JP2006234688A - Rotation angle detector and rotation angle controlling device for motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation angle detector for a motor capable of detecting rotation angles with superior responsiveness and high precision, and a rotation angle controlling device for the motor using for the same. <P>SOLUTION: When the rotation speed of the motor is faster than a predetermined speed, the rotation angle of the motor is detected by detecting a rising edge, a falling edge, or both rising and falling edges of a pulse edge section that a sine wave signal, a cosine wave signal, or both signals are waveform-shaped and then counting the number of pulses. Otherwise, when the rotation speed of the motor is slower than a predetermined speed, the rotation angle of the motor is detected based on the voltage value of the sine wave signal or cosine wave signal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotation angle control device for a motor used in a dome-shaped camera for monitoring and the like, and a rotation angle detection device for a motor used therein.

  In streets, amusement halls, condominiums, etc., cameras for surveillance purposes are generally popular. In addition, cameras for surveillance purposes have been installed in ordinary houses because of concerns over security. As the appearance of the surveillance camera, there are a box shape and a dome shape. The dome shape relieves the impression that people are being monitored, and has been considered in terms of shape so that there is no sense of incongruity in appearance.

  FIG. 2 shows an example of the shape of the surveillance dome shape camera. The configuration shown in FIG. 2 shows a conventional surveillance dome-shaped camera, but this configuration itself is also a configuration example of a surveillance dome-shaped camera to which the present invention can be applied, as will be described later. The base unit 2 is fixed to the ceiling or the like, and the imaging unit including the lens 4 moves in the pan / tilt direction to shoot. The lens 4 and the imaging unit are covered with a dome cover 3.

  When monitoring a wide range, a plurality of cameras may be installed, but it is better if a single camera can monitor a wider range. Therefore, 360 degrees endless is the mainstream in the pan direction, and the tilt range is now required to have a range of 180 degrees when the movement range is 90 degrees. A DD motor is used as means for performing the pan / tilt drive. In monitoring, it is required to quickly point the imaging unit toward the object and to accurately determine the imaging point.

When performing rotation angle control using a DD motor, a method of performing rotation angle detection using a voltage value of a two-phase encoder provided on the outer periphery of the motor is known. In order to measure the voltage value of the two-phase encoder and calculate the rotation angle, it is a common and inexpensive method to perform AD conversion using a microprocessor or the like. Patent Document 1 below discloses a technique for detecting a rotation angle by the above method.
JP 2002-54951 A

  When using a two-phase encoder signal voltage of sine wave signal (FGA) 520 and cosine wave signal (FGB) 521 as shown in FIG. 6 as means for obtaining rotation angle information indicating the rotation angle (also referred to as rotation position) of the motor. As shown in the block diagram of FIG. 5, A / D conversions 201 and 202 are applied to the sine wave signal (FGA) and the cosine wave signal (FGB), respectively, and arctangent (Arctangent (Fig. 5), the rotation angle information of the motor in the 1 / 2FG section can be obtained. Further, by detecting a portion where the value of Arctangent is intermittent and adding predetermined data (block 204), continuous rotation angle information or rotation angle information of one rotation or more of the motor can be obtained.

  FIG. 6 is a diagram showing a method of obtaining rotation angle information from the sine wave signal 520 and the cosine wave signal 521. As shown in FIG. 6, the value of Arctangent is a value that repeats with a period of 1 / 2FG, but at an intermittent point a, b, c, d, e,. In the negative rotation direction, by adding −π, a rotation angle of the motor or a straight line 303 proportional to the rotation angle is obtained.

  In this case, however, AD conversion processing and calculation processing require a certain amount of time, which limits the AD conversion sampling and calculation processing intervals. For this reason, if the rotation angle is detected only with the voltage value of the two-phase encoder signal, the rotation angle is erroneously detected when the rotation speed of the motor is high. Limiting the speed to a speed that does not cause false detections significantly deteriorates the responsiveness. When applied to a surveillance dome-shaped camera, the rotational performance (responsiveness) of the camera that performs rotational operations such as panning and tilting is impaired. There was a problem.

  As shown in FIG. 7, it is possible to detect the phase by shaping the waveform of the encoder signals 520 and 521 as rectangular waves 522 and 523, respectively, and detecting their edges. Can detect only 1 / 4FG phase, and the resolution is significantly worse than the method of detecting the rotation angle using the two-phase encoder signal voltage of sine wave signal and cosine wave signal, so it is difficult to control the rotation angle with high accuracy. It is.

  The present invention provides a motor rotation angle control device that solves the above-described problems, has excellent responsiveness, and can detect and control a rotation angle with high accuracy, and a motor rotation angle detection device used therefor. For the purpose.

  In order to achieve the above object, in the present invention, when the rotational speed of the motor is higher than a predetermined speed, the rising or falling edge or both of the edge part of the pulse obtained by waveform shaping the sine wave signal, the cosine wave signal, or both signals are used. By detecting the edge and counting the number of pulses, the rotation angle of the motor is detected. On the other hand, when the rotation speed of the motor is slower than a predetermined speed, the motor is based on the voltage values of the sine wave signal and the cosine wave signal. The rotation angle is detected.

That is, according to the present invention, in a rotation angle detection device for a motor that obtains rotation angle information by detecting a sine wave signal and a cosine wave signal output from an encoder provided in the motor,
When the rotational speed of the motor is higher than a predetermined speed, the number of pulses is determined by detecting rising or falling edges or both edges of a pulse shaped waveform of the sine wave signal or the cosine wave signal or both signals. Means for detecting the rotation angle of the motor by counting;
Means for detecting a rotation angle of the motor based on voltage values of the sine wave signal and the cosine wave signal when the rotation speed of the motor is slower than the predetermined speed;
An apparatus for detecting a rotation angle of a motor is provided.

According to the present invention, the rotation angle information is obtained by detecting the sine wave signal and the cosine wave signal output from the encoder provided in the motor, and the rotation angle of the motor is controlled using the rotation angle information. In the motor rotation angle control device,
When the rotational speed of the motor is higher than a predetermined speed, the number of pulses is determined by detecting rising or falling edges or both edges of a pulse shaped waveform of the sine wave signal or the cosine wave signal or both signals. Means for detecting the rotation angle of the motor by counting;
Means for detecting a rotation angle of the motor based on voltage values of the sine wave signal and the cosine wave signal when the rotation speed of the motor is slower than the predetermined speed;
A rotation angle control device for a motor is provided.

  According to the motor rotation angle detection device of the present invention, the rotation angle can be detected at high speed and with high accuracy. Further, according to the rotation angle control device for a motor of the present invention, it is possible to perform rotation angle control excellent in both responsiveness and rotation angle detection accuracy. As a result, when applied to a surveillance dome-shaped camera, the speed of pan / tilt operation can be increased, and the detection accuracy of the rotation angle can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram of a preferred embodiment of a motor rotation angle control device of the present invention. Since the motor rotation angle detection device of the present invention is included in the motor rotation angle control device of the present invention described below, the description of the latter embodiment is the same as the description of the former embodiment. Is also included. A preferred embodiment of the motor rotation angle control apparatus according to the present invention will be described by taking as an example a pan / tilt control of a monitoring dome-shaped camera as shown in FIG.

  In FIG. 1, the output 516 of the DA converter 514 inside the microprocessor 515 is amplified by a driver 506 to control the rotational torque of the motor 501. The direction of torque of the motor 501 is controlled by a rotation direction control signal 517.

  As the rotation angle information of the motor 501, an MR sensor (magnetoresistive element) using a change in magnetic resistance is used and output as FGA (518) and FGB (519). FGA and FGB are amplified by amplification sections 502 and 503, respectively, and become signals 520 and 521 shown in FIG. 6, which are input to AD converters 507 and 508 inside the microprocessor 515 and converted to digital data 524 and 525, respectively.

  The digital data 524 and 525 are converted into the current rotation angle information by the rotation angle calculation unit 510 by the method of FIG. On the other hand, the FGA (520) and FGB (521) respectively supplied to the waveform shaping units 504 and 505 are waveform-shaped to form rectangular waves 522 and 523 shown in FIG.

  The rectangular waves 522 and 523 input to the external interrupt input are counted by detecting F / R (Forward / Reverse) by edge detection interrupt processing, and detecting the rising or falling edge of the pulse edge or both. The count data 527 is sent to the rotation angle calculation unit 511. The rotation angle calculation unit 511 adds a predetermined value (1 / 2π in the case of two-phase both-edge detection) to the count data for each pulse, converts it into rotation angle information, and sends it to the switch 512.

  The switch control unit 530 that outputs the control signal of the switch 512 is when the previous error value is a predetermined value or more (in this embodiment, the error amount corresponding to 2.5FG = 2.5π or more) or the FG cycle is shorter than the predetermined value. In this case (when the rotation speed is higher than the predetermined rotation speed: in this embodiment, the 1 / 2FG cycle is less than 6 ms), the signal 528 is selected, and the previous error value is less than the predetermined value (corresponding to 2.5FG in this embodiment). Error amount is less than 2.5π) and the FG cycle is longer than a predetermined value (when the rotation speed is lower than the predetermined rotation speed: in this embodiment, the 1/2 FG cycle is 6 ms or more), the signal 526 is selected. The switch control signal is output to.

  The rotation angle information 529 switched by the switch 512 is used by the error calculation unit 513 to calculate a difference from the rotation angle target value. The error calculation unit 513 performs gain and filtering on the difference signal thus obtained, and sends the feedback data 531 to the DA converter 514. At the same time, when the feedback data 531 is negative, the error calculation unit 513 is high. A low-level rotation direction control signal 517 is output and supplied to the driver 506. This is the description based on the block diagram (FIG. 1) of the motor rotation angle control device of the present invention. In practice, however, processing is performed by software inside the microprocessor 515.

  FIG. 3 is a flowchart of A / D conversion end interrupt processing. In this interrupt processing, processing other than the counting & F / R detection unit 509 in the block diagram of FIG. 1 is performed. A / D conversion is set in advance to be performed automatically at regular intervals, and this interrupt processing is performed after the A / D conversion is completed.

  When an A / D conversion (simply represented as A / D in FIG. 3) end interrupt (step S600) is entered, FGA and FGB A / D conversion data are acquired in step S601, and then Arctangent is calculated in step S602. . Next, if the previous error amount is smaller than the predetermined value and the FG cycle is longer than the predetermined value in step S603, an error is calculated from Arctangent in step S604. On the other hand, if the previous error amount is larger than the predetermined value or the FG cycle is shorter than the other predetermined value, an error is calculated from the count value (count) of FG in step S605. Note that FG is counted according to the flowchart shown in FIG.

  When the error is calculated, a gain for stabilizing the feedback control characteristic and the digital filter step S606 are applied. Finally, in order to convert the data into an analog voltage, a D / A conversion step S607 is performed to output the converted signal, and the process returns (RETN) in step S608.

  FIG. 4 is a flowchart of FGA edge interrupt processing. When the FGB edge is also used, processing equivalent to this FGA edge interrupt processing is required, but this time only FGA edge interrupt processing is counted.

  When an FGA edge is detected, FGA edge interrupt processing (step S700) is entered. First, in step S701, the FG cycle is calculated. Next, it is detected in step S702 whether the rotation is in the forward direction (Fwd) or the reverse direction (Rev). In the case of Fwd in step S703, the FG counter is incremented in step S704, and in the case of Rev, the FG counter is decremented in step S705. After step S704 or step S705 ends, the process returns (RETN) at step S706.

  With this configuration, when the rotation speed of the motor is fast, a method that emphasizes responsiveness that can detect the rotation angle information by detecting the edge of the MR signal and responds at high speed is adopted, and when the rotation speed of the motor is slow, the rotation angle The information uses the voltage value of the MR signal to ensure the accuracy of the rotation angle. Therefore, when it is far from the target rotation angle, it can approach the target rotation angle at high speed, and fine rotation angle control can be performed when it approaches the target rotation angle.

  As described above, according to the rotation angle detection device of the motor of the present invention, the rotation angle can be detected at high speed and with high accuracy, and according to the rotation angle control device of the motor of the present invention, the response Rotation angle control excellent in both the performance and the rotation angle accuracy becomes possible. The apparatus of the present invention has been described by taking the surveillance camera as shown in FIG. 2 as an example, but can be applied to other devices. That is, the present invention is useful when detecting the rotation angle of the motor or controlling the motor using the detected rotation angle.

It is a block diagram of an embodiment of a motor rotation angle control device of the present invention. While showing an example of the conventional surveillance dome shape camera, it is an external view of the surveillance dome shape camera explaining the usage example of embodiment of FIG. It is a flowchart which shows the operation | movement of embodiment of this invention of FIG. It is a flowchart which shows the operation | movement of embodiment of this invention of FIG. It is a block diagram for demonstrating the conventional method of detecting a rotation angle from a 2-phase encoder output. It is a wave form diagram for demonstrating the conventional method of detecting a rotation angle from a 2-phase encoder output, and is also a wave form diagram for a part of operation | movement description of embodiment of this invention of FIG. It is a wave form diagram for demonstrating the conventional method of detecting a rotation angle from a 2-phase encoder output, and is also a wave form diagram for a part of operation | movement description of embodiment of this invention of FIG.

Explanation of symbols

501 motor
502, 503 Amplifier
504, 505 Waveform shaping part
506 driver
507, 508 AD converter
509 Counting & F / R detector
510, 511 rotation angle calculator
512 switches
513 Error calculator
514 DA converter
515 Microprocessor
530 Switch control unit

Claims (2)

In a rotation angle detection device for a motor for detecting rotation angle information by detecting a sine wave signal and a cosine wave signal output from an encoder provided in the motor,
When the rotational speed of the motor is higher than a predetermined speed, the number of pulses is determined by detecting the rising or falling edge of the pulse shaped waveform of the sine wave signal or the cosine wave signal or both signals, or both edges. Means for detecting the rotation angle of the motor by counting;
Means for detecting a rotation angle of the motor based on voltage values of the sine wave signal and the cosine wave signal when the rotation speed of the motor is slower than the predetermined speed;
An apparatus for detecting a rotation angle of a motor, comprising: In a rotation angle control device for a motor that detects a sine wave signal and a cosine wave signal output from an encoder provided in a motor to obtain rotation angle information, and controls the rotation angle of the motor using the rotation angle information. ,
When the rotational speed of the motor is higher than a predetermined speed, the number of pulses is determined by detecting rising or falling edges or both edges of a pulse shaped waveform of the sine wave signal or the cosine wave signal or both signals. Means for detecting the rotation angle of the motor by counting;
Means for detecting a rotation angle of the motor based on voltage values of the sine wave signal and the cosine wave signal when the rotation speed of the motor is slower than the predetermined speed;
A rotation angle control device for a motor, comprising:

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