JPH11188679A - Robot device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a robot which can facilitate speed control and taking measures against both faults caused by long heat exposure and short heat exposure by a joint driving motor in speed control work. SOLUTION: A load factor which is a value having a prescribed positive correlation to the generated heat or temperature of respective motors is calculated in prescribed timing during the operation of a working routine (S121), and is outputted to the outside in a prescribed timing during the operation of a working routine (S122). It is thus possible to provide a robot which can facilitate speed control and taking measures against both faults caused by long heat exposure and short heat exposure by a joint driving motor in speed control work.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot apparatus, and more particularly to teaching and adjusting a robot.

[0002]

2. Description of the Related Art In a four-axis type or six-axis type robot device, a work routine for determining the operation of the robot device repeatedly executes a predetermined cycle operation consisting of a number of step operations at a constant cycle time. At the same time, it is common to perform an unsteady operation such as a cycle stop under special operating conditions.

In order to optimize the work routine, in other words, to speed up the work routine, after learning the work routine, the execution speed of each step operation constituting the cycle operation is reduced in order to further improve the productivity. Conventionally, a cycle adjustment (speed optimization) work for optimizing (speeding up) is performed to reduce a cycle time to a required time level.

[0004]

However, the speed adjustment operation described above must be performed at less than the short-term or long-term allowable maximum load rate of the motor driving each joint. This is because the speeding up of each step operation causes heat generation of the motor driving each joint and a rise in temperature due to the heat generation. When this temperature rise exceeds a predetermined value, thermal degradation of the electrical insulation and short-circuiting occur. This is because, since a thermal failure occurs, it is necessary to shorten the cycle time by speeding up the step operation within a range in which the thermal failure does not occur.

There are two types of thermal failures in the motor: short-term thermal failure due to short-time, large-current application, and long-time thermal failure caused by accumulation of heat due to long-term application of a smaller current.
Further, the relationship between the shortening of each step operation and the increase in the above-mentioned thermal damage is extremely complicated and theoretical analysis is difficult. At present, a work routine consisting of a large number of cycle operations is repeatedly performed for a predetermined time by trial and error. After the implementation, the robot apparatus is stopped to check the degree of thermal damage.

Of course, it is easiest to investigate the degree of thermal damage by installing a large number of temperature sensors at each part of the motor and monitoring the output thereof. Difficult in terms of cost. Further, by utilizing the fact that the heat generation or temperature of the motor has a strong positive correlation with the accumulated value of the current flowing from the present time to a time before a predetermined time, after completing the execution of a work routine consisting of a number of cycle operations. If a function value (referred to as a load factor) corresponding to the past current history is calculated using a known functional relationship between the motor current and the heat generation amount or temperature of the motor and output to the outside, The coordinator can estimate the degree of thermal damage from the load factor.

However, the method of estimating the thermal fault using the load factor calculated and output after the end of the work routine has the following disadvantages in the above-mentioned speed adjustment work. First, in the above method, the load factor related to the past current history and having a positive correlation with the internal temperature of the motor is monitored only after the end of the work routine. The temperature tends to gradually rise with the start of the work routine and finally saturate, and the above-mentioned load factor changes accordingly, but the load factor corresponding to the vicinity of the maximum temperature of the motor is changed. In order to obtain it, a long work routine must be executed, and thereafter, only the execution speed of the predetermined step operation or the execution speed of all the step operations is uniformly adjusted based on the output load factor. And then again
It is necessary to execute the next adjustment cycle consisting of execution of a long work routine, monitoring of the load factor, and speed adjustment work, and gradually increase the execution speed until the load factor finally approaches the allowable maximum load factor. was there. That is, if the execution speed is increased too much, the load factor may exceed the allowable maximum load factor corresponding to the maximum temperature at which no thermal failure occurs, and the adjustment must be performed little by little.

In the end, the above-mentioned method has a disadvantage that a very long time is required to complete the speed adjustment operation. Secondly, in the above method, the load factor is output after a long working routine until the temperature corresponding to the load is substantially saturated. It has been difficult to monitor the short-term thermal damage that occurs in such cases. The present invention has been made in view of the above problems, and has a robot apparatus that can easily perform speed adjustment work, and can easily cope with both long-time heat damage and short-time heat damage of a motor for driving a joint in the speed adjustment work. Its purpose is to provide.

[0009]

According to the first aspect of the present invention, a load factor, which is a value having a predetermined positive correlation with the heat generation or temperature of each motor, is determined during execution of the work routine. And outputs it to the outside at a predetermined timing during execution of the work routine. With this configuration, it is possible to realize a robot device that can easily perform the speed adjustment work and can easily cope with both the long-term heat damage and the short-time heat damage of the joint driving motor in the speed adjustment work.

More specifically, in this configuration, during execution of a work routine consisting of repetition of a cycle operation,
A load factor related to the temperature of the motor is spontaneously output at a predetermined timing (for example, at predetermined time intervals or at predetermined steps). That is, since the load factor can be calculated during or immediately after the joint is operating, even if a large current temporarily flows, for example, a high-speed repetition of sudden reversal of the joint, the load factor can be calculated simultaneously with or immediately after that. It can be monitored in real time. Therefore, it is possible to predict the occurrence of the above-mentioned short-term thermal failure, and it is easy to respond to it.

Next, during the execution of the cycle operation, it is possible to estimate the load factor, that is, the degree of temperature rise, before the temperature or the load factor having a positive correlation with the temperature saturates, for example, by outputting at a certain timing. It is possible to predict in advance the temperature or its size before the temperature finally saturates, so that the above-mentioned prediction can be performed without executing the work routine until the temperature finally saturates. The speed adjustment can be performed based on the adjusted load factor, and the time required for completing the speed adjustment work can be reduced.

In a preferred embodiment, the calculation of the load factor can be performed in a predetermined period including or immediately after an operation step requiring a large current to be supplied, such as a sudden acceleration or a sudden reversal. Thus, it is possible to satisfactorily monitor the possibility of the occurrence of a short-term thermal failure. In a preferred embodiment, the load factor is calculated as a function value proportionally correlated with the temperature of a predetermined portion of the motor based on the weighted cumulative value of the current of the motor in the past. Furthermore, since the amount of current, particularly the amount of current other than that consumed during work, changes into heat, this heat that is periodically injected is released to a constant outside air temperature through a heat transfer circuit having a predetermined heat dissipation resistance. The load factor can be defined as the current temperature in the heat dissipation system. In the weighted cumulative value of the motor, it is preferable to set a function so that a current value closer to the present time has a larger weighting coefficient.

According to a second aspect of the present invention, in the robot apparatus according to the first aspect, a load factor is further calculated at a predetermined step of the work routine, and the load factor is output at a predetermined step of the work routine. I do. This makes it possible to calculate the load factor immediately after the specific large-current energizing step described above, or to calculate the load factor at each predetermined step, to detect a short-term thermal failure, It is easy to estimate the change of the load factor.

According to a third aspect of the present invention, in the robot apparatus according to the second aspect of the present invention, during the execution of the work routine including the repetition of a constant work cycle equal to each other, a period between adjacent work cycles is reduced. Outputs the load factor. With this configuration, the load factor is calculated and output at the end of a certain work cycle (cycle operation), so that the motor control controller can perform the above-described operation during a period in which the control load for controlling the joint operation is small. Calculation and output can be realized, and the processing capacity of the controller is hardly overloaded.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described based on the following examples.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a robot apparatus employing the present invention will be described with reference to a block circuit diagram shown in FIG. 1 and a flowchart shown in FIG. In FIG. 1, reference numeral 1 denotes a four-axis robot device, which includes an operation unit 11 and a control unit 12. The operating section 11 has four servo motors (hereinafter referred to as motors) 111 to 114 for driving each joint.
The control unit 12 stores the RAM, ROM, CPU, and I / O in a BU
And a buffer device 121 for power amplification for power-amplifying a motor control command output from the microcomputer device 120 and applying the amplified power to each of the motors 11 to 14 as a drive voltage. doing. The microcomputer 120 recognizes the current position of the rotor by processing a position signal from a rotary encoder incorporated in each of the motors 111 to 114, and determines the next operation amount of each of the motors 111 to 114 based on the recognized position. . The microcomputer device 120 sends and receives signals to and from the external console panel 2 with a monitor. The console panel 2 with the monitor performs the teaching of the robot apparatus 1 by playing back or transmitting a program, and also controls the operation of the robot apparatus 1. Adjustment of the work routine execution speed is performed.

The robot apparatus 1 executes a work program (work routine) stored therein. This work rule
The chin is configured to repeatedly execute a certain cycle operation unless any abnormality occurs and jumps to a special operation, and each cycle operation is completed by executing a series of step operations in a predetermined order. . The execution speed of the cycle operation can be adjusted by designating the speed of each step operation, but initially the work routine (work program)
Is set to the specified value specified by.

The speed adjusting work in this embodiment will be described below with reference to FIG. First, the work routine is executed from the beginning, and after completion of the first cycle operation (S1).
1) Calculate the load factor of each of the motors 111 to 114 and output it to the monitor-equipped console panel 2 (S12).
Thereafter, the next cycle operation is executed (S13). After the completion, the load ratio of each of the motors 111 to 114 is calculated again and output to the monitor-equipped console panel 2 (S1).
4) Hereinafter, these operations are repeated a predetermined number of times or until an external stop command is input. In the load factor calculation / output step (S12, S14), first, as shown in the flowchart of FIG. 3, a load factor is calculated (S121), and then the load factor is output to the external console panel 2 with a monitor. (S122). Each cycle operation (S11, S13) is set to about several seconds in this embodiment.

The calculation of the load factor in S121 will be described in more detail below. First, each motor 111-
The currents i1 to i4 of 114 are detected by a current sensor (not shown) provided in the buffer device 121, and are converted into digital signals by an A / D conversion circuit (not shown) provided in the buffer device 121 and periodically. Microcomputer device 1
20 is read by the interrupt routine.

The load factor is a signal amount for thermal protection of each of the motors 111 to 114.
It is sufficient that the signal amount has a positive correlation with the temperature (or the heat generation amount) of the signal 114. In this embodiment, the signal amount is calculated based on the currents i1 to i4. For example, the amount of heat generated per unit time of the motor is determined mainly by the resistance loss of the coil, ignoring frictional heat, iron loss and the like, and it is proportional to the square value of the currents i1 to i4. In addition, from the time point t0 before the predetermined time to the current time point t0.
The temperature rise amount ΔT up to 1 corresponds to the current i1 to
Assuming that the calorific value Qg which is substantially proportional to the square of i4, the calorific value variation ΔQ which is the difference between the calorific value Qd during this period, and the average heat capacity of the motors 111 to 114 are C,
It can be considered that ΔT = ΔQ / C. Since the temperature can be estimated by integrating the temperature change amount ΔT per unit time, it can be used as the load factor. Note that the heat release amount Qd within a unit time is determined by the heat capacity C,
It can be calculated as a function of the heat dissipation resistance Tr, the temperature difference Tx with the outside, and the like.

Further, only the current integrated value within the immediately preceding cycle operation time is output as the load factor to the monitor-equipped console panel 2 or the outside, and based on each current integrated value read externally, A similar temperature estimation program may be executed. Further, even if only the current integrated value within the immediately preceding cycle operation time is externally monitored as the load factor, it is extremely useful for speed adjustment work than when there is no information on the temperatures of the motors 111 to 114. Become.

Further, the motor knows the short-term allowable maximum current accumulation value and the long-term allowable maximum accumulated current value which do not cause the short-term thermal fault and the long-term thermal fault as described above. . For example, the short-term allowable maximum current accumulated value refers to a current accumulated value for several seconds, and the long-term allowable maximum accumulated current value refers to a current accumulated value for a few minutes at a substantially constant current. Therefore, the current integrated value for the immediately preceding short period (for example, several seconds) and the current integrated value for the immediately preceding few minutes are calculated during the execution of the work routine, further calculated as much as possible during the execution of the work routine, and output immediately. This makes it possible to compare these current integrated values with the above-mentioned short-term allowable maximum current cumulative value or long-term allowable maximum cumulative current value, thereby facilitating speed adjustment work for operating at the maximum possible speed below the usage limit. Can be performed. For example, if the difference is still large, the operation speed of the work routine may be greatly reduced, and if the difference is small, the operation speed of the work routine may be gradually reduced.

FIG. 4 is a flow chart showing a modification of this embodiment.
This will be described with reference to a chart. In this modification, the load factor is calculated and output in a predetermined operation step during the execution of the cycle operation. First, the load factor is calculated in S200, and the load factor calculated in the next S300 is calculated. Output. Here, the two steps are separated so that other operation steps of the work routine can be easily executed therebetween.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a robot device according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the robot apparatus of FIG. 1;

FIG. 3 is a flowchart showing a load factor calculation and output operation of FIG. 2;

FIG. 4 is a flowchart showing a modification of the load factor calculation and output operation of FIG. 2;

[Explanation of symbols]

1 is a robot device, 2 is a console panel with a monitor (external), 111 to 114 are motors, 120 is a microcomputer device (load factor calculating means, load factor output means), S121,
S200 is a load factor calculation unit, and S122 and S300 are load factor output units.

Claims (3)

[Claims] 1. A robot apparatus comprising: a plurality of joints each driven by a motor; and control means for controlling a movement of the joints to execute a predetermined work routine in the order of steps. The control means detects a physical quantity related to heat generation or temperature of each of the motors, and determines a load factor, which is a parameter having a positive correlation with heat generation or temperature of each of the motors, based on the physical quantity. Load factor calculation means for calculating at a predetermined timing during execution of the work routine; load factor output means for outputting the calculated load factor to the outside at a predetermined timing during execution of the work routine; A robot device comprising: 2. The robot apparatus according to claim 1, wherein said load factor calculating means calculates said load factor in a predetermined step of said work routine, and said load factor output means outputs said work routine. Outputting the load factor in a predetermined step. 3. The robot apparatus according to claim 2, wherein said load factor output means is a period between adjacent work cycles during execution of said work routine comprising repetition of a fixed work cycle equal to each other. Wherein the load factor is calculated and output.