicles, for example, the transport direction outside the frame 2, in other words, the three-dimensional structure shown in FIG. To fix a base 8 of a locator 4 to a slider 7 of a linear motion guide composed of a rail 6 laid extending in the Y-axis direction of a rectangular coordinate system and a slider 7 hooked on the rail 6. According to this, each locator 4
Can be freely horizontally moved in the extending direction of the rail 6 according to the type and model of the vehicle body to be assembled while being supported by the frame 2 on the outside thereof.

In the vehicle body assembling apparatus, these locators 4
This is for positioning and holding the side roof rail of the side body as a work, and in order to drive the approach shaft 5 penetrating through the base 8 and projecting to the inside of the frame 2 forward and backward with respect to the vehicle body to be assembled, in other words, tertiary. In order to drive in the X-axis direction of the original coordinate system, a servomotor 12 is connected to the rear end of the approach shaft 5, and the servomotor 12 is extended inside the approach shaft 5, and a screw shaft 13 of a ball screw is used. And a ball nut 15 fixed to the base 8 is screwed onto the screw shaft 13. Here, the tip of the screw shaft 13 is rotatably supported by a bearing 16 fixed to the approach shaft 5.

According to such an advance / retreat structure, by driving the servo motor 12 to rotate the screw shaft 13, the approach shaft 5
Based on the action of the screw shaft 13 and the ball nut 15 fixed to the base 8, the base 8 is preferably advanced and retracted in the X-axis direction together with the screw shaft 13 as required, under the guidance of a linear motion guide. I can exercise.

Further, a screw shaft 9 of a ball screw is mounted on the outside of the frame 2 so as to cause the respective locators 4 mounted on the frame 2 as described above to be driven in the Y-axis direction. A ball nut 10 to be screwed and a servo motor 11 for rotating the ball nut 10 via a timing belt or the like are attached to the base 8 of each locator 4.

Furthermore, in the locator 4, a wrist member 17 is attached to the tip of the approach shaft 5 so as to be able to advance and retreat in a direction orthogonal to the advance and retreat direction, that is, in the Z-axis direction in the three-dimensional coordinate system.

For this reason, here, the servomotor 18 is attached to the bracket fixed to the tip of the approach shaft 5, and
The screw shaft 19 connected to this servomotor 18 is
The screw 22 is screwed into a ball nut 20 fixed to the wrist portion 17 while the slider 22 fixed to the wrist portion 17 is also engaged with the rail 21 also mounted on the approach shaft side.
A wrist portion 17 is supported on the approach shaft 5 by a linear motion guide including a slider 21 and a slider 22, and the ball nut 20 is moved forward and backward together with the wrist portion 17 with respect to the screw shaft 13 rotating at a fixed position.

Such a wrist part 17 has a bracket
23 has a joint 24 pivotally supported in a vertical plane. The joint 24 is connected to a vehicle type switching cylinder 26 attached to a base member 25 of a wrist portion 17 by a piston rod thereof. By connecting to the bracket 23 at, it can be operated as required.

Further, at the tip of the bracket 23, a support device 28 for contacting and positioning and supporting the outer panel 27a of the side roof rail 27 as a workpiece is fixed, and is provided so as to protrude below the bracket 23. yoke
29 has a clamp cylinder 30 and this clamp cylinder
A clamp claw 32 that is connected to the side roof rail 27 via a toggle mechanism 31 and abuts on the inner panel 27b of the side roof rail 27, in other words, presses the side roof rail 27 against the support device 28 is attached.

Therefore, in the locator 4, the support device 28 and the clamp claw 32 can be moved to a required position in the three-dimensional coordinate system as required. , Can be pivoted in a vertical plane, so that the supporting device 28 and the clamp claw 32 can position and hold the side roof rail 27 between them at a required position, and the side roof rail 27 Can be shifted to an appropriate position.

FIG. 2 is a circuit diagram illustrating the configuration of the control circuit of the locator 4, and 50 indicates a servo control circuit.

The servo control circuit 50 includes interfaces 51 and 52, servo constant setting units 53 and 54, and a servo amplifier 55.
The interface 51 outputs an input signal from an encoder 56 for detecting a pulse corresponding to the number of rotations of the servo motor 12 (the case of the X axis; the Y and Z axes are servo motors 11 and 18). And input to the controller 57. Further, the interface 52 inputs an input signal from a vibration pickup 58 for detecting the vibration of the servo motor to the controller 57. The servo constant setting unit 53 compares the position command from the controller 57 with the input from the interface 51, determines a servo constant K that determines the position loop gain according to their deviation, and sends it to the constant setting unit 54 as a speed command. input. The constant setting unit 54 compares this input with the input from the interface 51, determines a servo constant K 'that determines the speed loop gain according to the deviation thereof, and inputs it to the servo amplifier 55 as a current command. The servo amplifier 55 operates the servo motor 12 (11, 18) based on the current command and the feedback current from the servo motor to position the work.

The controller 57 receives signals from the encoder 56 and the vibration pickup 58 corresponding to the rotation speed and vibration of the servo motor corresponding to the X, Y, and Z axes, respectively, executes the control program shown in FIG. Servo mechanism
Initial adjustment is performed for each of the X, Y, and Z axes.

That is, first, in step 101, standard parameters relating to acceleration / deceleration and servo constants (position loop gain, speed loop gain) are set. As the standard parameters, for example, design values obtained from the inertia and the torque of the servo motor in a loaded state and a non-loaded state are used.

In the next step 102, an operation check in the low speed range is performed. That is, the operation speed of the servo motor in response to a low speed command (for example, 10% of the maximum speed of the servo motor) is sampled for a predetermined period (this is determined based on the length of the ball screw) by an input signal from the encoder 56, and during this period, an extreme speed fluctuation occurs. If there is any abnormality, an alarm is issued in step 103 to urge the servo mechanism to be modified.

If it is determined in step 102 that it is normal, a medium speed command (for example, 50% of the maximum speed of the servo motor) is issued in step 104. In steps 105 to 110, an operation check in the medium speed range is performed. That is, in step 105, it is determined whether or not there is an undershoot or overshoot in the speed characteristic.If a predetermined amount of undershoot or overshoot is recognized, the acceleration / deceleration of the servomotor is reduced in step 106 until the undershoot or overshoot is eliminated, When the condition is resolved, the presence or absence of low-frequency vibration is checked in step 107. Here, a predetermined value (for example,
If there is a low-frequency vibration exceeding 0.1 G), the position loop gain K is reduced in step 108 until the low-frequency vibration is eliminated.
If there is a high-frequency vibration exceeding the predetermined value, the speed loop gain K 'is reduced in step 110 until the high-frequency vibration is eliminated.

In the next step 111, a high-speed command (for example, the maximum speed of the servo motor × 100%) is issued.
The same control as that of 5 to 110 is executed to check the operation in the high speed range.

When the above operation checks are completed, it is determined in step 113 whether or not a predetermined positioning accuracy is achieved. If not, acceleration / deceleration is increased in step 114, and the servomotor is restarted in step 115. At 116, it is checked again whether there is an undershoot or an overshoot (this check is executed for each of the above-mentioned medium speed range and high speed range). Here, if a predetermined amount of undershoot or overshoot is not recognized, it is determined again in step 117 whether or not the predetermined positioning accuracy is achieved.
The loop of 7-114-115-116-117 is repeated.

If a predetermined amount of undershoot or overcounting is recognized in step 116, the state where the acceleration / deceleration is increased in step 114 is canceled in step 118, and the acceleration / deceleration is returned to the state before execution of step 114, and in step 119 The speed loop gain K 'is increased, the servomotor is restarted in step 120, and the presence or absence of the high frequency vibration or the low frequency vibration is checked in step 121 (this check is performed for each of the medium speed range and the high speed range) Do). Here, if no vibration is recognized, it is determined again whether or not the predetermined positioning accuracy is achieved in step 122, and if not, steps 122-119-120-121-122 are performed until the predetermined positioning accuracy is achieved.
Repeat the loop.

If vibration is recognized in step 121, the state in which the speed loop gain K 'is increased in step 119 is canceled in step 123, K' is returned to the state before execution of step 119, and the positioning accuracy is loosened in step 124. After the fine adjustment, the control returns to step 113 to determine whether or not the finely adjusted positioning accuracy is achieved. If the finely adjusted positioning accuracy cannot be achieved, step 11 is performed until the finely adjusted positioning accuracy can be achieved.
Repeat the increase of acceleration / deceleration or increase of speed loop gain after 3.

The operation of the above control will be described. First, the operation of the servomotor is checked in the low-speed range by executing step 102 in FIG. 3, and if there is a malfunction of the servo mechanism, for example, a poor adjustment of the ball screw, an alarm is issued in step 103. Next, by executing steps 104 to 112, an operation check is performed in the medium speed range and the high speed range. That is, the acceleration / deceleration of the servomotor is reduced so as to eliminate the undershoot or overshoot of the speed characteristic, and the position loop gain K and the servo constant are set so as to eliminate the low frequency vibration and the high frequency vibration exceeding a predetermined amount. By making adjustments to lower the speed loop gain K ', the servo constants are corrected for the abnormal waveform of the speed characteristics and the above-mentioned vibration caused by the twisting of the ball screw of the servomotor, the rigidity of the coupling, and the like. Change the power when the motor stops positioning.

After the completion of the adjustment, it is checked whether or not the predetermined positioning accuracy has been achieved by executing step 113, and if it cannot be achieved, the parameters are further increased by executing steps 114 to 122. The check of the predetermined positioning accuracy is performed, for example, based on the detection result of the encoder 56, and the measured value of the N-th pulse (N is a constant corresponding to the predetermined positioning accuracy) after the positioning target value is achieved is again determined as the positioning target value. If it is confirmed twice that the value is within the tolerance, it is determined to be OK. If there is the undershoot or overshoot described above, this condition is not cleared.

When the servomotor is restarted after the adjustment to increase the parameter, the same positioning accuracy check as in step 113 is performed in steps 117 and 122. If the positioning accuracy condition cannot be cleared even by the adjustment to increase the parameter, step 124 is executed. Fine adjustment of the positioning accuracy itself. This fine adjustment is performed by, for example, setting the number of pulses N to N = N +
By increasing the number to 2, the required positioning accuracy is still ensured even if the positioning accuracy is reduced.

In this way, the above series of initial adjustment steps are automatically processed, so that a desired positioning accuracy can be achieved in any case, and the work time for the initial adjustment of the work positioning device can be greatly reduced. it can.

(Effect of the Invention) As described above, the initial adjustment method of the work positioning device of the present invention automatically adjusts the parameters of the operation mechanism so as to eliminate the cause of the error, and thus, in any case, the desired adjustment is performed. The positioning accuracy can be achieved, and the work time for the initial adjustment of the work positioning device can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the configuration of a work positioning device used in an embodiment of the method of the present invention, FIG. 2 is a circuit diagram illustrating the configuration of a control circuit of the work positioning device of the same example, and FIG. 4 is a flowchart showing a control program according to an embodiment of the invention method. 4 Work positioning device (locator) 11, 12, 18 Servo motor 50 Servo control circuit 56 Encoder 57 Controller 58 Vibration pickup

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23P 19/04 G05D 3/12 B25J 9/10

Claims (1)

(57) [Claims] When the parameters of an operation mechanism of a work positioning device are initially adjusted, vibration of the work positioning device is detected by vibration detection means, and operation speed is detected by speed detection means. , Determine whether normal operation is possible in the low-speed range, and if normal operation is possible, determine whether there is an undershoot or overshoot of the speed characteristic or the presence of predetermined high-frequency vibration or low-frequency vibration in the medium-speed range and high-speed range. Then, at least one of the acceleration / deceleration, the position loop gain, and the speed loop gain as the parameters is reduced, and it is determined whether or not a predetermined positioning accuracy is achieved when operating in this state. If the positioning accuracy cannot be obtained, the actuator is restarted with the acceleration / deceleration increased, and the specified positioning accuracy is obtained. It is determined whether or not is achieved.If the predetermined positioning accuracy is not obtained, the state where the acceleration / deceleration is increased is canceled, and then the operation is performed again with the speed loop gain increased. It is determined whether or not a predetermined positioning accuracy is achieved.If the predetermined positioning accuracy is not obtained, the state in which the speed loop gain is increased is canceled and then finely adjusted in a direction to loosen the positioning accuracy. In the state, it is determined whether or not the finely adjusted positioning accuracy is achieved. If the finely adjusted positioning accuracy is not obtained, the acceleration / deceleration is increased until the finely adjusted positioning accuracy is obtained. Alternatively, an initial adjustment method for a work positioning device, characterized by repeatedly increasing the speed loop gain.