JP2011183460A - Control device of robot and connection failure determining method of robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a robot, capable of detecting erroneous wiring while minimizing a malfunction quantity of a motor even while causing the erroneous wiring. <P>SOLUTION: This control circuit outputs a driving current to respective phase coils of an inspection object motor via a corresponding inverter (S11 and S12) so that a rotor of the inspection object motor maintains an initial position when acquiring the initial position of the inspection object motor from a position &theta;a provided by a position detector arranged in the inspection object motor when supplying a power source with any one of a plurality of servomotors as the inspection object motor (S4). When any of the servomotors arranged on respective shafts of a robot body rotates in its current output period (S14:YES), a connection state with servomotors respectively corresponding to the respective inverters is determined as defective (S22). <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a robot control device that drives and controls a permanent magnet type synchronous motor disposed on each axis of a multi-movable axis robot body, and a robot connection failure determination method.

Robot systems are designed and produced with sufficient considerations to minimize the occurrence of failures. However, it may be unavoidable that some parts may fail as a result of aged deterioration or a load exceeding the design assumption. Then, along with the repair of the failure, it is necessary to replace the parts of the robot or reconnect the wiring. If an operation error occurs at that time, the wiring connection may be wrong.
If you try to operate the robot with incorrect wiring in the motor drive control system, the torque that should be generated will not be generated, or if you try to stop the operation, the motor will accelerate or be specified as the operation target. It is assumed that a motor with a different axis from the expected axis suddenly operates. These may cause a robot operation unexpected by the user, and may be a safety problem in some situations.

  Various techniques have been proposed for detecting a motor failure, a wiring error between the motor and the drive circuit, and the like. For example, in Patent Document 1, the current flowing through the U and V phase output terminals of the servo motor is detected during the first acceleration performed after the power is turned on, and the current waveform pattern is monitored to connect the motor output terminals incorrectly. A technique for detecting the above is disclosed. Further, in Patent Document 2, after the brake is released, a timer is started and the servo amplifier is turned on to output a movement command to the servo controller. For each axis, a torque command value, a current feedback value, and a position command value are output. , Memorize the abnormality judgment index such as position feedback value, turn off the servo amplifier after time t0, apply the brake, and acquire each value of the above abnormality judgment index at that time, check the consistency relationship of each A technique for determining an abnormality is disclosed.

JP-A-9-16233 JP 2000-181521 A

However, in the determination methods disclosed in Patent Documents 1 and 2, since parameters such as current used for determination are affected by the magnitude of the load weight related to the motor, information on the load weight is obtained in advance for the determination. It is necessary to keep. Therefore, it is indispensable to receive information support from the user, and the user is burdened with work. In addition, since the information given in advance may be different from the actual load weight, there is a problem that reliable detection is difficult.
Further, the methods of Patent Documents 1 and 2 are based on the premise that the motor is rotated to some extent in order to make the determination. However, the operation control of the robot is generally feedback control performed while detecting the rotation amount of each axis motor by a position detector such as an encoder. For this reason, if erroneous wiring occurs between a plurality of axes, the feedback control amount is assumed to be an inappropriate value different from the original value, and it is also assumed that the malfunction amount greatly increases.

  In addition, if incorrect wiring occurs between one axis and the motor phase, the rotational direction of the motor may be reversed with respect to the given command value, so the deviation between the command value and the detected position is When this value increases, positive feedback acts, and the amount of malfunction may increase greatly. Furthermore, if there is an error or part of the disconnection in the wiring from which the position detector outputs the position detection signal, there will be a deviation between the detected position and the actual electrical angle of the motor. It may lead to a situation.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a robot control device and a robot capable of detecting erroneous wiring while minimizing the amount of malfunction of the motor even when erroneous wiring occurs. It is to provide a connection failure determination method.

  According to the robot control apparatus of the first aspect, the control circuit uses any one of a plurality of motors as the inspection target motor, and the position detection unit arranged in the inspection target motor when the power is turned on by the initial position acquisition unit. The electrical angle of the motor to be inspected is acquired from the position signal obtained by the instrument. Then, in a state where the electrical angle of the motor to be inspected is fixed at a current phase that maximizes the attractive force so as to maintain the initial position, a drive current is output to each phase winding of the motor to be inspected via the corresponding drive circuit. Then, when any of the motors arranged on each axis of the robot body rotates within the current output period, the connection state between each drive circuit and the corresponding motor is determined to be defective.

  If the determination is made in this way, even if any of the motors is rotated due to an incorrect connection between the drive circuit and the corresponding motor, the amount of rotation remains very small. That is, at most, the motor does not make one or more rotations at the mechanical angle, and it is within one-minute rotation determined by the relationship between the number of poles of the rotor and the number of slots of the stator. Accordingly, the amount of change in the operation of the robot main body associated therewith is also small, so that safety can be maintained. Moreover, since the above determination can be easily performed by changing the control program executed by the control circuit, it can be easily applied to an existing robot system.

  According to the robot control apparatus of the second aspect, when the control circuit first selects a motor having the smallest capacity as the inspection target motor among the plurality of motors, the control circuit sequentially selects the inspection target motors in the order of increasing capacity thereafter. Select and repeat the determination by the connection state determination means. If comprised in this way, in order to perform a connection determination, the amount of the drive current which a drive control means will flow will become a small value at the beginning, and it changes so that a current amount may become large sequentially from there. Therefore, it is possible to avoid a situation in which the permanent magnet disposed in the rotor is demagnetized by the magnetic field generated by the winding without flowing a too large driving current through the winding of the small motor having a small capacity.

  According to the robot control device of the third aspect, the drive control means drives so as to gradually increase the rotational force applied to the inspection target motor when the result of the determination by the connection state determination means is “good”. The current is output, and the connection state determination means further determines whether or not the connection state is good depending on whether or not the inspection target motor has rotated according to the drive current. That is, as a result of the determination as in claim 1, if any motor does not rotate, it is confirmed that there is no partial misconnection between the plurality of shafts.

  In addition, if the determination is made as in claim 3, if all connections are switched between the motor to be inspected and another motor, the determination is made by rotation of a motor other than the motor to be inspected. it can. In addition, when an erroneous connection occurs between the phases of the inspection target motor, the determination can be made by rotating the inspection target motor in the reverse direction with respect to the given drive current command value. Therefore, erroneous connection determination can be reliably performed for various cases.

In the first embodiment, (a) is a flowchart showing failure / incorrect connection determination processing, and (b) is a flowchart showing details of the inspection performed in step S4 of (a). Image of normal case where “YES” is determined in step S19 Image diagram of an abnormal case where “YES” is determined in step S18 Diagram showing the configuration of the robot system Block diagram showing servo motor drive system and control system Diagram showing the structure of the servo motor Diagram showing the relationship between the servomotor shaft angle (mechanical angle) and electrical angle The figure which shows the state from which the rotational force which generate | occur | produces in a servomotor according to the phase difference of an electrical angle and a drive current, and the attraction / repulsion force which acts between a stator and a rotor change. The figure which shows the one part state shown in FIG. 8 in a rotation coordinate system FIG. 1 equivalent view showing the second embodiment

(First embodiment)
The first embodiment will be described below with reference to FIGS. FIG. 4 shows the configuration of the robot system. The robot body 1 has a 6-axis arm on a base (rotating shaft) 2 in this case, and a tool such as a hand (not shown) is attached to the tip of the arm. A first arm 3 is rotatably connected to the base 2 via a first joint (movable shaft) J1. The first arm 3 is rotatably connected to the lower end portion of the second arm 4 extending upward via the second joint J2, and further, the upper end portion of the second arm 4 The third arm 5 is rotatably connected via the joint J3.

  A fourth arm 6 is rotatably connected to the tip of the third arm 5 via a fourth joint J4, and a fifth arm is connected to the tip of the fourth arm 6 via a fifth joint J5. 7 is rotatably connected, and the sixth arm 8 is rotatably connected to the fifth arm 7 via a sixth joint J6. In addition, in each joint J1-J6, each arm 3-8 is rotationally driven by the servomotor 9 (1-6) (refer FIG. 5).

  The control device 11 includes independent driver units 12 (1 to 6) corresponding to the servo motors 9 (1 to 6) of the respective axes, and these driver units 12 are controlled by a control circuit 13 (see FIG. 5). Be controlled. The main body of the robot 1 and each driver unit 12 (1 to 6) are connected by a motor line 14 and an encoder line 15. The motor wire 14 is a wiring that connects between each phase output terminal of the inverter (drive circuit, see FIG. 5) 16 built in the driver unit 12 and the stator winding of the servo motor 9. The driver unit 12 side of the motor wire 14 is branched into six, and each branch destination is connected to the driver unit 12 (1 to 6).

  In addition, the encoder wire 15 is connected to the position detectors 17 (1 to 6) (see FIG. 5) disposed in the servo motors 9 (1 to 6) and the driver units 12 (1 to 1) for each axis of the robot body 1. 6). The position detector 17 is constituted by, for example, a rotary encoder, detects the absolute position of the rotor of the servo motor 9 by, for example, an optical method, and transmits position data to the driver unit 12 side by serial communication. The driver unit 12 side of the encoder line 15 is also branched into six, and each branch destination is connected to the driver unit 12 (1 to 6).

  FIG. 5 is a block diagram showing a drive system and a control system of the servo motor 9. The inverter 16 is configured by connecting six switching elements such as power transistors in a three-phase bridge. The power supply circuit 18 includes a rectifier circuit 19 configured by connecting six diodes in a three-phase bridge and a smoothing capacitor 20, and rectifies and smoothes a three-phase AC power supply 21 to supply a DC power supply to the inverter 16. .

  Further, FIG. 5 shows the functions realized by software by the control circuit (initial position determination means, drive control means, connection state determination means) 13 constituted by a microcomputer, for example. The subtracter 22 is given the position command value and the position (electrical angle) θa detected by the position detector 17, and the difference (position deviation) between the two is output to the multiplier 23. The multiplier 23 multiplies the difference by a position loop proportional gain Kpp, and outputs the multiplication result to the subtractor 24 as a speed command value. A speed obtained by differentiating the position θa by the differentiator 25 is given to the subtractor 24 as a subtraction value.

  The subtraction result (speed deviation) in the subtractor 24 is given to the multiplier 26 and multiplied by the speed loop proportional gain Kvp, and then outputted to the adder 27, and also given to the integrator 28 for integration. The integration result obtained by the integrator 28 is supplied to the multiplier 29 and is output to the adder 27 when multiplied by the speed loop integration gain Kvi. The addition result in the adder 27 becomes a torque command value, which is given to the fixed contact 30 (t1) of the failure diagnosis change-over switch 30.

  A maximum torque command value is given to the fixed contact 30 (t2) of the failure diagnosis changeover switch 30 by the maximum torque command value applying unit 31, and the movable contact 30 (t3) is connected to the input terminal of the torque limiter (limiter) 32. It is connected. The torque limiter 32 limits the torque command value output from the adder 27 at the upper limit and the lower limit, and outputs it to the coordinate conversion units 33U and 33V. The coordinate converters 33U and 33V store waveform data for applying a sinusoidal current to the servo motor 9, and the position (electrical angle) detected by the position detector 17 via the failure diagnosis changeover switch 34. Either θa (t1 side) or an electrical angle for fault diagnosis (t2 side) output from the fault diagnosis device 35 is given.

  Switching control of the failure diagnosis change-over switches 30 and 34 is performed by the failure diagnosis device 35. When the servo motor 9 is normally controlled, the failure diagnosis device 35 moves the movable contacts 30 (t3) and 34 of the failure diagnosis change-over switches 30 and 34. When (t3) is switched to the fixed contacts 30 (t1) and 34 (t1), respectively, and the failure diagnosis is performed, the movable contacts 30 (t3) and 34 (t3) are respectively fixed contacts 30 (t2) and 34 (t2). ) Side.

The coordinate conversion unit 33 reads and outputs sinusoidal current waveform data according to the electrical angle given through the failure diagnosis changeover switch 34. The torque command value given through the torque limiter 32 is multiplied by the current waveform data to set an amplitude value. The waveform data output from the coordinate conversion units 33U and 33V is given a phase difference of 120 °.
The waveform data output from the coordinate conversion units 33U and 33V is given to the subtracters 36U and 36V, respectively, and is detected by the current detectors 37U and 37V arranged at the U and V phase output terminals of the inverter 16, respectively. The difference between the phase current and the V phase current is taken. The current detectors 37U and 37V are configured by, for example, a current transformer (CT). The subtraction results output from the subtractors 36U and 36V are multiplied by the current loop proportional gain Kcp by the multipliers 38U and 38V and output to the PWM generator / predriver 39.

  That is, only the U and V phase PWM command values are given to the PWM generator / predriver 39, and the PWM generator / predriver 39 internally generates the W phase PWM command value based on the PWM command value. To do. The PWM generator / predriver 39 outputs a three-phase PWM signal to the control terminal (base or gate) of each switching element (for example, power transistor, power MOSFET, IGBT, etc.) constituting the inverter 16.

  FIG. 6 is a diagram schematically showing the structure of the servo motor 9. The servo motor 9 is a permanent magnet type synchronous motor and is a 4 pole 6 slot internal rotation type, and the rotor 41 is configured by arranging permanent magnets 43 for 4 poles on the surface of the rotor core 42. On the other hand, in the stator 44, U-phase, V-, and W-phase coils 46 are sequentially wound around six teeth 45 of the stator core disposed so as to surround the outer periphery of the rotor 41. And the rotating shaft (not shown) of the servo motor 9 (1 to 6) drives the arms 3 to 8 through a speed reduction mechanism.

  Next, the operation of this embodiment will be described with reference to FIGS. 1 to 3, FIG. 7, and FIG. As shown in FIG. 4, the robot body 1 and the driver unit 12 (1-6) are connected by the motor wire 14 and the encoder wire 15, but the driver unit 12 (1-6) side is connected. Since there are 6 branches, the connection destination may be wrong. Therefore, in this embodiment, when the system is turned on, the quality of the connection state is determined as follows.

  If the robot body 1 is not energized to each servo motor 9 and there is no mechanical brake, the arms 4 and 5 maintain their current positions against gravity. There is a need. However, for example, if the speed reduction mechanism also has a certain load, and if a torque greater than a predetermined value is required to rotate the gears constituting the speed reduction mechanism (for example, when a worm gear or the like is interposed), the servo motor 9 It is possible for each axis of the robot body 1 to maintain the original position even when is not energized.

FIG. 1A is a flowchart (main routine) showing a failure / wrong connection determination process performed by the control circuit 13. First, when the control circuit 13 sets a counter n for selecting an axis (servo motor 9) to be inspected to “1” (step S1), the servo motor 9 (1-6) arranged on each axis. ), The capacity, that is, the maximum rated current value that can be energized is nth smallest, and the number of axes is set to the pointer j (step S2).
Here, in the multi-movable axis type robot, since the load on the servo motor is generally higher as it is closer to the base of the arm, a robot having a relatively large capacity is used. For example, in the case of a 6-axis robot, the capacity is 1500 W, 750 W, 400 W, 200 W, 200 W, 100 W from the first axis to the sixth axis. That is, since the capacity of the sixth axis servo motor 9 (6) is the smallest, the sixth axis is selected at first.

  When the counter n is incremented in step S3 following step S2, the j-th axis is inspected (step S4). FIG. 1B is a flowchart showing details of the inspection performed in step S4. First, the position detectors 17 arranged on all the axes acquire the rotor position (initial position) of each servo motor 9 detected when the power is turned on (step S11). Since the position detector 17 outputs a mechanical angle, in the case of a 4-pole motor, twice that indicates an electrical angle. That is, as shown in FIG. 7, while the mechanical angle (axis angle) of the motor changes from 0 [DEG] to ~ 360 [DEG], the electrical angle changes over two cycles. When step S11 is executed, the driver unit 12 (j) passes a maximum current with an energization phase difference that maximizes the attraction force between the stator and the rotor for the servo motor 9 (j) of the inspection target shaft (step S12). .

  Reference is now made to FIG. FIG. 8 shows a state in which the rotational force (torque) generated in the servo motor 9 and the attractive / repulsive force acting between the stator and the rotor change according to the phase difference between the electrical angle and the drive current. It is a thing. Here, the rotational force corresponds to the torque current in vector control; q-axis current, the magnetic force corresponds to the excitation current; d-axis current, and the drive current is the vector sum of these. The phase difference (hereinafter referred to as energization phase difference) indicates an angle on the dq coordinate.

From this figure, it can be seen that when the conduction phase difference is 0 degree, the d-axis current becomes maximum and the magnetic attractive force becomes maximum, and the q-axis current becomes zero and the rotational force becomes minimum. Further, when the energization phase difference is 180 degrees, the d-axis current has the maximum reverse polarity and the repulsive force of the magnetic force becomes the maximum. On the other hand, when the energization phase difference is 90 degrees, the d-axis current is zero and the magnetic force is minimized, the q-axis current is maximized and the right rotational force is maximized, and the energization phase difference is -90 degrees. The q-axis current is the maximum with the reverse polarity, and the left rotational force is the maximum.
FIG. 9 shows a part of the state shown in FIG. 8 in a rotating coordinate system. 9A corresponds to the case where (electrical angle θa) = (current phase angle θb); that is, the energization phase difference in FIG. 8 is 0 degree, and FIG. 9B shows (electrical angle θa) − (current Phase angle θb) = 90 [DEG]; That is, this corresponds to the case where the energization phase difference in FIG. 8 is 90 degrees.

  Reference is again made to FIG. In step S12, the energization phase difference between the electrical angle and the drive current is set to 0 degree so that the d-axis current is maximized. In this case, the failure diagnosis device 35 gives the maximum torque command value in a state where the movable contacts 30 (t3) and 34 (t3) are switched to the fixed contacts 30 (t2) and 34 (t2), respectively, as described above. At the same time, an electrical angle that maximizes the attractive force is output from the electrical angle θa detected by the position detector 17 to the fixed contact 34b. As a result, if the phase difference matches the actual condition, the initial position is maintained without generating a rotational force in the servomotor 9 (j) of the inspection target shaft.

However, if there is an error in the position data output by the position detector 17 (j) for the inspection target axis, or if the encoder line 15 for the inspection target axis is replaced with another axis and connected, the actual electrical angle A q-axis current flows based on the phase difference caused by the deviation from θa, and a rotational force is generated in the servo motor 9.
Accordingly, the position θa of each servo motor 9 is acquired again in the same manner as in step S11 (step S13), and it is determined whether the servo motor 9 of any axis has rotated from the difference from the initial position (step S14). ). If the servo motor 9 of any axis rotates (YES), the determination result of the j-th axis that is the inspection target becomes “abnormal” (step S22), and the process is terminated. On the other hand, if the servo motor 9 of any axis has not rotated (NO), the process proceeds to step S15.

  After step S15, further inspection is performed by a different method. Next, with respect to the inspection target axis, the energization phase difference is gradually shifted within a range of 0 to less than 90 degrees (step S16) (for example, by 5 degrees), that is, the q-axis current is gradually increased to increase the servo motor 9 (j). The rotational force applied to is gradually increased. Then, until the energization phase difference reaches 90 degrees (absolute value) (YES), the current positions are acquired for all axes (step S17), and whether or not the axes other than the inspection target axes (other axes) are rotated, Alternatively, when the own axis rotates in the direction opposite to the direction in which the energization phase difference is shifted (step S18), whether or not the inspection target axis (own axis) has rotated in the direction in which the energization phase difference is shifted (step S19). ). In this case, the failure diagnosis device 35 outputs the electrical phase θa detected by the position detector 17 (j) to the fixed contact 34 (t2) while gradually increasing the energization phase difference provided by itself.

  If rotation of the other axis is detected in step S18, or if the own axis rotates in the direction opposite to the direction in which the energization phase difference is shifted (YES), it is confirmed that there is an error in the wiring connection of the motor line 14. Since it shows, it transfers to step S22. In Step S19, if the inspection target axis rotates in the direction in which the energization phase difference is shifted (YES), it indicates that the wiring connection of the motor line 14 is normal. Therefore, if energization control is performed so that the position of the j-th axis returns to the initial position as necessary (step S20), the determination result of the j-th axis is set to “normal” (step S21), and the inspection is terminated.

In step S19, if rotation of the inspection target axis is not detected (NO), the process returns to step S15 to increase the energization phase difference. However, if the energization phase difference reaches 90 degrees without detecting the rotation (step S16: NO), it indicates that the servo motor 9 (j) is out of order or that there is a problem in the wiring connection of the motor wire 14. Therefore, also in this case, the process proceeds to step S22.
FIG. 2 is an image of a normal case where “YES” is determined in step S19. The j-axis servo motor 9 (j) to be inspected rotates in turn every time inspection is performed. Become. FIG. 3 is an image of an abnormal case determined as “YES” in step S18, and shows a case where the servo motor 9 of another axis different from the j-axis servo motor 9 (j) rotates. .

When the inspection of the jth axis is completed as described above, the process returns to the flow of FIG. 1A and proceeds to step S5. Then, it is determined whether or not the inspection result of the j-th axis is “normal”. If “normal” (YES), the value of the counter n exceeds the number of axes to be inspected (“6” if there are 6 axes). It is determined whether or not (step S6). If the number of inspection axes has not been exceeded (NO), the process returns to step S2, and the number of axes of the servo motor 9 with the next largest capacity (the next smallest rated current value that can be energized) is set to the pointer j, and the inspection continues. I do.
In step S6, when the number of inspection axes is exceeded (YES), the entire determination result is set to “normal” (step S8), and the process is terminated. If the inspection result on the j-th axis is “abnormal” in step S5 (NO), the entire determination result is “abnormal” at that time (step S7), and the process is terminated.

  As described above, according to the present embodiment, the control circuit 13 is arranged in the inspection target motor 9 (j) when the power is turned on, with any one of the plurality of servo motors 9 being the inspection target motor 9 (j). When the initial position of the inspection target motor 9 (j) is obtained from the position θa obtained by the position detector 17 (j), the corresponding inverter so that the rotor of the inspection target motor 9 (j) maintains the initial position. A drive current is output to each phase winding of the inspection target motor 9 (j) via 16 (j). Then, depending on whether any of the servo motors 9 arranged on the respective axes of the robot body 1 has rotated during the current output period, whether or not each inverter 16 is connected to the corresponding servo motor 9 is determined. judge. Moreover, the quality of the connection state of the encoder line 15 can also be determined.

  If the determination is made in this way, the connection between the inverter 16 and the corresponding servo motor 9 is incorrect, so even if any one of the servo motors 9 rotates, the amount of rotation remains very small. That is, at most, the servo motor 9 does not make one rotation or more in mechanical angle, and is within one rotation determined by the relationship between the number of poles of the rotor 41 and the number of slots of the stator 44. Therefore, the amount of change in the operation of the robot body 1 associated therewith is also small, so that safety can be maintained. Moreover, since the above determination can be easily performed by changing the control program executed by the control circuit 13, it can be easily applied to an existing robot system.

  In addition, when the control circuit 13 first selects the servo motor 9 having the smallest capacity among the plurality of servo motors 9 as the inspection target motor 9 (j), the inspection target motor 9 (j) is subsequently increased in order of the capacity. Are sequentially selected and repeatedly executed. Therefore, it is possible to avoid a situation in which the permanent magnet disposed in the rotor is demagnetized by the magnetic field generated by the winding without flowing an excessively large driving current through the winding of the servo motor 9 having a small capacity.

  Further, when the determination result is “good”, the control circuit 13 outputs a driving current so as to gradually increase the rotational force applied to the inspection target motor 9 (j), and the inspection target motor 9 (j). Since whether or not the connection state is further determined according to whether or not the motor has rotated in accordance with the drive current, when all the connections are switched between the inspection target motor 9 (j) and the other servo motor 9 This can be determined by rotation of any servo motor 9 other than the inspection target motor 9 (j). In addition, when an erroneous connection occurs between the phases of the inspection target motor 9 (j), the inspection target motor 9 (j) rotates in the opposite direction or does not rotate with respect to the given drive current command value. Can be determined. Therefore, erroneous connection determination can be reliably performed for various cases.

(Second embodiment)
FIG. 10 shows a second embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted. Hereinafter, different parts will be described. In the second embodiment, although not specifically shown, when the mechanical brake is applied to each axis of the robot body 1, when the mechanical brake is released, the rotational position of each axis is affected by the action of weight. Suppose that it is in a state that can be easily changed by disturbance. The case where failure detection is performed in this state is shown.

  In the initial state, it is assumed that the mechanical brake is acting on each axis of the robot body 1. In step S30 of FIG. 10A, when the initial positions of all the axes are acquired, the drive current is supplied so that the d-axis current becomes the maximum for all the axes (step S31), and the mechanical brake is released in that state. (Step S32). When the rotational positions at that time of all the axes are acquired (step S33), it is determined whether any of the axes has rotated (step S34).

  In step S34, if no axis is rotating (NO), the counter j is set to “1” (step S35), and the j-th axis is inspected. The inspection content on the j-th axis shown in FIG. 9B is substantially the same as that obtained by deleting steps S12 to S14 from FIG. 1B of the first embodiment. Then, after executing step S5, the counter j is incremented (step S36).

In step S6 ′ of FIG. 10A, it is determined whether or not the value of the counter j exceeds the number of axes to be inspected. Further, after execution of step S7, the mechanical brakes of all the axes are applied (step S37), the energization is turned off for all the axes (step S38), and then the process ends.
As described above, according to the second embodiment, the mechanical brake is applied to each axis of the robot body 1, and even when the rotational position of each axis can be changed by releasing the mechanical brake, Fault diagnosis can be performed as in the first embodiment.

The present invention is not limited to the embodiments described above or shown in the drawings, and the following modifications or expansions are possible.
For example, a resolver or the like may be used as the position detector.
The permanent magnet type synchronous motor may be either an SPM (Surface Permanent Magnet) type or an IPM (Interior Permanent Magnet) type. Further, it is not limited to the 4-pole 6-slot configuration.
The present invention may be applied to a horizontal multi-movable axis type robot.
The “movable shaft” includes not only the rotary shaft but also the linear motion shaft.

  In the drawings, 1 is a robot body, 9 is a servo motor (permanent magnet type motor), 16 is an inverter (drive circuit), 13 is a control circuit (initial position determination means, drive control means, connection state determination means), and 17 is a position. The detector is shown.

Claims (6)

A plurality of drive circuits arranged to correspond to the permanent magnet type motors arranged on the respective axes of the multi-movable axis type robot main body and outputting electric currents to the respective phase windings of the motors, and the electric angles of the motors In a robot control apparatus comprising: a plurality of position detectors to detect; and a control circuit that drives and controls each motor via the plurality of drive circuits when an electrical angle of each motor is obtained from the plurality of position detectors.
The control circuit uses any one of the plurality of motors as an inspection target motor,
Initial position acquisition means for acquiring an electrical angle of the inspection target motor as an initial position from a position signal obtained by a position detector disposed on the inspection target motor when the power is turned on;
Drive control means for outputting a drive current to each phase winding of the inspection target motor via a corresponding drive circuit so that the electrical angle of the inspection target motor maintains the initial position;
If any of the motors arranged on each of the shafts rotates during the period when the drive control means outputs the drive current, the connection state between the plurality of drive circuits and the corresponding motors is poor. A robot control apparatus comprising: a connection state determination means for determining   The control circuit first selects a motor having the smallest capacity as the inspection target motor among the plurality of motors, and thereafter sequentially selects the inspection target motors in order of increasing capacity, and the connection state determination unit The robot control apparatus according to claim 1, wherein the determination is repeatedly performed. The drive control unit drives each phase winding of the inspection target motor so as to gradually increase the rotational force applied to the inspection target motor when the result of the determination by the connection state determination unit is “good”. Output current,
3. The robot control device according to claim 1, wherein the connection state determination unit further determines whether or not the connection state is good depending on whether the inspection target motor is rotated according to the drive current. 4. . A plurality of drive circuits arranged to correspond to the permanent magnet type motors arranged on the respective axes of the multi-movable axis type robot main body and outputting electric currents to the respective phase windings of the motors, and the electric angles of the motors When obtaining the electrical angle of each motor from a plurality of position detectors to be detected and the plurality of position detectors, when driving the motors through the plurality of drive circuits,
Any one of the plurality of motors is used as an inspection target motor.
When the electric angle of the inspection target motor is acquired as an initial position from a position signal obtained by a position detector disposed on the inspection target motor at the time of power-on,
A drive current is output to each phase winding of the inspection target motor via a corresponding drive circuit so that the electrical angle of the inspection target motor maintains the initial position,
If any of the motors arranged on each of the shafts rotates during the period of outputting the drive current, the connection state between the plurality of drive circuits and the corresponding motors is determined. A method for determining poor connection of a robot.   When the motor with the smallest capacity is selected as the inspection target motor among the plurality of motors first, the inspection target motors are sequentially selected in order of increasing capacity, and the determination of the connection state is repeatedly executed. The robot connection failure determination method according to claim 4. When the determination result of the connection state is “good”, a driving current is output to each phase winding of the inspection target motor so as to gradually increase the rotational force applied to the inspection target motor,
6. The robot connection failure determination method according to claim 4, further comprising: determining whether the connection state is good or not based on whether or not the inspection target motor is rotated according to the drive current.

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