JP4987302B2 - Driving method of stepping motor - Google Patents

Description

The present invention relates to a method of driving a stepping motor, and more particularly to produce a velocity profile of the stepping motor, a driving method of the stepping motor for driving the stepping motor on the basis of the speed profile.

Conventionally, as a driving device for this type of stepping motor, for example, Patent Document 1 is known.
The stepping motor driving apparatus described in Patent Document 1 includes a driving circuit that sends an electric signal for exciting the stepping motor, a load torque detecting unit that detects a load torque related to the driving of the stepping motor, and a load torque. And a control circuit that determines an electrical signal in the drive circuit by sending a drive command value corresponding to the load torque detected by the detecting means.

FIG. 9 is a general positioning operation speed profile of the stepping motor.
A speed profile called “trapezoidal drive” is formed, in which the operation speed is not commanded immediately after starting, accelerates linearly over time to reach the operation speed, then decelerates linearly over time from the operation speed and stops. To do. In driving the stepping motor, shifting over time suppresses acceleration, that is, necessary torque for acceleration / deceleration, thereby preventing loss of motor synchronization (hereinafter referred to as step-out). In the conventional method, information related to the trapezoidal shape of the speed profile such as the starting speed, the driving speed, the acceleration time, and the deceleration time is input in addition to the movement amount or target position information to the driving profile generation function.
JP-A-1-218392

In general, the operation speed profile is determined (designed) by the user based on load information and motor torque information.
However, in such a conventional stepping motor operating speed profile generation method, the required torque determined from the load inertia, friction, and gravity is determined by the speed-torque characteristics and torque margin shown in FIG. The acceleration / deceleration time and operation speed must be determined so that the torque is less than or equal to the possible torque).

In many stepping motors, the motor torque decreases as the speed increases.
However, in the trapezoidal drive, the acceleration is linear with constant acceleration, so that the motor torque is the lowest as shown in FIG. It is almost always decided. In that case, a large motor torque at low speed is not used, and there is a problem that the positioning time cannot be shortened accordingly.

The present invention solves the above-described problem and generates an acceleration / deceleration profile based on specified load information and a utilization rate (torque margin) of motor output torque, thereby performing a positioning operation only with load information and movement amount input. It is an object of the present invention to provide a driving method for a stepping motor that can generate a shortest positioning with high efficiency.

In order to solve the above problems, the present invention moves to an operating speed profile generation function in a driving method of a stepping motor that generates an operating speed profile and controls a motor driving circuit based on the operating speed profile to drive a stepping motor. In addition to quantity, load information is input to create a driving speed profile, and the stepping motor is driven by controlling the motor drive circuit from position information that changes in real time based on this driving speed profile. The system of
Motor torque information at typical speed [V], set current [I], and input voltage [Vin] is previously stored in the storage device,
When an execution command for positioning operation is detected, each value related to the speed profile is calculated before the operation starts.
Calculating a rated torque TQ [n] for a specified set current from a speed-torque characteristic for a speed section V [n];
Calculating acceleration time TA [n] and deceleration time TD [n] from the calculated rated torque TQ [n] and load information;
Calculating a movement amount at the time of acceleration and deceleration in the section n, and adding this to calculate a cumulative movement amount;
The above three steps are set as one speed section, and the accumulated movement amount and the command movement amount are compared each time it is finished,
If the cumulative movement amount does not exceed the command movement amount, incrementing the section n and repeating the same three steps for the next speed section;
When the accumulated movement amount exceeds the command movement amount, the step returns one speed section, and recalculates the peak speed, acceleration time, and deceleration time that satisfy the remaining movement amount by triangular drive from that speed;
To complete the profile shape,
The command speed and command position are calculated in real time using the generated array in real time, the command position information is transmitted to the motor drive circuit in real time, and acceleration / deceleration is performed while switching acceleration during acceleration and deceleration. .
Further, the present invention is to use inertia, friction, and gravity as the load information .

According to the present invention, the effects listed below can be obtained.
In the stepping motor driving method for generating a driving speed profile and controlling the motor driving circuit based on the driving speed profile to drive the stepping motor, load information in addition to the movement amount is input to the driving speed profile generation function. A driving speed profile is created, and the stepping motor is driven by controlling the motor drive circuit from position information that changes in real time based on the driving speed profile. The motor torque information for the set current [I] and the input voltage [Vin] is stored in the storage device in advance, and when the positioning operation execution command is detected, each value related to the speed profile is calculated before the operation starts, and the specified setting Rated torque TQ [n] against current from speed-torque characteristics A step for calculating the degree interval V [n], a step for calculating the acceleration time TA [n] and the deceleration time TD [n] from the calculated rated torque TQ [n] and the load information, A step of obtaining a moving amount at the time of deceleration, adding this, calculating a cumulative moving amount, a step of comparing the cumulative moving amount and the command moving amount each time the above three steps are set as one speed section, and accumulating If the travel distance does not exceed the command travel distance, increment the section n and repeat the same three steps for the next speed section; if the cumulative travel distance exceeds the command travel distance, return one speed section; The profile shape is completed by the step of recalculating the peak speed, acceleration time, and deceleration time that satisfy the remaining travel amount by triangular drive from the speed, and the command speed is periodically processed using the generated array , Command position is calculated in real time, command position information is transmitted in real time to the motor drive circuit, and acceleration / deceleration is performed while switching acceleration during acceleration and deceleration, so positioning operation can be performed with only load information and movement amount input Thus, the shortest positioning with high efficiency can be automatically generated. Also, since it is not a feedback system (open loop), the response does not vary and the repeatability is good.
The system of the operating speed profile generation function has motor torque information inside, calculates acceleration from available torque for each speed based on specified load information, and accelerates / decelerates while switching acceleration during acceleration and deceleration. Since the acceleration / deceleration profile is generated based on the specified load information and the motor output torque utilization rate in the driving speed profile, the torque margin is kept constant and the operation is performed at the optimum efficiency, thereby reducing the fear of stepping out. To do.
Since inertia, friction, and gravity are used as the load information, the aggressiveness of the entire operation can be easily changed by specifying a torque margin according to the response and load of the device .

  Hereinafter, the illustrated embodiment will be described in detail with reference to the drawings.

FIG. 1 shows a driving device applied to the stepping motor driving method of the present invention, wherein 1 is a stepping motor and 2 is a motor driving circuit for driving the stepping motor 1.
Reference numeral 3 denotes an operation speed profile generation device, which controls the motor drive circuit 2 based on the operation speed profile. In this driving speed profile generation device 3, a command moving amount or a target position and load information are input to the driving speed profile generation function before driving to create a driving speed profile. As the load information, inertia, friction, gravity, torque margin, and the like are employed.

  The driving speed profile generated by the driving speed profile generation device 3 is input to the real-time command position generation device 4, and the real-time command position generation device 4 uses the generated array in accordance with a predetermined processing flow. The command speed and command position are calculated in real time by regular processing such as an interval of 0.1 mS, and the command position information is transmitted to the motor drive circuit 2 in real time. The motor drive circuit 2 drives the stepping motor 1 based on the command position information from the real time command position generator 4.

Next, a method for driving the stepping motor will be described.
In the operation profiler generation function, as shown in FIG. 2, the system previously stores motor torque information at a typical speed [V], set current [I], and input voltage [Vin] in a storage device such as a memory.

The arrangement of the data table in FIG. 2 is shown below.
・ Speed [RPS] [1, 2, 3.2, 5, 8, 10, 12, 15, 20, 25, 32, 40, 50, 70, 90]
・ Current [ratio to rated value (I) [%] [25, 50, 75, 100]
・ Driver voltage [V] [12, 24, 36, 48]
When the positioning operation execution command is detected, each value related to the speed profile as shown in FIG. 3 is calculated before the operation is started. FIG. 4 is a processing flow showing the calculation procedure.

The procedure will be described according to the processing flow.
(1). The rated torque TQ [n] for the specified set current is calculated for the speed section V [n] from the speed-torque characteristics (step S1). Start from 0 and increment by 1.
(N is the number of speed sections, n = 15 in this example)
(2). Acceleration time TA [n] and deceleration time TD [n] are calculated from the calculated rated torque TQ [n] and load information such as torque utilization factor TU, inertia LI, friction LF, and gravity LG (step S2). The acceleration time TA [n] and the deceleration time TD [n] are obtained by the following equations.

(3). The movement amounts PA and PD during acceleration and deceleration in the section n are calculated by the following equations 3 and 4, and these are added to calculate the cumulative movement amount (step S3).

  The accumulated movement amount is a value obtained by accumulating the movement amounts on the acceleration side and the deceleration side from low speed to high speed.

The above three steps are set as one speed section, and the accumulated movement amount is compared with the command movement amount every time it is finished (step S4). If the accumulated movement amount does not exceed the command movement amount, the section n is incremented to The same three steps are repeated for the speed section (step S5).

If the accumulated travel exceeds the command travel, the speed interval is returned by 1 (V [n] → V [n-1]), and the remaining travel is met by triangular drive from the speed of V [n-1]. Such peak speed, acceleration time, and deceleration time are recalculated (step S6) to complete the profile shape.
When the profile shape is completed, the command speed and command position are calculated in real time by periodic processing using an array generated according to the processing flow shown in FIG. 5, and the command position information is transmitted to the motor drive circuit 2 shown in FIG. 1 in real time. .

The processing flow of FIG. 5 is configured from step S10 to step S27, and creates an automatic driving speed profiler (step S10).
First, in step S11, it is determined whether the operation has been started (YES) or not (NO). If NO, confirmation is made in step S11. If YES, go to step S12 and perform pre-operation calculations.

If n = 0 (step S13), acceleration speed and position calculation (periodic processing) based on t = 0, T = TA [n], V = V [n + 1] (step S14) (step S15) )I do.

Next, t = T is determined (step S16). If YES, command speed = peak speed is determined (step S17).

If NO, n = n + 1 (step S17 ₁ ) and the process returns to step 14. If YES, the process goes to step S18 to calculate the speed and position at constant speed, and in the next step S19, the command position> deceleration start position is determined. If this is NO, the process returns to step S18, and if YES, the process goes to step S20. In step S20, based on t = 0, T = td [n], V = v [n + 1], deceleration speed and position calculation (periodic processing) is performed (step S21).

And t = T? (NO in step S22), if NO, the process returns to step S21, and if YES, the process goes to step S23. And command position = command movement amount? If NO, n = 0? (Step S24) is determined. If YES, the process returns to Step S21. If NO, go to step S25, set n = n-1, and return to step S20.

Command position = command movement amount? If the determination (step S23) is YES, the process goes to step S26, and the process is terminated with command position = command movement amount (step S27).

The acceleration of each speed section is linear acceleration, and when the speed section is switched by acceleration or deceleration, the commanded acceleration is switched in real time by switching the reference array element [n].

In FIG. 5, the processing of step S15, step S18, and step S21 is the update of the command speed and command position, but these are the same linear acceleration methods as in the prior art.

Next, the operation of the above embodiment will be described.
FIG. 6 shows a comparison with linear acceleration. FIG. 6A on the left is an example of response of the automatic driving speed profiler according to the present invention, and FIG. 6B on the right is an example of response of linear acceleration.
Waveform: Command speed 50 [RPS / 2div], command torque 1 [Nm / 2div], actual speed 32.05 [RPS / div], time axis 100 [msec / div]
In the automatic speed profiler of FIG. 6A, positioning is possible without step-out. In the linear acceleration shown in FIG. 6 (b), it is indicated that the same acceleration / deceleration time is commanded, but the follow-up cannot be performed and the step-out has occurred.

FIG. 7 shows a speed response when the inertia load is changed according to the present invention. In contrast to FIG. 7A, FIG. 7B increases the inertial load. FIG. 7A shows a response example of the inertial load 1542 [gcm ² ], and FIG. 7B shows a response example of the inertial load 2994 [gcm ² ].
Waveform: Command speed 30 [RPS / 2div], command torque 1 [Nm / 2div], actual speed 12.82 [RPS / div], time axis 50 [msec / div]
It can be seen that the acceleration / deceleration becomes gentle as the inertial load increases.

FIG. 8 shows the speed response when the friction load is changed. In FIG. 8B, the friction load is set larger than that in FIG. FIG. 8A shows a response example of a friction load of 0.08 [Nm], and FIG. 8B shows a response example of a friction load of 0.2 [Nm].
Waveform: Command speed 30 [RPS / 2div], command torque 1 [Nm / 2div], actual speed 12.82 [RPS / div], time axis 50 [msec / div]
It can be seen that when there is a friction load, the friction becomes the braking torque during deceleration and the deceleration time is shortened.

It is a feature of the present invention that these profiles can be automatically generated for each operation only by specifying load information.

According to the above embodiment, the system has motor torque information inside, calculates acceleration from acceleration torque for each speed based on designated load information, and accelerates / decelerates while switching acceleration during acceleration and deceleration. As a result, the driving speed profile is determined by the system by specifying the movement amount and load information.
As described above, according to the present invention, the positioning operation can be performed only by inputting the load information and the movement amount, and the shortest positioning with high efficiency can be automatically generated.
Since the torque margin is kept constant and the motor is operated at the optimum efficiency, the fear of step-out is reduced.
The aggressiveness of the entire operation can be easily changed by specifying the torque margin according to the response and load of the equipment.
Since it is not a feedback system (open loop), the response does not vary and repeatability is good.

  Needless to say, the present invention is not limited to the above-described embodiment, and may be appropriately modified and implemented without departing from the scope of the present invention.

It is a block diagram which shows the drive device of the stepping motor of this invention. It is a characteristic view which shows an example of the motor torque information which a system has in this invention. It is a characteristic view which shows an example of the data calculated before a driving | operation in this invention. It is a flowchart which shows the production | generation procedure of the profile data in the drive method of this invention. It is a flowchart which shows the output process of the positional information which changes in real time in the drive method of this invention. FIGS. 6 (a) and 6 (b) are graphs comparing the characteristics of the automatic driving profile of the present invention and linear acceleration. FIGS. 7A and 7B are characteristic diagrams showing profiles with respect to differences in inertia load in the automatic driving profile of the present invention. FIGS. 8A and 8B are characteristic diagrams showing profiles with respect to differences in friction load in the automatic driving profile of the present invention. It is a figure which shows the general positioning operation speed profile of the stepping motor in the drive method of the conventional stepping motor. It is a characteristic view which shows the relationship between the speed-torque characteristic of the conventional stepping motor, and the usable torque. It is a characteristic view which shows the torque area | region which cannot be used by the linear acceleration in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stepping motor 2 Motor drive circuit 3 Operation speed profile production | generation apparatus 4 Real time command position production | generation apparatus

Claims (2)

In the stepping motor driving method for generating a driving speed profile and controlling the motor driving circuit based on the driving speed profile to drive the stepping motor, load information in addition to the movement amount is input to the driving speed profile generation function. Create a driving speed profile and control the motor drive circuit from position information that changes in real time based on this driving speed profile to drive the stepping motor,
The system of the operation speed profile generation function has motor torque information in a typical speed [V], set current [I], and input voltage [Vin] in a storage device in advance.
When an execution command for positioning operation is detected, each value related to the speed profile is calculated before the operation starts.
Calculating a rated torque TQ [n] for a specified set current from a speed-torque characteristic for a speed section V [n];
Calculating acceleration time TA [n] and deceleration time TD [n] from the calculated rated torque TQ [n] and load information;
Calculating a movement amount at the time of acceleration and deceleration in the section n, and adding this to calculate a cumulative movement amount;
The above three steps are set as one speed section, and the accumulated movement amount and the command movement amount are compared each time it is finished,
If the cumulative movement amount does not exceed the command movement amount, incrementing the section n and repeating the same three steps for the next speed section;
When the accumulated movement amount exceeds the command movement amount, the step returns one speed section, and recalculates the peak speed, acceleration time, and deceleration time that satisfy the remaining movement amount by triangular drive from that speed;
To complete the profile shape,
Using the generated array, the command speed and command position are calculated in real time by regular processing, and command position information is transmitted to the motor drive circuit in real time.
A driving method for a stepping motor, wherein acceleration and deceleration are performed while switching acceleration during acceleration and deceleration.   The stepping motor driving method according to claim 1, wherein inertia, friction, and gravity are used as the load information.

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