JPS60118088A - Rotating angle controlling method for motor - Google Patents

Abstract

PURPOSE:To accurately control a rotary angle of a motor by presuming the frictional force and the generated torque on the basis of the measured value of the rotary angle of the motor during a motor current supplying period and a motor current stopping zone. CONSTITUTION:A microprocessor 4 applies a command to a drive current calculator 11 to apply the drive current of the amplitude Im to the motor during a current supplying period T1. A command for stopping the current is applied to the calculator 11 during the current stopping period T2. A presumed value calculator 10 inputs the motor rotary angles X1, X2 at the finishing time points of the periods T1, T2, and presumes the frictional force and the generated torque by the angles X1, X2. The microprocessor 4 corrects the accelerating and decelerating currents on the basis of the presumed value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a motor rotation angle control method that can control the rotation angle of a motor to an accurate value.

[Prior art]

Conventionally, the rotation angle of a motor is controlled in an analog manner to arbitrarily control the position of a controlled object, and the positioning accuracy in this case is determined by the control accuracy of the motor rotation angle. In recent years, as digital signal processing circuit elements such as microprocessors have become more sophisticated and lower in price, attempts have been made to introduce digital control using these elements for motor rotation angle control. This control detects the rotation angle of the motor at each sampling time, compares it with a target value, determines the motor drive current based on the comparison result, and performs drive control of the motor.

When digital control is performed, the motor drive current is not updated at every sampling time, so in order to perform accurate external rotation angle control, the drive current must be set to a value that matches the characteristics of the motor. For this reason, it is important to accurately understand the characteristics of the motor.
(U.S. Patent No. 4,383,208) and [Method for estimating friction force using an observer with a built-in friction force generation model-1 (Yamada: Estimation of solid friction and positioning control using an observer, 22nd SIC Academic Conference, July 1958,
(p. 835) discloses a method for estimating a frictional force of approximately ±3% of the rated torque present in an actual motor. This is a method of estimating the frictional force from the difference between the calculated value of the rotational angle for the drive current of an ideal motor with no frictional force and the measured value of the rotational angle of the actual motor.

However, in an actual motor, the generated torque varies by about ±10%, but the above proposal assumes that the generated torque of the motor is constant. Even if this method is applied to control the rotation angle of the motor, accurate control is rarely possible.

[Object and structure of the invention]

Therefore, the purpose of this invention is not only to estimate the frictional force, but also to
An object of the present invention is to provide a motor rotation angle control method that allows accurate estimation of generated torque.

In order to achieve such an object, the present invention provides a motor current supply period and a motor current stop period, and calculates the actual value of the motor rotation angle during the current supply period, which is affected by the frictional force and generated torque, and the frictional force. The frictional force and generated torque are estimated based on the actual measured value of the rotation angle during the current stop period when only the influence was received. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to drawings showing embodiments.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a rotation angle control device constructed by applying the present invention. In the figure, 1 is a power amplifier, 2 is a motor, 3 is a rotation angle detector, 4fd microprocessor, 5id D/A converter, 6 is a power amplifier signal line, 7 is a motor drive signal line, and 8 is a motor rotation angle Detector connecting rod, nine rotation angle signal lines, 10 is an estimated value calculation circuit, 11 is a drive current calculation circuit, 12 is an estimated value calculation circuit control line, and 13 is a drive current calculation circuit control line.

Figure 2(a) shows an example of the current waveform applied to the motor to estimate the frictional force and generated torque of the motor, and Figure 2(b)
) is an example of the response waveform of motor rotation angle due to applied current,
In the case), the dotted line is the locus of the motor rotation angle when there is no frictional force, and the solid line is the locus of the motor rotation angle when there is an M vibration force.

In the following explanation, the motor is stopped when estimation starts.)
The explanation will be made assuming that the periods TI and T2 are equal (the time period is 1 second, TI = T3T).

During the current supply period (acceleration period) TI, in order to apply a drive current of 1 m in magnitude as shown in FIG. Give commands to 11. The drive current calculation circuit 11 receiving the command applies predetermined data kT seconds to the D/A converter 5.

At the end of data application, the microprocessor 4 inputs the motor rotation angle XI during the current supply period into the estimated value calculation circuit 18 and into the estimated value calculation circuit control unit 10. A data acquisition command is given to the estimated value calculation circuit 10 via a line 12.

Next, in the current stop period (constant speed period) Tg, 1 second (a
), in order to stop the current, the microprocessor 4 gives a command to the drive current calculation circuit 11 via the drive current calculation circuit control line 13.

At this time, if there is no frictional force, the motor moves at a constant speed as shown by the dotted line in (b) and rotates to a rotation angle of X2A, but
If there is a frictional force, this frictional force will cause it to rotate to the rotation angle X2, tracing the entire trajectory as shown by the solid line in (b). Unfortunately, in order to capture the entire rotation angle Xi of the motor at the end of the current stop period T2, the microprocessor 4 inputs the estimated value calculation circuit control line 12.
A data acquisition command is given to the estimated value calculation circuit 10 via.

Next, from the rotation angles XI and X2, we calculate the frictional force and the generated torque'
ff: The estimation method will be explained. If Kt and F are the generated torque and friction force per unit current of the motor to be estimated from this, and J is the moment of inertia of the motor's load, then the motor rotation angle X1 during the first acceleration period TI and the constant speed period (T2) The rotation angle X2 of the motor in can be expressed by equations (1) and (2).

According to Equation (1)9 and Equation (2), there are two independent equations for the three unknowns Kt, F'', and J, so Kt and F cannot be calculated independently from both equations.

Therefore, the acceleration of the load due to the torque generated by the motor (Kt/
J) and the load reduction acceleration (F/J) due to frictional force as total unknowns, (Kt/U) and (F/J) are calculated from equations (1) and (2). The results are shown in equations (3) and (4).

FIG. 3 shows a flowchart of the estimation calculation processing procedure described above.

In this estimation method, even if the moment of inertia J of the motor load is unknown, the acceleration of the load due to the torque generated by the motor (
Kt/J) and motor deceleration due to frictional force (F/
J') can be obtained from equations (3)9 and (4), so
Use a practically effective estimation method.

Also, it is assumed that the periods T1 and T2 are equal, but if they are different, should the rotation angle be corrected in each period? Just do it.

Next, we will explain how to accurately control the rotation angle of the motor using the acceleration of the load due to the torque generated by the motor (Kt/J) and the reduction acceleration of the load due to frictional force (F/J) determined as described above. I will explain about it.

This type of motor is controlled by supplying a forward current to rotate the motor, and then supplying a reverse current to stop the motor rotation, thereby setting the motor rotation angle to a target value. .

FIG. 4(a) shows an example of the current waveform applied to the motor 2 when the method of the present invention is applied to a motor that performs such control. In the figure, Im+ +1ml is a forward current, Im* and Im4 are reverse currents of 1, the current Im+ and ImzQ values are determined by the method described later, but the torque generated by the motor 2 is determined using the design value, and the frictional force is uses values that are not taken into account. In addition, '11, T2 is 1 in the current supply period and current stop period, and the current Irru+,
Im4 is the load acceleration (Kt
/J) and the load reduction acceleration due to frictional force CF/J),
Based on the value of the rotation angle at time t3, a corrected acceleration current and a corrected deceleration current are used to correct the rotation of the motor 2, and Tc
This is the calculation period for calculating the 1t basket currents Ima and Im4. FIG. 4(b) shows the response waveform of the Fi motor rotation angle. The dotted line is the waveform when there is no friction, and the solid line is the waveform when there is friction.

By such a method, the entire rotation angle of the motor 2 can be adjusted as shown in Fig. 4 (
The operation when controlling to the target value Xr in b) will be explained. First, assuming that the motor 2 has no frictional force, the forward current Im1 'e is calculated during the period TI using the design value of the generated torque.
During the period T2, the current supply is stopped, and during the period T3, a reverse current Imz k is supplied to the motor 2. The determination of this current 1ml, Iry+, + is based on the analogy “Digital System Control J (Narita, 174).
This can be easily done by referring to Shokodo, p.-, p.-181, so an outline will be explained here.

Motor 2 at time to, t, l t2+ ts
rotation angle and motor rotation speed kXo, X+,
Xi.

X3 Oyohi v. , V+ + V2 T V3,
The following formula holds.

(7) For the three equations, there are two unknowns, Irr++ and Im2, so for example, Im+'e is 80% of the maximum rated current (
Im1 = Imax
2 can be determined.

Therefore, Im2 that can be claimed can be determined by equation (8).

2.J When determining the current Im+ and 1 m2 at 2 (8), the design value is used for the torque generated by the motor, and the full frictional force is not taken into account, so the rotation angle of the motor is as shown in Figure 4 (
Following the trajectory of the dotted line in b), the rotation angle reaches the target value Xri at time t3, but in reality, the rotation angle becomes stiff and small because of the frictional force, and only reaches X3.

Therefore, using the above-mentioned estimation method from the rotation angle XI at time 11 and the rotation angle X3 at time t2, the acceleration of the load (Kt/J) corresponding to the torque generated by the motor is calculated as follows:
Determine the load reduction acceleration (F/J) due to frictional force. Using this value, the corrected acceleration current I, which is the corrected current required to rotate the motor fully from rotation angle X3 to Xr.
ms and corrected deceleration current Im<ffi are calculated. This current is derived from the reference cited above and is summarized as follows.

Assuming that the acceleration tTa required to rotate the motor at rotation angles X3 to Xr4 is given, the drive current Imt for obtaining this acceleration is determined by the following equation.

On the other hand, in order to cancel the frictional force, the required motor drive current t(C) can be calculated by the following equation.

) The corrected acceleration current Ims in the period T4 can be determined by the following equation.

Ims = Imt + If111+611 (11
) Also, the corrected deceleration current Im4 in the period T6 is calculated by the following equation.

lm4=-Imt+If *1m (12) Therefore, the microprocessor 4 operates the drive current calculation circuit 11 so that the above-mentioned forward current Im+ is supplied during the period TI, and the reverse current Im2 is supplied during the period T3.
, and the rotation angle X1 at time t1 and the time t2
The estimated value calculation circuit 10 is configured to calculate the acceleration f (Kt/J) of the load due to the torque generated by the motor 2 and the deceleration acceleration t (F/J) of the load due to the frictional force from the respective measured values of the rotation angle X2 at . The values of the corrected acceleration current Im3 and corrected deceleration current Im4 are determined from the astronomical value of the rotation angle X3 at time t3 and the value of the target rotation angle The modified acceleration current Im3'z, and the modified deceleration current l in the period Ts
Drive current calculation circuit 11 to supply to m4Q motor 2
control.

Therefore, the motor 2 rotates at the rotation angle The rotation angle Xr can be reached accurately.

In the above embodiment, the estimated value calculation circuit 10 and the drive current calculation circuit 11 perform predetermined calculations, but this function is included in the microprocessor 4 and the microprocessor Affi formula (1) to formula ( 12)' may be operated by a predetermined program that takes into consideration.

〔Effect of the invention〕

As explained above, the motor rotation angle control method according to the present invention provides a current supply period and a current stop period, grasps the characteristics of the motor from the actual measurement value of the rotation angle in each period, and Since the rotation angle of the motor is controlled based on the following effects, the following effects can be obtained.

(1) Since control can be performed taking into account fluctuations in generated torque and frictional force, accurate rotation angle control can be performed.

(2) Since the generated torque and frictional force can be estimated as a function of the load moment of inertia of the motor, it is possible to perform high-precision rotation angle control of a time-varying controlled object in which the magnitude of the load changes during operation.

(3) Since the generated torque and frictional force can be estimated as a function of the motor's load moment of inertia, it is possible to estimate the load through the gears, which can cause backlash, which causes the motor's rotation to be unable to be accurately transmitted to the load. High-precision rotation angle control can be performed even when controlling objects that are driven by metal.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a rotation angle control device to which the present invention is fully applied, and FIG. (b) is a graph showing an example of the current waveform applied to the motor and an example of the response waveform of the motor rotation angle due to the applied current to explain this invention, and Fig. 3 shows a method for estimating all fluctuations in frictional force and generated torque. Flowchart, Figure 4(a)
, (b) is a graph showing an example of the current waveform applied to the motor when actually controlling the motor by applying the method of the present invention, and an example of the response waveform of the motor rotation angle depending on the applied current. 1...Power amplifier, 2...Motor, 3...
Rotation angle detector, 4...Microprocessor, 5...
・・D/A converter, 6・・Power amplifier signal line, 7・
... Motor drive signal line, 8 ... Motor rotation angle detector connecting rod, 9 ... Rotation angle signal line, 10 ... Estimated value calculation circuit, 11 ... Drive current calculation circuit , 12...
... Estimated value calculation circuit control line, 13... Drive current calculation circuit control win. Patent applicant Masaki Yamakawa, agent of Nippon Telegraph and Telephone Public Corporation

Claims (1)

[Claims] In a motor rotation angle control method, the motor is rotated by supplying a forward current, and then the rotation of the motor is stopped by supplying a reverse current to control the rotation angle of the motor to a target angle. i1i+ current is supplied for a certain period of time, the current is stopped for the next certain period of time, the motor is rotated by a predetermined angle, and the rotation angle during the motor drive current supply period and the rotation angle during the motor drive current stop period are all detected and this rotation angle is determined. Estimate the motor's friction force and generated torque from the values of A motor rotation angle control method characterized in that the rotation angle is completely corrected by supplying the rotation angle to the motor.