JPH0828989B2 - Electric motor controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor control device, and more particularly to an electric motor control device suitable for driving a machine that performs various movements such as a robot.

[Background of the Invention]

As a control device for an electric motor that drives a robot, for example, as described in pages 27 to 27 of Vol. 27, No. 11 of the magazine "System and Control," a position command is generated for each electric motor, and its position is set. It is generally used to control each joint angle according to a command. A control system that adds the results obtained from acceleration and velocity control to the output of the position control system is also described, but it is used to limit the values of acceleration and velocity, and basically The operation according to the position command is executed. On the other hand, recently, as the operation of the robot has become complicated, the control operation of the electric motor has also become complicated. For this reason, it is becoming difficult to cope with the optimal operation of the robot with only the position control operation.

[Object of the Invention]

An object of the present invention is to control a position control system in a motor,
By arbitrarily selecting the three-mode control system of the speed control system and the torque control system, it becomes possible to perform optimum control for performing a series of work of the controlled object such as a robot, and also to change the speed control from the torque control to the speed control or An object of the present invention is to provide a control device for an electric motor that does not generate vibration to a mechanical system even when switching to position control or switching from speed control to position control is performed in real time.

[Outline of Invention]

The present invention provides, as a control device for an electric motor, a command generating means for outputting a rotational position command, a speed command and a torque command for the electric motor according to a predetermined sequence control, and a first device during driving of the electric motor according to the predetermined sequence control. A switching signal generating means for generating at least one of a first switching signal and a second switching signal; and a position control means for outputting a calculation speed command so that a feedback value of an actual rotation position of the electric motor is added to the rotation position command. A first switching means for selecting and outputting either the speed command output by the command generating means or the calculated speed command by the first switching signal, and an output signal from the first switching means. Speed control means for outputting a calculated torque command so that a feedback value of the actual speed of the electric motor becomes a command value, and the command generation means. Second switching means for selecting and outputting one of the torque command output by the stage or the calculated torque command by the second switching signal, and an output signal from the second switching means as a command value A torque control unit that outputs a drive command for the electric motor so that a feedback value of the actual torque of the electric motor becomes a value, a unit that controls the drive of the electric motor based on the drive command, and a control of the electric motor is performed by the first control unit.
When switching from the speed control system to the position control system mode or from the torque control system to the speed control system or the position control system mode by the first and second switching means, the input command signal of the control system immediately after the switching is changed. An initial value setting means for setting, as an initial value, a feedback value of the control system before switching or a command value of the control system feedback value after switching divided by a control gain of the control system after switching. It is characterized by having done.

Example of Invention

 FIG. 1 shows an embodiment according to the present invention.

In FIG. 1, 1 is a command generation circuit, which is a switching signal.
Generate c ₁ , c _2, position command x _r , speed command n _r1 , and torque command τ _r1 . Reference numeral 2 denotes a position control circuit, which takes in the position command x _r output from the command generation circuit 1 and the position feedback amount x _f output from the position detector 4 directly connected to the electric motor 3 to obtain a speed command (calculated speed). Command) n _r2 is generated. Reference numeral 5 denotes a first switching circuit, which is output from the command generation circuit 1 as the speed command n _r of the speed control circuit 6 in response to the switching signal c _1.
It is determined whether to use n _r1 or the calculated speed command n _r2 output from the position control circuit 2. The speed control circuit 6 generates a torque command (calculated torque command) τ _r2 using the speed command n _r output from the switching circuit 5 and the output n _f of the speed detector 7 directly connected to the electric motor 3. Reference numeral 8 denotes a second switching circuit, which uses the torque command τ _r1 output from the command generation circuit 1 as the torque command τ _r of the torque control circuit 9 according to the switching signal c ₂ or outputs it from the speed control circuit 6. It is determined whether to use the calculated torque command τ _r2 . Torque control circuit 9
Is the torque command τ _r output from the switching circuit 8 and the motor 3
Using the output of the current detector 10 which detects the current flowing in
The torque generated by the electric motor 3 is controlled so as to match τ _r .

When controlling the rotational position of the electric motor 3, the command generation circuit 1 outputs the switching signals c ₁ and c ₂ , and the switching circuits 5 and 8 operate. As a result, the output n _r2 of the position control circuit 2 is used as the speed command n _r , and the output τ _r2 of the speed control circuit 2 is used as the torque command τ _r . After this, the position command x _r is output and the electric motor 3 is controlled to the desired position. In this way, during position control, the speed control and torque control loops operate as minor loops, so stable and responsive position control is possible. When the switching signal c ₁ is connected so that the speed command n _r becomes n _r1 , the electric motor 3 rotates at the speed corresponding to the speed command n _r1 from the command generation circuit 1. That is, the speed of the electric motor can be controlled. Similarly, the switching signal c _{2 is set} to the torque command τ
When _r is connected in a tau _r1, the motor 3 a torque value corresponding to the torque command tau _r1 from the command generating circuit 1 is rotated.

Thus, in the embodiment shown in FIG. 1, three control loops are connected in a cascade, and two switching circuits 5 and 8 are provided between them.
Since 3 is inserted, position, speed, current (torque) 3
It is possible to perform various types of control operations, and because speed and torque control exist as a minor loop of the position control loop, and torque control exists as a minor loop of the speed control loop, position and speed control that is stable and has good response Is possible. Further, the torque control circuit 9 is commonly used not only during the torque control operation but also during the speed and position control. The speed control circuit 6 is commonly used not only during the speed control operation but also during the position control operation. Therefore, the configuration is simple.

 FIG. 2 shows another embodiment of the present invention.

In FIG. 2, the microcomputer 15 takes out the sequence of command generation stored in the memory 16, performs position or speed control calculation processing, and transfers it to the digital / analog converter 17 (hereinafter abbreviated as D / A converter). , Torque command τ
Set _r . Reference numeral 18 denotes a current control circuit of the DC motor 19, which uses the value detected by the current detector 20 as a feedback signal. In the DC motor 19, the current control circuit 18 can be regarded as a torque control circuit because the current and torque are almost proportional to each other. The output of the current control circuit 18 is a base driver that creates the base signal of the transistor that forms the power conversion circuit 21.
Sent to 22. The power conversion circuit 21 operates according to the signal output from the base driver 22, the voltage of the DC power supply 23 is applied to the DC motor 19, and the DC motor 19 rotates. The rotational position of the DC electric motor 19 is detected by the incremental encoder 24 and the counter 25 which are directly connected, and the value thereof is taken into the microcomputer 15.

Flow charts of the operations performed by the microcomputer 15 in such an operation are shown in FIGS. 3 to 5, and time charts are shown in FIG. An example of the instructions stored in the memory 16 is shown in FIG.

The microcomputer will be described below with reference to FIGS. 3 to 7.
The processing contents of 15 will be described.

The micro computer 15 executes the three processes shown in the time chart of FIG. Position control (APR) activated by interrupt pulse INT1 and speed control (ASR) activated by interrupt pulse INT2 and main program (MALN) executed when the interrupt processing program is not running
There is. Note that the ASR processing is configured to have priority over the APR processing, so if the ASR processing is started simultaneously,
The time chart ASR as shown is processed first.

The processing shown in FIG. 3 is executed in the MAIN program. First, at step 30, the command shown in FIG. 7 is fetched. For example, in the case of the first command, it is the APR indicating the meaning of the position control shown in sequence No. 1, the ASR indicating the command value to move up to 10 rad in 2 seconds and the command value of the rotation speed, and the command value. In the case of speed control, in the example of FIG. 7, the time to continue that is shown, and in the case of torque control, the command value of ATR and torque indicating that and the time to continue the command value are shown in the example of FIG. is there. Next, in step 31, the first data is decoded and the control mode is judged. In the case of position control, steps 32 to 36 are performed. In step 32, it is judged whether or not the control mode is different from the previous control mode, and if not, the process proceeds to step 36. If they are different, it means that the mode has been switched, so it is determined in step 33 which control mode has been switched. When the control is switched from the torque control, the flag is set to TP in step 34, and when the control is switched from the speed control, the flag is set to SP in step 35. This flag is used in the position control and speed control interrupt processing programs described later. In step 36, the processing for canceling the position control interrupt is prohibited.

On the other hand, when it is determined that the speed is controlled in step 31,
The process moves to step 37 and it is determined whether the mode is the same as the previous mode. If different, move to the processing of step 38,
The flag is set to TS to indicate the shift from torque control to speed control. If the control mode does not change, the speed control mode is set and the process proceeds to step 40. In the speed control mode, the position control calculation process is not performed, so that the interrupt is prohibited. In the torque control mode, only the mode is set in step 41 and the process proceeds to step 40.

The processing of step 42 is executed after the processing of steps 36 and 40. Here, it is determined whether or not the sequence processing is completed, and if it is not completed, the processing of step 42 is repeated. When the process is completed, the process returns to step 30, and the above operation is repeated.

When the interrupt pulse INT1 is generated during the execution of such a MAIN operation, the APR process of FIG. 4 is executed. It is determined in steps 45 and 46 of the flag state. When the flag is SP,
Immediately after switching from speed control to position control,
At 47, the initial calculation of the position command is performed. That is, the current rotational position is taken in, the movement amount is calculated from the value and the command value, and the movement amount Δx in the cycle of the interrupt pulse 1 necessary for positioning the movement amount in a predetermined time is calculated. The position command is calculated so that the speed command in (1) matches the speed immediately before switching. That is, when proportional compensation is used as the compensation element of the position control system, if the gain is k _P , the current position at the time of switching is x _f , and the speed is n _f , the position command x immediately after switching is x.
Determine _r0 by the following formula.

X _r0 = X _f + n _f / K _r (1) The obtained X _r0 is set as the initial value of the APR position command signal X _r immediately after switching the switching circuit. This allows ASR to A
Immediately after switching to PR, n _f is obtained as the output signal n _r2 of APR. After switching is updated X _r to the target value X _r0 as the initial value.
In this way, since switching from the minor control system to the major control system can be performed smoothly, shocklessness can be achieved.

When the processing of step 47 is completed, step 48 resets the flag. On the other hand, in step 46, it is determined whether the blowfish is TP. When the control is switched from the torque control to the position control, TP is set as the flag, so that the process proceeds to step 49. In step 49, the current position x _f and speed n _f are fetched by the same method as the processing performed in step 47, and the position command is performed so that the torque command immediately after switching to position control matches the torque command before switching. Calculate x _r and speed command n _r . Then, in step 50, the flag TP is reset. here,
If the flag is not set, the position control end determination processing of step 51 is performed. Here, it is determined whether or not the position deviation has become zero, and when the deviation has become zero, the processing end mode is set at step 52 in order to proceed to the next sequence. If the position deviation is not zero, position control calculation is performed using the position command x _r and the position detection value x _f , and the speed command n _r2 is calculated. Such processing is executed every time the interrupt pulse INT1 is generated.

On the other hand, when the interrupt pulse INT2 is generated, the ASR process of FIG. 5 is executed. The flag is determined in step 55, and in the case of TS, steps 56 and 57 are processed. APR in step 56
Similar to steps 47 and 49 of the process, the initial value of the speed command is calculated so that there is no change in the torque command when switching from torque control to speed control, and if the speed control calculation uses compensation that includes an integral term If so, the initial value is also set. When TS is not set in the flag, the process proceeds to step 58 to determine the torque control mode. When operating in torque control, only the torque command is generated in step 59. That is, the command value written in the sequence No. 3, No. 6, etc. of FIG. 8 is given to the current control circuit 18 via the D / A converter 17 of FIG. The command generation is repeatedly executed for the time written in the program, and the end judgment is made in step 60. Further, the mode setting for ending the process is performed in step 61. On the other hand, in the modes other than the torque control mode, the speed control calculation is executed in step 62. As the speed command in this case, during position control, from the control calculation result,
For speed control, sequence No.2 and No shown in ASR in Fig. 7
The command value of 4 is used. Then, in steps 63 and 64, it is determined whether the processing is completed. The above ASR processing is interrupt pulse INT
It is executed every time 2 is entered.

As described above, according to the embodiment of FIG. 2, position control, speed control,
The torque control can be easily switched only by software processing, and when the torque control is switched to the speed control or the position control, or when the speed control is switched to the position control, there is no significant change in the command and the connection is smooth. Has the effect of being possible. It should be noted that, when switching from position control to speed or torque control without performing processing when switching from speed control to torque control, there is no practical problem if each step response is considered.

〔The invention's effect〕

As described above, according to the present invention, it is possible to perform optimal control for performing a series of work of a controlled object such as a robot by arbitrarily selecting the control system of the three-mode electric motor by the two switching means. In addition, even if the torque control is switched to the speed control or the position control, or the speed control is switched to the position control in real time, there is no significant change in the command output by the command generating means and the operation command, and the smooth operation is achieved. Since the control system shifts to, there is an effect that vibration due to switching does not occur in the mechanical system.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
FIG. 3 is a block diagram showing another embodiment of the present invention.
5 to 5 are flow charts for explaining the operation of the embodiment shown in FIG. 2, FIG. 6 is a time chart for explaining the operation of the embodiment shown in FIG. 2, and FIG. It is a figure which shows the content of the memory for demonstrating operation | movement of the Example shown in FIG. 1 ... Command generation circuit, 2 ... Position control circuit, 3 ... Electric motor, 4 ... Position detector, 5,8 ... Switching circuit, 6 ... Speed control circuit, 9 ... Torque control circuit.

Front Page Continuation (72) Inventor Toshihiko Matsuda 4026 Kuji Town, Hitachi City, Ibaraki Prefecture, Hitachi Research Laboratory, Ltd. (72) Masahiko Watanabe 4026 Kuji Town, Hitachi City, Ibaraki Prefecture, Hitachi Research Laboratory, Hitachi Ltd (56) References JP-A-59-161708 (JP, A) JP-A-55-41582 (JP, A) JP-A-57-55413 (JP, A) JP-A-56-82298 (JP, A) Kai 57-71282 (JP, A) JP 59-107882 (JP, A) JP 59-220806 (JP, A) Actual JP 54-12688 (JP, U) JP 55-31921 (JP) JP, B2) Nikkei Mechanical 1981.9.28P. 113- 118

Claims (1)

[Claims] 1. A command generating means for outputting a rotational position command, a speed command and a torque command of an electric motor according to a predetermined sequence control, and a first switching signal during driving of the electric motor according to a predetermined sequence control. Switching signal generating means for generating at least one of the second switching signals; position control means for outputting a calculated speed command so that the rotational position command has a feedback value of the actual rotational position of the electric motor; and the command generating means. A first switching means for selecting and outputting one of the speed command output by the first switching signal and the calculated speed command according to the first switching signal; and an output signal from the first switching means as a command value for the first switching device. A speed control unit that outputs a calculated torque command so that the feedback value of the actual speed of the electric motor becomes equal to the torque output by the command generation unit. Command or the calculated torque command, the second switching means for selecting and outputting the second switching signal, and the output signal from the second switching means as a command value and the actual torque of the electric motor. Torque control means for outputting a drive command for the electric motor so that the feedback value of the electric motor becomes equal to, feedback control means for controlling the electric motor based on the drive command, and control of the electric motor by the first and second switching means. When switching from speed control system to position control system mode, or from torque control system to speed control system or position control system mode, as the initial value of the input command signal of the control system immediately after switching,
Control of a motor having an initial value setting means for setting a feedback value of a control system before switching or a command value of the control system feedback value after switching divided by a control gain of the control system after switching apparatus.