JPH0793832B2 - Motor position control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motor position control method, and has an operating axis that has an encoder that measures the angle of a rotating axis, and drives an electric motor related to the motor at a predetermined operating rotational speed. In order to provide a control circuit having a switching element,
The present invention relates to a motor position control method in which an arbitrary angle is stepped forward and backward.

Conventionally, a step motor or a motor with a clutch (clutch motor) is known as a device for stepwise driving an arbitrary angle.

Among them, the step motor has an advantage that step feed can be performed by open control, but has a disadvantage that the total volume becomes large when a large torque is required or for high speed response.

On the other hand, the clutch motor is used in industrial sewing machines and the like, and is characterized by good high-speed response.

In industrial sewing machines, it is important to send a predetermined angle in the shortest time, and control methods have been devised.

However, the clutch motor has disadvantages such as wear of the clutch and loud noise when the clutch is turned on and off.

On the other hand, there is a method of improving the high-speed response and the life by using a DC motor with an encoder in which an encoder for detecting a rotation angle is attached to the shaft of the DC motor.

In this case, it is the control circuit that gives the motor main body the ability to perform positioning by performing the switching operation based on the signal from the encoder and applying the variable voltage in the forward and reverse directions to the motor.

On the other hand, as the load of the motor, there are many information devices, and the inertia moment of the target motor shaft or the load torque is various.

In this case, conventionally, the motor is directly connected to the device to adjust the gain of the control loop and the like, so that the positioning operation is stopped as smoothly as possible and the hunting is stopped with a small amount.

However, when the power supply voltage for driving the motor changes, it becomes equal to the change in the gain of the control loop, and each time the gain is readjusted, or a circuit that detects the voltage and automatically adjusts the gain is added. I needed it.

As prior art of the present invention, there are JP-A-54-79374 and JP-A-54-89171.

The invention disclosed in Japanese Unexamined Patent Publication No. 54-79374 discloses that the motor is driven and the load is accelerated at a constant positive acceleration, and then the constant speed is determined from the description of the specification and the drawings as a whole. In the positioning control method by so-called trapezoidal speed control, in which the load is moved to the desired position by decelerating with a non-acceleration of the same magnitude as the acceleration, the effective input current that can go up to the motor is maximized with respect to the movement amount of the load. By keeping the value constant, the load can be driven in a short time.

Further, Japanese Laid-Open Patent Publication No. 54-89171 discloses a technique relating to a deceleration method during transfer of a controlled object, more specifically, a technique for determining a deceleration timing. The invention disclosed in the publication From the description of the specification and the drawings as a whole, when the deceleration command is issued during the acceleration of the pulse motor, that is, when the movement amount of the controlled object is small, the deceleration timing is calculated only by acceleration. When a microcomputer that does not have a division mechanism is used as a system, a program for division is unnecessary.

However, in each of the above-mentioned publications, as in the present invention described below, positioning control is always performed with little hunting against changes in power supply voltage, changes in motor characteristics due to temperature, and load changes during positioning control. There is an unsolved problem that the position control cannot be performed with high accuracy when these problems occur without recognizing the points.

By the way, Japanese Patent Laid-Open No. 48-2010 discloses a technique relating to position control in consideration of the friction torque of the motor and the internal impedance drop of the motor.

Further, Japanese Patent Application Laid-Open No. 53-102578 discloses a technique relating to position control in consideration of traveling inertia fluctuation of a carrier.

However, the above-mentioned JP-A-48-2010 and JP-A-53-102578.
No., the remaining distance from the deceleration start point to the target position θd
Like the present invention described later to obtain, Here, the specific constituent requirements of ω ₁ : command speed α ₁ : acceleration are not adopted.
In No. 53-102578, the deceleration pattern is calculated based on the acceleration data, and the deceleration pattern is not calculated based on the acceleration data, and a huge amount of acceleration data must be plotted.

Further, in the above-mentioned JP-A-48-2010 and JP-A-53-102578, the deceleration control from the remaining distance .theta.d to the target position is performed in advance in a ROM or a RAM as in the present invention described later. One of the patterns that is closest to the speed pattern of the measured acceleration is selected from the multiple deceleration patterns that have been set, and the pattern is used as a speed command value to control the speed so that the actual speed matches this, and to reduce the speed. Not not.

On the other hand, in the present invention, since the deceleration pattern is stored in the memory in advance as a speed command for the position, a large amount of information can be extracted in a short time compared to the case where the deceleration pattern is calculated and obtained. High-resolution position control can be performed.

Japanese Patent Laid-Open No. 54-49706 discloses a technique of storing a plurality of types of deceleration patterns and selecting an optimal deceleration pattern as needed.

However, the technique described in JP-A-54-49706,
The deceleration patterns of a plurality of vehicles in the transportation system are stored, and the optimal deceleration pattern is selected as needed. Only one deceleration pattern is provided for one target stop position. This is different from the present invention to be described later, which has a plurality of deceleration patterns for one target stop position and selects an optimum deceleration pattern from the plurality of deceleration patterns.

Further, Japanese Patent Application Laid-Open No. 52-72077 discloses a technique for storing a deceleration pattern. In the case of the same publication, a set of velocity set values corresponding to positions and velocities related to acceleration, constant velocity, and deceleration are all stored. It is necessary to store it in the memory, and the specific constitutional requirements are completely different from the method of the present invention described later, and a large capacity memory is required as compared with the present invention in which only the deceleration pattern is stored in the memory. The present invention (a) has a small amount of hunting in response to a change in power supply voltage, a change in motor characteristic due to temperature, and a load change during positioning control. The distance can be directly obtained as an absolute position from the commanded speed and the acceleration, and therefore even if the commanded speed and the acceleration are changed due to a change in the applied product, this can be easily dealt with. It is an object of the present invention to provide a motor position control method that does not require a large-capacity memory because it is sufficient to store only the deceleration pattern in the memory.

The purpose is a motor position control method for positioning a motor having an encoder for measuring a position on an operation axis to a target position by an arbitrary positioning command value, and is determined based on a device driven by the motor. The commanded speed ω _{1 of the} device to be commanded and speed control are performed so that the motor current maintains a predetermined value at each startup, and the acceleration α ₁ is measured from the speed fluctuation per unit time at that time or the time to reach the unit speed. , Command speed ω ₁ and acceleration α ₁
The remaining distance θd from the point where deceleration should be started to In addition to the above calculation, the remaining distance θd to the target position is selected from a plurality of deceleration patterns stored in ROM or RAM in advance, and one pattern closest to the speed pattern of the measured acceleration is selected. This is achieved by performing speed control so as to match the actual speed as the command value and decelerating.

Before describing the embodiments of the present invention, the basic technical idea of the present invention and the essential points of the invention will be described below.

As a sequence, let us consider the elements relating to the positioning control in a motor having an encoder for measuring position on the operating axis.

First, there is (a) a positioning command value θ ₀ (rad).

This is a target value for driving an arbitrary angle from a certain motor angle in the forward rotation direction or the reverse rotation direction.

In a clutch motor such as a sewing machine, this value rarely exceeds one rotation, but in a printer, for example, in terms of a normal angle, the positioning command value is 1800 degrees, which is several rotations or more on the motor shaft. It is not uncommon to become.

Next, (b) there is the number of pulses P per rotation of the encoder directly connected to the motor shaft.

If the number of pulses P is large, the resolution of the feed angle that can be selected during positioning control (the number of selectable feed amounts) can be increased.

The above-mentioned positioning command value θ ₀ (rad) is applied to the above-mentioned pulse number P
The positioning command value θ _0p (pulse) represented by is as follows.

θ _0p = θ ₀ × (P / 2π) (pulse) (1) Next, there is (c) the torque generated by the motor, that is, the motor torque T _M (kg-m).

This motor torque T _M is expressed by the following equation.

T _M = K _t × I _M (2) where K _t is the motor torque constant (kg-m / A), I
_M is the motor current (A).

This torque constant K _t is a value unique to each motor and is represented by the following equation.

K _t = K ₁ × N ₁ × φ (3) Here, K ₁ is a constant, N ₁ is the number of motor windings, and φ is the magnetic flux (wb) of the motor.

However, most motors for information equipment are small motors of several hundred W or less, and permanent magnet motors are the mainstream.

The above-mentioned magnetic flux φ is generated by the permanent magnet of this permanent magnet motor, but the magnetic flux of the permanent magnet changes depending on the temperature.

For a ferrite magnet, the temperature coefficient is -0.2% / ° C.

For example, if the temperature changes from -20 ° C to 80 ° C, 20%
Magnetic flux change occurs.

The current I _M is given by the following equation.

I _M = (E−E ₀ ) / R (A) (4) Here, E is a voltage (V) applied to the motor,
This is the voltage of the control circuit having the switching element.

With this voltage E, the duty during switching is set to D _t ,
Given the power supply voltage E _dc (V), it is given by the following equation.

E = D _t × E _dc (5) Further, E _{0 in the} above equation (4) is the induced voltage (V) of the motor and is given by the following equation.

E ₀ = K ₂ × ω × N ₁ × φ (6) where K ₂ is a constant, ω is the motor rotation speed, that is, speed (rad / sec), and N ₁ and φ are the motors as described above. The number of windings and the magnetic flux of the motor.

Further, R in the above equation (4) is the armature resistance R _{a of the} motor.
And the wiring resistance R _x from the control circuit to the motor, and the armature resistance R _a of this motor changes depending on the operating temperature of the motor.

Next, (d) the moment of inertia of the motor and the load are also important factors.

The moment of inertia J (kg-m · sec ² ) is shown by the following equation.

J = J _M + J _L (7) Here, J _M is the moment of inertia of the motor, and J _L is the value obtained by converting the moment of inertia of the load connected to the motor shaft into the motor shaft.

Then, (e) another factor to be considered on the load side is the load torque T _L.

This load torque T _L and the motor torque of the above formula (2)
The difference from T _M is the acceleration torque T ₁ when accelerating the motor shaft.

That is, the acceleration torque T ₁ is expressed by the following equation.

T ₁ = T _M −T _L (8) On the other hand, the deceleration torque T ₂ at the time of deceleration of the motor is expressed by the following equation because the motor torque and the load torque are in the same direction.

T ₂ = T _M + T _L (9) Furthermore, (f) the maximum speed ω _{1-1 of the} device is an important factor.

Motor, motor speed in the case of the maximum control voltage E _m,
That is, the speed ω _m is the maximum rotation speed, but the maximum speed ω _1-1 allowable by the device is often lower than the maximum rotation speed that the motor can output.

This maximum speed ω _1-1 is selected as a value that satisfies the operation of the device and can sufficiently secure reliability and durability.
Once the mechanism and operation of the device is decided, it is decided accordingly.

Therefore, even if the same motor is used, the above-mentioned ω _{1_1} changes due to the difference in the device in which the motor is mounted.

Next, (g) acceleration α ₁ and deceleration α ₂ which are important factors during acceleration and deceleration of the motor are expressed by the following equations.

α ₁ = (T _M −T _L ) / (J _M −J _L ) = T ₁ / J (10) α ₂ = (T _M + T _L ) / (J _M + J _L ) = T ₂ / J… ( 11) Above, the various elements related to positioning control are as described above.

With reference also to the above-mentioned points, the positioning control method will now be described below by controlling the motor speed with respect to the distance to be reached.

The position θ is shown by the velocity ω (rad / sec) as follows.

That is, the position θ is an integrated value of speed.

The position θ corresponds to the angle (rad) in the rotating body.

Here, the motor operation to reach the positioning command value θ ₀ to be reached is accelerated to the motor speed command value ω ₁ (rad / sec),
After the constant speed operation at the speed ω ₁ , it is determined whether or not the position θ _B at which the predetermined deceleration should be started is reached, and if the position θ _B is reached, the speed is reduced from the speed ω ₁ .

FIG. 1 is a motor deceleration state explanatory view showing this state.

That is, FIG. 1A shows the motor speed ω, FIG. 1B shows the motor current I _M , and FIG. 1C shows the motor position θ.

Further, in each figure, the solid line shows the case where the device, the motor and the control circuit are sufficiently adjusted, and there is no hunting at the time of stop, and the operation is smooth.

On the other hand, the alternate long and short dash line shows the case where hunting occurs due to the difference in the device to be driven by this motor or the difference in the voltage applied to the control circuit.

First, the operation in the case of the above solid line will be described.

In FIG. 1 (a), t ₁ is the time for accelerating to the motor command speed ω ₁ . When the time t _{1 has} elapsed, the motor reaches the acceleration end position θ _A , ends acceleration, and thereafter is operated at a constant speed at the command speed ω ₁ . t ₂ is the time for deceleration from the speed ω ₁ , and t ₃ is the time for constant speed operation at the speed ω ₁ .

Further, FIG. 1 (b) shows the motor current I _M , and the values thereof are almost the same during acceleration and deceleration, but the directions are opposite. The current during constant speed operation at speed ω ₁ has a very small value as compared with during acceleration and deceleration.

Further, in FIG. 1 (c), the positioning command value θ ₀
When reaching, the position θ changes parabolicly during acceleration, linearly during constant speed operation, and exponentially during deceleration.

The deceleration is started when the motor reaches the deceleration start position θ _B , but if the deceleration characteristics are matched with the load state, the motor smoothly stops as shown by the solid line.

On the other hand, the case indicated by the alternate long and short dash line shows the case where the acceleration and deceleration at the time of acceleration and deceleration are reduced by 30% as compared with the case of the solid line described above.

This is because, for example, when the same motor is installed in different devices, or due to the difference in the power supply voltage of the control circuit,
This is the case when the values calculated by Eqs. (10) and (11) have decreased by 30%.

In this case, the acceleration time is a time increased by 30% as compared with the case of the solid line, the constant speed operation is performed after reaching the motor command speed ω ₁ , and the deceleration is started when the deceleration start position θ _B is reached.
At time t ₄ when the speed reaches zero, the position θ exceeds the positioning command value (target position) θ ₀ by Δθ ₁ .

This is because the deceleration is less than that of the solid line when decelerating.
Since the deceleration time is increased by 30% because it is 30% smaller, the distance to be advanced during deceleration is (θ ₀ −
This is because it becomes larger than θ _B ).

The speed reverses from the time point t _4, and it stops due to the damping action of the control system and the action of the stop control routine while hunting several times so that the excess Δθ ₁ becomes zero.

From the above, the main point of the present invention is that the acceleration during acceleration and the deceleration during deceleration have a certain fixed relationship, the acceleration is measured, and the deceleration start position θ _B is targeted. This is to calculate back from the position θ ₀ .

That is, to explain this in detail, the relation between the deceleration α ₂ and the acceleration α ₁ can be expressed as follows from the equations (10) and (11).

a ₂ = [(T _M + T _L ) / (T _M −T _L )] × α ₁ (13) As a result, the deceleration start position θ _{B from the} target position θ ₀
The distance θ _{d to} is determined as follows.

_{θ d = (1/2) × ω} 1 × (ω 1 / α 2) = 1/2 × (T M -T L / T M + T L) × ω 1 2 / α 1 = (1/2) × K _ad × (ω ₁ ² / α ₁ ) ... (14) Here, K _ad is (T _M −T _L ) / (T _M + T _L ), which is a coefficient.

By doing so, the acceleration α ₁ is the above-mentioned motor current I _M , magnetic flux φ, current voltage E _dc , duty D _t , motor armature resistance R _a and wiring resistance R _x , motor and load inertia moment J. _Since the effect of _M and J _L is taken into account, the deceleration α ₂ in the stepwise sending operation of an arbitrary angle is
It can be calculated each time.

As a result, since θ _d related to the distance is calculated each time, a smooth stopping operation without hunting can be expected every time the system is started, as in the case of the solid line shown in FIG. 1 above. In the case of the one-dot chain line shown in FIG. 1, it is improved as shown by the solid line in FIG.

Here, for simplification, it is assumed that the load torque T _L is small enough to be ignored with respect to the motor torque T _M during acceleration and deceleration.

In fact, in applications for information equipment, the above T _L is a few% of T _M.
There are many cases below.

The deceleration α ₂ and the distance θ _d are obtained as follows under the above conditions, that is, the condition that K _ad is close to 1.

α ₂ = α ₁ (15) θ _d = (1/2) × (ω ₁ ² / α ₁ ) (16) That is, the improved value is calculated by the formula (16) shown in FIG. The distance θ _d2 is 1 / 0.7≈1.5, which is 1.5 times larger than the distance θ _d1 before the improvement shown in FIG.

Here, current I _M during acceleration and deceleration are as the same. Usually, considering that the motor is accelerated and decelerated in the minimum time, it is desirable that this value be matched with the maximum current capacity of the control circuit.

Next, as a method of measuring acceleration, there are a method of measuring a speed change amount per unit time and a method of measuring a time required for the unit speed change amount.

FIG. 3 shows a method for detecting the speed change amount in the unit time.

That is, when measuring the speed variation omega _u in the unit time t _u, previous acceleration alpha ₁ is determined by the following equation.

α ₁ = ω _u / t _u (17) When the time t ₁ required for the unit velocity change amount is measured from the relationship curve between velocity ω and time shown in FIG. 4, the acceleration α
₁ can be obtained by the following equation.

a ₁ = ω ₁ / t ₁ (18) With the acceleration α ₁ obtained as described above, the deceleration α ₂
And the distance θ _d is obtained from the above equations (15) and (16).

The deceleration α ₂ is controlled in relation to the velocity ω at the position θ.

FIGS. 5A and 5B show the speed ω during deceleration and the distance θ _d (deceleration region).

When the deceleration start time is set to zero, the relationship between the distance θ ′ from the target value to a predetermined position in the deceleration region and the speed ω is
It looks like this:

θ ′ (t) = θ _d − [ω ₁ t− (1/2) α ₂ t ² ] ... (19) ω (t) = ω ₁ −α ₂ t… (20) (19), (20) From the formula, it becomes as follows.

Substituting the equations (15) and (16), the speed command value ω _N during deceleration
Then, assuming that ω _N is equal to ω, the following is obtained.

From this equation, the relationship between the distance θ ′ and the speed ω can be expressed as follows:
It becomes like the figure.

That is, the speed ω for the distance θ ′ is obtained, and the deceleration α ₂ is controlled by controlling this ω as the speed command value ω _N.

Then, by obtaining the speed command value ω _N for the distance θ ′ shown in FIG. 6 each time from the acceleration at the time of acceleration, it is possible to sufficiently adapt to fluctuations in the load and perform smooth positioning control. .

As described in detail above, the present invention has the characteristics as described above.

Next, an embodiment relating to the motor position control method of the present invention,
A description will be given with reference to each drawing.

Here, FIG. 7 is a configuration diagram of a position control device used for carrying out the method of the present invention, FIG. 8 is an exemplary diagram of a rotation direction detection circuit thereof, FIG. 9 is an operation explanatory diagram thereof, and FIG. Is also an illustration of the position detection circuit, and FIG.
FIG. 12 is an exemplary diagram of the speed detection circuit, FIG. 13 is an explanatory diagram of its operation, and FIG. 14 is an exemplary diagram of the drive circuit.
FIG. 15 is an operation explanatory diagram thereof, FIG. 16 is an exemplary block diagram of the same microcomputer circuit, FIG. 17 is an operational explanatory flow chart, and FIG. 18 is a deceleration pattern selection exemplary explanatory diagram.

First, in FIG. 7, the power source 1 is connected to the H-shaped bridge circuits of the transistors 20 to 23 and the bridge circuits of the diodes 24 to 27.

That is, the collectors of the transistors 20 and 22 and the cathodes of the diodes 24 and 26 are connected to the positive side of the power source 1, and the emitters of the transistors 21 and 23 and the anodes of the diodes 25 and 27 are connected to the negative side. Connected.

The emitter of the transistor 20 is connected to one terminal of the motor 2 together with the collector of the transistor 21, the anode of the diode 24 and the cathode of the diode 25, and the other terminal of the motor 2 is connected to the emitter of the transistor 22 and the collector of the transistor 23. It is connected to the anode of the diode 26 and the cathode of the diode 27.

The shaft of the motor 2 drives the load 3 and the encoder 4, and the rotation signal 10 output from the encoder 4 is input to the rotation direction detection circuit 5, the position detection circuit 6, and the speed detection circuit 7, respectively.

The rotation direction signal 11 which is the output of the above rotation direction detection circuit 5
Is a microcomputer circuit 9 and a position detection circuit 6
Entered in.

Further, both the position signal 12 output from the position detection circuit 6 and the speed signal 13 output from the speed detection circuit 7 are input to the microcomputer circuit 9.

Further, a position command 18 and a maximum speed command 19 are input to the microcomputer circuit 9 from an external device.

A duty signal 14 and a forward / reverse rotation signal 15 are output from the microcomputer computer 9, the forward rotation output 16 which is the output of the drive circuit 8 is at the bases of the transistors 21 and 22, and the reverse rotation output 17 is the transistor 20, On the basis of 23,
Each is connected.

The operation of the above configuration is as follows.

First, when a position command 18 and a maximum speed command 19 are given to the microcomputer circuit 9, a rotation direction signal 11 for checking the rotation direction of the motor 2, a speed signal 13 for checking the speed of the motor 2, and a position for checking the position of the motor 2 are given. Each of the drive circuits 8 receives a signal 12 for fetching the signal 12 for calculation and determining a voltage applied to the motor 2 and a forward / reverse rotation signal 15 for determining the rotation direction of the motor 2.
Output to.

In the drive circuit 8, in the case of normal rotation, the normal rotation output 16 is output, the transistors 21 and 22 are turned on according to the duty signal 14, and the motor 2 is given a rotational force.

Initially, the position signal 12 of the motor 2 is separated from the position command 18, and the duty of the voltage applied to the motor 2 is increased,
Speed up the start-up of the motor 2.

The speed of the motor 2 increases and the speed signal 13 is the maximum speed command.
When approaching 19, this time, the reverse rotation output 17 is output so that the motor 2 can be stopped by the position command 18, and the transistor 2
0 and 23 are conducted, and a braking force is applied to the motor 2 so that the motor 2
It operates to quickly and stably stop at the position command 18.

Each block shown in FIG. 7 will be described in more detail next.

In the rotation direction detection circuit 5 shown in FIG. 8, 51 is a D-type flip-flop, and one rotation signal 10-1 of the encoder 4 relating to the two-phase output is inputted to the input of the clock terminal 52 by D
The other rotation signal 10- of the encoder 4 is input to the terminal 53.
Add 2.

Since the input of the clock terminal 52 operates at the edge at the time of rising, the rotation direction signal 11 output from the flip-flop 51 is output.
As shown in FIG. 9, when the rotation signal 10-2 at the two-phase output of the encoder 4 leads the rotation signal 10-2,
When the rotation signal 10-1 related to the clock signal rises, D
The rotation signal 10-2, which is the input signal of the terminal 53, is always at the "1" level.

If the rotation direction of the encoder 4 changes and the rotation signal 10-2 of the two-phase output lags behind the rotation signal 10-1, the 9th
As shown in (a) in the figure, the rotation signal 10-
At the rising edge of 1, the rotation signal 10-2 which is the D input signal is at "0" level, and the rotation direction signal 11 from the output terminal 54 which is the output of the flip-flop 51 is at "0" level.

As described above, the rotation direction can be detected by the rotation direction detection circuit 5.

Next, the position detection circuit 6 will be described in detail with reference to FIG.

That is, this circuit consists of an UP / DOWN counter 61 and a latch 62.
It consists of and.

Rotation signal 10 as clock input for UP / DOWN counter 61
Is used as the UP / DOWN input.

The outputs P ₀ -P _n of the UP / DOWN counter 61 are connected to the inputs of the latch 62, and the output of the latch 62 is taken out as the position signal 12.

The strobe pin of latch 62 is connected to strobe signal 63.
To perform the latch.

Furthermore, in the UP / DOWN counter 61 and the latch 62,
Reset input 64 is input.

These operations are performed by changing the clock input rotation signal 10 to the UP / DOWN counter 6 as shown in the time chart in FIG.
Although it counts at 1, it counts up as an UP counter while the rotation direction signal 11 is at "1" level, and the counter output signal of the counter 61 changes from P _{0 to} P ₂ .

However, when the rotation of the motor 2 is reversed, the rotation direction signal 11 becomes "0" as shown in FIG. 11A, the counter 61 becomes a DOWN counter and starts DOWN counting.

Then, the strobe signal 63 is latched 62 every predetermined time.
In addition, the contents of the UP / DOWN counter 61 are latched to keep the position signal 12 at a new value.

Then, when a new position command 18 is input, UP / D
The OWN counter 61 and the latch 62 are reset by the input of the reset signal 64.

Next, the speed detection circuit 7 is composed of a counter 71 and a latch 72, as shown in FIG.

The rotation signal 10 from the encoder 4 is input to the clock input of the counter 71, the counter enable signal 73 for a fixed time is input to the enable terminal of the counter 71, and the counter reset signal 74 is input to the reset terminal.

The counter output signals S _{0 to} S _n of the counter 71 are input to the input of the latch 72, and the output of the latch 72 is taken out as the speed signal 13 to the outside.

A latch strobe signal 75 is input to the latch 72.

These operations are performed while the counter 71 operates while the counter enable signal 73 is present and counts the rotation signal 10 as shown in the time chart of FIG. 13, and the counter output signal S ₀
Output ~ S _n .

Next, the Ratsuchisutorobu signal 75 of latch 72 to latch the contents of the output signal S ₀ to S _n of the above latch 72.

The next moment, the counter reset signal 74 causes the counter 71 to
To prepare for the next plan.

Therefore, the rotation signal 10 during the counter enable signal 73 for a certain period of time is counted, and a value proportional to the speed of the motor 2 is obtained as the speed signal 13.

Next, the drive circuit 8 is composed of an inverter gate 81 and AND gates 82 and 83, as shown in FIG.

The duty signal 14 is connected to one input of AND gates 82 and 83, and the other input of AND gate 82 is forward / reverse signal.
15 and the other input of the AND gate 83 are connected through an inverter gate 81.

With this configuration, when the duty signal 14 and the forward / reverse rotation signal 15 as shown in FIG.
At the output of 82, the duty signal 14 appears only when the forward / reverse rotation signal 15 is at "1" level, and the forward rotation output 16 is obtained.

Also, the reversible signal 15 is "0" at the output of the AND gate 83.
The duty signal 14 appears only when the level is set, and the reverse rotation output is output.
It will be 17.

Next, the microcomputer circuit 9 includes a central processing unit,
It is composed of a RAM (random access memory), a (ROM read only memory), an input / output unit, etc., and operates according to a program recorded in the ROM.

FIG. 16 shows a block diagram of this operation.

The position command 18 and the maximum speed command 19 are read from the external device via the input / output unit, and this is compared with the current position signal 12 to calculate the speed command value ω _N corresponding thereto.

Next, the current speed signal 13 is read and the speed command value ω _N
Calculate the duty corresponding to the difference between
Output 14

Further, the rotation direction signal 11 is read, forward / reverse rotation is judged based on the position command 18, the position signal 12, etc., and the forward / reverse rotation signal 15 is output.

Thus, in the ROM of the computer 9, as will be described later, a plurality of deceleration patterns relating to speed command values for distances are recorded in advance.

The operation of the position control method related to the position control device described above will be described with reference to the flow chart of FIG.

First, when the program starts in the acceleration operation part, the positioning command value θ ₀ and the motor speed command value ω ₁ given from the external device are calculated from the position command and the maximum speed command 18 and 19 in FIG. 7, respectively. Read in.

Next, the rotation direction signal, the position signal, and the speed signal 11,1 in FIG.
From 2 and 13, the rotation direction signal Rw, the signal related to the position θ, and the signal related to the speed ω are read, and the speed command value ω _N and the duty D _t that determines the voltage applied to the motor are determined from these information. The signals related to the reverse rotation signal R ₀ are calculated and output to the duty signal and the forward / reverse rotation signals 14 and 15 in FIG. 7, respectively.

Further, it is checked whether or not the signal related to the speed ω has reached the motor speed command value ω _1, and if not, return to the original,
The duty D _t and the forward / reverse rotation signal R ₀ are calculated and output again.

If so, record the time t ₁ required for that in memory,
Θ _d related to the position to start deceleration for stopping is calculated and stored.

Next, a constant speed operation is started. First, the signal relating to the speed ω is read and compared with the motor speed command value ω _1, and if the values are the same, the process proceeds to the next step, but if they are different, the duty D _t and the forward / reverse signal R ₀ are calculated, and a new The value is output and constant speed control is performed. Next, the signal relating to the position θ is read, and it is checked whether or not the position θ _d for starting deceleration calculated earlier is reached.
If not reached, continue constant speed operation, and if reached,
Based on the time t ₁ required to reach the motor speed command value ω ₁ stored in the acceleration operation, one is selected from among several deceleration patterns stored in the ROM, and the deceleration operation is performed according to this deceleration pattern. To do. In the deceleration operation, the signal related to the position θ is read, and the deceleration pattern corresponding to the signal is used to calculate and output those related to the duty D _t and the forward / reverse rotation command R ₀ .

Next, it is checked whether or not the signal relating to the position θ has reached the position θ _t sufficient for the stop operation. If the signal has not reached the position, the deceleration operation is continued. If the signal has reached the position θ _t , the stop routine is entered to stop the operation.

This stopping routine is performed at a small position θ _t at which the vehicle can be stopped without hunting.

FIG. 18 is an explanatory diagram illustrating a deceleration pattern selection example.

That is, the speed ω with respect to the position θ at the time of starting the motor is measured, the deceleration start positions θ _{d1 to} θ _d4 are calculated, and the deceleration pattern closest to the acceleration pattern from the previously recorded deceleration patterns A to D is calculated. You choose and decelerate.

For example, when standing up as shown in (a) at the time of starting, the deceleration start position θ _d3 is calculated by detecting the inclination of the rising edge, and B, which is similar to this, is selected as the deceleration pattern curve. Control with. Further, in the case of the rising as shown in (b), θ _d1 is calculated and the deceleration pattern of D is selected.

As described above, according to the above-described embodiment of the present invention, in the position control, the position θ _{d at} which deceleration for stopping is started is calculated based on the data at the time of acceleration, and the deceleration in the ROM is adjusted. Since the most suitable deceleration pattern can be selected to decelerate and stop, even if the characteristics of the motor or the state of the load changes, the optimum speed can always be achieved, and smooth position control without hunting can be performed.

Note that, in the case shown in FIG. 17, the time t ₁ required to reach the motor speed command value ω ₁ is calculated, and the position θ _{d at} which deceleration is started is calculated.
And the selection of the deceleration pattern. However, instead of the motor speed command value ω ₁ , the time during which the speed value is less than ω ₁ and reaching a certain speed value is measured and the position θ _d at which deceleration is started and the deceleration pattern are selected. Is obtained.

Also, during acceleration operation, the elapsed time t ₁ was measured with reference to ω ₁ related to a constant speed, but conversely, the speed at that time was measured with reference to a constant time, and deceleration was started. Similar effects can be obtained by calculating the position and selecting the deceleration pattern.

In summary of the points described above, according to the present invention, (a) during positioning control, hunting is always performed against changes in power supply voltage, changes in motor characteristics due to temperature, and load changes. (B) The remaining distance to start deceleration can be directly obtained as an absolute position from the command speed and acceleration. Therefore, even if the command speed and acceleration change due to changes in the applicable product, In addition, it is possible to provide a motor position control method that does not require a large-capacity memory because it is sufficient to store only the deceleration pattern in the memory. It can be said that the invention has excellent practical effects.

[Brief description of drawings]

(A) to (c) of FIG. 1 are explanatory diagrams of the deceleration state of the motor,
2 (a) to (c) are explanatory views of the improved state of FIG. 1,
FIG. 3 is an explanatory view of a method for detecting speed in unit time, FIG. 4 is a relationship curve diagram between speed and time, (a) of FIG.
(B) is a speed / time / position / time relationship curve diagram during deceleration, FIG. 6 is a speed / position relationship curve diagram, and FIG. 7 is a position control device used for carrying out the method of the present invention. FIG. 8, FIG. 8 is an illustration of the rotation direction detection circuit, FIG. 9 is an operation illustration thereof, FIG. 10 is an illustration of a position detection circuit, and FIG. 11 is an operation illustration thereof. , FIG. 12 is a similar illustration of the speed detection circuit, and FIG. 13 is its operation explanatory diagram, FIG.
FIG. 14 is also an exemplary diagram of a drive circuit, FIG. 15 is an explanatory diagram of its operation, FIG. 16 is an exemplary block diagram of the same micro computer circuit, FIG. 17 is an operational explanatory flowchart, and FIG. FIG. 6 is an explanatory diagram illustrating a deceleration pattern selection example. 1 ... Power supply, 2 ... Motor, 3 ... Load, 4 ... Encoder, 5 ... Rotation direction detection circuit, 6 ... Position detection circuit,
7-speed detection circuit, 8-drive circuit, 9-microcomputer circuit, 10-rotation signal, 11-rotation direction signal, 12-position signal, 13-speed signal, 14-duty signal , 15 …… Forward / reverse rotation signal, 16 …… Forward rotation output, 17
...... Reverse rotation output, 18 …… Position command, 19 …… Maximum speed command, 20-23 …… Transistor, 24-27 …… Diode,
51 …… D type flip-flop, 52 …… Clock terminal, 53 …… D terminal, 54 …… Output terminal, 61 …… UP / DOWN counter, 62 …… Latch, 63 …… Strobe signal, 64 ……
Reset signal, P _{0 to} P _n ...... UP / DOWN counter output signal, 7
1 …… Counter, 72 …… Latch, 73 …… Counter enable signal, 74 …… Counter reset signal, 75 …… Latch strobe signal, S _{0 to} S _n …… Counter output signal, 81 ……
Inverter gate, 82,83 AND gate, ω speed, ω ₁ ...... motor speed command value ω _1-1 ...... maximum speed of device, ω _N ...... speed command value, ω _C ...... speed signal, θ ……
Position, θ ₀ …… Positioning command value, θ _C …… Reference value, θ _d ,
θ _d1 , θ _d2 …… The distance (angle) from the position where deceleration should be started to the target position.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Hayashida 3-1-1, Saiwaicho, Hitachi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Shigeki Morinaga 3-chome, Saiwaicho, Hitachi, Ibaraki No. 1 in Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor, Kimiyo Ishizaki 1-1-1, Higashitaga-cho, Hitachi, Hitachi, Ibaraki (56) References, Hitachi, Ltd. Taga Factory (56) Reference JP-A-48-2010 (JP, A) JP-A-53-102578 (JP, A) JP-A-54-49706 (JP, A) JP-A-54-79374 (JP, A) JP-A-57-160377 (JP, A)

Claims (3)

[Claims] 1. A motor position control method for controlling the positioning of a motor having an encoder for measuring a position on an operating axis to a target position by an arbitrary positioning command value, which is determined on the basis of a device driven by the motor. Based on the commanded speed ω _{1 of the} device and speed control so that the motor current maintains a predetermined value at each start, the acceleration α ₁ is measured from the speed fluctuation per unit time at that time or the time to reach the unit speed. Then, the remaining distance θd from the point where deceleration calculated by the command speed ω ₁ and the acceleration α ₁ should be started to the target position is In addition to the above calculation, the remaining distance θd to the target position is selected from a plurality of deceleration patterns stored in ROM or RAM in advance, and one pattern closest to the speed pattern of the measured acceleration is selected. A motor position control method characterized in that speed control is performed so as to match the actual speed as a command value to decelerate. 2. A motor position control method according to claim 1, wherein acceleration is calculated by measuring a time required to reach a preset unit speed change. 3. A motor position control method according to claim 1, wherein acceleration is calculated by measuring a change in speed per preset unit time.