JPH0430205A - Robot controller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a control device for a horizontal articulated robot, particularly an industrial robot equipped with a vertical motion axis and a horizontal motion axis.

More specifically, first the vertical movement axis starts to move and lifts the object grabbed by the hand in the vertical direction, then the horizontal movement axis starts to move and rotates the hand in the horizontal direction,
After that, in the assembly robot 7), which uses the movement of the vertical movement axis to vertically lower the object it has grabbed and place it in a predetermined position, when the vertical movement axis first starts moving, A robot control device that enables high-speed operation by estimating the current load (the weight of the hand and the object held by the hand) and increasing or decreasing the acceleration/deceleration of subsequent movement of the movement axis accordingly. It is related to.

[Prior Art] Although the speed of assembly robots has been increasing in recent years, the driving force of the robot's arm is greatly influenced by the weight of the object, the load of the hand that grips the object, and the amount of movement. Therefore, a robot control device has been developed that reduces takt time by increasing or decreasing the acceleration/deceleration of robot motion depending on the robot's motion path and the mass of the object, making effective use of the capabilities of the motor for driving the motion axis, etc. There is. An example of such a conventional control device is shown below.

As described in Japanese Patent Laid-Open No. 63-271613, the conventional device detects the current value of the arm drive motor using a current detection means when the arm of the robot is stationary.
The load on the robot at that time is determined by comparing the current value data stored in the storage means in advance in the current comparison calculation means with the current value data when the motor load is applied. Then, by selecting a subsequent speed pattern that matches the determined load, it is possible to safely, smoothly, and quickly operate the robot arm.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, since the motor current value is detected when the arm is stationary, it is difficult for the robot to determine whether the current value is the current value when the object is actually being lifted with the hand. cannot be determined. In other words, for example, when the robot closes the node to grasp the target part, the part is still on the parts feeder, etc., and the load is not applied to the robot at this point. When estimated, it becomes O. Therefore, it cannot be said that the appropriate speed pattern corresponding to the load is determined at any time, and the robot may mistakenly judge that the load is not increasing and shorten the acceleration/deceleration, resulting in overloading the robot. sell.

The purpose of the present invention is to maximize the ability of the motor and motor drive circuit within a safe temperature range by operating a horizontal articulated robot at an appropriate speed pattern corresponding to the load at any time, and to achieve high speed and precision. The object of the present invention is to provide a robot control device that realizes motion.

[Means for Solving the Problems] In order to achieve the above object, the present invention calculates the current value of the vertical axis drive motor when the vertical axis once descends, stops for a certain period of time, and then starts to rise. means for detecting and storing; means for detecting and storing the vertical axis acceleration at that time; means for estimating the current load at that time from the stored current value and acceleration data; The assembly robot is equipped with a means to increase/decrease the acceleration/deceleration of the robot.

[Effect]

In a horizontal articulated robot, the present invention detects and stores the current value of the vertical axis drive motor using a current detection means when the robot starts moving and the vertical axis starts to rise, and The acceleration at that time is detected and memorized by the vertical axis acceleration detection means, the current value and acceleration are used to estimate the load at that point, and the robot is accelerated/decelerated accordingly to maximize the motor's ability. It has been made available.

Since the load is estimated and the acceleration/deceleration is changed, the motor's capacity is effectively utilized, and when the load on the motor is large, the acceleration is reduced, so that the motor is not overloaded.

(Example〕 Next, the present invention will be described in detail with reference to the drawings.

FIG. 3 is a block diagram showing the overall structure of the robot node to which the present invention is implemented.

In the figure, 14 is a horizontal axis drive motor, 15 is a vertical axis drive motor, 16 is a horizontal axis pulse encoder, 17 is a vertical axis pulse encoder, 18 is a robot control device, and 19 is a horizontal axis drive motor.
1 is the teaching box, 20 is the robot body, 21
is the first arm, 22 is the vertical axis, 23 is the second arm, 24
: It is a twist axis.

In the third step, position teaching and motion sequence programs are input by key operations on the child teaching box 19. The input data is sent to the robot control device 18.
The robot main body 20 is stored in the control circuit of the controller, and the robot body 20 is operated in a programmed sequence by pressing the operation key in the test operation mode or continuous operation mode.

On the other hand, the robot main body 20 is moved by the first arm 21, which is a horizontal axis, by the controlled current from the robot throat control device 18.
, a horizontal axis drive motor 14 for driving the second arm 23 and the twist shaft 24, and a vertical axis drive motor 15 for driving the vertical axis 22.

Here, the horizontal axis drive motor 14 is controlled by a horizontal axis pulse encoder 16 and a vertical axis pulse encoder 17, which are drive motor position and speed detectors attached to each drive motor.
7) The state of the vertical axis drive motor 15 is controlled by the control device 18.
A servo control system is configured by feeding the pulse signal to the servo control system.

The robot is controlled and operated using the method described above.

The first part is a block diagram showing the internal configuration of a robot control device as an embodiment of the present invention.

In the figure, ■ is a central processing unit, 2 is a horizontal axis integrator, 3 is a horizontal axis current control circuit, 4 is a horizontal axis PWM pulse generation circuit, 5 is a horizontal axis motor drive circuit, 6 is a horizontal axis counter, 14 is a horizontal axis drive motor, 16 is a horizontal axis pulse encoder, 7 is a vertical axis integrator, 8 is a vertical axis current control circuit, 9 is a vertical axis PWM pulse generation circuit, 10 is a vertical axis motor drive circuit, 11 is a vertical axis counter , 12 is A
/D converter, 13 is a memory, 15 is a vertical axis drive motor,
17 is a vertical axis pulse encoder.

Although only one horizontal axis drive motor 14 and one horizontal axis pulse encoder 16 are shown here, each axis actually has a motor and constitutes a servo system, but they are not shown for simplicity. is omitted.

Referring to FIG. 1, the motor servo control system will first be explained using the horizontal axis as an example.

The central processing unit 1 oscillates the current command value of the horizontal drive motor 14 with a PWM (pulse width modulation) command value in order to set the current horizontal axis position state to the current position state of the horizontal axis based on the current horizontal axis position and speed feedback value, The horizontal axis integrator 2 functioning as a D/A converter converts it into an analog command value and transmits it to the horizontal axis current control circuit 3.

On the other hand, the current value of the horizontal axis drive motor 14 is fed-hacked from the horizontal axis motor drive circuit 5 as an analog signal to the horizontal axis current control circuit 3. A differential level signal between the command value and the motor current value signal from the horizontal axis motor drive circuit 5 is created and output, and the horizontal axis PWM pulse generation circuit 4 generates a PWM current command value that is proportional to the differential level signal. is transmitted, and the horizontal axis drive motor 14 is controlled and driven via the drive circuit 5.

The rotational position and speed of the horizontal axis drive motor 14 are obtained by counting the transmitted pulses from the horizontal axis pulse encoder 16 with the horizontal axis pulse counter 6, and the values are fed back to the central processing unit I and a new This constitutes a servo system that generates a current command value.

Also, regarding the vertical axis 22, a vertical axis integrator 7, a vertical axis current control circuit 8, a vertical axis PWM pulse generation circuit 9, a vertical axis motor drive circuit IO1, a vertical axis drive motor 15, a vertical axis Hals encoder 17, a vertical axis pulse The counter 11 constitutes the same servo system as that of the horizontal axis.

Furthermore, in the vertical axis servo system, the current command value of the vertical axis drive motor from the vertical axis motor drive circuit 10 is converted from an analog signal to a digital signal by an A/D converter 12, and the data bus of the central processing unit l is A circuit is provided to connect to the

Now, in one embodiment of the present invention, the acceleration/deceleration is increased or decreased depending on the load weight of the work object, etc., but the operation pattern of the assembly robot is vertical axis descent → object grip → vertical axis rise → horizontal It takes advantage of the fact that an object repeats one vertical axis upward movement, one vertical axis upward movement, and one horizontal axis movement.

The load changes here, 1, when another object is grasped and lifted (or when it is released and starts to rise), so it is immediately after the vertical axis moves. Therefore, the load is estimated by detecting the vertical axis operating current, and the maximum acceleration/deceleration is applied to that load.

Now, if you enter the continuous operation or test operation mode by operating the keys on the teaching box 19 and operate it according to the robot operation sequence program already stored in the control device, the vertical axis will descend and stop at a certain position for a certain period of time. When this is done, the central processing unit 1 determines that the robot has made an action to pick up or release the object.

Next, immediately after the vertical axis starts to rise from that position, the current value of the vertical axis drive motor is read from the vertical axis motor drive circuit 0 into the central processing unit 1 as a digital signal through the A/D converter 12, and temporarily Store the data in memory 13.

In addition, the central processing unit 1 determines the acceleration immediately after the vertical axis starts to rise, that is, when the motor current value is detected, based on the count value of the output pulse number of the vertical axis pulse encoder 17 output by the vertical axis counter 11. Calculate. here,
There are several ways to consider the current value and acceleration, such as using the value a certain time after the start of operation as the data, or using the average value within a certain time after the start of operation as the data, but here we will use the average value as the data. The method is as follows.

On the other hand, in the memory 13, a desirable acceleration/deceleration time of the horizontal axis drive is calculated in advance in correspondence with the current value and acceleration of the vertical axis drive motor 15, and is stored as a table as shown in Table 1 below.

In Table 1, t, to t, . . . indicate acceleration/deceleration times. That is, this table is used to estimate the mass of a load based on the current value and acceleration, and to find the shortest acceleration/deceleration time that can be achieved for that load.

Table 1 Now, the central processing unit l calculates the approximate values of the current value and acceleration data of the vertical axis drive motor 15 immediately after the vertical axis rises, which have already been stored in the memory 13, in the table A, -, respectively.
A, and a1 to a7, and determine the corresponding acceleration/deceleration time t.

For example, if the current value is Ao and the acceleration is a7, the acceleration/deceleration time at that time is to.

Now, the central processing unit 1 processes the servo system of each axis at regular intervals, and from the processing of the servo system of the horizontal axis after determining the acceleration/deceleration time, the central processing unit 1 processes the speed pattern based on the acceleration/deceleration time. The first arm 21 and the second arm 2 are horizontal axes.
Control 3.

Note that the maximum speed is limited to the speed specified in the robot operation sequence program, and will not exceed this speed.

Next, the increase and decrease in speed of the robot in the embodiment of the present invention will be explained with reference to FIG. 2.

FIG. 2 is a speed pattern diagram showing how the speed of the robot changes over time by implementing the present invention.

Here, the robot will be described as having an operation pattern in which the vertical axis first moves up, and then the horizontal axis moves.

In FIG. 2, the vertical axis movement pattern VP takes the movement pattern as shown in the figure, whereas the horizontal axis movement pattern that starts the movement thereafter is pattern a or pattern b.
It shows that it will be as follows. That is, when the vertical axis starts to operate, the load is estimated, and the acceleration/deceleration pattern for the horizontal axis to be operated next is determined, for example, pattern a or pattern b. The horizontal axis that starts moving next moves according to the determined pattern.

This will be explained in detail below.

When the robot moves, the vertical axis that starts moving first moves according to the movement pattern VP, but at the beginning (speed pattern determination period), the acceleration/deceleration pattern of the horizontal axis that should move next is determined. . That is, vertical axis 2
During the speed pattern determination period immediately after the vertical axis drive motor I5 starts increasing, the central processing unit W1 detects the current value and acceleration of the vertical axis drive motor I5, and determines the desired acceleration/deceleration time t from the table in the memory 13. .

Next, the load corresponding speed pattern period in FIG. 2 is the operation period of the horizontal movement axis due to the acceleration/deceleration determined as described above. For example, when the current value of the vertical axis drive motor 15 is small and the acceleration is large, Case (near (AI, a,) in Table 1)
means that the load applied to the vertical axis 22 is small, so pattern a (acceleration/deceleration time t) in Fig.
When the throat (horizontal axis) moves rapidly and, conversely, the current value of the vertical axis drive motor 15 is large and the acceleration is small ((A in Table 1)
. Note that the determined acceleration/deceleration time is maintained at the determined value until the vertical axis is newly raised.

As described above, according to this embodiment, the acceleration and deceleration of the robot increases or decreases depending on the mass of the target workpiece, which is the load on the robot, so that the motor's ability is always fully demonstrated, and the load can also be detected. Even when grasping an object, detection is performed after the vertical axis begins to move, so detection can be performed with high accuracy, and this is highly effective in providing a robot that is safe and has a short takt time.

The above explanation has been made on the assumption that the horizontal axis to be operated next operates in accordance with pattern a or b substantially determined in the initial velocity pattern determination period of the vertical axis operation pattern VP in FIG. However, since pattern a or b is substantially determined during the initial velocity pattern determination period of the vertical axis motion pattern VP,
The subsequent vertical axis movement pattern itself is pattern a or b.
In this way, it is possible to rationalize the robot's operation.

〔Effect of the invention〕

According to the present invention, in order to control the acceleration/deceleration of the next operation depending on the magnitude of the load such as the mass of the workpiece of the horizontal articulated assembly robot, the acceleration and deceleration of the next operation is controlled within the safe temperature range of the robot drive motor and motor drive circuit. It is possible to easily draw out the capabilities of robots and create high-speed, highly safe robots.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the circuit configuration of a robot control device as an embodiment of the present invention, FIG. 2 is a diagram of the operating speed pattern of the robot in an embodiment of the present invention, and FIG. 3 is an object of implementation of the present invention. 1 is a perspective view showing an outline of the configuration of a graduation robot. Explanation of symbols 1...Central processing unit, 2...Horizontal axis integrator, 3
...Horizontal axis current control circuit, 4...Horizontal axis PWM pulse generation circuit, 5...Horizontal axis motor drive circuit, 6.
・Horizontal axis counter, 7... Vertical axis integrator, 8... Vertical axis current control circuit, 9... Vertical axis PWM pulse generation circuit, 10... Vertical axis motor drive circuit, 11...
Vertical axis counter, 12... A/D converter, 13...
Memory, 14...Horizontal axis drive motor, 15...Vertical axis drive motor, 16...Horizontal axis pulse encoder, 1
7...Vertical axis pulse encoder, 18...Robot ill? Il outfit! , 19... Teaching box, 20... Robot body, 21... First arm,
22... Vertical axis, 23... Second arm, 24...
Twist Axis Agent Patent Attorney Akio Namiki Diagram - Calendar

Claims (1)

[Claims] 1. The device includes a vertical operating axis driven by a motor and a horizontal operating axis driven by a motor, and the vertical operating axis starts operating first, and then the horizontal operating axis starts operating. In the industrial robot according to the present invention, after the start of the operation of the vertical movement axis, means for detecting a current value of a motor driving the vertical movement axis and an acceleration of the movement of the vertical movement axis, and a means for detecting the detected motor current value. and means for estimating the magnitude of the load applied to the vertical motion axis from the acceleration of the vertical motion axis and determining the corresponding acceleration/deceleration time; A robot control device comprising: means for increasing/decreasing acceleration/deceleration of motion of a motion axis.