JPS584390A - Inhibition system for uncontrolled motion - 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 The present invention relates to a method for suppressing line runaway according to the present invention, and particularly relates to a method for suppressing line runaway in an articulated robot in which each arm is drive-controlled by a speed control method.

For example, as shown in FIG. 1, the robot has a plurality of arms la, lb, and io. Each is rotatably attached and has 4 joints.
ab, 4bO is formed. And each axis 3a, 3b,
3cKas servo motors (not shown) are attached, and commands are given to each servo motor from an arithmetic processing device such as a computer to control the robot so that it performs desired movements.

There are two control methods for controlling the motion of this robot: one is a control method in which the rotation angle of the nine servo motors provided on each axis, that is, the movement position of each link, is given as a command, and sequential positioning is performed according to this command; There is a speed control type control method in which a servo motor is driven according to a speed commanded by an arithmetic processing device such as a computer, that is, a joint angular speed. The speed control type control system has become widely used because the robot can move at a higher speed and smoother than the sequential positioning type control system9.

However, if the arithmetic processing unit stops its operation for some reason, in the case of a robot that uses a sequential positioning control method, even if the arithmetic processing unit instructs the next position to be positioned and stops, the robot Since the robot will stop at that position, runaway problems will not occur.However, in the case of a robot with a speed control type control system, the processing unit will suddenly stop executing the next speed command after commanding a certain speed. In this case, the robot does not immediately stop its movement, but instead faithfully executes its movement according to its last speed command, causing a dangerous situation in which it loses its control function and goes out of control to the limit of its movement. A situation arises.

Processing unit operates normally1. If so, the arithmetic processing unit monitors the position of the robot, that is, the angle of each joint, and based on this, it sequentially commands acceleration and deceleration.
Although it is possible to prevent such reckless behavior from occurring,
Unless there are zero accidents in which the arithmetic processing unit stops executing, safety cannot be guaranteed. However, in the past, such problems were not considered,
Therefore, the countermeasures could not be said to be sufficient.

There are various causes for a processing unit to stop executing, but some special ones include, for example, during the development of a program to instruct a robot, execution may be interrupted due to a mistake in the program, or a loop may occur. There are many cases where the speed command cannot be issued because the speed command is not output. For specialized machines that only perform specific tasks, this kind of problem rarely occurs because the program development is completed once, but robots are highly versatile, so they have to be programmed many times each time the task changes. The problem is important because it is common for robot manufacturers to make changes to the robot, but not the robot manufacturer. Moreover, in recent years, sensory functions, especially important visual and tactile functions, have been added to robots in order to improve their working capabilities, and the practical use of nine robots has been progressing, but the system is extremely complex. It is predicted that there will be more accidents caused by programs running out of control with chairs, etc., and safety measures to prevent such accidents are becoming an important issue.

Therefore, the present invention effectively deals with these problems, and solves the problem of arithmetic processing devices that may occur in speed-controlled robots.

The purpose of this paper is to provide a method for suppressing runaway rounding that prevents runaway rounds due to line stops.

To summarize, in the runaway suppression method of the present invention, in a speed control tube servo control device equipped with a servo motor that is driven according to speed instruction data sequentially commanded by an arithmetic processing device, a gate means; A time limit means is provided, and if the speed instruction data of the rear side is not transmitted even after the time determined by the time limit means has elapsed, the transmission of the speed instruction data of the front side is blocked by closing the gate means, and the servo motor is It is characterized by stopping the driving of the vehicle.

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

FIG. 2 shows the configuration of an embodiment of the present invention, and FIG. 3 explains its operation.

In Fig. 2, 5 is an arithmetic processing unit, and 6 a is a servo mechanism with 40 axes (3b, 3G in Fig. 1) for each joint of the robot (4mb, 4ba in Fig. 1), and there are as many joints as there are degrees of freedom. However, one of them is shown in FIG. The servo mechanisms for the other axes also have the same configuration as the servo mechanism 6.

Servo mechanism 6 is register gate 8, lid IJ-m
It has a monostable multivibrator 9, a bias converter 10, a subtracter 11, an amplifier 12, a servo motor 13, a speed detector 14 consisting of a tacho generator, etc., and a position detector 15 consisting of a rotary encoder, etc. Of the servo mechanism 6, the servo motor 13 is connected to the shaft of each joint of the robot.

Next, the operation shown in FIG. 2 will be explained in conjunction with FIG. 3.

In order to move each arm of the robot to a predetermined position or perform a task, the arithmetic processing unit 5 sends a constant cycle TO strobe pulse 81 to the servo mechanism 6 of each axis.
1! : Speed instruction data S that commands the angular velocity of the servo motor 130 in synchronization with this strobe noculus 81! is transmitted as a digital signal.

The speed instruction data S3 transmitted to the servomechanism 6 is latched into the register 7 by the timing of the strobe pulse S1. The register clam holds this speed instruction data 83 and transmits it to the D/A converter 10 if the gate 8 is open at that time. The get 8 and retrie monostable multivibrator 90 portions are a characteristic feature of the present invention, but will be explained after explaining the operations after the D/A converter 10 to facilitate understanding.

It should be noted that if the period T of the strobe pulse 81 is short, the movement of the robot will be performed smoothly and finely. , high-speed response characteristics are required. On the other hand, if the period T is long, the arithmetic processing unit 5 only needs to have a low-speed processing capacity, and the response characteristics of the servo mechanism 6 can also be made slow, but the robot's movements will not be as smooth and detailed movements will not be possible.
Become. Therefore, the period T of the strobe conflict pulse S1 is determined based on the motion required of the robot and the performance of the device.

The D/A converter 10 converts the digital speed instruction data S3 into analog speed instruction data 8s and supplies it to the subtracter 11. Note that when the input to the D/A converter 1o is zero,
That is, the color output is configured to be zero when the speed instruction data 83 is not applied.

On the other hand, the speed detector 14 detects the rotational speed of the servo motor 130 and supplies the angular velocity signal S4 to the subtracter 11. The amplifier 12 receives a difference of 8 s between the speed instruction data Sm and the angular velocity signal 84 supplied from the subtracter 11 (Sm = 8s S
m) is amplified to control the servo motor tat, and therefore the speed instruction data S, when the actual angular velocity signal 84 of the servo motor 13 is output, the output of the amplifier tr 20 increases to control the speed of the servo motor 13. The height is controlled so that these match. Conversely, when 81<84, the output of the amplifier 12 is decreased and controlled so that the two match. In this way, the robot moves or performs tasks as instructed by the arithmetic processing unit 5.

The position detector 15 detects the position signal 86 of the servo motor 13, that is, the rotation angle, and feeds it to the arithmetic processing unit 5.
, p<F. The arithmetic processing unit 5 is a servo motor 13
The position of each arm of the robot is calculated from the position signal S- of It is also transmitted to the servo mechanism 6.

When a robot moves on a certain trajectory, for example, when performing uniform wire-making motion between two points in a three-dimensional space, the angular velocity of each joint of the robot is generally not constant, but changes from moment to moment. It is necessary to calculate the angular velocity that each servo motor should take one by one, and then issue a command to each servo mechanism.

However, if some abnormality occurs in the arithmetic processing unit 5 and the strobe pulse S1 and the speed instruction data sm cannot be transmitted to the mechanism 6 at time t3 of the third IIl, the register fK is stored at the previous time tLD. If the output speed instruction data 5s (ts) is held, the speed instruction data am (tm) will continue to be sent to the servo controller 13. For this reason, the servo motor 13 of each axis will continue to move at the speed Ss (tm), so
If things continue like this, the robot will go out of control and go out of control.

However, as shown in FIG. 2, a gate 8 and a lidric acid source monostable multivibrator 9 are provided to prevent such runaway.

That is, when the strobe pulse s1 is applied to the redrip monostable multipipe rake 9, it outputs a gate pulse with a constant width TW, as shown at 81 in FIG. The pulse width TV of this gate pulse S1 is
As shown, the period T of the strobe pulse 8 is also selected to be long.

As is well known, the Litorisen monostable multivibrator 9 is treed to generate a gate pulse Sv (logic "1").
When the pulse width TW is generated, if it is retriggered within the time of the pulse width TW, TW will continue from the time of this retrigger as the starting point.
It operates to generate a gate pulse S7 for a period of time. Therefore, when the arithmetic processing unit 5 operates normally and the strobe pulse S1 is reliably generated at every cycle T and the retrieval signal is applied to the monostable multivibrator 9, the retrieval signal is applied to the monostable multivibrator 9 as the gate pulse. S? (logic "1") is generated continuously to turn on the gate 8.

When the arithmetic processing unit 5 is operating normally, the strobe pulse S1 is reliably generated every cycle T, the gate 8 is always on, and the speed instruction data SaD/A converter in the register τ is 10, and the speed of the aforementioned servo motor 13 is controlled.

Next, at time tlt in Fig. 3, it operates normally and the strobe
Pulse S, and speed instruction data8. If the arithmetic processing unit 5 that had been generating the error becomes abnormal for some reason and the strobe pulse Sl is not transmitted even at time tlO in FIG. The starting point is low level (logic “0”) after the time TW.
”) and turn off gate 8. As a result, the speed instruction data 82 ('h) held in the register 7 is not transmitted to the D/A converter 10. Therefore, as described above, since the output S3 of the D/A converter 10 is configured to be zero, the servo motor 13 is controlled so that its speed becomes zero and stops immediately, which may cause runaway. can be prevented from occurring.

Further, the signal by which the monostable multivibrator 9 is trigged is not limited to the strobe pulse S1, but may be any signal as long as it is generated together with the speed instruction data S3.

As explained above, according to the present invention, when an abnormality occurs in the arithmetic processing unit and the predetermined speed instruction data S is not sent out, this is promptly detected and the rotation of the servo motor is immediately stopped, thereby controlling the robot. It is possible to prevent depression due to disability.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of a robot arm, FIG. 2 is a configuration of an embodiment of the present invention, and FIG. 3 is a timing chart illustrating its operation. In the figure, la, lb, and lc are 7-m and 2's2b, respectively.
are the ends of the arms, 3b and 3a are the shafts, and 4
mb, 4bo are joints, 5 is an arithmetic processing unit, 6 is a servo mechanism, 7 is a register, 8 is a gate, 9 is a monostable multi-pipe rake, 10 is a D/A converter, 11
12 is a subtracter, 12 is an amplifier, 13 is a servo motor, 14 is a speed detector, and 15 is a position detector. Patent applicant: Fujitsu Limited 1 Patent attorney Akira Yamatani: Figures 1-3

Claims (1)

[Claims] 0) In a speed control panel servo control device equipped with a servo motor that is driven according to speed instruction data sequentially commanded by an arithmetic processing unit, a gate means and a time limit means are provided to control the speed instruction data of the downstream side. If the speed instruction data is not transmitted even after the time determined by the time limit means, the gate means is closed to prevent the transmission of the previous speed instruction data;
A runaway suppression method characterized by stopping the drive of the servo motor.