JP2012257425A - Motor drive method, motor drive device, and robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive method, motor drive device, and robot, capable of operating a driven section, such as a robot arm, at a high speed.SOLUTION: The motor drive method includes: a driving data acquisition process for acquiring driving torque measurement data and rotational speed measurement data for a motor; a comparison process for comparing the driving torque measurement data and the rotational speed measurement data to a rotational speed/torque characteristic table for the motor; and a voltage increasing process for increasing a driving voltage of the motor when the driving torque measurement data and the rotational speed measurement data is at a drivable region boundary of the rotational speed/torque characteristic table according to the comparison result of the comparison process.

Description

  The present invention relates to a motor driving method, a motor driving device, and a robot.

  The introduction of robots to the manufacturing site of industrial products has been extended to various fields such as replacement of simple work, precision work that requires repeated positional accuracy, and work that handles heavy objects. In addition, a number of robots are placed on the production line, and the unmanned flow work is rapidly progressing. When arranging a plurality of robots on a production line, in order to increase the productivity of the production line, it is necessary to increase the productivity of each of the arranged robots. The productivity of the robot depends on the operation speed, but it is important to accelerate to a predetermined speed in a short time from the start.

  In Patent Document 1, the viscosity of a lubricant such as grease increases at a low temperature, and the viscosity resistance causes, for example, an increase in operation time and a decrease in locus accuracy with respect to a command operation. It is disclosed that a predetermined acceleration / deceleration and speed of a motor are adjusted from detected torque and corrected by an acceleration / deceleration determiner that prevents the motor torque from being saturated.

  Patent Document 2 discloses a control device for controlling a motor of a single-phase rectifier converter power supply, which includes a step-up / step-down chopper and a power storage unit, and boosts the voltage of the power storage unit when a DC voltage signal falls below a threshold value. It is disclosed that a DC voltage is maintained at a threshold value by discharging a capacitor.

JP-A-9-311713 JP 2009-195018 A

  However, in Patent Document 1 described above, the acceleration / deceleration determiner provided in the control device is controlled so as to decrease the motor speed when the reference torque value is exceeded in order to avoid the saturation state of the motor torque. Therefore, the productivity is not improved. Further, Patent Document 2 discloses that a decrease in DC voltage when load fluctuation occurs in normal operation is compensated by the power source of the power storage unit, and the motor operation with less fluctuation is performed, and the speed of the motor is increased. There is no.

  Therefore, a motor driving method, a driving device, and a robot that can be driven temporarily beyond a drivable region and can operate a driven part such as a robot arm at high speed are provided.

  The present invention can be realized as the following forms or application examples so as to solve at least one of the above-described problems.

  [Application Example 1] A motor driving method according to this application example includes a drive data acquisition step of acquiring motor drive torque measurement data and rotation speed measurement data, and the drive torque measurement data and rotation speed measurement data. In the comparison step of comparing with the rotation speed / torque characteristic table of the motor, and in the comparison result of the comparison step, the drive torque measurement data and the rotation speed measurement data are the boundaries of the driveable area of the rotation speed / torque characteristic table. And a voltage raising step for boosting the driving voltage of the motor.

  In the so-called TN characteristic, which shows the relationship between the motor torque and the rotational speed, during acceleration driving from motor start to constant speed driving, the rotational speed gradually increases as the load torque decreases, and the predetermined torque It rotates at a constant speed below the value. At the time of this acceleration drive, the motor drive voltage of the application example is increased to a voltage exceeding the rated drive voltage by the motor drive method of this application example. The time required from starting the motor to constant speed driving can be shortened.

  [Application Example 2] In the application example described above, the voltage increase step includes the drive torque measurement data and the rotation speed measurement data, the driveable region boundary and a threshold value set inside the driveable region boundary. , The drive voltage of the motor is boosted.

  According to the application example described above, the determination value for boosting the driving voltage of the motor is set in a region formed by the driveable region boundary and the threshold value set inside the driveable region boundary. As a result, the timing for boosting the drive voltage can be advanced, and the delay in boosting the drive voltage can be prevented. Therefore, the required time from the motor start to the constant speed drive can be shortened more reliably.

  Application Example 3 A motor drive device according to this application example includes: drive data acquisition means for acquiring motor drive torque measurement data and rotation speed measurement data; and the drive torque measurement data and rotation speed measurement data. Comparing means for comparing with the rotational speed / torque characteristic table of the motor, and from the comparison result of the comparing means, the driving torque measurement data and the rotational speed measurement data are the boundary of the driveable area of the rotational speed / torque characteristic table. And a voltage raising means for boosting the driving voltage of the motor.

  In the so-called TN characteristic, which shows the relationship between the motor torque and the rotational speed, during acceleration driving from motor start to constant speed driving, the rotational speed gradually increases as the load torque decreases, and the predetermined torque It rotates at a constant speed below the value. During this acceleration drive, the motor drive device of this application example has a voltage booster that boosts the motor drive voltage to a voltage exceeding the rated drive voltage, so that the motor drive torque or rotation speed during acceleration drive can be rated. The time required from the start of the motor to the constant speed drive can be shortened by setting it higher than the value.

  Application Example 4 In the application example described above, the voltage raising means includes a threshold value at which the driving torque measurement data and the rotation speed measurement data are set inside the driveable region boundary and the driveable region boundary. , The drive voltage of the motor is boosted.

  According to the application example described above, the determination value for boosting the driving voltage of the motor is set in the region formed by the driveable region boundary and the threshold value set inside the driveable region boundary, and the comparison result of the comparison unit This is a device comprising a voltage raising means for boosting the power supply voltage. As a result, the timing for boosting the drive voltage can be advanced, and the delay in boosting the drive voltage can be prevented. Therefore, it is possible to obtain a motor drive device that more reliably shortens the time required from motor start to constant speed drive.

  Application Example 5 A robot including the motor driving device of the application example described above.

  According to the robot of this application example, the time from the start of driving to the constant speed driving can be shortened, and the target movement time of the robot arm can be shortened. Therefore, a highly productive robot can be obtained.

The block diagram which shows the structure of the robot which concerns on embodiment. The flowchart which shows the drive method of the robot which concerns on embodiment. The TN characteristic diagram which shows the outline | summary of the drive characteristic of the motor with which the robot which concerns on embodiment is equipped. The TN characteristic diagram explaining the comparison judgment method of the motor with which the robot which concerns on embodiment is equipped. FIG. 3 is a circuit block diagram illustrating an example of a booster circuit. The driving method of the robot according to another embodiment will be described. (A) is a conceptual diagram of an arm trajectory, (b) is a conceptual diagram of torque characteristics, and (c) is a conceptual diagram showing changes in driving voltage. The driving method of the robot according to another embodiment will be described. (A) is a conceptual diagram of an arm trajectory, (b) is a conceptual diagram of rotation speed characteristics, and (c) is a conceptual diagram showing changes in driving voltage. The circuit block diagram which shows the other example of a booster circuit.

  Embodiments according to the present invention will be described below with reference to the drawings.

(Embodiment)
FIG. 1 is a conceptual diagram showing the configuration of the robot according to the present embodiment. A robot 100 shown in FIG. 1 includes a first arm 21 whose one side is rotatably fixed to the base 10, and a second arm whose one side is relatively rotatably fixed to the other side of the first arm 21. The arm 22 and the hand portion 30 that performs work on the work piece 40 are provided on the other side of the second arm 22. The base 10 and the first arm 21 are rotatably fixed by a motor 51, and the first arm 21 and the second arm 22 are rotatably fixed by a motor 52.

  The robot 100 also includes a drive control device 70 as a motor drive device that controls the drive of the robot 100, and the drive control device 70 receives an instruction from an external drive instruction device 200, which is an external control device such as a computer, for example. 71, the arms 21, 22 and the hand unit 30 are driven. Further, the drive control device 70 includes a control unit 72 that controls the robot 100 via the drive unit 71 based on the drive information of the robot 100.

  The motor 51 provided in the base 10 and the motor 52 provided in the first arm 21 are provided with detection means 61 and 62 for detecting the output torque and the rotational speed of each motor. Data detected by the detection means 61 and 62 is acquired by a control unit 72 provided in the drive control device 70, and the control unit 72 temporarily boosts drive voltages of motors 51 and 52, which will be described later, based on the acquired signals. Execute control to The control unit 72 includes a drive data acquisition unit 72a that acquires detection data signals from the detection units 61 and 62, a rotation speed / torque characteristic table 72b that stores the rotation speed and torque characteristics of the motors 51 and 52, and a drive. Comparison means 72c for comparing the drive data acquired by the data acquisition means 72a with the drive characteristic data acquired from the rotation speed / torque characteristic table 72b, and a voltage increase means for boosting the motor drive voltage based on the comparison result in the comparison means 72c. 72d.

  FIG. 2 is a flowchart showing a method for driving the motors 51 and 52 of the robot 100. A method for driving the robot 100 will be described with reference to FIG.

<Motor torque / rotational speed measurement process>
First, a driving signal for the robot 100 based on an instruction from the external driving instruction device 200 is sent from the driving unit 71, and driving of the motors 51 and 52 is started (S1). Immediately after the start of motor driving (S1), the detection means 61 and 62 measure the rotational speed and output torque of the motors 51 and 52, and the motor torque / rotational speed measuring step (S2) (hereinafter, measuring step (S2)). Is executed).

<Motor rotation speed judgment process>
It is determined whether the rotation speed data detected in the measurement step (S2) is the maximum rotation speed in the motor rotation speed determination step (S3). FIG. 3 is a graph schematically showing the rotational speed / torque characteristics (TN characteristics) of the motors 51 and 52. Motor 51 and 52 provided in the robot 100 according to this embodiment has a TN characteristic as shown in FIG. 3, the inner region U _A is drivable region of the TN characteristic line, TN characteristic line as a driving region boundary Defined. In the TN characteristic shown in FIG. 3, the motor can be driven up to the change point P1, that is, the load torque up to the torque T _P1 and the maximum speed R _max . However, from the changing point P1 up to the output torque T _max is the maximum load torque is changing point P2 rotatable motor rotational speed decreases, the maximum rotational speed at the changing point P2 becomes the R _P2. Therefore, in the TN characteristic diagram showing the performance of the motors 51 and 52 provided in the robot 100 according to the present embodiment, the changing point P1 shown in FIG. 3 is made closer to the higher load torque side, that is, T _P1 is closer to the T _max side. in, is larger 0 to T _P1 is the load region R _max can be maintained, the first arm 21, it is to allow the moving to the target position of the second arm 22 in a shorter time.

In the motor rotation number determination step (S3), it is determined whether the rotation number detected in the measurement step (S2) is R _max shown in FIG. If the determination result is that the motor rotation speed is R _max, that is, YES, the process proceeds to the next deceleration target position arrival determination step (S4). When the determination result is that the motor rotation speed is not R _max, that is, NO, the process proceeds to a motor torque / rotation speed comparison process (S10) as a comparison process.

<Motor torque / rotation speed comparison process>
In the motor torque / rotational speed comparison step (S10) (hereinafter referred to as torque rotational speed comparison step (S10)), a comparison determination is performed using the TN characteristic diagram shown in FIG. The TN characteristic diagram shown in FIG. 4 is created from the TN characteristic diagram shown in FIG. As shown in FIG. 4, a threshold value L that is a reference for comparison determination is set. The threshold value L is a determination value for boosting the power supply voltage of the motors 51 and 52, which will be described later, and gives a TN characteristic including a line P1′-P2 ′ indicating drive performance exceeding the line P1-P2.

In the torque rotational speed comparison step (S10), based on the TN characteristic diagram shown in FIG. 4, the rotational speed and torque data from the detection means 61 and 62 acquired in the measurement step (S2) are stored in the regions U1, U2, and U2. Compare which region of U3 it is. The region U1 is a region up to the change point P1 excluding the R _max line. The region U2 is a region formed by the threshold value L and the rotation speed 0 (coordinate line). The region U3 is a region formed by the threshold value L and the lines P1-P2. In the region U1, by supplying power to the motors 51 and 52 with the voltage of the rated power supply, the maximum rotational speed _Rmax can be reached.

In the region U2, there is a margin with respect to the driveable region U _A (see FIG. 3) of the motors 51 and 52, and the rotational speed is increased. This region U2 is a region in which the rotational speed is increased by supplying power to the motors 51 and 52 with the voltage of the rated power supply. The region U3 is a region that exceeds the threshold value L. That is, if the driving is further performed to increase the rotational speed, the region of the line P1-P2 that is lower than the maximum rotational speed _Rmax is reached. Therefore, when it is determined that the detected values of the torque and the rotational speed of the motors 51 and 52 are in the region U3, the boosted power supply 72d (FIG. 1) The process proceeds to a step of supplying the motors 51 and 52 to the motor 51 and 52.

  That is, in the torque rotation speed comparison step (S10), a comparison is made with the threshold value L in the TN characteristic diagram shown in FIG. 4 as a characteristic table, and when it is in the regions U1 and U2, that is, when it is determined that the threshold value L or less ( YES), the motor drive by the rated power supply voltage is continued, and the measurement process (S2) is executed again. In the case of the region U3, that is, when it is determined that the threshold value L is exceeded (NO), a power supply having a voltage higher than the rated power supply voltage is generated by the voltage raising means 72d (see FIG. 1), and is supplied to the motors 51 and 52. The process proceeds to the motor drive voltage boosting step (S20) as the step of increasing the voltage.

<Motor drive voltage boosting process>
In the motor drive voltage boosting step (S20) (hereinafter referred to as the drive voltage boosting step (S20)), the drive voltage generated by the rated voltage source 72d shown in FIG. The generated power is sent to the driving unit 71 and the boosted power is supplied to the motors 51 and 52. The voltage raising means 72d includes a booster circuit as shown in the circuit block of FIG. The booster circuit shown in FIG. 5 calculates a coil current command in the drive voltage control unit 72f based on the drive voltage command and the drive voltage from the drive voltage command calculation unit 72e provided in the voltage raising means 72d, and the coil current command and the coil current are calculated. Based on the calculated PWM command, the PWM generator 72h generates switches SW1 and SW2 to control the discharge to boost the drive voltage.

By thus boost the driving power source, the TN characteristic shown in FIG. 4, the maximum rotational speed R _max be a load condition of a large torque T _P1' than the driving torque T _P1 which can be driven at the maximum speed R _max Thus, the first arm 21 and the second arm 22 can be moved to the target position in a shorter time. That is, the operable region can be temporarily expanded to the region U4 by supplying the boosted power to the operable region of the motors 51 and 52 at the rated power supply voltage.

Driven by the boosted power source in the region U4 that exceeds the driveable range of the motors 51 and 52, the rotation speed of the motors 51 and 52 is measured again by the measuring step (S2). In the motor rotation speed determination step (S3) described above, when the determination result is that the motor rotation speed is R _max, that is, YES, the routine proceeds to the next deceleration target position arrival determination step (S4).

<Deceleration target position arrival determination process>
In the deceleration target position arrival determination step (S4) (hereinafter referred to as the deceleration position determination step (S4)), the deceleration start of the movement speed before reaching the movement target position of the arms 21 and 22 instructed by the external drive instruction device 200 is started. The position, that is, the deceleration target position is determined. In the deceleration position determination step (S4), when it is determined that the deceleration target position has been reached (YES), the process proceeds to the motor deceleration step (S5). If it is determined in the deceleration position determination step (S4) that the deceleration target position has not been reached (NO), the motors 51 and 52 continue to drive and repeat the steps from the measurement step (S2).

<Motor deceleration process>
In the motor deceleration process (S5), the motors 51 and 52 are decelerated using an electromagnetic brake or a motor regenerative brake as a deceleration means, and the process proceeds to the target position arrival determination process (S6).

<Target position arrival determination process>
In the target position arrival determination step (S6), in the motor deceleration step (S5), the motors 51 and 52 are decelerated, and it is determined whether the arms 21 and 22 have reached the target position, which is a predetermined stop position. If it is determined that it has reached (YES), the routine proceeds to motor drive stop (S7), and the motors 51 and 52 stop, that is, the movement of the arms 21 and 22 ends. If it is determined that it has not reached (NO), the motors 51 and 52 are driven until the target position is reached while continuing the motor deceleration step (S5).

  As described in the above motor driving method, the load (torque) is increased by temporarily boosting and supplying the power supply voltage to the drive region (see the TN characteristic diagram shown in FIG. 3) in the rated drive power supply of the motor. ), A region where the motor can be driven to the maximum speed can be formed. As a result, the area where the maximum number of revolutions of the motor can be exhibited can be expanded and the arm can be moved at a higher speed, especially with respect to the load increase that occurs in the acceleration area from the start of arm movement to the constant speed movement. Therefore, a highly productive robot can be obtained.

(Other embodiments)
In the robot 100 according to the above-described embodiment, when the result of measuring the torque and the rotational speed of the motors 51 and 52 is in the region U3 in the TN characteristic shown in FIG. 4, the motor drive voltage boosting step (S20) is executed. It was. However, the present invention is not limited to this, and only the torque of the motors 51 and 52 is measured, and the motor drive voltage boosting step (S20) is executed by comparison with the torque threshold, or only the rotation speed of the motors 51 and 52 is obtained. And the motor drive voltage boosting step (S20) can be executed by comparing with the rotation speed threshold value.

FIG. 6 is an explanatory diagram for explaining a mode in which the motor drive voltage boosting step (S20) is executed by comparing the torque measurement values of the motors 51 and 52 with the torque threshold value. As shown in the trajectory diagram shown in FIG. 6A, for example, the trajectory of the first arm 21 driven by the motor 51 reaches the target position with the passage of time. In the meantime, it is composed of an acceleration section from a motor start to a constant speed drive, a constant speed section, and a deceleration section from a drive stop. In the acceleration section, the torque characteristics shown in FIG. 6B require high torque toward the beginning of the constant speed section. However, the maximum torque at the rated power supply voltage shows a low value of the torque T _m fraction relative to the maximum torque required, as shown in Figure 6 (b). The difference is increased by the motor driving voltage boosting step (S20) shown in FIG.

FIG. 6C shows the elapsed time of the drive voltage. As described above, in order to generate torque exceeding the maximum torque at the rated power source, a torque threshold value lower than the rated power source maximum torque is set as shown in FIG. 6B, and the measured torque value exceeds this torque threshold value. In this case, the boosted power supply voltage shown in FIG. 6C is generated and supplied as the drive voltage. Thus to obtain a T _m greater torque than the rated power maximum torque, it is possible to shorten the acceleration time.

FIG. 7 is an explanatory diagram for explaining a mode in which the motor drive voltage boosting step (S20) is executed by comparing the rotation speed measurement values of the motors 51 and 52 with the rotation speed threshold value. Similarly to the trajectory diagram shown in FIG. 6 (a), in the trajectory diagram shown in FIG. 7 (a), for example, the trajectory of the first arm 21 driven by the motor 51 has an acceleration zone, a constant speed zone, The target position is reached through the deceleration zone. As shown in FIG. 7B, when the motor 51 is driven by the rated power supply voltage in the acceleration section, the increase in the rotational speed increases along the graph line _LR , and the time t until the rated power supply maximum rotational speed is reached. Requires _m . Here, a rotation speed threshold lower than the rated power supply maximum rotation speed, for example, 50% of the rated power supply maximum rotation speed is set as the rotation speed threshold, and when this rotation speed threshold is exceeded, the boost power supply shown in FIG. A voltage is generated and supplied as a driving voltage. Thus it is that the time to reach the rated power maximum speed is the time t _a before the t _m, it is possible to shorten the acceleration time.

  The robot 100 according to the above embodiment uses an external AC power source as the power source of the voltage raising means 72d as shown in FIG. 5, but stores the regenerative energy at the time of deceleration of the motors 51 and 52 as electric power to drive the motor. It can also be used as a boosting power source in the voltage boosting step (S20). FIG. 8 is a circuit block illustrating an example of a booster circuit using regenerative power. The motors 51 and 52 are provided with a regenerative brake (not shown) for converting deceleration and deceleration energy into electric power, and the electric power sent from the regenerative brake is stored in a charging / discharging capacitor. In the booster circuit shown in FIG. 8, a coil current command is calculated in the drive voltage control unit 72f based on the drive voltage command and the drive voltage from the drive voltage command calculation unit 72e provided with the voltage raising means 72d. Based on the calculated PWM command, the PWM generator 72h generates switches SW1 and SW2 to control the discharge to boost the drive voltage. At this time, the charge / discharge capacitors can be arranged in series to increase the withstand voltage, and by increasing the withstand voltage and charging at a high voltage, the desired high voltage can be easily obtained when generating the boost power supply. And high-speed arm movement can be realized.

  In the robot 100 according to the above-described embodiment, the motor drive voltage boosting step (S20) shown in FIG. 2 performs torque rotation for comparing the measurement result of the motor torque and the rotational speed in the measurement step (S2) with the threshold value. This is a mode that is executed based on the comparison result of the number comparison step (S10). However, when the trajectories to reach the target positions of the arms 21 and 22 of the robot 100 are set in advance, the drive voltage corresponding to the trajectory is set. It is also possible to generate a boosting instruction profile and control the driving voltage. As a result, there is no need to execute torque, rotational speed data acquisition, data calculation, and the like in real time, and a drive control device with a simple configuration can be obtained, and low cost and improved reliability can be achieved. .

  In addition, although the robot 100 which concerns on embodiment mentioned above illustrated the horizontal articulated robot provided with the arms 21 and 22, it is not limited to this. For example, it may be a vertical articulated robot or the like, and can be applied to a motor driving method of a robot by motor driving.

  DESCRIPTION OF SYMBOLS 10 ... Base 21, 22 ... Arm, 30 ... Hand part, 40 ... Workpiece, 51, 52 ... Motor, 61, 62 ... Detection means, 70 ... Drive control apparatus, 100 ... Robot, 200 ... External drive instruction apparatus.

Claims (5)

A drive data acquisition step of acquiring motor drive torque measurement data and rotation speed measurement data;
A comparison step of comparing the drive torque measurement data and the rotation speed measurement data with a rotation speed / torque characteristic table of the motor;
In the comparison result of the comparison step, when the drive torque measurement data and the rotation speed measurement data are at a driveable region boundary of the rotation speed / torque characteristic table, a voltage increase step for boosting the drive voltage of the motor; Comprising
The motor drive method characterized by the above-mentioned. In the voltage raising step, when the driving torque measurement data and the rotation speed measurement data are in a region formed by the driveable region boundary and a threshold value set inside the driveable region boundary, Boost the motor drive voltage,
The motor driving method according to claim 1. Drive data acquisition means for acquiring motor drive torque measurement data and rotation speed measurement data;
A comparison means for comparing the drive torque measurement data and the rotation speed measurement data with a rotation speed / torque characteristic table of the motor;
From the comparison result of the comparison means, when the drive torque measurement data and the rotation speed measurement data are at a driveable area boundary of the rotation speed / torque characteristic table, a voltage increase means for boosting the drive voltage of the motor; Comprising
A motor drive device characterized by that. When the driving voltage measurement data and the rotation speed measurement data are in a region formed by the driveable region boundary and a threshold value set inside the driveable region boundary, Boost the motor drive voltage,
The motor drive device according to claim 3.   A robot comprising the motor drive device according to claim 3.

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