JP5016633B2 - Positioning device - Google Patents

Description

  The present invention relates to a positioning device that uses a stepping motor to move a movable part in a positionable manner.

  In the positioning stage or the like, it is indispensable to return the movable part to the origin position as an initial setting at the time of power-on or power failure recovery. In this case, it is common to use an origin position sensor to detect whether or not the movable part has returned to the origin position. As the origin position sensor, for example, a proximity sensor or a switch arranged on a stage or the like is used. In addition, there are an encoder and a potentiometer attached to a motor (for example, Patent Document 1). The origin return method using this origin position sensor is referred to as a first conventional example.

  Moreover, when moving a movable part using a stepping motor, the method which can detect having returned to the origin position, without using an origin position sensor is proposed. That is, the motor is stepped out when returning to the origin, and when the step-out is detected by monitoring a change in the motor voltage, the motor is stopped in a predetermined excitation state (for example, Patent Document 2). The origin return method using this step-out detection is referred to as a second conventional example.

JP 2003-309990 A Japanese Patent Laid-Open No. 9-9688

  However, in the case of the first conventional example, it is difficult to reduce the size of the device and save wiring, resulting in high costs. Further, in the case of the second conventional example, since the stepping motor is stepped out, mechanical damage is great, and it is difficult to reduce noise and vibration.

 The present invention was created under the background described above, and the object of the present invention is to detect the origin position without using the origin position sensor, and to use a stepping motor. However, an object of the present invention is to provide a positioning device capable of quickly returning the movable portion to the origin position without causing step-out.

In order to solve the above-described problems, a positioning device of the present invention is a device that moves a movable part so that the movable part can be positioned using a stepping motor, and an origin block provided so as to be able to contact the movable part, and a movable with respect to the origin block An elastic member that absorbs the impact of contact of the motor to avoid stepping out of the motor, a stepout sign detection unit that detects the stepping out of the motor and outputs it as a stepping out sign signal, and an input position command And a control unit for controlling the driving of the motor. When the control unit receives the step-out indication signal and the excitation origin signal related to the motor and drives the motor in the direction of home return when returning to the origin, and then the step-out indication signal indicates the step-out indication of the motor. is finely driven in the reverse or forward direction to the motor, the excitation origin signal in this state has a structure for stopping the driving of the motor when it becomes active, the synchronism loss symptom detecting unit, each of the motor Changes in the voltage level, frequency, or waveform at the midpoint on the phase coil connection are monitored, and the presence or absence of signs of step-out of the motor is detected based on the monitoring results.

  According to this invention, when the stepping motor is driven in the direction of returning to the origin when returning to the origin, the movable portion moves and then contacts the origin block. Since the impact when the movable part comes into contact with the origin block is absorbed by the elastic member, step-out of the motor is avoided, and the state close to step-out is obtained. On the other hand, if the out-of-step indication signal indicates an out-of-step indication of the motor, the motor will be finely driven, and when the excitation origin signal becomes active, the motor will stop driving, causing the motor to step out. The moving part quickly returns to the origin position without any problems.

  Therefore, it is possible to detect the origin position without using the origin position sensor, and it is possible to easily reduce the size of the device and save wiring. In addition, although the configuration uses a stepping motor, it is possible to return the movable portion to the origin position without causing a step-out, and noise and vibration can be easily reduced. Further, since the impact when the movable part comes into contact with the origin block is absorbed by the elastic member, mechanical damage is very small. That is, since all the disadvantages inherent in the conventional apparatus are eliminated, there is a great merit in reducing the size, performance and cost of the apparatus.

The step-out sign detection method of the step-out sign detection unit is based on the following new knowledge. In other words, when the stepping motor is almost out of step, a characteristic change appears in the voltage level, frequency, waveform, or the like at the midpoint on the connection of each phase coil of the motor. Therefore, if the voltage at the midpoint on the connection of each phase coil of the same motor is detected and the change appearing in the level, frequency or waveform of the voltage at the midpoint is monitored, the sign of step-out of the motor is detected. It becomes possible. Therefore, even if a step-out sign detection unit is connected to the middle point on the connection of each phase coil of the stepping motor, a large current does not flow through the same part, so the loss is very small. It becomes possible to achieve higher efficiency.

It is a block diagram of a positioning device concerning an embodiment of the invention. It is a block diagram of the step-out sign detector of the same apparatus. It is a flowchart of the software processed at the time of origin return in the controller of the same apparatus. It is a wave form diagram of a signal after pre-processing the voltage of the middle point on the connection of each phase coil at the time of origin return of a stepping motor. It is a wave form diagram of a signal after pre-processing the voltage of the middle point on the connection of each phase coil just before a stepping motor step-out. It is a wave form diagram of a signal after pre-processing the voltage of the middle point on the connection of each phase coil at the time of a stepping motor stepping out. It is a winding structure figure of a three phase star type stepping motor. It is a winding structure figure of a new 4-phase type stepping motor. It is a winding structure figure of a 5-phase star type stepping motor. It is a winding structure figure of a three phase delta type stepping motor. It is a winding structure figure of a 5-phase pentagon type stepping motor.

  Hereinafter, a positioning device according to an embodiment of the present invention will be described with reference to FIGS. In addition, about the thing whose correspondence is unknown between the invention specific matter described in the claim, and the component of the apparatus, it shall show together in the column of the description of the postscript.

  As shown in FIG. 1, the positioning device A exemplified here is a device that moves the movable portion 8 in a direction indicated by an arrow using a stepping motor 2 and a positioning stage 3. In the figure, 1 is a step-out sign detector, 4 is a driver, 5 is a controller, 6 is an origin block, and 7 is a shock absorber. These parts constitute a positioning device A.

  The positioning stage 3 is a table that supports the movable part 8 so as to be movable in a horizontal direction and linearly. The stepping motor 2 that moves the movable part 8 is attached to the outside of the frame 31, while the frame 31 has the stepping motor 2. A conversion mechanism 32 that converts the rotational motion of the motor 2 into a linear motion of the movable portion 8 is attached. The conversion mechanism 32 is a ball screw mechanism, a rack and pinion mechanism, a mechanism using a timing belt, or the like.

  The origin block 6 is a plate-like positioning block disposed at the stroke end of the positioning stage 3 so as to be able to come into contact with one surface of the movable portion 8, and is fixed to the frame 31 of the positioning stage 3 via the shock absorber 7. Has been.

  The shock absorber 7 is an elastic body such as a spring or rubber for absorbing an impact when the movable part 8 contacts the origin block 6, and the stepping motor 2 when the movable part 8 contacts the origin block 6. The elastic force is set to such an extent that the step-out of the motor 2 is avoided even by a high load acting on the motor.

  The controller 5 is a device that receives the input position command a and generates a command pulse d for driving the stepping motor 2 in the pattern indicated by the command a. In addition to the input position command a, the step-out sign detector 1 The derived step-out sign signal b and the excitation origin signal c derived from the driver 4 are input. In this embodiment, a microprocessor (CPU) is used, and the software shown in FIG. 3 is used as software that is processed when returning to the origin. Details will be described later.

  The driver 4 is connected to the subsequent stage of the controller 5, and in addition to each phase excitation signal e for actually driving the stepping motor 2 in accordance with the command pulse d by a drive method such as full step, half step or micro step, This is an apparatus for generating an excitation origin signal c indicating the origin on the excitation timing.

  As shown in FIG. 2, the stepping motor 2 has a rotor 21, an A-phase coil 22, and a B-phase coil 23, and each intermediate portion of the A-phase coil 22 and the B-phase coil 23 is commonly connected as a middle point α. The winding structure is made. That is, the stepping motor 2 uses a new two-phase stepping motor in the present embodiment.

  The out-of-step indication detector 1 is a circuit that detects an out-of-step indication of the stepping motor 2 at the time of return to origin and outputs it as a out-of-step indication signal b, and is electrically connected to the middle point α of the motor 2. Of the stepping motor 2 based on the midpoint voltage signal “a”, the output section 12 that preprocesses the voltage of the midpoint α guided through the leadwire 11 and outputs it as a midpoint voltage signal “f”. It has a configuration including a detection unit 13 that detects the presence or absence of a sign of step-out.

  One end of the lead wire 11 is electrically connected to the middle point α in the stepping motor 2, while the other end is taken out of the motor 2. However, depending on the structure of the lead terminal of the motor 2, it may not be necessary to take it out. The same applies to the midpoint circuit portions 14 and 14 '(see FIGS. 10 and 11) described later.

  As for the output unit 12, a voltage dividing circuit 121 that divides the voltage at the middle point α and blocks a DC component, an amplitude limiting circuit 122 that is connected to the subsequent stage of the circuit 121, and a subsequent stage of the circuit 122. The operational amplifier amplifier circuit 123 is configured. The midpoint voltage signal f output from the operational amplifier amplifier circuit 123 is a signal obtained by preprocessing the voltage at the midpoint α into a form suitable for the processing of the detection unit 13, but the level and frequency of the voltage at the midpoint α The content includes information such as a waveform.

 The detection unit 13 monitors changes in the voltage level, frequency or waveform of the midpoint α of the stepping motor 2 based on the analog form midpoint voltage signal f, and the motor 2 is removed based on the monitoring result. In this embodiment, a microprocessor (CPU) is used to detect the presence or absence of a tone sign and output the detection result as a step-out sign signal b.

  4 to 6, the vertical axis represents the A / D conversion value of the midpoint voltage signal f, and the horizontal axis represents the sampling time. When the stepping motor 2 is driven at the speed at the time of returning to the origin (input frequency is 1.5 KHz), FIG. 4 shows the normal rotation of the motor, FIG. 5 shows the case just before the motor step-out, and FIG. Show.

  That is, when the stepping motor 2 reaches from the normal rotation shown in FIG. 4 to just before the step-out shown in FIG. 5, a characteristic change appears in the voltage level, frequency, waveform or the like of the middle point α of the motor 2. The same applies to the case where the motor 2 reaches the step-out state shown in FIG. 6 immediately before the step-out, but the change in the voltage level of the middle point α of the motor 2 is completely different from that immediately before the step-out. . It has been confirmed by experiments that this phenomenon is not greatly affected by the type of the motor 2 and the level of the drive current. Therefore, by constantly monitoring the voltage level, frequency, waveform, etc. of the middle point α during the process of returning to the origin of the motor 2, it is possible to effectively detect the presence or absence of signs of step-out of the motor 2. .

  Based on this principle, the detection unit 13 detects a sign of step-out of the motor 2. In the present embodiment, in order to simplify the processing in the detection unit 13, it is determined whether or not the voltage level of the middle point α exceeds the reference value. When a sign is detected, the step-out sign signal b is activated.

  Since the voltage indicating the step-out or high load state varies depending on the type of the stepping motor 2, the drive current value, the input frequency, etc., the above-described reference value required for detecting the presence or absence of a step-out sign is an experiment. It may be adjusted appropriately through the above.

  The number of phases and the winding structure of the stepping motor to which the step-out indication detector 1 is applied are not limited to the new two-phase stepping motor shown in FIG. For example, a first type stepping motor in which one end of each phase coil is commonly connected as a midpoint (for example, a three-phase star type, a new four-phase type, a five-phase type shown in FIGS. 7, 8, and 9 respectively) In addition to the phase star type stepping motor, a second type stepping motor in which each phase coil is annularly connected (for example, the three-phase delta type and the five-phase pentagon type stepping shown in FIGS. 10 and 11, respectively) It can also be applied to motors.

  However, in the case of the second type stepping motor, there is no midpoint on the connection of each phase coil. For example, the three-phase delta stepping motor shown in FIG. A central circuit section 14 is provided in which three resistors R are connected to each other in a star shape corresponding to each phase coil, one end of the central circuit section 14 is connected to each connection point of each phase coil, The end is a middle point α, and the lead portion 11 is electrically connected. The same applies to the five-phase pentagon type stepping motor shown in FIG. 11, and a central circuit section 14 'in which five resistors R having the same resistance and high resistance are connected to each other in a star shape corresponding to each phase coil. The one end of the central circuit portion 14 'is connected to each connection point of each phase coil, and the other end on the common connection side is set as a middle point α, so that the lead portion 11 is electrically connected.

  Next, the origin return software processed by the controller 5 will be described with reference to FIG.

  The software for returning to the origin shown in FIG. 3 is processed as an initial setting upon power-on or power recovery. First, the stepping motor 2 is driven, and the movable part 8 is moved at a predetermined speed in the origin return direction (s1). This operation is continued until the step-out indication signal a becomes active (s2, s3).

  Thereafter, when the movable portion 8 comes into contact with the origin block 6 and the motor 2 is about to step out, the step out sign signal b becomes active at that point. Then, the origin temporary memory in the controller 5 is turned on (s4), the stepping motor 2 is finely driven, and the movable part 8 is moved in the reverse or forward direction at the self-starting speed (s5). This operation is continued until the excitation origin signal b becomes active (s6, s7).

  When the rotation angle of the stepping motor 2 reaches the excitation origin, the excitation origin signal b becomes active. Then, the temporary memory for origin is turned off (s8), and the stepping motor 2 is stopped (s9). Thus, the movable portion 8 returns to the origin position, and the processing of the origin return software shown in FIG. 3 ends. Note that the origin temporary memory is necessary in the case of a sequence that takes a logical product, and the origin temporary memory may be omitted depending on the sequence.

  According to the step-out symptom detector 1 configured as described above, it is possible to detect the origin position without using the origin position sensor, and it is possible to easily achieve downsizing of the device and labor saving of wiring. is there. Moreover, although the stepping motor 2 is used, the movable portion 8 can be returned to the origin position without causing a step-out. This is because the step-out of the motor 2 is avoided by the elastic force of the shock absorber 7 when returning to the origin, and the force of the movable part 8 against the origin block 6 is canceled out. This is because a sign of step-out is detected at the position, and the movable portion 8 can be stopped accordingly. Furthermore, since the shock when the movable part 8 comes into contact with the origin block 6 is absorbed by the shock absorber 7, the mechanical damage is very small and the motor 2 does not step out. In addition, it is possible to easily reduce the vibration. In short, it is possible to reduce the size, performance, and cost of the device as compared with the conventional device.

  In addition, as long as the positioning device according to the present invention has a basic configuration that moves the movable part so that the movable part can be positioned using a stepping motor, the type and number of the motor, and the motor and the movable part are interposed. It is applicable to a robot hand or the like regardless of the type of movement mechanism.

  As long as the origin block can be used for mechanical origin positioning of the movable part, the shape and the arrangement position are not limited, and the origin block may be in an indirect contact with the movable part.

  As for the elastic member, as long as it absorbs the impact when the movable part contacts the origin block and avoids the stepping motor step-out, the type of the elastic member is not limited, and the mechanism is interposed between the stepping motor and the movable part. The form which provides may be sufficient.

  As long as it has a function of detecting a step-out sign of the stepping motor based on the voltage or current of each part of the stepping motor and outputting it as a step-out sign signal, the configuration etc. I will not. For example, the voltage level, frequency or waveform at the midpoint on the connection of each phase coil of the same motor is monitored, and the presence or absence of signs of step-out of the motor is detected based on the monitoring result. The change in the voltage and current of each phase coil may be monitored directly or indirectly, and the presence / absence of a sign of step-out of the motor may be detected based on the monitoring result. Moreover, the form integrated with the driver and the controller may be sufficient.

  The control unit controls the driving of the stepping motor in accordance with the input position command, drives the motor in the direction of return to origin when returning to the origin, and then when the out-of-step indication signal indicates the out of step indication As long as it has a function to finely drive the motor in the reverse or forward direction and stop the motor drive when the excitation origin signal becomes active in this state, the control method of the stepping motor, the contents of the hardware and software used Is not questioned.

A Positioning device 1 Out-of-step sign detector (out-of-step sign detector)
2 Stepping motor 3 Positioning stage 4 Driver 5 Controller (control unit)
6 Origin block 7 Shock absorber (elastic member)
8 Movable part α Midpoint (midpoint on the connection of each phase coil)
a Input position command b Step-out indication signal c Excitation origin signal

Claims (2)

In a positioning device that moves a movable part so that the movable part can be positioned using a stepping motor, an origin block, an elastic member that absorbs an impact when the movable part contacts the origin block and avoids step-out of the motor, and the motor A step-out sign detection unit that detects a step-out sign and outputs it as a step-out sign signal, and a control unit that controls driving of the motor in accordance with an input position command, the control unit including a step-out sign related to the motor Signal and excitation origin signal are input, the motor is driven in the origin return direction at the time of return to origin, and then the motor is finely rotated in the reverse or forward direction when the out-of-step indication signal indicates the out-of-step indication of the motor. was driven, the excitation origin signal in this state has a structure for stopping the driving of the motor when it becomes active, the step-out sign detection unit of each phase coil of the motor Level of the voltage on the line midpoint, monitor changes appearing in frequency or waveform, positioning device, characterized in that it is configured to detect the presence or absence of signs of out-of the motor on the basis of the monitoring result. In a positioning device that moves the movable part so that the movable part can be positioned using a stepping motor in which each phase coil is connected in an annular shape, the shock at the contact of the movable part with the origin block and the origin block is absorbed and the motor is stepped out. An elastic member to be avoided, a resistor group connected to each other in a star shape corresponding to each phase coil, and a midpoint circuit portion having one end connected to each connection point of each phase coil ; A step-out sign detection unit that detects a step-out sign and outputs it as a step-out sign signal, and a control unit that controls driving of the motor in accordance with an input position command, the control unit including a step-out sign related to the motor Signal and excitation origin signal are input, the motor is driven in the origin return direction at the time of return to origin, and then the motor is finely rotated in the reverse or forward direction when the out-of-step indication signal indicates the out-of-step indication of the motor. Is moving has become excited origin signal in this state and configuration for stopping the driving of the motor when it becomes active, the step-out sign detector, the other end of the common connection side of the middle point circuit Configuration that monitors the change in voltage level, frequency, or waveform at the midpoint as the midpoint on the connection of each phase coil of the motor, and detects the presence or absence of signs of step-out of the motor based on the monitoring results A positioning device characterized by that.

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