JP2005254410A - Brake performance detecting method and brake performance detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake performance detecting method and a brake performance detecting device capable of simply and accurately detecting the brake performance of a brake means. <P>SOLUTION: While braking force is added to a motor, a command signal for brake performance detection instructing the motor to operate only by predetermined operation amount is added to the motor. The change amount of the motor between before adding the command signal and after adding the command signal is detected. Therefore, driving force corresponding to gravity added to an arm can be generated in the motor, and the brake performance of a brake can be detected regardless the gravity of the arm. Even when the holding torque of the brake is lowered, the arm driven by the motor can be prevented from excessively moving and colliding to another device or work. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a braking performance detection method for detecting braking performance of braking means provided in an actuator. For example, the present invention relates to a method for detecting a brake abnormality of a servo motor mounted on an industrial robot.

  The industrial robot is equipped with a servo motor to drive the arm. The output shaft of the motor is rotatably provided and transmits driving force to the arm. The motor is provided with a brake for maintaining the posture of the arm. The brake holding torque decreases as the industrial robot is used.

  If the brake holding torque falls below the allowable torque, the posture of the arm may not be held. Therefore, it is necessary to periodically inspect whether the brake holding torque is equal to or greater than the allowable torque.

  As a first conventional technique, there is a technique for removing a motor from an industrial robot and measuring a holding torque of a brake. In this technique, a decrease in brake holding torque is determined based on a torque measurement result.

  As a second conventional technique, there is a technique for comparing the posture of the arm when the robot is stopped and the posture of the arm when removable. In this technique, it is determined that the holding torque of the brake is lowered when the posture of the arm is changed between when stopped and when it is removable due to falling of its own weight (see, for example, Patent Document 1).

  As a third conventional technique, there is a technique for detecting presence or absence of rotation of a motor when a brake is operated and a predetermined reference torque is generated in the motor. In this technique, when the motor rotates in the brake operation state, it is determined that the brake holding torque is reduced (see, for example, Patent Document 2).

JP 7-39190 A JP-A-6-246684

  In the first conventional technique, it is necessary to remove the motor from the industrial robot in order to check the holding torque of the brake. Therefore, there is a problem that the work of measuring the brake holding torque cannot be easily performed.

  In the second prior art, depending on the posture of the arm, even if the holding torque decreases, the weight may not fall. In this case, it is not possible to determine a decrease in brake holding torque. Further, it cannot be determined that the holding torque is reduced until the holding torque is reduced so that the arm falls by its own weight. Therefore, there is a problem that the decrease in holding torque cannot be accurately determined.

  In the third prior art, the motor generates a constant reference torque when detecting the holding torque of the brake. However, the torque required to rotate the arm varies depending on the posture of the arm. Therefore, only by generating a constant reference torque, the presence or absence of rotation of the motor changes in relation to the posture of the arm, and a decrease in holding torque cannot be accurately detected. In addition, the reference torque generated by the motor is constant regardless of the decrease in brake holding torque. Therefore, when the holding torque of the brake is greatly reduced, the arm may move greatly and collide with another device or a workpiece.

  Such a problem is the same even in cases other than industrial robot motors. That is, it is not possible to easily and accurately detect the braking performance of the actuator having the braking means.

  Accordingly, an object of the present invention is to provide a braking performance detection method and a braking performance detection device capable of simply, accurately and safely performing the braking performance of the braking means.

The present invention provides an actuator body that operates by an operation amount commanded by the command signal when a command signal that commands an operation amount is given, and an actuator that includes a braking means that applies a braking force to the actuator body to brake the actuator body. A braking performance detection method for detecting braking performance of braking means in
Either a braking state in which a braking force is applied to the actuator body to brake the actuator body, or a braking release state in which the braking of the actuator body is released by stopping the supply of the braking force to the actuator body, A braking state setting step for setting braking means;
An operation command step for giving a command signal for detecting braking performance to the actuator main body for commanding to operate by a predetermined operation amount in a state where the braking means is set to either one of the braking state and the braking release state;
Brake performance detection, comprising: an operation amount detection step for detecting a change in the operation amount of the actuator body before the command signal for detecting the braking performance is provided and after the command signal for detecting the braking performance is supplied. Is the method.

  According to the present invention, when the operation of detecting the braking performance is started, the braking means is set to either the braking state or the braking release state. Next, a command signal is given to the actuator body so as to operate by a predetermined operation amount. The actuator body to which the command signal is given generates a driving force necessary for moving by a predetermined operation amount.

  When the braking means is in a braking state, the actuator body hardly operates if the braking force of the braking means is sufficiently high. When the braking force of the braking means is reduced, the actuator body operates. Therefore, by detecting the change in the operation amount of the actuator body before and after giving the command signal for detecting the braking performance, it is possible to detect the degree of reduction of the braking force in the braking performance of the braking means.

  Similarly, when the brake means is in a brake release state, the actuator body operates when the brake release operation of the brake means is normally performed. Further, when an abnormality occurs in the braking release operation of the braking means, the operation amount of the actuator body is suppressed. Therefore, by detecting a change in the operation amount of the actuator body before and after giving a command signal for detecting a braking signal, it is possible to detect a braking release abnormality in the braking performance of the braking means.

  According to the present invention, the operation commanding step generates a command signal for detecting braking performance based on a posture of a movable body driven by the actuator body.

  According to the present invention, the driving force that should be generated by the actuator main body to move the movable body varies depending on the posture of the movable body. In the present invention, since the command signal for detecting the braking performance is generated based on the posture of the movable body, the command signal for moving the predetermined operation amount can be accurately generated, and the braking means regardless of the posture of the movable body. The braking performance can be detected.

  The present invention further includes a notifying step of comparing the change in the amount of operation of the actuator body detected by the operation amount detecting step with a predetermined threshold value to evaluate the braking performance and notifying the evaluation result. It is characterized by that.

  According to the present invention, when the braking performance is evaluated, the evaluation result is notified in the notification step. As a result, the operator can be made aware of the braking performance of the braking means.

  Further, the present invention is characterized in that a decrease in the braking performance of the braking means is detected immediately before the power supply to the actuator body is stopped.

  According to the present invention, it is possible to recognize that the posture of the movable body may change due to an external force when the actuator body is braked by the braking means by detecting the decrease in the braking force of the braking means. Therefore, it is possible to prevent the actuator body from moving undesirably when a braking command for the actuator body by the braking means is given.

  According to the present invention, the actuator is mounted on an industrial robot and drives an arm of the industrial robot.

  According to the present invention, the actuator is mounted on the industrial robot, and the braking means brakes the actuator body to maintain the posture of the arm. Industrial robots rarely hold arms in a fixed posture, and hold arms in different postures for different work modes. When the posture for holding the arm is different, the braking force required to maintain the posture of the arm also changes. In the present invention, since the braking performance can be detected regardless of the posture of the arm, the braking performance of the braking means can be accurately detected even when the posture of holding the arm is different.

The present invention also includes a performance degradation determination step for detecting a degradation in the braking performance of the braking means based on a change in the operation amount of the actuator body detected by the braking performance detection method and a predetermined threshold value;
A posture maintaining step of supplying power to the actuator main body in order to maintain the posture of the movable body driven by the actuator main body when a decrease in the braking performance of the braking means is detected in the performance deterioration determining step. This is a method for controlling an actuator.

  According to the present invention, when the posture of the movable body is maintained, the posture of the movable body is maintained by supplying power to the actuator body in a state where the braking force of the braking means is reduced. Thereby, even when the braking force of the braking means is reduced, the posture of the movable body can be prevented from changing.

  According to another aspect of the present invention, there is provided an actuator control method in which the actuator body is operated so as to be in a state before the command signal for detecting the braking performance is given after the execution of the braking performance detecting method.

  According to the present invention, after executing the braking performance detection operation, the actuator body is returned to the state before the braking performance is detected. Accordingly, even when the actuator is performing another operation, the braking performance detection operation can be performed, and convenience can be improved.

Further, the present invention includes an actuator body that operates by an operation amount commanded by the command signal when a command signal that commands an operation amount is given, and a braking unit that applies a braking force to the actuator body to brake the actuator body. A braking performance detecting device for detecting a braking performance of a braking means in an actuator,
An input means for receiving a braking performance detection command;
Braking performance that sets the braking means to either one of the braking state to brake the actuator body or the braking release state to release the actuator body, and commands to operate by a predetermined amount of movement in that state A control means for detecting a change in the operation amount of the actuator body before giving a command signal for detection to the actuator body and giving a command signal for detecting braking performance and after giving a command signal for detecting braking performance;
The braking performance detecting apparatus includes an output means for outputting a detection result by the control means.

  According to the present invention, the control means starts a braking performance detection operation when a braking performance detection command is given to the input means. The control means sets the braking means in either a braking state or a braking release state. Next, a command signal is given to the actuator body so as to operate by a predetermined operation amount. The actuator body to which the command signal is given generates a driving force necessary for moving by a predetermined operation amount.

  When the braking means is in a braking state, the actuator body hardly operates if the braking force of the braking means is sufficiently high. When the braking force of the braking means is reduced, the actuator body operates. Therefore, the control means can detect a decrease in the braking force in the braking performance of the braking means by detecting a change in the operation amount of the actuator body before and after giving the command signal for detecting the braking performance.

  Similarly, when the brake means is in a brake release state, the actuator body operates when the brake release operation of the brake means is normally performed. Further, when an abnormality occurs in the braking release operation of the braking means, the operation amount of the actuator body is suppressed. Therefore, by detecting a change in the operation amount of the actuator body before and after giving a command signal for detecting a braking signal, it is possible to detect a braking release abnormality in the braking performance of the braking means.

  According to the present invention, a command signal for detecting braking performance that commands to operate by a predetermined operation amount is given to the actuator body. Then, the braking performance of the braking means is detected by detecting a change in the operation amount of the actuator body. The actuator body does not operate more than a predetermined operation amount. Therefore, even when the braking force of the braking means is reduced, it is possible to prevent the movable body driven by the actuator body from moving excessively, and the movable body collides with other devices and workpieces. Can be prevented.

  Further, the actuator body generates a driving force necessary for moving a predetermined movement amount. Therefore, the performance of the braking means can be accurately determined regardless of the movable body. For example, a driving force corresponding to the weight of the movable body can be generated in the actuator body, and the braking performance of the braking means can be accurately detected regardless of the weight of the movable body.

  Further, according to the present invention, a command signal for detecting braking performance is given to the actuator body based on the posture of the movable body. Accordingly, the braking performance of the braking means can be accurately detected regardless of the posture of the movable body. For example, the braking performance of the braking means can be accurately detected even when the posture of the movable body is not fixed to one and is changed at any time. In addition, in order to perform the braking performance detection operation of the braking means, it is not necessary to move the movable body to a predetermined posture, and the braking performance detection operation can be performed in a short time.

  Further, according to the present invention, by notifying the evaluation result of the braking performance of the braking means, it is possible to notify the operator of the braking performance and to improve convenience. For example, by notifying the decrease in the braking force of the braking means, a warning can be issued before the damage due to the decrease in the braking force occurs, and the occurrence of the damage can be prevented in advance. Further, for example, the cause of the failure of the actuator can be clarified by notifying the braking release abnormality of the braking means.

  Further, according to the present invention, immediately before the power supply to the actuator body is stopped, the detection of the braking force drop of the braking means is executed. Thus, when a braking force is applied to the actuator body by the braking means, it can be recognized that the actuator body may move due to an external force, and the actuator body can be prevented from moving undesirably.

  For example, when the braking force of the braking means is reduced, it can be recognized that the posture of the movable body will change, so it is possible to take some measures against the change in posture of the movable body due to its own weight. it can.

  According to the invention, the actuator is mounted on an industrial robot, and the braking means maintains the posture of the arm. The arm of an industrial robot differs in the posture of the arm depending on the work form. In the present invention, the braking performance of the braking means can be detected regardless of the posture of the arm. As a result, the braking performance can be detected without changing the posture of the arm, and convenience can be improved. In addition, the braking performance of the braking means can be detected without removing the actuator from the industrial robot, and the braking performance can be detected easily and in a short time.

  Further, according to the present invention, when the posture of the movable body is maintained in a state where the braking force of the braking means is reduced, power is supplied to the actuator body to maintain the posture of the movable body. Thereby, even when the braking force of the braking means is reduced, the posture of the movable body can be prevented from changing. As a result, the movable body can be prevented from colliding with other devices, and the actuator can be operated even during the period until the brake unit is replaced with new braking means, thereby improving work efficiency.

  Further, according to the present invention, after executing the braking performance detection operation, the actuator body is operated so as to be in a state before the braking performance is detected. Accordingly, even when the actuator is performing another operation, the braking performance detection operation can be performed, and convenience can be improved.

  Further, according to the present invention, the control means gives a command signal for detecting braking performance to the actuator main body so as to instruct to operate by a predetermined operation amount. Then, the braking performance of the braking means is detected by detecting a change in the operation amount of the actuator body. As a result, the actuator body does not operate more than a predetermined operation amount. Thus, even when the braking force of the braking means is reduced, it is possible to prevent the movable body driven by the actuator body from moving excessively, and the movable body collides with other devices and workpieces. This can be prevented.

  Further, the actuator body generates a driving force necessary for moving a predetermined movement amount. Therefore, the performance of the braking means can be accurately determined regardless of the movable body. For example, a driving force corresponding to the weight of the movable body can be generated in the actuator body, and the braking performance of the braking means can be accurately detected regardless of the weight of the movable body.

  FIG. 1 is a flowchart showing an operation procedure of a braking performance detection method according to an embodiment of the present invention. The braking performance detection method of the present invention detects an abnormality of a brake mounted on, for example, an industrial robot.

  FIG. 2 is a perspective view showing the industrial robot 1, and FIG. 3 is a block diagram showing a part of the electrical configuration of the industrial robot 1. The industrial robot 1 (hereinafter simply referred to as the robot 1) is configured by connecting a plurality of arms 2, and each arm 2 is provided so as to be displaceable with respect to each other. As an example of the embodiment of the present invention, the robot 1 is a six-axis articulated robot, and a resistance spot welding device is connected to the tip.

  The robot 1 is equipped with an actuator 3 for each arm. The actuator 3 drives the corresponding arm 2 to be displaced. The actuator 3 includes a servo motor 6 (hereinafter referred to as a motor 6) serving as an actuator body, a brake 8 serving as a braking means, and an encoder 7 serving as an operation amount detecting means. As the output shaft of the motor 6 rotates, one of the two adjacent arms rotates relative to the other arm. In the present invention, the term “rotation” includes a state of angular displacement.

  The robot 1 includes an amplifier 4 that causes a current to flow to each motor 6 and a control unit 5 that controls the amplifier 4. The motor 6 rotates the output shaft when electric power is supplied from the amplifier 4. The driving force of each motor 6 increases as the flowing current increases. The encoder 7 detects the angular position of the output shaft of the motor 6 and gives a position detection value as a detection result to the control means 5.

  In the operating state, the brake 8 applies a braking force to the output shaft of the motor 6 to prevent the rotation of the output shaft of the motor 6. In addition, the brake 8 stops the supply of the braking force to the motor 6 and permits the output shaft of the motor 6 to rotate when the operation is released. The control means 5 can set the brake 8 to either a braking state or a braking release state by giving a command to the brake 8.

  Note that the robot according to the present embodiment has an automatic servo-off function. The automatic servo-off function will be described in detail. When the posture of the arm 2 is maintained, the control means 5 stops the rotation of the output shaft of the motor 6 by the brake 8 and then stops the current supply to the motor 6. In this case, even if an external force such as gravity is applied to the arm 2, the rotation of the output shaft is prevented by the brake 8 and the posture of the arm 2 is maintained. Thus, by eliminating the power supply to the motor 6, the power consumption of the robot 1 can be reduced.

  The braking force that the brake 8 applies to the output shaft of the motor 6, in other words, the holding torque, decreases with time. When the holding torque of the brake 8 decreases below the allowable torque, the posture of the arm 2 changes due to gravity, and the posture of the arm 2 may not be maintained. The braking performance detection method of the present invention detects whether or not the holding torque of the brake 8 is greater than or equal to the allowable torque. In other words, a decrease in the holding torque of the brake 9 is detected.

  FIG. 4 is a block diagram showing the control means 5. The control means 5 executes the braking performance detection method of the present invention. The control means 5 includes an input unit 11, an output unit 12, a calculation unit 13, and a storage unit 14. The input unit 11 receives a detection command for commanding a braking performance detection operation from an operator or the like. The input unit 11 may receive a power supply start command for starting power supply to the motor 6 and a power supply stop command for stopping power supply to the motor 6. The input unit 11 gives the input commands to the calculation unit 13.

  The output unit 12 outputs the braking performance of the brake 8 calculated by the calculation unit 13. The storage unit 14 temporarily stores a calculation program for the calculation unit 13 to execute the braking performance detection operation and data calculated at the time of calculation. The calculation part 13 reads the calculation program memorize | stored in the memory | storage part 14, and performs each procedure of a braking performance detection method one by one by executing the calculation program.

The control means 5 is realized by a computer, for example. In this case, the input unit 11 is realized by a keyboard and a switch. The output unit 12 is realized by a display device such as a display. The storage unit 14 is realized by a storage circuit such as a random access memory (RAM) and a read only memory (ROM).
It is realized by an arithmetic circuit such as Central Processing Unit.

  The control means 5 is realized as a braking performance detection device that detects the braking performance of the brake 8. The control means 5 may be provided separately for detecting the detection performance of the brake 8, but can also be realized by using a robot controller that controls the robot 1. In this case, it is only necessary to store the arithmetic program in the robot controller. Therefore, it is not necessary to add a new configuration, and the braking performance detection device can be easily realized.

  The robot 1 also includes a notification unit 9. The notification means 9 is given a signal indicating the braking performance of the brake 8 output from the control means 5 and notifies the abnormality of the brake 8. The notification means 9 is realized by display means such as a display or sound emission means such as a buzzer.

  As shown in FIG. 1, in step a <b> 0, the worker inputs a holding torque detection command for the brake 8 from the input unit 11. When a holding torque detection command is input to the input unit 11, the control unit 5 proceeds to step a <b> 1 and starts a holding torque detection operation for the brake 8. The holding torque detection operation of the brake 8 is one of the performance detection operations of the brake 8.

  In step a <b> 1, the control unit 5 operates the brake 8 to apply a braking force to the output shaft of the motor 6. Then, the motor 6 is set to a braking state, and the process proceeds to step a2. In step a2, the control means 5 generates a current setting value necessary for the motor 6 to move by a predetermined movement amount based on the position detection value given from the encoder 7, and proceeds to step a3.

  In step a3, the control means 5 commands the motor 6 to operate by a predetermined amount of movement, and proceeds to step a4. Specifically, the generated current set value is given to the amplifier 4 while the motor 6 is braked by the brake 8. The amplifier 4 passes a current based on the current set value given from the control means 5 to the motor 6.

  In step a4, the control means 5 releases the operation of the brake 8, and proceeds to step a5. As a result, the supply of the braking force to the motor 6 is stopped, and the motor 6 is set to the braking release state. In step a5, the control means 5 obtains a change in the operation amount of the motor 6, that is, a change amount in the motor 6, based on the position detection value given from the encoder 7.

  The change amount of the motor 6 is a deviation amount between the angular position of the output shaft of the motor 6 at the time of the braking operation in step a1 and the angular position of the output shaft of the motor 6 at the time of releasing the brake operation in step a4. In other words, it is the amount of change in the output shaft of the motor 6 before and after the power for holding torque detection is applied to the motor. The control means 5 compares the amount of change of the motor 6 with a predetermined slip threshold value.

  The output shaft of the motor 6 transmits the driving force to the arm 2 via the speed reducer. Further, the arm is not angularly displaced unless the output shaft of the motor 6 rotates more than a certain angle due to play by the power transmission mechanism of the robot 1. In this case, the slip threshold is set to an angle obtained by adding a predetermined margin angle to an angle corresponding to play of the power transmission mechanism.

  When the change amount of the motor 6 is larger than the slip threshold, the process proceeds to step a6. If the change amount of the motor 6 is smaller than the slip threshold, the process proceeds to step a7. The slip threshold is a change amount of the motor 6 when the holding torque of the brake 8 is the same as the allowable torque. Note that when the change amount of the motor 6 is large, the control means 5 determines that the holding torque of the brake 8 is reduced.

  In step a6, the notifying means 9 warns that the holding torque is smaller than the allowable torque value, that is, the brake 8 is abnormal, and the process proceeds to step a7. In step a7, the holding torque detection operation is terminated. In this way, the holding torque that is one of the braking performances of the brake 8 can be detected.

  According to the present embodiment, when the brake 8 is in a braking state, the motor 6 hardly operates if the holding torque of the brake 8 is sufficiently high. When the braking force of the brake 8 is reduced, the motor 6 operates. Therefore, by detecting the amount of change of the motor 6 before and after the current for detecting the braking performance is applied to the motor 6, it is possible to detect the degree of reduction of the braking force in the braking performance of the brake 8.

  In accordance with an instruction from the control means 5, the amplifier 4 supplies a current to the motor 6 so as to operate by a predetermined operation amount. As a result, the motor 6 does not operate more than a predetermined operation amount. Therefore, even when the holding torque of the brake 8 is significantly reduced, the arm 2 can be prevented from excessively moving, and the arm 2 can be prevented from colliding with other devices and workpieces. it can. Further, the motor 6 generates a driving force necessary for moving a predetermined amount of movement. Therefore, a driving force corresponding to the weight of the arm 2 can be generated in the motor 6, and the holding torque of the brake 8 can be accurately detected regardless of the gravity applied to the arm 2.

  In addition, by notifying the decrease in the holding torque by the notification means 9, it is possible to notify the operator of the decrease in the holding torque. As a result, the operator can take measures to eliminate the problems caused by the decrease in holding torque.

  In the above-described flowchart, the allowable change amount of the motor 6 when the holding torque of the brake 8 is an allowable torque that is a critical value for maintaining the posture of the arm is set as the slip threshold. The slip threshold may be another value.

  For example, the amount of change of the motor 6 when the holding torque of the brake 8 is slightly larger than the allowable torque may be set as the slip threshold. In this case, when the change amount of the motor 6 is larger than the slip threshold value in step a5, it is possible to notify the operator that the time for replacing the brake 8 is approaching. Thus, before the brake 8 needs to be replaced, a new brake 8 can be prepared, and convenience can be improved.

  The control means 5 may detect the amount of change of the motor 6 in step a5 and estimate the magnitude of the holding torque of the brake 8 based on the amount of change. Then, the replacement time of the brake 8 may be estimated from the estimation result, and the notification time may be notified by the notification means 9. This can further improve convenience.

  In step a0, it is assumed that a holding torque detection command for the brake 8 is given by an operator, and a holding torque detection operation for the brake 8 is started. As another example, in step a0, when a power supply stop command for stopping power supply to the motor 6 is given, the control means 5 detects the holding torque of the brake 8 before stopping the power supply to the motor 6. The operation may be started. Thus, the operator can determine whether or not the posture of the arm 2 can be maintained by the brake 8 before stopping the power supply to the motor 6. Thus, the operator can take a measure to prevent the arm 2 from falling by its own weight.

  FIG. 5 is a block diagram showing a control system of the motor 6 by the control means 5. When the control unit 5 is realized by the robot controller, the control unit 5 feedback-controls the motor 6 based on the position detection value b given from the encoder 7.

  Specifically, the control unit 5 includes, as a control system, a position command value setting unit 20, a first comparison unit 21, a second comparison unit 22, a third comparison unit 23, a first multiplication unit 24, A second multiplication unit 25, a differential calculation unit 26, an integration calculation unit 27, a limiter 28, and a gravity compensation unit 29 are included. Actually, the arithmetic units 20 to 27 described above realize the functions of the arithmetic units 20 to 27 by executing the program stored in the storage unit 14 by the arithmetic unit 13 of the control means 5. Can do.

  The position command value setting unit 20 sets a position command value a indicating the position to which the arm 2 should move according to the calculation program. The position command value setting unit 20 gives the set position command value a to the first comparison unit 21. The first comparison unit 21 acquires the position command value a from the position command value setting unit 20 and acquires the position detection value b from the encoder 7. The first comparison unit 21 subtracts the position detection value b from the position command value a and gives the calculation result c to the first multiplication unit 24.

  The first multiplication unit 24 multiplies the calculation result c of the first comparison unit 21 by a position gain Kp, which is a predetermined coefficient, and gives the calculation result d to the second comparison unit 22. The differential calculation unit 26 performs a differential calculation on the position detection value b given from the encoder 7 and gives the calculation result e to the second comparison unit 22.

  The second comparison unit 22 acquires the calculation result d by the first multiplication unit 24 and the calculation result e by the differentiation calculation unit 26. Then, the second comparison unit 22 subtracts the calculation result e by the differentiation calculation unit 26 from the calculation result d by the first multiplication unit 24 and gives the calculation result f to the second multiplication unit 25. The second multiplication unit 25 multiplies the calculation result f of the second comparison unit 22 by a speed gain Kv, which is a predetermined coefficient, and gives the calculation result g to the third comparison unit 23 and the integration calculation unit 27, respectively.

  The integration calculation unit 27 acquires the calculation result g of the second comparison unit 25, integrates the value, further multiplies the integration calculation result by a speed compensation gain Ki that is a predetermined coefficient, and calculates the calculation result h. Is given to the third comparison unit 23. The third comparison unit 23 acquires the calculation result g by the second multiplication unit 25 and the calculation result h by the integration calculation unit 27, adds them, and generates a current command value i. Then, the third comparison unit 23 gives the generated current command value i to the limiter 28.

  When the input current command value i is within the allowable current command value range, the limiter 28 outputs the input current command value without limitation. The limiter 28 limits and outputs the input current command value i when the input current command value i is outside the allowable current command value range. The limiter 28 gives the output current command value to the amplifier 4.

  The allowable current value command range of the limiter 28 is set by the gravity compensation unit 29. The gravity compensation unit 29 acquires the position detection value b from each encoder 7 and calculates the posture of the arm 2 based on the position detection value b. Based on the calculated posture of the arm 2, the allowable current command value range of the limiter 28 is determined.

  The control means 5 determines a current command value to be given to the amplifier 4 by the control system described above when moving the arm 2 to the target position. The control means 5 also determines the current command value to be given to the amplifier 4 by the control system described above even when performing the performance detection operation of the brake 8, for example, the holding torque detection operation.

  The position command value setting unit 20 sequentially updates the position command values in the holding torque detection operation of the brake 8. The position command value setting unit 20 sets the position command value a to a value equal to the position detection value b, and then updates the position command value by sequentially integrating the predetermined unit position command value. In other words, the position command value is updated by the unit position command value from the same value as the position detection value b before the holding torque detection operation, and the maximum position command value is calculated from the position detection value b before the holding torque detection. The position command value is updated until is reached.

  For example, the unit position command value is a command value necessary to angularly displace the output shaft of the motor 6 by 0.03 degrees. Further, the maximum position command value is a command value necessary for angular displacement of the output shaft of the motor 6 by 1 degree or a command value corresponding to an angular displacement amount necessary for moving the tip of the arm 2 by 1 mm.

  In the present embodiment, the amount of angular displacement of the arm 2 can be set. When the angular displacement amount of the arm 2 is set small, the angular displacement amount of the arm 2 is small even when the position command value setting unit 20 sets the position command value to the maximum position command value. Therefore, even when the arm 2 is arranged in a narrow space, it is possible to prevent the arm 2 from colliding with an obstacle such as a workpiece and other devices. Further, the amount of angular displacement of the arm 2 can be made somewhat smaller than that of the motor 6 by using the speed reducer.

  FIG. 6 is a graph showing the input / output relationship of the limiter 28 related to the motor 6 that drives the arm 2 that is not affected by gravity. When the arm 2 is not affected by gravity, the current command value required to move the arm 2 in one direction is equal to the current command value required to move the arm 2 in the other direction. The limiter 28 has a different current command value input / output relationship between when no braking is applied to the output shaft of the motor 6 and when braking is applied to the output shaft of the motor 6.

  During no braking, the limiter 28 outputs the input current command value that is input as the output current command value when the input current command value falls within the predetermined no-braking allowable range. The limiter 28 outputs a predetermined no-braking output current upper limit command value i5 when the input current command value is equal to or greater than a predetermined no-braking allowable upper limit command value i1. Further, the limiter 28 outputs a predetermined no-braking output current lower limit command value i6 when the input current command value is equal to or less than a predetermined no-braking allowable lower limit command value i2. As a result, it is possible to prevent an overcurrent from flowing through the motor 6.

  During braking, the limiter 28 outputs the input current command value that is input as the output current command value when the absolute value of the input current command value is included in the predetermined allowable range during braking. When the input current command value is equal to or greater than the predetermined braking allowable upper limit command value i3, the limiter 28 outputs a predetermined braking output current upper limit command value i7. Further, the limiter 28 outputs a predetermined braking output current lower limit command value i8 when the input current command value is equal to or smaller than a predetermined allowable lower limit command value i4.

  Note that the non-braking allowable range and the braking allowable range include a state where the current command value is zero. The allowable range during braking is set to a range narrower than the allowable range during non-braking. The braking-time output current upper limit command value i7 is equal to or less than the no-braking output current upper limit command value i5, and the braking-time output current lower limit command value i8 is equal to or greater than the no-braking output current lower limit command value i6. As a result, the maximum current flowing through the motor 6 during braking can be made smaller than that during no braking, and acceleration of the arm 2 when detecting the braking ability of the brake 8 can be suppressed.

  FIG. 7 is a graph showing the input / output relationship of the limiter 28 related to the motor 6 that drives the arm 2 affected by gravity. When the arm 2 is affected by gravity, the current command value required to move the arm 2 in one direction is different from the current command value required to move the arm 2 in the other direction. When moving against gravity, the current command value required to move the arm 2 is large, and when moving according to gravity, the current command value required to move the arm 2 is small.

  The limiter 28 changes the output current command value for the input current command value by a predetermined gravity compensation setting value based on the posture of the arm 2 in consideration of the influence of gravity. Specifically, an input / output relation line in which the input / output relation line shown in FIG. 6 is slid by the gravity compensation set value along the vertical axis representing the output current command value is set. The change of the input / output relationship and the derivation of the gravity compensation set value are set by the gravity compensation unit 29. The compensation for gravity can be realized by using a well-known technique.

  When it is affected by gravity, the limiter 28 adds the gravity compensation set value to the input current command value to be input when the input current command value is included in the predetermined no-braking allowable range at the time of no braking. Output as the output current command value. When the input current command value is equal to or greater than a predetermined no-braking allowable upper limit command value i11, the limiter 28 outputs a predetermined no-braking output current upper limit command value i15. Further, the limiter 28 outputs a predetermined no-braking output current lower limit command value i16 when the input current command value is equal to or less than a predetermined no-braking allowable lower limit command value i12. In this case, the output current upper limit command value i15 and the output current upper limit command value i16 are values obtained by adding the gravity compensation set value as compared with the case where the influence is not influenced by gravity. The gravity compensation set value may be a negative value depending on the posture of the arm 2.

  In the case of the influence of gravity, the limiter 28 outputs the gravity compensation set value added to the input current command value to be input when the input current command value is included in the predetermined allowable range during braking when braking. Output as current command value. When the input current command value is equal to or greater than the predetermined braking allowable upper limit command value i13, the limiter 28 outputs a predetermined braking output current upper limit command value i17. The limiter 28 outputs a predetermined braking-time output current lower limit command value i18 when the input current command value is equal to or smaller than a predetermined allowable lower limit command value i14.

  Note that the non-braking allowable range and the braking allowable range include the origin. Further, the allowable range during braking is set to a range narrower than the allowable range during non-braking described above. The braking-time output current upper limit command value i17 is equal to or less than the unbraking output current upper limit command value i5, and the braking-time output current lower limit command value i8 is equal to or greater than the non-braking output current lower limit command value i6.

  Thus, when the arm 2 is affected by gravity, an output current command value based on the posture of the arm 2 is set. As a result, the current flowing through the motor 6 changes according to the posture of the arm 2. That is, the driving force generated by the output shaft of the motor 6 can be changed according to the posture of the arm 2, and the braking performance of the brake 8 can be detected regardless of the posture of the arm 2.

  FIG. 8 is a flowchart showing details of the operation procedure of the braking performance detection method by the control means 5. The flowchart shown in FIG. 8 specifically shows the flowchart shown in FIG. When a holding torque detection command for the brake 8 is given via the input unit 11 at step b0, the control means 5 proceeds to step b1 and starts a holding torque detection operation for the brake 8.

  In step b1, the control means 5 determines whether or not the arm 2 is stopped based on the position detection value given from the encoder 7. When the arm 2 is stopped, the process proceeds to step b3, and the holding torque detection operation of the brake 8 is continued.

  In step b1, when the arm 2 is operating, the process proceeds to step b2. In step b2, the control means 5 stops the holding torque detection operation of the brake 8, and proceeds to step b23. In step b23, the control means 5 ends the holding torque detection operation of the brake 8.

  In step b3, the control means 5 acquires the angular position of the output shaft of the motor 6 based on the position detection value given from the encoder 7. The control means 5 stores the acquired angular position as a return angular position at which the output shaft of the motor 6 returns after the holding torque detection operation of the brake 8, and proceeds to step b4. Step b1 and step b3 are return preparation operation steps for returning the arm 2 to the return angle position before the holding torque of the brake 8 is detected.

  In step b4, the control means 5 stores the no-braking allowable range, the no-braking output current upper limit command value, the no-braking output current lower limit command value, and the gravity compensation set value shown in FIG. 6 and FIG. Proceed to b5. In step b5, the control means 5 gives a command to the brake 8 via the amplifier 4, and gives a braking force to the output shaft of the motor 6 by the brake 8. When the brake 8 is operated in this way and a braking force is applied to the output shaft of the motor 6, the process proceeds to step b6.

  In step b6, the control means 5 reads the braking allowable range, the braking output current upper limit command value, and the braking output current lower limit command value shown in FIG. 6 and FIG. Sets the value input / output relationship. The braking allowable range, the braking output current upper limit command value, and the braking output current lower limit command value are set in consideration of the gravity compensation set value. The braking allowable range, the braking output current upper limit command value, and the braking output current lower limit command value are stored in the storage unit 14 in advance. The gravity compensation set value is calculated by the gravity compensation unit 29 based on the posture of each arm in step b6. When the setting of the limiter 28 is changed in this way, the process proceeds to step b7.

  In step b7, the control means 5 stores the integrated value integrated by the integral calculation unit 27, and then resets the integrated value, that is, once clears it to zero, and proceeds to step b8. In step b8, the control means 5 reads the position detection value b from the encoder 7, and sets the position command value a of the position command value setting unit 20 to the same value as the position detection value b detected from the encoder 7. That is, the position deviation that is the difference between the position command value a and the position detection value b in the first comparison unit 21 is set to zero, and the process proceeds to step b9. Steps b <b> 5 to b <b> 8 are pre-current supply operation steps for passing a current through the motor 6.

  In step b9, the control means 5 acquires the angular position of the output shaft of the motor 6 from the position detection value b given from the encoder 7, and proceeds to step b10. In step b10, the value added once to the position command value set in step b9 is updated as a new position command value, and the process proceeds to step b11.

  In step b11, the control means 5 determines whether or not a predetermined command value update end condition has been reached. When the command value update condition is reached, the control means 5 proceeds to step b12. Otherwise, the process returns to step b9.

  There are three command value update end conditions. When any one of the three end conditions is satisfied, the control means 5 stores the change in the operation amount in which the output shaft of the motor 6 is angularly displaced from the position detection value read in step b9, that is, the change amount of the motor. Then, the process proceeds to step b12. In steps b10 to b11, the position command value is updated, whereby a current flows through the motor 6 and a driving force is applied to the output shaft. Therefore, step b9 to step b11 are current supply operation steps for generating a driving force on the output shaft of the motor 6.

  The first command value update end condition is when the change amount of the motor 6 obtained based on the position detection value given from the encoder 7 is equal to or greater than the slip threshold. As described above, the slip threshold value is set to an angle that gives a margin to play.

  The second command value update end condition is when the position command value set by the position command value setting unit 20 reaches a predetermined maximum position command value. The maximum position command value is represented by the amount of angular displacement of the output shaft of the motor 6. For example, the maximum position command value is set to 1 degree or an angle necessary for moving the tip of the arm 2 by 1 mm.

  The third command value update end condition is that the output current command value reaches either the braking output current upper limit command value or the braking output current lower limit command value, and the position command value is a predetermined update end position command value. Is reached. For example, the update end position command value is set to a movement amount that is smaller than the maximum position command value and 10 times the slip threshold value.

  In step b12, the control means 5 acquires the angular position of the output shaft of the motor 6 from the position detection value given from the encoder 7, and proceeds to step b13. In step b <b> 13, the control means 5 sets the position command value of the position command value setting unit 20 to the position detection value detected from the encoder 7. As a result, the position deviation which is the difference between the position command value a and the position detection value b in the first comparison unit 21 is set to zero, and the process proceeds to step b14.

  In step b14, the control means 5 resets the accumulated value accumulated by the integral calculation unit 27, that is, once cleared to zero, and proceeds to step b15. In step b15, the control means 5 determines whether or not the current supply operation step constituted by step b10 and step b11 has been performed a predetermined number of times. If the current supply operation process has been performed the number of times of detection, the process proceeds to step b17. Otherwise, the process returns to step b9.

  In the present embodiment, the holding torque of the brake 8 is detected both when the rotation direction of the output shaft of the motor 6 is rotated forward and when it is reversed. Therefore, in step b15, the control means 5 determines whether or not the current supply operation process has been performed for both forward and reverse rotations. If the current supply operation process is performed only in the normal rotation direction, the process proceeds to step b16. In step b16, the rotation direction of the output shaft of the motor 6 is set to the reverse direction, and the process proceeds to step b9. Thereafter, the current supply operation step configured by Step b9 to Step b11 is performed in a state where the output shaft of the motor 6 is rotated in the reverse rotation direction. If the control means 5 determines in step b15 that the current supply operation process has been performed for both forward rotation and reverse rotation, the process proceeds to step b17. Steps b9 to b16 are detection operation steps for detecting the holding torque of the brake 8.

  In step b17, the control means 5 reads the no-braking allowable range, the no-braking output current upper limit command value, the no-braking output current lower limit command value, and the gravity compensation set value stored in step b4. Change the input / output relationship of the command value. Further, the control means 5 reads the integrated value of the integral calculation unit 27 stored in step b7, and gives the read integrated value to the integral calculation unit 27. Then, the process proceeds to step b18.

  In step b18, the control means 5 gives a command to the brake 8 via the amplifier 4, and releases the braking force applied to the motor 6 by the brake 8. When the operation of the brake 8 is thus released and the braking force applied to the motor 6 is released, the process proceeds to step b19. In step b19, the control means 5 returns the output shaft of the motor 6 to the angular position stored in step b3, and proceeds to step b20. Steps b17 to b19 are a return operation step for returning the arm 2 to the return angle position before the holding torque of the brake 8 is detected.

  In step b20, the angular displacement amount of the output shaft of the motor 6 stored in step b11, that is, the change amount of the motor 6 is read. In the present embodiment, the maximum angular displacement amount is read out from the stored plurality of angular displacement amounts. Then, it is determined whether or not the angular displacement is equal to or greater than the slip threshold. If the angular displacement amount of the output shaft of the motor 6 is greater than or equal to the slip threshold, the process proceeds to step b21. If the angular displacement amount of the output shaft of the motor 6 is less than the slip threshold value, the process proceeds to step b22.

  In step b21, the control means 5 notifies the notification means 9 that the holding torque of the brake 8 has decreased below the allowable torque, and proceeds to step b23. In step b22, the control means 5 determines that the holding torque of the brake 8 is an allowable torque abnormality and the braking performance of the brake 8 is normal, and proceeds to step b23. In step b23, the control means 5 ends the holding torque detection operation of the brake 8. Steps b20 to b22 are display operation steps for displaying a decrease in the holding torque of the brake 8.

  As described above, according to the present embodiment, after the brake 8 is operated, an abnormality detection current based on the posture of the arm 2 is supplied to the motor. The motor 6 generates a torque necessary for moving the arm 2 when an abnormality detection current is applied. When the holding torque of the brake 8 is normal, the output shaft of the motor 6 does not rotate. Further, when the holding torque of the brake 8 is reduced, the output shaft of the motor 6 rotates. By detecting the rotation state of the output shaft of the motor 6, a brake abnormality is determined.

  For example, according to the present embodiment, depending on the posture of the arm 2, if a large torque is not generated and the output shaft of the motor 6 cannot be moved by a predetermined amount of movement, a large current is passed through the motor. When the output shaft of the motor 6 can be moved by a predetermined amount of movement only by generating a small torque, a small current is passed through the motor.

  As described above, since the current flowing through the motor 6 is set according to the posture of the arm 2, it is possible to accurately determine the decrease in the holding torque of the brake 8 regardless of the posture of the arm 2.

  In the present embodiment, the holding torque of the brake 8 is detected for each of the forward rotation direction and the reverse rotation direction of the output shaft of the motor 6. As a result, it is possible to cope with the case where the holding torque of the brake 8 is different between the forward rotation direction and the reverse rotation direction, and it is possible to accurately detect a decrease in the holding torque.

  Further, the return angle position of the output shaft of the motor 6 before the holding torque detection is stored in the return preparation operation step shown in step b1 and step b3. Then, after detecting the holding torque by supplying a current to the motor 6 in the detection operation process shown in steps b9 to b15, the output shaft of the motor 6 is returned to the return angle position in the return operation process shown in steps b17 to b19. Let Accordingly, even when the robot 1 is performing an operation other than the holding torque detection operation, the holding torque detection operation of the brake 8 can be performed, and convenience can be improved.

  In step b11, under the first command value update end condition, when the amount of change of the motor 6 is equal to or greater than the slip threshold, the update of the position command value is ended. In this case, it is possible to prevent the arm 2 from further moving by ending the update of the position command value. In other words, when a decrease in the holding torque is detected, the arm 2 can be prevented from moving further, and the time spent for detecting the holding torque can be reduced. Further, the arm 2 can be prevented from colliding with an obstacle.

  In step b11, under the second command value update condition, when the position command value reaches the maximum position command value, the update of the position command value is terminated. This prevents the arm 2 from moving beyond the maximum position command value even when the holding torque of the brake 8 is extremely small or when the holding torque of the brake 8 is not effective. That is, it is possible to prevent the arm 2 from moving excessively. This can prevent the arm 2 from colliding with an obstacle.

  In step b12, under the third command value update condition, even if the position command value does not reach the maximum position command value, if the current command value is saturated and the update end position command value is reached, the position command value Finish the update. Thus, when the holding torque of the brake 8 is large, the current supply to the motor can be stopped before the position command value reaches the maximum position command value, and the time spent for detecting the holding torque can be reduced.

  In step b7 and step b14, the integrated value integrated by the integral calculation unit 27 is reset. In step b8, the positional deviation between the position command value a and the position detection value bt is set to zero. That is, each variable in the feedback control system is reset to the initial state. As a result, a current corresponding to the posture of the arm 2 can be supplied to the motor 6 regardless of the arm operation before the holding torque of the brake 8 is detected.

  Further, by resetting the integrated value, the followability of the motor 6 can be improved when the position command value is changed for holding torque detection. As a result, the time spent for detecting the holding torque can be shortened.

  Further, in step b8 and step b13, position command value replacement processing is performed, and the position deviation that is the difference between the position command value a and the position detection value b in the first comparison unit 21 is set to zero. Thus, even if the driving force is applied to the output shaft of the motor 6 for the holding torque detection operation a plurality of times, the influence when the driving force is applied to the previous output shaft can be eliminated. The amount of change can be determined.

  The industrial robot is provided with a plurality of actuators 3 for each arm. In the present embodiment, the holding torque detection operation of the brake 8 for each actuator 3 is performed simultaneously. Accordingly, the holding torque detection operation of each brake 8 can be performed in a short time. Further, the holding torque detection operation of the brake 8 for each actuator 3 may be sequentially performed independently. Thus, when the holding torque of one brake 8 is detected, the holding torque can be detected more accurately without the other arms 2 moving.

  FIG. 9 is a flowchart showing another embodiment of the control means 5. When the controller 5 is a controller that controls the operation of the robot, the controller 5 performs an automatic power supply stop operation of the motor 6. That is, the control means 5 is a control device for the actuator 3.

  In step c0, when the control unit 5 is instructed to stop the automatic power supply of the motor 6, the process proceeds to step c1 and the automatic power supply stop operation of the motor 6 is started. In step c1, when the control means 5 determines that the operation of the motor 6 is stopped for a predetermined time based on the position detection value given from the encoder 7, the process proceeds to step c2. In step c2, the operation of detecting the holding torque of the brake 8 described above is performed, and it is determined whether or not the holding torque of the brake 8 is greater than or equal to the allowable torque. In step c2, if the holding torque of the brake 8 is greater than or equal to the allowable torque, the process proceeds to step c3, and if not, the process proceeds to step c4. In step c3, the brake 8 is operated to apply driving force to the output shaft of the motor 6, and power supply to the motor 6 is stopped, and the process proceeds to step c6.

  In step c4, since the holding torque of the brake 8 is less than the allowable torque, the notifying means 9 indicates that the posture of the arm 2 may change when the brake 8 is operated to stop the power supply to the motor 6. Warning. Then, the process proceeds to step c5. In step c5, the power supply to the motor 6 is continued to maintain the posture of the arm 2, and the process proceeds to step c6. In step c6, the automatic power supply stop operation of the motor 6 is terminated.

  Thus, when the arm 2 is stopped for a long time, the power consumption of the robot 1 can be reduced by stopping the power supply to the motor 2. In the automatic power supply stop operation of the present embodiment, the holding torque of the brake 8 is detected before the power supply to the motor 6 is stopped. When the holding torque of the brake 8 is reduced, the power supply to the motor 6 is continued. As a result, the posture of the arm 2 can be prevented from changing due to its own weight.

  In step c5, the brake 8 is operated and the power supply to the motor 6 is continued, so that the arm 6 is supplied to the motor 6 as compared with the case where the posture of the arm 2 is maintained only by the power supply to the motor 6. Electric power can be reduced.

  In step c5, instead of continuing to supply power to the motor 6, an operation is performed to move the arm 2 to a safe position where the arm 2 does not collide with an obstacle even if the holding torque of the brake 8 decreases. Also good.

  Further, when the holding torque detection operation shown in FIG. 8 is performed in step c2, even if the posture of the arm 2 is changed by the holding torque detection operation, it returns to the position before the holding torque detection operation. As a result, the influence of the holding torque detection operation is eliminated, and the motor can be operated immediately from the state in step c6.

  FIG. 10 is a flowchart showing still another embodiment of the control means 5. When the controller 5 is a controller that controls the operation of the robot, the controller 5 holds the teaching. Specifically, when the worker teaches the arm movement path, if the worker holds the teaching of the arm movement path, the motor power supply stop operation is performed.

  In this case, when the worker releases the trigger of the teaching pendant, the power supply stop operation of the motor 6 is performed. The teaching pendant is an operation means for operating the robot, and the trigger is an operation signal input means for giving an operation continuation signal for continuing the robot operation to the control means. When the operator releases the trigger, it is determined that the operation operation signal is not supplied to the control unit 5 and the operator has suspended the robot operation.

  In step d0, when it is determined that the operator has started teaching the arm movement path using the teaching pendant, the process proceeds to step d1, and the automatic power supply stopping operation of the motor 6 is started. In step d1, when the control means 5 determines that the operation continuation signal given from the trigger is interrupted, the control means 5 proceeds to step d2. Then, the operations from step d2 to step d6 are sequentially performed. The operations of Step d2 to Step d6 correspond to Step c2 to Step c6 shown in FIG. Therefore, a specific description is omitted.

  As a result, when the worker releases the trigger and leaves the teaching site, the control means 5 performs the automatic power supply stop operation described above. When the holding torque of the brake 8 is not reduced, the power supply to the motor 6 is stopped. When the worker leaves the teaching site, there is no need to give the control means 5 a command to stop power supply to the motor 6 and a command to operate the brake 8. Therefore, convenience can be improved.

  Even if the holding torque of the brake 8 is reduced, the electric power for maintaining the posture of the arm 2 is applied to the motor 6, so that the posture of the arm 2 can be maintained. Thus, when the operator returns to the teaching site, the posture of the arm 2 is maintained, so that the teaching operation can be continued immediately.

  FIG. 11 is a flowchart showing an operation procedure of a braking performance detection method according to still another embodiment of the present invention. In the braking performance detection method shown in FIG. 11, a braking release abnormality is detected in the braking performance of the brake 8. The braking performance detection method shown in FIG. 11 can also be realized by executing the arithmetic program by the control means 5 described above. Therefore, the description of the configuration of the control means 5 is omitted.

  For example, an operation command for the brake 8 is transmitted via a cable. Therefore, when the cable is disconnected, electric power cannot be supplied to the brake, and the brake 8 cannot be released. In addition, the brake 8 cannot be released even when a solenoid failure or mechanical malfunction occurs.

  In step e <b> 0, the worker inputs a brake release abnormality detection command for the brake 8 from the input unit 11. When the brake release abnormality detection command is input to the input unit 11, the control unit 5 proceeds to step e <b> 1 and starts a brake release abnormality detection operation of the brake 8. The brake release abnormality detection operation of the brake 8 is one of the performance detection operations of the brake 8.

  In step e1, the control means 5 confirms whether or not the driving force applied to the motor 6 by the brake 8 is released. If it is confirmed that the brake is released, the control means 5 proceeds to step e2. In step e2, the control means 5 generates a current set value necessary for the motor 6 to move by a predetermined movement amount based on the position detection value given from the encoder 7, and proceeds to step e3.

  In step e3, the control means 5 commands the motor 6 to operate by a predetermined amount of movement, and proceeds to step e4. Specifically, the generated current set value is given to the amplifier 4 in a state where braking of the motor 6 is released. The amplifier 4 passes a current based on the current set value given from the control means 5 to the motor 6.

  In step e4, the control means 5 obtains the change amount of the motor 6 based on the position detection value given from the encoder 7. The amount of change of the motor 6 is a deviation position between the angular position of the output shaft of the motor 6 when the brake operation is released in step e1 and the angular position of the output shaft of the motor 6 after supplying current to the motor in step e3. In other words, it is the amount of change in the output shaft of the motor 6 before and after the electric power for detecting the brake release abnormality is applied to the motor.

  The control means 5 compares this amount of change with a predetermined slip threshold. When the change amount of the motor 6 is larger than the slip threshold, it is determined that the brake release state is normal. If the change amount of the motor 6 is smaller than the slip threshold, it is determined that the brake release state is abnormal.

  If it is determined in step e4 that the brake is released normally, the process proceeds to step e5, and if not, the process proceeds to step e6. In step e5, the notifying means 9 warns that the braking of the brake 8 cannot be released normally, and proceeds to step e6. In step e6, the detection operation of the brake release abnormality of the brake 8 is terminated.

  Thus, according to the present embodiment, it is possible to detect the braking release abnormal force in the braking performance of the brake 8. Further, since the current is supplied to the motor 6 so that the amplifier 4 operates by a predetermined operation amount, the motor 6 does not operate more than a predetermined operation amount.

  Therefore, when the braking of the brake 8 is normally released, the arm 2 can be prevented from moving excessively, and the arm 2 can be prevented from colliding with an obstacle. Further, the motor 6 generates a driving force necessary for moving a predetermined amount of movement. Therefore, a driving force corresponding to the weight of the arm 2 can be generated in the motor 6, and a braking release abnormality of the brake 8 can be accurately detected regardless of the gravity applied to the arm 2.

  In addition, the notification means 9 can notify the operator that the brake release is abnormal. For example, when the arm is emergency stopped due to excessive power supply to the motor, it is determined whether or not the cause of the emergency stop of the arm 2 is caused by the brake release abnormality of the brake 8 by performing a brake release abnormality detection operation. Can do.

  In step e0, a brake release abnormality detection command is given by the operator, and the brake release abnormality detection operation of the brake 8 is started. As another example, in step e0, when a motor power supply start command for starting power supply to the motor 6 is given, the control means 5 performs a brake release abnormality of the brake 8 before starting power supply to the motor 6. The detection operation may be started.

  In addition, the holding torque detection operation of the brake 8 shown in FIG. 1 and the brake release abnormality detection operation of the brake 8 shown in FIG. 11 may be performed continuously. In this case, the holding torque detection operation and the braking release abnormality detection operation are performed by applying a braking force to the output shaft of the motor 6 to brake the output shaft of the motor 6, and a braking force applied to the output shaft of the motor 6. Can be easily switched by setting the brake 8 to any one of a brake release state in which the brake of the output shaft of the motor 6 is released. Further, it is preferable to change the slip threshold value between the holding torque detection operation and the braking release abnormality detection operation, and the slip threshold value is set smaller in the detection operation at the braking eye position or more.

  FIG. 12 is a flowchart showing details of the operation procedure of the braking performance detection method by the control means 5. The flowchart shown in FIG. 12 shows the flowchart shown in FIG. 11 more specifically. When a brake release abnormality detection command is given via the input unit 11 at step f0, the control means 5 gives a brake release command to the brake 8. Then, the process proceeds to step f1, and the detection operation of the brake release abnormality of the brake 8 is started.

  In step f1, the control means 5 determines whether or not the arm 2 is stopped based on the position detection value given from the encoder 7. When the arm 2 is stopped, the process proceeds to step f3, and the operation for detecting the brake release abnormality of the brake 8 is continued. In step f1, when the arm 2 is operating, the process proceeds to step f2. In step f2, the control means 5 stops the detection operation of the brake release abnormality of the brake 8, and proceeds to step f19. In step f19, the control means 5 ends the detection operation of the brake release abnormality of the brake 8.

  In step f <b> 3, the control means 5 acquires the angular position of the output shaft of the motor 6 based on the position detection value given from the encoder 7. The control means 5 stores the acquired angular position as a return angular position at which the motor 6 returns after detecting the brake release abnormality of the brake 8, and proceeds to step f4. Steps f1 and f3 are return preparation operation steps for returning the arm 2 to the return angle position before the detection of the brake release abnormality of the brake 8.

  In step f4, the control means 5 stores the no-braking allowable range, the no-braking output current upper limit command value, the no-braking output current lower limit command value, and the gravity compensation set value shown in FIG. 6 and FIG. Proceed to f5. In step f5, the control means 5 reads the braking allowable range, the braking output current upper limit command value, the braking output current lower limit command value, and the braking time shown in FIGS. Sets the input / output relationship of the current command value. The braking allowable range, the braking output current upper limit command value, and the braking output current lower limit command value are set in consideration of the gravity compensation set value. The braking allowable range, the braking output current upper limit command value, and the braking output current lower limit command value are stored in the storage unit in advance. Further, the gravity compensation set value is calculated by the gravity compensation unit 29 based on the posture of each arm 2 in step f5. When the setting of the limiter 28 is changed in this way, the process proceeds to step f6.

  In step f6, the control means 5 stores the integrated value integrated by the integral calculation unit 27, resets the integrated value, that is, once sets it to zero, and proceeds to step f7. In step f7, the control means 5 reads the position detection value b from the encoder 7 and sets the position command value a of the position command value setting unit 20 to the same value as the position detection value b detected from the encoder 7. That is, the position deviation which is the difference between the position command value a and the position detection value b in the first comparison unit 21 is set to zero, and the process proceeds to step f7. Steps f4 to f6 are operation steps before supplying current for flowing current to the motor.

  In step f7, the control means 5 acquires the angular position of the output shaft of the motor 6 from the position detection value b given from the encoder 7, and proceeds to step f8. In step f8, the value added once to the position command value set in step f6 is updated as a new position command value, and the process proceeds to step f9.

  In step f9, the control means 5 determines whether or not a predetermined command value update end condition has been reached. When the command value update condition has been reached, the process proceeds to step f10. Otherwise, the process returns to step f8. There are three command value update end conditions. When any one of the three end conditions is satisfied, the control unit 5 stores a change amount that is a displacement amount in which the output shaft of the motor 6 is angularly displaced from the position detection value read in step f7, and step f10. Proceed to The three command value update end conditions are the same as those described above. Note that, in the case of detecting an abnormality in brake release, the slip threshold is set to an angle with a margin as described above. In step f7 to step f9, the position command value is updated, whereby a current flows through the motor and a driving force is applied to the output shaft. Therefore, steps f7 to f9 are current supply operation steps for generating a driving force on the output shaft of the motor 6.

  In step f10, the control means 5 acquires the angular position of the output shaft of the motor 6 from the position detection value given from the encoder 7, and proceeds to step f11. In step f <b> 11, the control means 5 sets the position command value of the position command value setting unit 20 to the position detection value detected from the encoder 7. As a result, the position deviation that is the difference between the position command value a and the position detection value b in the first comparison unit 21 is set to zero, and the process proceeds to step f12.

  In step f12, the control means 5 determines whether or not the operations of steps f8 and f9 have been performed a predetermined number of times. If the predetermined number of times has been performed, the process proceeds to step f14. If the predetermined number of times has not been performed, the process proceeds to step f13.

  In step f13, the brake is operated to apply a driving force to the motor, the driving force to the motor is released, and the process returns to step f7. Thereafter, the control means 5 performs Step f9 to Step f11 again. In step f12, when the control means 5 determines that steps f8 to f9 have been performed a predetermined number of times, the process proceeds to step f14. Steps f8 to f12 are detection operation steps for detecting a brake release abnormality of the brake 8.

  In step f14, the control means 5 reads the no-braking allowable range, the no-braking output current upper limit command value, the no-braking output current lower limit command value and the gravity compensation set value stored in step f4, and the current of the limiting unit 28 is read. Change the input / output relationship of the command value. Further, the control means 5 reads the integrated value of the integral calculation unit 27 stored in step f4 and gives the read integrated value to the integral calculation unit 27. Then, the process proceeds to step f15.

  In step f15, the angular displacement amount of the output shaft of the motor 6 stored in step f9, that is, the change amount of the motor 6 is read. In the present embodiment, the maximum angular displacement amount is read out from the stored plurality of angular displacement amounts. Then, it is determined whether or not the angular displacement is equal to or greater than the slip threshold. If the angular displacement amount of the output shaft of the motor 6 is greater than or equal to the slip threshold, the process proceeds to step f17. If the angular displacement amount of the output shaft of the motor 6 is less than the slip threshold, the process proceeds to step f16. In step f16, the notification means 9 notifies the brake 8 that the brake release is abnormal, and the process proceeds to step f19. Steps f15 to f16 are display operation steps for displaying an abnormality in the brake release of the brake 8.

  In step f17, the control means 5 determines that the brake release of the brake 8 is normal, and proceeds to step f18. In step f18, the control means 5 moves the output shaft of the motor 6 to the angular position stored in step f3, and proceeds to step f19. Step f18 is a return operation step for returning the arm 2 to the return angle position before detecting the brake release abnormality of the brake 8. In step f19, the control means ends the operation of detecting the brake release abnormality of the brake 8.

  As described above, according to the present embodiment, the same effects as those in the flowchart shown in FIG. 8 can be obtained. For example, the return angle position of the output shaft of the motor 6 before the detection of the brake release abnormality of the brake 8 is stored in the return preparation operation step shown in step f3 and step f4. In the detection operation process shown in steps f7 to f9, a current is supplied to the motor to detect the holding torque, and in the return operation process shown in step f18, the output shaft of the motor 6 is returned to the return angle position.

  As a result, even when an operation other than the abnormality detection operation for releasing the brake 8 is being performed, the abnormality detection operation for releasing the brake 8 can be performed, and the convenience can be improved.

  The feedback control system is reset to the initial state. As a result, a current corresponding to the posture of the arm 2 can be supplied to the motor 6 regardless of the operation before detecting the brake release abnormality of the brake 8. Further, by resetting the integrated value, the followability of the motor 6 can be improved when the position command value is changed for detecting an abnormality in the braking release of the brake 8. As a result, it is possible to reduce the time spent for detecting the abnormality of the brake release.

  Further, in step f7 and step f11, position command value replacement processing is performed, and the position deviation that is the difference between the position command value a and the position detection value b in the first comparison unit 21 is set to zero. As a result, even if a driving force is applied to the output shaft of the motor 6 for the abnormality detection operation of the brake release of the brake 8 a plurality of times, the influence of the driving force applied to the previous output shaft can be eliminated. The amount of change of 6 can be obtained.

  The industrial robot is provided with a plurality of actuators 3 for each arm. Therefore, in practice, the brake 8 abnormality detection operation of the brake 8 of each actuator 3 is simultaneously performed. As a result, the brake detection abnormality detection operation of each brake 8 can be performed in a short time. Further, the brake detection abnormality detection operation of the brake 8 for each actuator 4 may be performed sequentially and independently. As a result, when the brake release abnormality of one brake 8 is detected, the brake release abnormality can be detected more accurately without the other arms moving.

  As described above, the control means 5 according to the embodiment of the present invention can detect the holding torque of the brake 8 and the brake release abnormality. Such a detection timing of the braking performance of the brake 8 can be set in advance.

  FIG. 13 is a diagram showing a setting screen relating to detection of brake braking performance. The control means 5 has a display unit, and displays a setting screen related to detection of brake braking performance on the display unit. The control means 5 may perform the automatic power supply stop operation (shown as automatic servo OFF in FIG. 13) shown in FIG. 9 when the robot enters a signal waiting state and a predetermined time has elapsed. In this case, the control means 5 displays on the display screen whether or not to perform holding torque detection and brake release abnormality detection when stopping automatic power supply, and sets the setting according to an instruction from the operator. Can be changed.

  Further, the control means 5 may perform a so-called cycle operation when repeatedly performing a predetermined reference operation. In this case, the holding torque is detected and braked at the start of the reference operation (indicated as “cycle start” in FIG. 13) after the elapse of a check interval, which is a predetermined time, after the previous operation of detecting the braking performance of the brake 8 is performed. It is possible to display a setting as to whether or not to detect abnormality of cancellation on the display screen and to change the setting according to an instruction from the operator.

  FIG. 14 is a diagram showing a setting screen relating to detection of brake braking performance. The control means 5 displays the setting as to whether or not to detect the braking performance of the brake 8 on the display screen for each motor, and can change these settings according to instructions from the operator. That is, the brake braking performance can be detected only for the brake desired by the operator.

  FIG. 15 is a diagram showing a setting screen relating to detection of brake braking performance. The control means 5 displays the motor 6 that has executed the braking performance detection operation, the detection result, and the detection date and time on the display screen in association with each other. The detection results are displayed as a history in order of time. As a result, the failure tendency can be grasped, and convenience can be improved.

  The embodiment of the present invention as described above is merely an example of the invention, and the configuration can be changed. For example, although a brake abnormality detection method and a brake abnormality detection device for an industrial robot have been shown, the present invention can be used for other than industrial robots, and can be used for a movable device including an actuator having a braking means and an actuator body. Can do. Although a motor is shown as the actuator body, other than the motor, for example, a pneumatic or hydraulic cylinder may be used.

It is a flowchart which shows the operation | movement procedure of the braking performance detection method which is one Embodiment of this invention. FIG. 3 is a perspective view showing the industrial robot 1, and FIG. 3 is a block diagram showing a part of the electrical configuration of the industrial robot 1. 2 is a block diagram showing a part of the electrical configuration of the industrial robot 1. FIG. It is a block diagram which shows the control means. 3 is a block diagram showing a control system of a motor 6 by a control means 5. FIG. It is a graph which shows the input-output relationship of the limiter 28 relevant to the motor 6 which drives the arm 2 which is not influenced by gravity. It is a graph which shows the input-output relationship of the limiter 28 relevant to the motor 6 which drives the arm 2 influenced by gravity. 4 is a flowchart showing details of an operation procedure of a braking performance detection method by a control means 5; It is a flowchart which shows other embodiment of the control means. 10 is a flowchart showing still another embodiment of the control means 5. It is a flowchart which shows the operation | movement procedure of the braking performance detection method of further another embodiment of this invention. 4 is a flowchart showing details of an operation procedure of a braking performance detection method by a control means 5; It is a figure which shows the setting screen regarding the detection of brake braking performance. It is a figure which shows the setting screen regarding the detection of brake braking performance. It is a figure which shows the setting screen regarding the detection of brake braking performance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Robot 2 Arm 3 Actuator 4 Amplifier 5 Control means 6 Motor 7 Encoder 8 Brake 9 Notification means

Claims (8)

When a command signal for instructing an operation amount is given, an actuator main body that operates by an operation amount instructed by the command signal, and a braking unit in the actuator that includes a braking unit that applies a braking force to the actuator main body to brake the actuator main body. A braking performance detection method for detecting braking performance,
Either a braking state in which a braking force is applied to the actuator body to brake the actuator body, or a brake release state in which the braking of the actuator body is released by stopping the supply of the braking force to the actuator body, A braking state setting step for setting braking means;
An operation command step for giving a command signal for detecting braking performance to the actuator main body for commanding to operate by a predetermined operation amount in a state where the braking means is set to either one of the braking state and the braking release state;
Brake performance detection, comprising: an operation amount detection step for detecting a change in the operation amount of the actuator body before the command signal for detecting the braking performance is provided and after the command signal for detecting the braking performance is supplied. Method.   The braking performance detecting method according to claim 1, wherein the operation commanding step generates a command signal for detecting braking performance based on a posture of a movable body driven by the actuator body.   It further includes a notification step of comparing the change in the operation amount of the actuator body detected by the operation amount detection step with a predetermined threshold value, evaluating the braking performance, and notifying the evaluation result. The braking performance detection method according to claim 1 or 2.   The braking performance detection method according to any one of claims 1 to 3, wherein a decrease in braking performance of the braking means is detected immediately before the power supply to the actuator body is stopped.   The braking performance detecting method according to any one of claims 1 to 4, wherein the actuator is mounted on an industrial robot and drives an arm of the industrial robot. A decrease in the braking performance of the braking means is detected based on a change in the operation amount of the actuator body detected by the braking performance detection method according to any one of claims 1 to 5 and a predetermined threshold value. A performance degradation determination step;
A posture maintaining step of supplying power to the actuator main body in order to maintain the posture of the movable body driven by the actuator main body when a decrease in the braking performance of the braking means is detected in the performance deterioration determining step. Actuator control method.   An actuator characterized in that, after the braking performance detection method according to any one of claims 1 to 5 is executed, the actuator body is operated so as to be in a state before giving a command signal for braking performance detection. Control method. When a command signal for instructing an operation amount is given, an actuator main body that operates by an operation amount instructed by the command signal, and a braking unit in the actuator that includes a braking unit that applies a braking force to the actuator main body to brake the actuator main body. A braking performance detection device for detecting braking performance,
An input means for receiving a braking performance detection command;
Braking performance that sets the braking means to either one of the braking state to brake the actuator body or the braking release state to release the actuator body, and commands to operate by a predetermined amount of movement in that state A control means for detecting a change in the operation amount of the actuator body before giving a command signal for detection to the actuator body and giving a command signal for detecting braking performance and after giving a command signal for detecting braking performance;
A braking performance detection device comprising: output means for outputting a detection result by the control means.

Images