JPS63245389A - Method of controlling robot - 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 OBJECTS OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of controlling a robot that can detect an abnormality and issue a warning or stop operation 1-.

(Prior Art) A typical industrial robot is composed of a plurality of arms, wrists, hands, etc., each of which is driven by a dedicated motor. On the other hand, the controller includes memory and a microprocessor.

A driver etc. is provided to directly control each motor, and a microprocessor retrieves position information and operation program information stored in memory, and controls the motor via each driver based on this information. I have to.

By the way, recent industrial robots are becoming faster.

There is a demand for higher acceleration, and on the other hand, there is a tendency for it to be applied to more advanced work, and as a result, complex linked operations with peripheral devices are increasingly required. In such a vehicle, a slight timing difference may cause the arm to collide with a peripheral device during driving.

Therefore, a current detection function is added to each driver to detect the current value flowing through the motor, and by comparing the current value with the rated current value of the motor, it is detected that the arm is locked due to a collision, etc. I try to do that.

(Problem to be Solved by the Invention) However, in the method described above, in which the current value flowing through the motor is compared with the rated current value, the arm collides with peripheral equipment and is completely locked from moving further. However, there is a problem in that it is not possible to detect abnormalities in the motor or drive system that would eventually lead to the robot becoming inoperable. Ta.

The present invention has been made in view of the above circumstances, and its purpose is to detect abnormalities such as collisions with peripheral equipment and stop the operation.
- It is an object of the present invention to provide a robot control method that can detect abnormalities in motors and drive systems at an early stage.

[Structure of the Invention (Means for Solving the Problems)] The robot control method of the present invention is based on the fact that the actual torque of the motor that is the driving source of the arm and the actual torque of the output shaft of the reducer connected to this motor are The detection means detects the motor torque, the output shaft actual torque, the ratio of the motor actual torque to the output shaft actual torque are detected by the arithmetic processing means, and the motor setting torque and output shaft setting are stored in advance in the memory. torque.

The system is characterized in that it is compared with a set torque ratio and, based on the comparison result, a warning or an operation stoppage is issued.

(Operation) While the arm is operating, the motor actual torque, output shaft actual torque, and their ratio are constantly compared with the motor set torque, output shaft set torque, and set torque ratio.

If the actual motor torque, output shaft actual torque, and their ratio exceed the motor set torque, output shaft set torque, and set torque ratio, it will be determined that there is an abnormality and the operation will be stopped or a warning will be issued. be. When a warning is issued, inspection and repair can be carried out at an appropriate time based on the warning, resulting in a long service life and constant operation at a high performance level.

(Example) An example in which the present invention is applied to an articulated robot will be described below with reference to the drawings.

First, as shown in FIG. 2, an articulated robot consists of a rotating arm 2 provided on a fixed base 1, and
It is composed of a plurality of rotating arms 3 which are sequentially connected to each other, and a wrist portion 4 is provided at the tip end of the arm. Each arm 2.3 and wrist portion 4 is driven by a dedicated motor 5, and the rotation of the motor 5 is reduced by a speed reducer 6 and transmitted to each arm 2.3 and wrist portion 4. Ru. A hand (not shown) provided on the wrist 4 is moved three-dimensionally by the movement of the arm 2.3 and the wrist 4. The robot configured in this way is controlled by a controller 7.

As shown in FIG. 3, this controller 7 directly controls a memory 8 that stores the coordinate values and operation programs of the movement paths of each arm 2 and 3, a microprocessor 9 as an arithmetic processing means, and each motor 5. The driver 10 and the like are provided. The microprocessor 9 manually inputs a speed command value to the driver 10 based on the contents stored in the memory 8, and the driver 10 controls the motor 5 based on the command value.
It controls the In this case, driver 1
0 includes a speed feedback circuit, and controls the speed of the motor 5 using position information fed back from a position detector 11 provided on the motor 5 and speed information obtained from the speed feedback circuit based on this position information.

On the other hand, the driver 10 is provided with a torque detection means for detecting the actual torque of the motor 5 by current detection, and the actual torque signal of the motor 5 detected by the motor torque detection means is manually inputted to the microprocessor 9. ing. Further, a torque sensor 12 serving as a torque detection means for detecting the actual torque of the output shaft 6a is provided on the reducer 6 side that decelerates the rotation of the motor 5 and transmits it to the arms 2 and 3. Output shaft detected by
The real I/L signal of 6a is inputted to the microprocessor 9 via the A/D converter 13.

Then, the microprocessor 9 calculates the motor actual torque, the output shaft actual torque, and the ratio of these actual torques from the motor actual torque signal and the output shaft actual torque signal, and calculates this and the motor setting torque stored in the memory 8. , the output shaft setting torque and the ratio of these setting torques are compared, and an abnormality is detected based on the comparison result. The abnormality detection will be explained below.The abnormality detection method is for each arm 2.3.
Since the same is true for the - arm, only the - arm will be explained here.

First, when the arm makes one movement, as shown in Fig. 4, the rotational speed of the arm increases with approximately constant acceleration (acceleration stroke) from a stopped state, and when it increases to a predetermined speed, the speed increases. It exhibits a rotation mode in which the motor continues to rotate at a constant speed (a constant speed stroke), then decelerates at a substantially constant deceleration (a deceleration stroke), and then comes to a stop (a stop stroke). As shown in FIG. 4, the torque of the motor 5 and the torque of the output shaft 6a of the reducer 6 corresponding to such a rotation mode are relatively large in the acceleration stroke to accelerate against the inertial force of the arm. In the constant speed stroke, it shows a relatively small positive value that can maintain a constant speed against friction in the drive system, and in the deceleration stroke, it shows a negative value to decelerate against inertia force. value, and in the stop stroke, the output shaft 6 is connected from the arm side.
a and the torque acting on the motor 5. The actual output shaft torque is more accurate than the motor torque, but since it is directly proportional to the motor torque, it is shown superimposed on the motor torque curve.

For the motor torque, output, and torque that exhibit these characteristics, a tolerance range within which normal operation is considered to be established for each stroke is set, and the 1U limit value and upper limit value of that tolerance range are determined for each stroke. Both the motor torque and the output shaft torque are stored in the memory 8. Regarding the limit value of the motor torque for each stroke, TM- is replaced by an Arabic numeral indicating the step (1 for IJll speed stroke, 2 for constant speed stroke, 3 for deceleration stroke, 4 for stop stroke) and the upper and lower Alphabet indicating which limit value it is (U for upper limit, d for addition/subtraction value)
are expressed as subscripts in order, and for the output shaft torque, T
Next to s, the same subscript as above is added and expressed.

Also, the maximum allowable torque T of the motor 5 is independent of each stroke.
M-maX and maximum allowable torque TS-m of output shaft 6a
) IX is also stored in the memory 8, and the two limit values Ku, lower limit value Kd, and maximum allowable value KmaX of the ratio of motor torque to output shaft torque when operating normally are stored in the memory 8.
Let me remember it.

The abnormality detection operation is performed by a program stored in the memory 8 according to the flowchart shown in FIG. That is, assume that the robot starts operating and the motor 5 enters an acceleration stroke. Then, first, processing step S1
, the maximum allowable values T M-max and TS-m of the motor torque and output shaft torque stored in the memory 8
ax, both limit values of motor torque and output shaft torque in acceleration stroke T M-1u, T M-1d and T5-Lu, T5-1d, motor 5 and output shaft 6a
The maximum permissible value Kmax and both limit values Ku and Kd of the torque ratio between the two are input to the microprocessor 9, and the actual torque TM- of the motor 5 is input from the motor torque detection means and the output shaft torque detection sensor 12 (not shown). The LOD and the actual torque T S-1,OD of the output shaft 6a are manually input to the microprocessor 9.

Next, in judgment step S2, the absolute value of the motor actual torque I T
M-1,01) l and motor torque maximum allowable value T M-
maX is compared. l TM-LOD l > T
If M-max, the absolute value of the output shaft actual torque ITS-LOD is determined in judgment step S3 according to the flow of rYESJ.
l and the output shaft maximum allowable torque T S-max are compared, and if ITL-L (month) 1 ≦ T S-max, it is determined that there is an abnormality in the motor torque, and a display (not shown) is displayed according to the flow of rNOJ. "Motor torque abnormality (A)" is displayed and the robot operation is stopped. ITs-1,
01) If 1>T S-max, it is determined that the arm is locked, and according to the flow of rYEsJ, "arm lock" is displayed on the display (not shown), and the operation of the robot yh is stopped. IT in judgment step S2
If it is determined that M-1,0D I≦T M-maw, the process moves to the next determination step S4 according to the flow of "No".

In this judgment step S4, the motor actual torque TM-1,
01) is less than the upper limit value TM-1u of the motor torque and exceeds the lower limit value TM-1tJ. TM
-LOD≧T M-1u or T M-LOD≦T
If it is M-1d, it is determined that the motor torque is abnormal,
Following the flow of "NO", "Motor torque abnormality (B)" is displayed on the display (not shown), and the next processing step S
Move to 5. Also, T M-1d< T M-LOD
<TM-1u, the process moves to the next processing step S5 following the flow of rYESJ.

In processing step S5, the motor actual torque T M-1,O
To find the ratio K between D and the actual output torque T 5-Lot), the following calculation is performed: It is determined whether or not the IKI＞
In the case of Kmix, following the flow of rYESJ, "reduction gear abnormality" is displayed on a display (not shown), and the operation of the R robots is stopped. Further, if IKI≦K11laX, the process moves to the next judgment step S7 according to the flow of rNOJ.

In judgment step S7, the absolute value of the actual torque ratio IK1 or I
・It is judged whether or not the lower limit value Kd of the torque ratio is exceeded and less than the upper limit value K u, and whether l K l≦K d or II (1
If ≧Ku, it is determined that the efficiency of the reducer 6 has decreased, and following the flow of “NO”, a display (not shown) will display “
"Reducer efficiency deteriorated" is displayed and the process moves to the next judgment step S8. In the case of Kd<IKI<Ku, the process proceeds directly to the next judgment step S8 according to the flow of rYEsJ. In judgment step S8, ■force axis actual torque T5-LOl
) exceeds the upper limit value TS-1d and the upper limit (LTSlu un;
-1d or TS-LOI)≧TS-1u, it is determined that there is an overload, and "overload" is displayed on a display (not shown) according to the flow of rNO'J, and the original data manual processing step Sl Return to Also, T
If 5-1d<T5-LOD<T5-1u, the process returns to the original data input processing step S1 according to the flow of rYESJ. The abnormality detection operation as described above is during the acceleration process.
This is constantly repeated during the constant speed stroke, deceleration stroke, and stop stroke, and depending on the type of abnormality, a warning is displayed on the display or the operation of the robot is stopped.

According to this embodiment, during operation of the robot, the motor actual torque T M-LOD and the output shaft actual torque TS-1
, OI), and the maximum allowable motor torque value TM-max and the maximum allowable output shaft torque value T S-max for these torque ratios.
x and the maximum permissible torque ratio value Kmax, and if the former value exceeds the latter value, the arm is locked (such as when the arm collides with a peripheral device and comes to a complete stop) or decelerated. Safety is improved because operation is stopped in the event of an abnormality (damage to the reducer, etc.). Moreover, while the robot is operating, the motor actual torque T M-LOD,
Constantly check whether the output shaft actual torque T 5-LOD and the torque ratio K are within the allowable range,
If the allowable range is exceeded, the robot will either not be stopped, or a warning will be issued with a message such as ``abnormal motor torque,'' ``deterioration of reducer efficiency,'' or ``overload,'' resulting in the robot becoming inoperable. It is possible to detect in advance any abnormality in the motor 5 or abnormality in the speed reducer that is likely to occur, and to perform inspection and repair at an appropriate time, making it possible to extend the life of the robot and maintain high performance.

In the above embodiment, if there is an abnormality in the judgment step S4, only the display may be performed or the operation may be stopped.If the arm lock state occurs in this way, This can be detected instantly and the operation can be stopped. This is because motor torque detection directly detects the current value, so compared to detecting arm lock using the maximum allowable motor torque value (large current value), acceleration, constant speed, deceleration, and This is because there is no time delay and arm lock can be detected instantaneously by detecting the motor torque at the permissible upper limit value and permissible lower limit value (current value smaller than the maximum permissible value) in each stroke of the stop.

[Effects of the Invention] As explained above, according to the robot control method of the present invention, when an abnormality such as arm lock or reduction gear damage occurs, operation of the robot can be stopped, improving safety. It also detects and issues warnings about motor abnormalities and drive system abnormalities that would eventually cause the robot to become inoperable, allowing inspection and repair to be carried out at an appropriate time and extending the lifespan of the robot. Maintaining high standards for conversion and performance II
It is possible to obtain the excellent effect of becoming J-noh.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a flowchart, FIG. 2 is a schematic diagram showing the overall configuration of the robot,
FIG. 3 is a block diagram for controlling the robot, and FIG. 4 is a characteristic diagram showing the relationship between motor rotational speed and torque in one operation of the robot. In the figure, 2 is a rotating arm, 3 is a movable arm, 4 is a part of the wrist, 5 is a motor, 6 is a reducer, 6a is an output shaft, 7 is a controller, 8 is a memory, and 9 is a microprocessor (arithmetic processing means) , 12 is a torque sensor (torque detection means). Applicant Toshiba Corporation Figure 2

Claims (1)

[Claims] 1. The actual torque of the motor that is the drive source of the arm and the actual torque of the output shaft of the reducer connected to this motor are detected by the torque detection means, and these motor actual torque, output shaft actual torque, and motor The ratio between the actual torque and the output shaft actual torque is compared with the motor setting torque, output shaft setting torque, and setting torque ratio stored in memory in advance, and a warning or operation stop is executed based on the comparison result. A robot control method characterized by the following.