JP2018004627A - Position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and cost of the position detector and allow arithmetic processing of an absolute position using a low-speed arithmetic processing unit.SOLUTION: An arithmetic processing unit 30 operates the absolute position of a rotating shaft 14 when a position detector 10 is activated, based on first to third analog signals according to first to third rotational angles detected by first to third rotational angle detectors 24 to 28. Meanwhile, a current position counter 54 detects the current absolute position of the rotating shaft 14 when the rotating shaft 14 is rotated, by counting the number of pulses of clockwise pulses or counterclockwise pulses according to the first rotational angle detected by the first rotational angle detector 24 based on a total pulse number TP according to the absolute position of the rotational shaft 14 at the activation.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a position detection device that detects the absolute position of a rotating shaft based on the rotation angle of the rotating shaft and the rotation angle of the output shaft of the speed reducer when a speed reducer is connected to the rotating shaft of the rotating body. About.

  2. Description of the Related Art Conventionally, a position detection device that detects an absolute position of a rotating shaft of a rotating body is mounted on an electric actuator including a rotating body such as a motor. Such position detection devices are disclosed in, for example, Patent Documents 1 to 6.

  Patent Documents 1 to 3 disclose a multi-rotation angle detection type position detection device using a planetary gear as a speed reducer connected to a rotation shaft of a rotating body. Patent Documents 4 and 5 disclose a position detection device in which a code recording medium is attached to a rotating shaft of a rotating body and a multi-rotation angle detector is attached to an output shaft of a speed reducer connected to the rotating shaft. Patent Document 6 discloses a position detection device that converts detected rotation angle data of an axis of rotation into an absolute position after converting from orthogonal coordinates to polar coordinates.

JP 2013-164316 A JP 2012-145380 A JP 2007-78459 A JP-T-2002-513923 JP-A-64-23107 JP 2003-161641 A

  However, in the position detection devices of Patent Documents 1 to 3, a magnet is attached to the shafts of a plurality of driven gears, and a plurality of sets of rotation angle detectors are attached to opposite positions. There is a disadvantage that the size is increased.

  In the position detection devices of Patent Documents 4 and 5, the code recording medium attached to the rotating shaft is an absolute position disk on which a special code that can be scanned is carried by vapor deposition or the like. Therefore, high accuracy is required, and the position detection device becomes expensive.

  Furthermore, the position detection device of Patent Document 6 requires a high-speed arithmetic processing device in order to be able to output the absolute position in real time.

  The present invention has been made to solve the above-described problem, and provides a position detection device that is small in size and low in cost, and that can perform absolute position calculation processing using a low-speed calculation processing device. Objective.

  The present invention relates to a position detection device in which a speed reducer is connected to a rotating shaft of a rotating body, and an absolute position of the rotating shaft is detected based on a rotating angle of the rotating shaft and a rotating angle of an output shaft of the reducer. Is.

  And in order to achieve said objective, the position detection apparatus which concerns on this invention has the 1st-3rd rotation angle detector, the arithmetic processing part, and the present position detection part.

  The first rotation angle detector detects a first rotation angle between pitches of gears attached substantially coaxially to the rotation shaft. The second rotation angle detector detects a second rotation angle within one rotation of the rotation shaft. The third rotation angle detector detects a third rotation angle within one rotation of the output shaft according to multiple rotations of the rotation shaft.

  The arithmetic processing unit calculates an absolute position of the rotation shaft at the time of starting based on the first to third rotation angles detected by the first to third rotation angle detectors when the position detecting device is started. Calculate. The current position detection unit is based on the first rotation angle detected by the first rotation angle detector during rotation of the rotation shaft by driving the rotating body and the absolute position of the rotation shaft at the time of activation. Thus, the current absolute position of the rotating shaft is detected.

  According to this configuration, the gear, the speed reducer, and the output shaft are provided along the axial direction of the rotation shaft, and the first to third rotation angle detectors are disposed around the rotation shaft and the output shaft. Then, the radial size of the rotating shaft in the position detection device can be reduced.

  In addition, the first rotation angle detector is a code recording medium carrying a special code as disclosed in Patent Documents 4 and 5 in order to detect the first rotation angle between the pitches of the gears attached to the rotation shaft. Is no longer necessary. Therefore, the cost of the position detection device can be reduced.

  Furthermore, the calculation processing unit calculates the absolute position of the rotating shaft in a stopped state at the time of activation based on the first to third rotation angles only at the time of activation. As a result, the current position detection unit detects the current rotation angle from the first rotation angle detected by the first rotation angle detector based on the absolute position of the rotation shaft at the time of start-up while the rotation shaft is rotating. The absolute position of the rotating shaft can be obtained in a pseudo manner.

  That is, the position detecting device functions as an absolute rotary encoder only at the time of activation, and thereafter functions as an incremental rotary encoder. That is, at the time of starting, the absolute position of the rotating shaft in a stopped state is detected, and during the subsequent rotation of the rotating shaft, the first rotation angle corresponding to the amount of movement of the rotating shaft with respect to the absolute position at the time of starting. And the position of the first rotation angle with respect to the absolute position at the time of activation may be obtained as the current absolute position of the rotation axis. As a result, the calculation of the absolute position in real time is not required as in Patent Document 6, and a low-speed and low-cost arithmetic processing unit (CPU) can be used.

  Further, in the conventional incremental type rotary encoder, it is necessary to perform the magnetic pole detection operation and the origin return operation when the power is turned on and off. On the other hand, in the present invention, since the absolute position of the rotating shaft in the stopped state is detected at the time of starting, each operation described above is not necessary. As a result, if the position detection device is mounted on an electric actuator or the like, the tact time can be shortened.

  As described above, according to the present invention, it is possible to reduce the size and cost of the position detection device, and to perform the absolute position calculation processing using a low-speed calculation processing device.

  Here, it is preferable that the first to third rotation angle detectors are configured as follows.

  First, the first rotation angle detector has a phase shift of 90 ° between the spur gear made of a magnetic material attached substantially coaxially to the rotation shaft and the tooth tip of the spur gear as one cycle. Two first magnetic detection elements disposed opposite to the spur gear and a first bias magnet are provided. In this case, each of the first magnetic detection elements outputs a first analog signal corresponding to the first rotation angle and having a phase shifted by 90 ° from each other.

  Therefore, when the magnetic field generated in the region including the first magnetic detection elements by the first bias magnet is changed by the rotation of the spur gear, the first magnetic detection elements change the magnetic field. Each is output as one analog signal. Since each of the first analog signals is a signal corresponding to the first rotation angle, the arithmetic processing unit determines that the absolute position of the rotating shaft at the time of activation is based on the first analog signal or the like. It is possible to accurately determine the position of the tooth position of the gear. Moreover, since it is possible to use the commercially available spur gear, it is possible to realize further cost reduction of the position detection device as compared with Patent Documents 4 and 5.

  Next, the second rotation angle detector shifts the phase by 90 ° from each other when the ring-shaped second bias magnet attached substantially coaxially to the rotation shaft and one rotation of the rotation shaft are defined as one cycle. And two second magnetic detection elements disposed opposite to the second bias magnet. In this case, each of the second magnetic detection elements outputs a second analog signal corresponding to the second rotation angle and having a phase shifted by 90 ° from each other.

  Therefore, when the magnetic field generated in the region including each second magnetic detection element is changed by the rotation of the second bias magnet, each second magnetic detection element uses the change in the magnetic field as each second analog signal. Output each. Since each of the second analog signals is a signal corresponding to the second rotation angle, the arithmetic processing unit determines that the absolute position of the rotating shaft at the time of activation is based on the second analog signal or the like. It is possible to easily determine which angle within one rotation of the rotating shaft corresponds.

  Further, the third rotation angle detector has a ring-shaped third bias magnet attached substantially coaxially to the output shaft and a phase shifted by 90 ° from each other when one rotation of the output shaft is defined as one cycle. And two third magnetic detection elements arranged opposite to the third bias magnet. Accordingly, each of the third magnetic detection elements outputs a third analog signal corresponding to the third rotation angle and having a phase shifted by 90 ° from each other.

  Therefore, when the magnetic field generated in the region including each third magnetic detection element is changed by the rotation of the third bias magnet, each third magnetic detection element uses the change in the magnetic field as each third analog signal. Output each. In this case, since the speed reducer decelerates the rotational speed of the rotating body at a predetermined speed reduction ratio and rotates the output shaft, the arithmetic processing unit is based on each third analog signal, etc. It can be easily determined which angle in the multiple rotations of the rotating shaft the absolute position of the rotating shaft at the time of activation corresponds to.

  The position detection device may further include an interpolator that converts each first analog signal output from each first magnetic detection element into a two-phase first pulse signal. In this case, the calculation processing unit calculates the absolute position of the rotating shaft at the time of starting based on the first to third analog signals output from the first to third magnetic detection elements, respectively. A second pulse signal corresponding to the calculated absolute position is output.

  Thus, the current position detection unit is configured to detect the current absolute position of the rotation shaft based on each first pulse signal output from the interpolator and the second pulse signal output from the arithmetic processing unit. Can be easily detected. Further, the influence of the backlash of the speed reducer can be ignored regardless of whether the rotating shaft is rotated forward or backward.

  In this case, the arithmetic processing unit may transmit the second pulse signal to the current position detection unit as a serial signal having the number of pulses corresponding to the absolute position of the rotating shaft at the time of activation. As a result, a relatively low-speed arithmetic processing device is used as the arithmetic processing unit, and the serial signal is transmitted to the current position detecting unit by serial communication, thereby further reducing the cost of the position detecting device. .

  The position detecting device may further include a multiplying circuit that generates a multiplied pulse signal obtained by multiplying the first pulse signals and outputs the multiplied pulse signal to the current position detecting unit. In this case, the current position detection unit presets the number of pulses according to the serial signal at the time of activation, and counts the number of pulses according to the multiplied pulse signal from the preset number of pulses during rotation of the rotating shaft. Thus, any current position counter that detects the current absolute position of the rotating shaft may be used.

  In this way, the current position counter counts the number of pulses corresponding to the multiplied pulse signal based on the preset number of pulses, so that the current absolute position of the rotating shaft can be easily and efficiently obtained. it can. Further, by supplying the multiplied pulse signal from the multiplication circuit to the current position counter, the resolution of the current absolute position of the rotating shaft in the current position counter is improved, and the absolute position can be obtained with high accuracy. it can.

  In this case, the multiplication circuit may determine the normal rotation or reverse rotation of the rotation shaft by comparing the first pulse signals, and generate the determined normal rotation or reverse rotation pulse signal. Thus, the current position counter can accurately obtain the current absolute position of the rotating shaft.

  The position detecting device further includes a rotating body drive control unit that drives the rotating body to rotate the rotating shaft when the number of pulses corresponding to the serial signal is preset in the current position counter. Also good. As a result, the rotating body can be operated after presetting, and the absolute position of the rotating shaft during the rotation of the rotating shaft can be reliably acquired.

  Further, the position detection device according to the present invention can be changed to the following configuration instead of the above configuration (hereinafter also referred to as a basic configuration).

  That is, in order to achieve the above object, the position detection device according to the present invention includes, as another first configuration, a first rotation angle detector, a second rotation angle detector, an arithmetic processing unit, and a current position detection unit. Have.

  The first rotation angle detector detects a first rotation angle within one rotation of the rotation shaft. The second rotation angle detector detects a second rotation angle within one rotation of the output shaft according to multiple rotations of the rotation shaft. The arithmetic processing unit is configured to start the position detection device based on the first rotation angle and the second rotation angle detected by the first rotation angle detector and the second rotation angle detector, respectively. The absolute position of the rotating shaft at the time is calculated. The current position detection unit is based on the first rotation angle detected by the first rotation angle detector during rotation of the rotation shaft by driving the rotating body and the absolute position of the rotation shaft at the time of activation. Thus, the current absolute position of the rotating shaft is detected.

  In this case, the first rotation angle detector includes a columnar bias magnet attached substantially coaxially to the rotation shaft, and a magnetic detection element arranged to face the bias magnet. The magnetic detection element outputs a serial signal corresponding to the first rotation angle to the arithmetic processing unit, and on the other hand, a two-phase pulse signal corresponding to the first rotation angle and having a phase shifted by 90 ° from each other. Output to the current position detector.

  In the first configuration, the magnetic detection element has the function of outputting the serial signal to the arithmetic processing unit and the function of interpolator processing of outputting the two-phase pulse signal to the current position detection unit. Yes. Further, the arithmetic processing unit calculates an absolute position of the rotating shaft at the start-up based on the serial signal and the second rotation angle detected by the second rotation angle detector. Therefore, according to the first configuration, the number of parts of the position detection device is reduced, and the calculation load on the calculation processing unit is reduced. Therefore, the cost of the position detection device can be reduced. . Further, by adopting the cylindrical bias magnet, it is possible to improve the detection accuracy of the first rotation angle.

  Also in the first configuration, the following effects can be obtained as in the case of the position detection device having the basic configuration described above.

  That is, the speed reducer and the output shaft are provided along the axial direction of the rotation shaft, and the first rotation angle detector and the second rotation angle detector are disposed around the rotation shaft and the output shaft. Thus, the radial size of the rotating shaft can be reduced.

  In addition, the calculation processing unit calculates the absolute position of the rotating shaft in a stopped state at the time of activation based on the first rotation angle and the second rotation angle only at the time of activation. As a result, the current position detection unit simulates the current absolute position of the rotating shaft from the two-phase pulse signal based on the absolute position of the rotating shaft at the time of start-up while the rotating shaft is rotating. And it can obtain | require easily. Further, the influence of the backlash of the speed reducer can be ignored regardless of whether the rotating shaft is rotated forward or backward.

  That is, the position detecting device functions as an absolute rotary encoder only at the time of activation, and thereafter functions as an incremental rotary encoder. Thereby, the calculation of the absolute position in real time is unnecessary, and a low-speed and low-cost CPU can be used. If such a position detection device is mounted on an electric actuator or the like, the tact time can be shortened.

  Therefore, also in the first configuration, the position detection device can be reduced in size and cost, and the absolute position calculation processing can be performed using a low-speed calculation processing device.

  The position detection device further includes a rotation transmission mechanism that transmits the rotational force of the rotation shaft to the input shaft of the speed reducer, and the rotation shaft, the input shaft, and the output shaft are arranged substantially coaxially. It only has to be. By the rotation transmission mechanism, the position detection device becomes slightly larger in the radial direction, but by providing the first rotation angle detector having an interpolator function, the number of parts of the position detection device is reduced. Overall cost reduction can be realized. As the rotation transmission mechanism, for example, various rotation transmission mechanisms such as other speed reducers having a reduction ratio of 1 and rotation transmission means using a belt can be suitably employed.

  Furthermore, in order to achieve the above object, the position detection device according to the present invention includes, as another second configuration, first to third rotation angle detectors, a first reducer, a second reducer, and an arithmetic processing unit. And a current position detector.

  The first rotation angle detector detects a first rotation angle within one rotation of the rotation shaft. The first speed reducer decelerates and outputs the rotational speed of the rotating shaft. The second speed reducer has an input shaft connected to the first speed reducer, further reduces the rotational speed of the rotary shaft decelerated by the first speed reducer, and outputs it to the output shaft. The second rotation angle detector detects a second rotation angle within one rotation of the input shaft according to multiple rotations of the rotation shaft. The third rotation angle detector detects a third rotation angle within one rotation of the output shaft according to multiple rotations of the rotation shaft.

  The arithmetic processing unit calculates an absolute position of the rotation shaft at the time of starting based on the first to third rotation angles detected by the first to third rotation angle detectors when the position detecting device is started. Calculate. The current position detection unit is based on the first rotation angle detected by the first rotation angle detector during rotation of the rotation shaft by driving the rotating body and the absolute position of the rotation shaft at the time of activation. Thus, the current absolute position of the rotating shaft is detected.

  In this case, the first rotation angle detector includes a columnar bias magnet attached substantially coaxially to the rotation shaft, and a magnetic detection element arranged to face the bias magnet. The magnetic detection element outputs a serial signal corresponding to the first rotation angle to the arithmetic processing unit, and on the other hand, a two-phase pulse corresponding to the first rotation angle and having a phase shifted by 90 ° from each other. A signal is output to the current position detector.

  In this 2nd structure, compared with the position detection apparatus provided with the above-mentioned 1st rotation angle detector and 2nd rotation angle detector, it is three rotation angle detectors (1st-3rd rotation angle detector). And two speed reducers (first speed reducer and second speed reducer). Therefore, as compared with the first configuration, the number of parts is increased, and the calculation load in the calculation processing unit is increased, so that the cost is increased.

  However, the second rotation angle detector and the third rotation angle detector respectively detect the second rotation angle and the third rotation angle corresponding to multiple rotations of the rotation shaft, and the detected second rotation. Using the angle, the third rotation angle, and the like, the calculation processing unit can calculate the absolute position of the rotation shaft at the time of starting with high accuracy. As a result, the absolute position can be calculated with high accuracy and cost can be reduced as compared with the conventional position detecting device. Further, by adopting the cylindrical bias magnet, it is possible to improve the detection accuracy of the first rotation angle.

  Also in the second configuration, by providing the first to third rotation angle detectors, the same effect as the position detection device having the basic configuration described above can be obtained.

  According to the present invention, it is possible to reduce the size and cost of the position detection device, and to perform an absolute position calculation process using a low-speed calculation processing device.

It is a block diagram of the position detection apparatus which concerns on this embodiment. It is a schematic block diagram of the rotation angle detection mechanism of FIG. It is explanatory drawing of the 1st rotation angle detector of FIG.1 and FIG.2. 4A is a waveform diagram of an output voltage waveform output from the first magnetic detection element, and FIG. 4B is a waveform diagram of a two-phase first pulse signal converted from the output voltage waveform by an interpolator. FIG. 5A is a waveform diagram of output voltage waveforms output from the second and third magnetic detection elements, and FIG. 5B is a diagram illustrating a phase change within one rotation. It is a wave form diagram of a 1st pulse signal and a normal rotation pulse. It is a waveform diagram of a first pulse signal and a reverse pulse. It is a sequence diagram for demonstrating operation | movement of the position detection apparatus of FIG. It is a sequence diagram for demonstrating operation | movement of the position detection apparatus of FIG. It is a block diagram of the position detection apparatus concerning the 1st modification. It is a schematic block diagram of the rotation angle detection mechanism of FIG. FIG. 12A is a waveform diagram of a two-phase first pulse signal output from the magnetic detection element, and FIG. 12B is a waveform diagram of a serial signal output from the magnetic detection element. It is a block diagram of the position detection apparatus concerning the 2nd modification. It is a schematic block diagram of the rotation angle detection mechanism of FIG.

  A preferred embodiment of a position detection device according to the present invention will be described below in detail with reference to the drawings.

[Configuration of this embodiment]
FIG. 1 is a block diagram of a position detection apparatus 10 according to the present embodiment.

  The position detection device 10 includes a rotation angle detection mechanism 16 that detects the rotation angle of the rotation shaft 14 of the rotating body 12 such as a motor, and a controller 18 that drives and controls the rotating body 12.

  A reduction gear 20 is connected to the rotary shaft 14. The speed reducer 20 reduces the rotational speed of the rotary shaft 14 to 1 / N and rotates the output shaft 22. N is a reduction ratio of the speed reducer 20.

  The rotation angle detection mechanism 16 includes first to third rotation angle detectors 24 to 28, an arithmetic processing unit 30, and an interpolator 32.

  As shown in FIGS. 1 to 3, the first rotation angle detector 24 includes a spur gear 34 attached substantially coaxially to the rotating shaft 14, and two first magnetic detection elements disposed opposite to the spur gear 34. The spur gear angle detector includes 36a and 36b and a first bias magnet 38 disposed behind each first magnetic detection element 36a and 36b (outside in the radial direction of the spur gear 34).

  As the spur gear 34, a commercially available spur gear that can be attached to the rotating shaft 14 can be used. The two first magnetic detection elements 36a and 36b are magnetoresistive elements. When the interval between the tooth tips of the spur gear 34 (between the pitches) is one cycle (360 °), the phase in the circumferential direction of the spur gear 34 is increased. Are opposed to the spur gear 34 in a state of being shifted from each other by 90 °. The first bias magnet 38 is disposed behind the first magnetic detection elements 36a and 36b in a state where the N pole is radially inward of the spur gear 34 and the S pole is radially outward.

  In the first rotation angle detector 24, when the magnetic field is generated in the region including the first magnetic detection elements 36 a and 36 b by the first bias magnet 38, the magnetic force is increased along with the rotation operation of the rotary shaft 14. When the spur gear 34 as a body rotates, the magnetic field changes. Each of the first magnetic detection elements 36a and 36b detects the change in the magnetic field as a change in voltage, and outputs the detected voltage as a first analog signal.

  FIG. 4A is a waveform diagram of the first analog signal (output voltage waveform) output from the first magnetic detection elements 36a and 36b. In FIG. 4A, the A phase indicates a first analog signal (sine wave signal) output from one first magnetic detection element 36a, and the B phase indicates a first analog signal output from the other first magnetic detection element 36b. Indicates an analog signal (cosine wave signal). In FIG. 4A, it should be noted that the horizontal axis represents the rotation angle of the spur gear 34 corresponding to a change with time.

  As described above, since the two first magnetic detection elements 36a and 36b are arranged with a 90 ° phase shift, a phase difference of 90 ° is generated between the A phase and the B phase. Further, in the A phase and the B phase, a rotation angle of 360 ° corresponds to one cycle between the tooth tips of the spur gear 34. That is, one cycle corresponds to an electrical angle of 360 °. Therefore, the first rotation angle detector 24 detects an arbitrary position (first rotation angle) of the spur gear 34 in one cycle when the interval between the tooth tips of the spur gear 34 is one cycle, and the first analog The signal is output to the arithmetic processor 30 and the interpolator 32 as a signal.

  The interpolator 32 is an analog voltage comparison type phase interpolation circuit using a resistor network, and the first analog signal shown in FIG. 4A is interpolated by a predetermined division number S to obtain a 90 ° position shown in FIG. 4B. The signal is converted into a two-phase first pulse signal having a phase difference and output to the controller 18. Note that the transmission of the two-phase first pulse signal from the interpolator 32 to the controller 18 is faster than the transmission of the second pulse signal by serial communication from the arithmetic processing unit 30 to the controller 18 described later.

  As shown in FIGS. 1 and 2, the second rotation angle detector 26 includes a ring-shaped second bias magnet 40 attached substantially coaxially to the rotation shaft 14, and 2 arranged opposite to the second bias magnet 40. It is a 1 rotation angle detector comprised from the piece of 2nd magnetic detection element 42a, 42b.

  The second bias magnet 40 is attached to a location between the spur gear 34 and the speed reducer 20 on the rotating shaft 14. In this case, in the ring-shaped second bias magnet 40, one semicircular portion is assigned to the N pole and the other semicircular portion is assigned to the S pole. The two second magnetic detection elements 42a and 42b are Hall elements. When one rotation of the rotating shaft 14 and the second bias magnet 40 is one cycle (360 °), the rotating shaft 14 and the second bias magnet 40 are used. Are arranged opposite to the second bias magnet 40 with their phases shifted by 90 ° from each other.

  In the second rotation angle detector 26, when the magnetic field is generated in the region including the second magnetic detection elements 42 a and 42 b by the second bias magnet 40, When the two-bias magnet 40 rotates, the magnetic field changes. Each of the second magnetic detection elements 42a and 42b detects the change in the magnetic field as a change in voltage, and outputs the detected voltage as a second analog signal.

  FIG. 5A is a waveform diagram of a second analog signal output from the second magnetic detection elements 42a and 42b. In FIG. 5A, “A” indicates a second analog signal (cosine wave signal) output from one second magnetic detection element 42a, and “B” is output from the other second magnetic detection element 42b. A 2nd analog signal (sine wave signal) is shown. In FIG. 5A, the horizontal axis is the rotation angle of the rotation shaft 14 and the second bias magnet 40 according to the time change.

  FIG. 5B shows a change in the rotation angle within one rotation of the rotating shaft 14 and the second bias magnet 40. Here, a counterclockwise rotation with respect to 0 ° (when the phase of B is delayed with respect to the phase of A) is rotated forward, and a clockwise rotation (the phase of A is delayed with respect to the phase of B). Defined as reverse).

  As described above, since the two second magnetic detection elements 42a and 42b are arranged with a 90 ° phase shift, there is a 90 ° phase difference between A and B. In A and B, 360 ° corresponds to one cycle of the rotating shaft 14 and the second bias magnet 40. That is, one cycle corresponds to an electrical angle of 360 °. Accordingly, the second rotation angle detector 26 assumes that the rotation shaft 14 and the second bias magnet 40 are in any one position (first position) when one rotation of the rotation shaft 14 and the second bias magnet 40 is one cycle. 2 rotation angles) is detected and output to the arithmetic processing unit 30 as a second analog signal.

  As shown in FIGS. 1 and 2, the third rotation angle detector 28 includes a ring-shaped third bias magnet 44 attached substantially coaxially to the output shaft 22, and 2 arranged opposite to the third bias magnet 44. This is a multi-rotation angle detector composed of the third magnetic detection elements 46c and 46d. In the ring-shaped third bias magnet 44, one semicircular portion is assigned to the N pole, and the other semicircular portion is assigned to the S pole. The two third magnetic detection elements 46c and 46d are Hall elements, and when one rotation of the output shaft 22 is set to one cycle (360 °), the phase is formed in the circumferential direction of the output shaft 22 and the third bias magnet 44. Are opposed to the third bias magnet 44 in a state where they are shifted from each other by 90 °.

  In the third rotation angle detector 28, when the magnetic field is generated in the region including the third magnetic detection elements 46 c and 46 d by the third bias magnet 44, When the three-bias magnet 44 rotates, the magnetic field changes. Each of the third magnetic detection elements 46c and 46d detects this change in magnetic field as a change in voltage, and outputs the detected voltage as a third analog signal.

  Accordingly, the waveform of the third analog signal output from the third magnetic detection elements 46c and 46d is the same as that of the second analog signal, as shown in FIG. 5A. In FIG. 5A, “C” indicates a third analog signal (cosine wave signal) output from one third magnetic detection element 46c, and “D” indicates an output from the other third magnetic detection element 46d. The 3rd analog signal (sine wave signal) to be performed is shown. Further, since the two third magnetic detection elements 46c and 46d are arranged with the phase shifted by 90 °, a phase difference of 90 ° is generated between C and D. Further, in C and D, an electrical angle of 360 ° corresponds to one cycle of the output shaft 22 and the third bias magnet 44.

  However, the speed reducer 20 reduces the rotational speed of the rotary shaft 14 to 1 / N and rotates the output shaft 22. Therefore, the third rotation angle detector 28 has the output shaft 22 and the third bias magnet 44 corresponding to the multi-rotation rotation shaft 14 when one rotation of the output shaft 22 and the third bias magnet 44 is one cycle. An arbitrary position (third rotation angle) is detected and output to the arithmetic processing unit 30 as a third analog signal. Therefore, the maximum amount of rotation of the rotating shaft 14 corresponds to within one rotation of the output shaft 22.

  The arithmetic processing unit 30 is composed of a comparatively low speed and small arithmetic processing unit (CPU). When the position detection device 10 is activated, the arithmetic processing unit 30 is based on the first to third analog signals from the first to third rotation angle detectors 24 to 28, and the absolute value of the rotating shaft 14 in the stopped state at the time of activation. Calculate the position. When the absolute position transfer request is received from the controller 18, the arithmetic processing unit 30 transfers a serial signal corresponding to the absolute position to the controller 18 by serial communication.

  Here, the processing of the arithmetic processing unit 30 will be specifically described. First, the arithmetic processing unit 30 converts the output voltages of the first to third analog signals from orthogonal coordinates to polar coordinates.

  In this case, for the first analog signal, the interval between the tooth tips of the spur gear 34 is one cycle (360 °), and one cycle is divided into S pieces. For the second analog signal, one rotation of the rotating shaft 14 and the second bias magnet 40 is one cycle (360 °), and one cycle is divided into T pieces. For the third analog signal, one rotation of the output shaft 22 is defined as one cycle (360 °), and one cycle is divided into N. Further, the maximum rotation amount of the rotary shaft 14 is made to correspond within one cycle of the output shaft 22. In addition, what is necessary is just to apply the well-known interpolation method currently disclosed by patent document 4, for the conversion process (division | segmentation process) from a rectangular coordinate to a polar coordinate, for example.

Here, the position of the spur gear 34 is P1 (first rotation angle), the number of divisions in the spur gear 34 is S, the position of the second bias magnet 40 is P2 (second rotation angle), and the second bias magnet 40 When the number of divisions is T, the position of the third bias magnet 44 is P3 (third rotation angle), and the number of divisions in the third bias magnet 44 is N, the rotation amount TA of the rotating shaft 14 is as follows (1) It can be expressed by an expression.
TA = (P1 ÷ T) + INT (P2 × T ÷ 360)
× (360 ÷ T) + (P3 × N) (1)

  Note that INT (P2 × T ÷ 360) means that the calculation result of P2 × T ÷ 360 is rounded down to a whole number. The division number T is the number T of teeth of the spur gear 34, and the division number N is the reduction ratio N.

When the absolute position is transferred from the arithmetic processing unit 30 to the controller 18 by serial communication, if the number of pulses when the rotation shaft 14 is rotated once is PP, the number of pulses corresponding to the rotation amount TA (total number of pulses) ) TP is represented by the following equation (2).
TP = TA ÷ (360 ÷ PP) (2)

Therefore, when the calculation result of the total pulse number TP is rounded down to an integer, the following equation (3) is obtained.
TP = INT (TA × PP ÷ 360) (3)
The arithmetic processing unit 30 calculates the total pulse number TP according to the absolute position of the rotating shaft 14 in the stopped state at the time of start using the equations (1) and (3), and according to the calculated total pulse number TP. The serial signal (second pulse signal) is transferred to the controller 18.

  Here, for example, when T = 25, N = 150, P1 = 55 °, P2 = 175 °, P3 = 156 °, PP = 200, S = 8, TA = 23575 ° and TP = 13097.

  The controller 18 includes a serial communication unit 50, a multiplication circuit 52, a current position counter (current position detection unit) 54, and a rotating body drive control unit 56.

  The serial communication unit 50 performs serial communication with the arithmetic processing unit 30. For example, a transfer request for the total number of pulses TP is transmitted to the arithmetic processing unit 30, and a serial signal corresponding to the transfer request (second pulse signal with the total number of pulses TP) is received.

  The multiplication circuit 52 multiplies the first pulse signal received from the interpolator 32 and outputs the first pulse signal after multiplication (multiplication pulse signal) to the current position counter 54. In this case, as shown in FIG. 6 and FIG. 7, the multiplication circuit 52 examines the voltage level of the B phase at the time of rising of the A phase, for example, so as to ) Forward rotation or reverse rotation is determined, and the determined forward or reverse multiplied pulse signal is generated.

  In the case of FIG. 6, since the voltage level of the B phase is low (L level) when the A phase rises, the multiplication circuit 52 determines that the two-phase first pulse signal is normal rotation, A quadruple multiplied pulse signal (forward pulse signal) is generated. In the case of FIG. 7, since the voltage level of the B phase is high (H level) when the A phase rises, the multiplication circuit 52 determines that the two-phase first pulse signal is reverse, and quadruples by reverse rotation. A multiplied pulse signal (reverse pulse signal) is generated.

  FIGS. 6 and 7 are examples, and the multiplying circuit 52 is configured to multiply the double-phase first pulse signal by 1 (× 1), 2 (× 2), or 4 (× 4) multiplied pulse signals. Can be generated. Further, the multiplication circuit 52 can change the high-frequency multiplication pulse signal to the low-frequency multiplication pulse signal and output it (4 multiplication → 2 multiplication → 1 multiplication).

  The current position counter 54 presets the total pulse number TP acquired by the serial communication unit 50 when the position detection device 10 is activated. Further, the current position counter 54 receives a multiplied pulse signal from the multiplication circuit 52 while the rotary shaft 14 is rotating. Therefore, the current position counter 54 detects the current absolute position of the rotating shaft 14 in a pseudo manner by counting the number of pulses corresponding to the multiplied pulse signal with the preset total number of pulses TP as a reference.

  When the total pulse number TP is preset in the current position counter 54, the rotating body drive control unit 56 drives the rotating body 12 to rotate the rotating shaft 14 by supplying a rotating body operation signal to the rotating body 12. .

[Operation of this embodiment]
Next, the operation of the position detection apparatus 10 according to the present embodiment will be described with reference to the sequence diagrams of FIGS. In the description of the operation, the description will be given with reference to FIGS.

  First, in step S <b> 1, the worker turns on the controller 18 of the position detection device 10. Thereby, in step S <b> 2, the controller 18 starts power supply to the rotation angle detection mechanism 16. As a result, in step S <b> 3, the rotation angle detection mechanism 16 is activated upon receiving power supply from the controller 18. In this case, the rotation angle detection mechanism 16 activates only the first to third rotation angle detectors 24 to 28 and the arithmetic processing unit 30.

  In the next step S4, the first to third rotation angle detectors 24 to 28 detect the first to third rotation angles at the present time (when the position detection device 10 is activated), and set the first to third rotation angles. The corresponding first to third analog signals are output to the arithmetic processing unit 30.

  In the next step S5, the arithmetic processing unit 30 determines the stop state at the time of starting the position detecting device 10 from the above formulas (1) and (3) based on the input first to third analog signals. A total pulse number TP corresponding to the absolute position of the rotating shaft 14 is calculated. In step S6, the arithmetic processing unit 30 converts the total pulse number TP into a serial signal (second pulse signal).

  In the next step S <b> 7, the arithmetic processing unit 30 confirms whether or not there is a serial signal transfer request from the controller 18. If there is no transfer request, the process returns to step S4, and the processes of steps S4 to S7 are executed again. Accordingly, the rotation angle detection mechanism 16 sequentially executes the absolute position detection process of the rotating shaft 14 in a stopped state until receiving a transfer request notification from the controller 18.

  On the other hand, when the serial communication unit 50 of the controller 18 requests the arithmetic processing unit 30 to transfer a serial signal in step S8, the arithmetic processing unit 30 receives a transfer request notification (step S7: YES). Transmission of a serial signal to the serial communication unit 50 is started (step S9). The arithmetic processing unit 30 continues the serial signal transmission process until the serial communication unit 50 receives a notification of completion of serial signal reception (step S9, step S10: NO).

  When the serial communication unit 50 starts receiving the serial signal, the serial communication unit 50 determines whether or not the reception of the serial signal is completed in step S11. If the reception of the serial signal is not completed (step S11: NO), step S8 is executed again, and a serial signal transfer request is sent to the arithmetic processing unit 30.

  On the other hand, when the reception of the serial signal is completed (step S11: YES), the serial communication unit 50 outputs the serial signal to the current position counter 54. In step S12, the current position counter 54 converts the input serial signal into the input serial signal. Preset the total number of pulses TP.

  In step S <b> 13, when the serial communication unit 50 confirms the preset of the total pulse number TP, the serial communication unit 50 transmits a reception completion notification to the arithmetic processing unit 30. When receiving the reception completion notification, the arithmetic processing unit 30 determines that the transmission of the serial signal is completed (step S10: YES), and shifts to an operation mode in which the rotating body 12 is driven to rotate (step S14 in FIG. 9). In the operation mode, the rotation angle detection mechanism 16 operates only the first rotation angle detector 24 and the interpolator 32.

  In step S15, when the rotary body drive control unit 56 confirms the preset of the total number of pulses TP, the rotary body drive signal is supplied to the rotary body 12 to rotate the rotary body 12. The rotating body 12 is driven based on the supply of the rotating body operation signal to rotate the rotating shaft 14 (step S16).

  In step S <b> 17, the first magnetic detection elements 36 a and 36 b of the first rotation angle detector 24 output a first analog signal corresponding to the first rotation angle of the rotating rotating shaft 14 to the interpolator 32. The first rotation angle is a rotation angle indicating the movement amount (rotation amount) of the rotation shaft 14 with respect to the absolute position of the rotation shaft 14 in a stopped state, and each first analog signal is an analog corresponding to the movement amount. Signal. The interpolator 32 converts each first analog signal into a two-phase first pulse signal, and outputs the converted first pulse signal to the multiplication circuit 52 of the controller 18.

  In the next step S18, the rotation angle detection mechanism 16 determines whether or not the power supply from the controller 18 is stopped. When the power supply is not stopped (step S18: NO), the processes of steps S16 to S18 are executed again. That is, the rotation angle detection mechanism 16 repeatedly performs the first rotation angle detection operation and the two-phase first pulse signal output operation until the power supply from the controller 18 is stopped (step S18: YES). To do.

  On the other hand, when each first pulse signal is input to the multiplier circuit 52 in step S19, the multiplier circuit 52 compares the two-phase first pulse signals so that the two-phase first pulse signals are forward or reverse. It is determined which is. The multiplication circuit 52 generates a forward multiplied pulse signal (forward rotation pulse) or a reverse multiplied pulse signal (reverse rotation pulse) obtained by multiplying the first pulse signal based on the determination result, and the generated forward rotation pulse or reverse rotation. The pulse is output to the current position counter 54.

  The current position counter 54 counts the number of forward or reverse pulses from the total pulse number TP with reference to the preset total pulse number TP. That is, the current position counter 54 corresponds to the rotation angle (movement amount, rotation amount) of the rotating rotating shaft 14 with the absolute position of the rotating shaft 14 in the stopped state at the time of starting according to the total number of pulses TP as the origin. The absolute position is detected in a pseudo manner.

  In the next step S20, the controller 18 checks whether or not the controller 18 is powered off. If the power is not turned off (step S20: NO), the controller 18 executes the processes of steps S15, S19, and S20 again. That is, in the position detection device 10, the absolute position detection process of the rotating shaft 14 is sequentially executed until the controller 18 is turned off.

  In step S20, when the operator turns off the controller 18 (step S20: YES), each part in the controller 18 is stopped (step S21), and power supply to the rotation angle detection mechanism 16 is also stopped (step S21). S18: YES). As a result, each part in the rotation angle detection mechanism 16 is also stopped (step S22).

[Effect of this embodiment]
As described above, according to the position detection device 10 according to the present embodiment, the spur gear 34, the speed reducer 20, and the output shaft 22 are provided along the axial direction of the rotary shaft 14. By arranging the first to third rotation angle detectors 24 to 28 around the periphery, the radial size of the rotation shaft 14 in the position detection device 10 can be reduced.

  In addition, the first rotation angle detector 24 detects a first rotation angle between the pitches of the spur gears 34 attached to the rotation shaft 14, and thus a code recording medium carrying a special code as in Patent Documents 4 and 5. Is no longer necessary. Therefore, the cost of the position detection device 10 can be reduced.

  Furthermore, the arithmetic processing unit 30 calculates the absolute position of the rotating shaft 14 in the stopped state at the time of activation based on the first to third rotation angles only when the position detection device 10 is activated. As a result, the current position counter 54 determines the current position counter 54 from the first rotation angle detected by the first rotation angle detector 24 based on the absolute position of the rotating shaft 14 in the stopped state at the time of starting while the rotating shaft 14 is rotating. The absolute position of the rotating shaft 14 can be obtained in a pseudo manner.

  That is, the position detection device 10 functions as an absolute rotary encoder only at the time of activation, and thereafter functions as an incremental rotary encoder. That is, the position detection device 10 detects the absolute position of the rotating shaft 14 in a stopped state at the time of activation, and during the subsequent rotation of the rotating shaft 14, the movement amount (rotation amount) of the rotation shaft 14 with respect to the absolute position at the time of activation. Is detected, and the position of the first rotation angle with respect to the absolute position at the time of activation is obtained as the current absolute position of the rotary shaft 14. As a result, it is not necessary to calculate the absolute position in real time as in Patent Document 6, and a low-speed and low-price arithmetic processing unit (CPU) can be used as the arithmetic processing unit 30.

  Further, in the conventional incremental type rotary encoder, it is necessary to perform the magnetic pole detection operation and the origin return operation when the power is turned on and off. On the other hand, since the position detection device 10 can detect the absolute position of the rotating shaft 14 at the time of activation, these operations are unnecessary. As a result, if the position detecting device 10 is mounted on an electric actuator or the like, the tact time can be shortened.

  As described above, according to the position detection device 10 according to the present embodiment, the position detection device 10 can be reduced in size and cost, and an absolute position calculation process can be performed using a low-speed calculation processing device. It becomes possible.

  Further, in the first rotation angle detector 24, when the magnetic field generated in the region including the first magnetic detection elements 36a and 36b by the first bias magnet 38 is changed by the rotation of the spur gear 34, the first magnetic detection elements. 36a and 36b each output the change of a magnetic field as each 1st analog signal. Since each first analog signal is a signal corresponding to the first rotation angle, the arithmetic processing unit 30 determines that the absolute position of the rotating shaft 14 at the time of activation is that of the spur gear 34 based on each first analog signal or the like. It is possible to accurately determine which tooth position corresponds to the tooth position. In addition, since a commercially available spur gear 34 can be used, the cost of the position detection device 10 can be further reduced as compared with Patent Documents 4 and 5.

  Further, in the second rotation angle detector 26, when the magnetic field generated in the region including the second magnetic detection elements 42a and 42b is changed by the rotation of the second bias magnet 40, the second magnetic detection elements 42a and 42b are The change in the magnetic field is output as each second analog signal. Since each second analog signal is a signal corresponding to the second rotation angle, the arithmetic processing unit 30 determines that the absolute position of the rotating shaft 14 at the time of activation is based on each second analog signal and the like. It is possible to easily determine which angle within one rotation corresponds to.

  In the third rotation angle detector 28, when the magnetic field generated in the region including the third magnetic detection elements 46c and 46d is changed by the rotation of the third bias magnet 44, the third magnetic detection elements 46c and 46d are The change in the magnetic field is output as each third analog signal. In this case, the speed reducer 20 decelerates the rotational speed of the rotating body 12 by a predetermined reduction ratio N and rotates the output shaft 22, so that the arithmetic processing unit 30 is based on each third analog signal, etc. It can be easily determined which angle in the multi-rotation of the rotating shaft 14 corresponds to the absolute position of the rotating shaft 14 at the time of activation.

  Since the rotary shaft 14 passes through the second bias magnet 40 and the output shaft 22 passes through the third bias magnet 44, the second rotation in the second rotation angle detector 26 and the third rotation angle detector 28 is performed. There is a possibility that the detection accuracy of the angle and the third rotation angle is lowered. However, in the position detection device 10, the first rotation angle detector 24 uses the spur gear 34 to detect the first rotation angle with high accuracy. As a result, the decrease in the detection accuracy of the second rotation angle and the third rotation angle is compensated by the detection accuracy of the first rotation angle, so that the influence on the calculation processing of the absolute position in the calculation processing unit 30 can be suppressed. it can.

  In addition, the interpolator 32 converts each first analog signal into a two-phase first pulse signal, and the arithmetic processing unit 30 determines the absolute position of the rotating shaft 14 at the time of activation based on each first to third analog signal. The second pulse signal corresponding to the calculated absolute position is output. As a result, the current position counter 54 easily determines the absolute position of the current rotating shaft 14 based on each first pulse signal output from the interpolator 32 and the second pulse signal output from the arithmetic processing unit 30. It becomes possible to detect. Further, the influence of the backlash of the speed reducer 20 can be ignored regardless of whether the rotating shaft 14 is rotating forward or backward.

  The backlash of the speed reducer 20 is preferably within 360 ° / (2 × N). Further, as described above, the backlash can be corrected by software processing using the interpolator 32, the current position counter 54, and the like. In the present embodiment, by providing a mechanism such as a spring that applies torque to the output shaft 22 of the speed reducer 20 in a certain direction, correction processing by software can be made unnecessary.

  In the position detection device 10, the arithmetic processing unit 30 converts the second pulse signal as a serial signal having a total number of pulses TP corresponding to the absolute position of the rotating shaft 14 at the time of activation via the serial communication unit 50. 54, the cost of the position detection device 10 can be further reduced.

  Further, the current position counter 54 presets the total number of pulses TP when the position detection device 10 is activated. Further, during the rotation of the rotating shaft 14, the multiplication circuit 52 generates a multiplied pulse signal based on the first pulse signal. The current position counter 54 detects the current absolute position of the rotating shaft 14 by counting the number of pulses corresponding to the multiplied pulse signal with the preset total number of pulses TP as a reference. As a result, the current absolute position of the rotating shaft 14 can be obtained easily and efficiently. Further, by supplying a multiplied pulse signal from the multiplication circuit 52 to the current position counter 54, the resolution of the absolute position of the current rotating shaft 14 in the current position counter 54 is improved, and the absolute position can be obtained with high accuracy. .

  Further, the multiplication circuit 52 compares the two-phase first pulse signals to determine the normal rotation or reverse rotation of the rotating shaft 14 and generates the determined normal rotation or reverse rotation pulse signal. Can accurately determine the absolute position of the current rotating shaft 14.

  Further, when the total pulse number TP is preset in the current position counter 54, the rotating body drive control unit 56 drives the rotating body 12 to rotate the rotating shaft 14, so that the absolute position of the rotating rotating shaft 14 is determined. It can be acquired with certainty.

[Modification of this embodiment]
Next, modifications of the position detection device 10 according to the present embodiment (the position detection device 10A according to the first modification, the position detection device 10B according to the second modification) will be described with reference to FIGS. To do. In the position detection devices 10A and 10B, the same components as those of the position detection device 10 described in FIGS. 1 to 9 are denoted by the same reference numerals, and detailed description thereof is omitted.

<First Modification>
First, a position detection apparatus 10A according to a first modification as the first configuration will be described with reference to FIGS. 10 to 12B.

  The position detection device 10A is shown in FIGS. 1 to 9 in that the rotation angle detection mechanism 16 includes a first reduction device 60, a second reduction device 62, a first rotation angle detector 64, and a second rotation angle detector 66. It is different from the position detection device 10 as the basic configuration shown.

  The first speed reducer 60 can reduce the rotational speed of the rotating shaft 14 of the rotating body 12 and transmit the rotational speed after the deceleration to the input shaft 68 of the second speed reducer 62 that is the output shaft of the first speed reducer 60. It is a rotation transmission mechanism. Note that in the first modification, the reduction ratio of the first reduction gear 60 is 1, and the rotational speed (rotational force) of the rotary shaft 14 is output to the input shaft 68 as it is.

  The first speed reducer 60 extends substantially parallel to the first speed reducer 60a provided on the rotary shaft 14 side, the rotary shaft 14, the input shaft 68, and the output shaft 22, and one end is connected to the first speed reducer 60a. An intermediate shaft 60b, and a second reduction portion 60c provided on the input shaft 68 side and connected to the other end of the intermediate shaft 60b.

  The first reduction gear 60a includes an input-side first gear 70a attached substantially coaxially to the rotary shaft 14 and an output-side second gear attached substantially coaxially to one end of the intermediate shaft 60b and meshing with the first gear 70a. And a gear 72a. The second speed reducing portion 60c includes an input side third gear 70b attached substantially coaxially to the other end side of the intermediate shaft 60b, and an output side first gear attached to the input shaft 68 substantially coaxially and meshing with the third gear 70b. 4 gears 72b. As described above, since the reduction ratio of the first reduction gear 60 is 1, each reduction ratio n of the first reduction part 60a and the second reduction part 60c is set to n = 1.

  The second speed reducer 62 has substantially the same configuration as the speed reducer 20 of the position detection device 10, is disposed substantially coaxially with the rotary shaft 14, and the rotational force of the rotary shaft 14 is transmitted via the first speed reducer 60. And an output shaft 22 that is disposed substantially coaxially with the rotation shaft 14 and the input shaft 68 and that rotates at a rotational speed reduced by a reduction ratio N from the rotational speed of the input shaft 68. Therefore, in the first modification, the reduction ratio of the entire first reduction gear 60 and the second reduction gear 62 is N (= 1 × N).

  The first rotation angle detector 64 includes a columnar bias magnet 74 attached substantially coaxially to the tip end side of the rotation shaft 14 and a magnetic detection element 76 disposed to face the center of the bias magnet 74. The In the bias magnet 74, one semicircular portion is assigned to the N pole and the other semicircular portion is assigned to the S pole. Therefore, the first rotation angle detector 64 is a one rotation angle detector that detects the first rotation angle within one rotation of the rotating shaft 14. The magnetic detection element 76 outputs a serial signal corresponding to the first rotation angle (the rotation angle data signal shown in FIG. 12B) to the arithmetic processing unit 30 by serial communication, while corresponding to the first rotation angle and the phase. Output two-phase digital pulse signals (A-phase and B-phase first pulse signals shown in FIG. 12A) to the multiplier circuit 52.

  That is, in the first modified example, the magnetic detection element 76 has a function of outputting a serial signal to the arithmetic processing unit 30 and a function of an interpolator process of outputting a two-phase first pulse signal to the multiplication circuit 52. . That is, in the position detection device 10A according to the first modification, the first rotation angle detector 24 and the second rotation angle detector 26 of the position detection device 10 are replaced with the first rotation angle detector 64. 12B illustrates a case where a serial signal is transmitted from the magnetic detection element 76 to the arithmetic processing unit 30 during a predetermined period (serial transfer period).

  The second rotation angle detector 66 has the same configuration as the third rotation angle detector 28 (see FIGS. 1 and 2) of the position detection device 10, and the output shaft 22 corresponding to the multiple rotations of the rotation shaft 14. The second rotation angle within one rotation is detected by the third magnetic detection elements 46c and 46d, and an analog signal corresponding to the detected second rotation angle (a signal similar to the third analog signal) is output to the arithmetic processing unit 30. .

  The arithmetic processing unit 30 samples the serial signal from the magnetic detection element 76 at a predetermined sampling interval shown in FIG. 12B. Further, the arithmetic processing unit 30 converts the output voltage of the analog signal from the third magnetic detection elements 46c and 46d from orthogonal coordinates to polar coordinates. And the arithmetic processing part 30 calculates the absolute position of the rotating shaft 14 at the time of starting based on the serial signal after sampling, and the output voltage converted into the polar coordinate.

In this case, the arithmetic processing unit 30 calculates the rotation amount TA of the rotating shaft 14 based on the following equation (4).
TA = P1 + (P3 × N) (4)

  Note that in the first modified example, since the spur gear 34 does not exist, P1 is an angle of the rotation shaft 14 (first rotation angle) in the equation (4).

In the first modification, the total pulse number TP is calculated by the following equation (5).
TP = INT (TA × PP ÷ 360) (5)

  Note that the position detection apparatus 10A according to the first modification can also operate according to the sequence diagrams of FIGS. In this case, with regard to steps S4, S5, and S17, the two-phase first pulse signal is directly output from the magnetic detection element 76 to the multiplication circuit 52, the serial signal is output from the magnetic detection element 76 to the arithmetic processing unit 30, and the third An analog signal is output from the magnetic detection elements 46c and 46d to the arithmetic processing unit 30, and the arithmetic processing unit 30 calculates the total pulse number TP based on the equations (4) and (5). It is the same operation. Therefore, the detailed operation will not be described.

  As described above, in the position detection device 10 </ b> A according to the first modification, the function of outputting the serial signal to the arithmetic processing unit 30 and the interpolator process of outputting the two-phase first pulse signal to the multiplication circuit 52 of the controller 18. The magnetic detection element 76 of the first rotation angle detector 64 also has the above function. Further, the arithmetic processing unit 30 calculates the absolute value of the rotary shaft 14 at the time of activation based on the serial signal and the second rotation angle detected by the second rotation angle detector 66 (the third magnetic detection elements 46c and 46d). Calculate the position. Therefore, in the first modified example, the number of parts of the position detection device 10A is reduced and the calculation load on the calculation processing unit 30 is reduced. Therefore, the cost of the position detection device 10A can be reduced. Further, by adopting the cylindrical bias magnet 74, a decrease in the magnetic flux density can be suppressed as compared with the ring-shaped magnet, and the detection accuracy of the first rotation angle can be improved.

  Also in the position detection device 10A according to the first modification, the following effects can be obtained as in the case of the position detection device 10.

  That is, the second speed reducer 62 and the output shaft 22 are provided along the axial direction of the rotation shaft 14, and the first rotation angle detector 64 and the second rotation angle detector 66 are arranged around the rotation shaft 14 and the output shaft 22. By doing so, the size of the rotating shaft 14 in the radial direction can be reduced.

  In addition, the calculation processing unit 30 calculates the absolute position of the rotating shaft 14 in the stopped state at the time of activation based on the first rotation angle and the second rotation angle only at the time of activation. As a result, the controller 18 (current position counter 54) detects the absolute value of the current rotating shaft 14 from the two-phase first pulse signal based on the absolute position of the rotating shaft 14 at the time of startup while the rotating shaft 14 is rotating. The position can be determined in a pseudo and easy manner.

  That is, the position detection device 10A functions as an absolute rotary encoder only at the time of activation, and thereafter functions as an incremental rotary encoder. Thereby, the calculation of the absolute position in real time is unnecessary, and a low-speed and low-cost CPU can be used. If such a position detection device 10A is mounted on an electric actuator or the like, the tact time can be shortened.

  Therefore, also in the first modified example, it is possible to reduce the size and cost of the position detection device 10A, and to perform an absolute position calculation process using a low-speed calculation processing device.

  Also in the first modification, the influence of backlash of the first reduction gear 60 and the second reduction gear 62 can be ignored regardless of whether the rotating shaft 14 rotates forward or backward. In this case, it is preferable that the backlash of the first reduction gear 60 be within 360 ° / (4 × n × n). In the first modified example, since n = 1, the backlash is preferably within 90 °.

  Further, the position detection apparatus 10A further includes a first reduction gear 60 that transmits the rotational force of the rotation shaft 14 to the input shaft 68 of the second reduction gear 62, and the rotation shaft 14, the input shaft 68, and the output shaft 22 are It is arranged substantially coaxially. The first speed reducer 60 makes the position detection device 10A slightly larger in the radial direction, but by providing the first rotation angle detector 64 having an interpolator function, the number of parts of the position detection device 10A is reduced. Overall cost reduction can be realized. In the above description, the case of using the first speed reducer 60 having a reduction ratio of 1 has been described. However, instead of the first speed reducer 60, various rotation transmission mechanisms such as a rotation transmission means using a belt. Can be suitably employed.

<Second Modification>
Next, a position detection device 10B according to a second modification as the second configuration will be described with reference to FIGS.

  In the position detection device 10B, the rotation angle detection mechanism 16 includes first to third rotation angle detectors 64, 78, and 80, and each deceleration of the first reduction unit 60a and the second reduction unit 60c of the first reduction device 60. It differs from the configuration of the position detection apparatus 10A according to the first modification (see FIGS. 10 and 11) in that the ratio n is larger than 1. Accordingly, the overall reduction ratio of the first reduction gear 60 and the second reduction gear 62 is n × n × N (first reduction gear 60a: n, second reduction gear 60c: n, second reduction gear 62: N). The rotation speed of the output shaft 22 is a rotation speed obtained by reducing the rotation speed of the rotation shaft 14 by (1 / n) × (1 / n) × (1 / N) times.

  The second rotation angle detector 78 has substantially the same configuration as the second rotation angle detector 26 of the position detection device 10 (see FIGS. 1 and 2). However, the second rotation angle detector 78 is provided not on the rotating shaft 14 but on the input shaft 68. In other words, in the second modification, the first magnetic reduction element 60 of the second rotation angle detector 78 is provided by providing the first reduction gear 60 having a reduction ratio of n × n between the rotation shaft 14 and the input shaft 68. 42 a and 42 b can detect the second rotation angle within one rotation of the input shaft 68 according to the multiple rotations of the rotation shaft 14.

  The third rotation angle detector 80 has the same configuration as the second rotation angle detector 66 (see FIGS. 10 and 11) of the position detection device 10A, and the third magnetic angle of the third rotation angle detector 80 is the same. The detection elements 46 c and 46 d detect the third rotation angle within one rotation of the output shaft 22 in accordance with the multiple rotations of the rotation shaft 14.

  The arithmetic processing unit 30 samples the serial signal from the magnetic detection element 76 at a predetermined sampling interval shown in FIG. 12B. In addition, the arithmetic processing unit 30 outputs an analog signal corresponding to the second rotation angle from the second magnetic detection elements 42a and 42b (a signal similar to the second analog signal) and the third magnetic detection elements 46c and 46d. For the analog signal corresponding to the three rotation angles (the same signal as the third analog signal), the output voltage of each analog signal is converted from orthogonal coordinates to polar coordinates. And the arithmetic processing part 30 calculates the absolute position of the rotating shaft 14 at the time of starting based on the serial signal after sampling, and each output voltage converted into the polar coordinate.

In this case, the arithmetic processing unit 30 calculates the rotation amount TA of the rotating shaft 14 based on the following equation (6).
TA = P1 + (P2 × n × n) + (P3 × N × n × n) (6)

  In the second modification, the spur gear 34 is not present, and the second rotation angle detector 78 is disposed on the input shaft 68. Therefore, in the equation (6), P1 is the angle of the rotation shaft 14. Note that (first rotation angle), and P2 is the angle of the input shaft 68 (second rotation angle). In the second modification, the total pulse number TP is calculated by the above-described equation (5).

  Note that the position detection device 10B according to the second modification can also operate according to the sequence diagrams of FIGS. 8 and 9, similarly to the position detection device 10A. Also in this case, with regard to steps S4, S5, and S17, the two-phase first pulse signal is directly output from the magnetic detection element 76 to the multiplication circuit 52, and the serial signal is output from the magnetic detection element 76 to the arithmetic processing unit 30. Analog signals are respectively output from the 2 magnetic detection elements 42a and 42b and the third magnetic detection elements 46c and 46d to the arithmetic processing unit 30, and the arithmetic processing unit 30 calculates the total number of pulses TP based on the equations (5) and (6). Except for the calculation point, the operation is the same as that of the position detection device 10. Therefore, the detailed operation will not be described.

  As described above, in the position detection device 10B according to the second modification, compared with the position detection device 10A according to the first modification, there are three rotation angle detectors (first to third rotation angle detectors 64). , 78, 80) and two reduction gears (first reduction gear 60 and second reduction gear 62) having reduction ratios n and N exceeding 1. Therefore, as compared with the position detection apparatus 10A, the number of parts is increased, and the calculation load on the calculation processing unit 30 is increased.

  However, in the second modification, the second rotation angle detector 78 and the third rotation angle detector 80 detect and detect the second rotation angle and the third rotation angle corresponding to the multiple rotations of the rotation shaft 14, respectively. Using the second rotation angle, the third rotation angle, and the like, the calculation processing unit 30 can calculate the absolute position of the rotating shaft 14 at the time of activation with high accuracy. As a result, the absolute position can be calculated with high accuracy and the cost can be reduced as compared with the conventional position detecting device. Also, in the second modified example, since the cylindrical bias magnet 74 is employed, a decrease in magnetic flux density can be suppressed as compared with a ring magnet, and the detection accuracy of the first rotation angle can be improved. Can do.

  In addition, the position detection device 10B according to the second modification also has the same effects as those of the position detection device 10 by including the first to third rotation angle detectors 64, 78, and 80.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10, 10A, 10B ... Position detection device 12 ... Rotating body 14 ... Rotating shaft 16 ... Rotation angle detection mechanism 18 ... Controller 20 ... Reduction gear 22 ... Output shaft 24, 64 ... 1st rotation angle detector 26, 66, 78 ... Second rotation angle detector 28, 80 ... Third rotation angle detector 30 ... Arithmetic processing unit 32 ... Interpolator 34 ... Spur gears 36a, 36b ... First magnetic detection element 38 ... First bias magnet 40 ... Second bias magnet 42a , 42b ... second magnetic detection element 44 ... third bias magnet 46c, 46d ... third magnetic detection element 50 ... serial communication unit 52 ... multiplication circuit 54 ... current position counter 56 ... rotating body drive control unit 60 ... first reduction gear 60a ... 1st reduction part 60b ... Intermediate shaft 60c ... 2nd reduction part 62 ... 2nd reduction device 68 ... Input shaft 74 ... Bias magnet 76 ... Magnetic detection element

Claims (12)

In a position detection device in which a speed reducer is connected to a rotating shaft of a rotating body, and an absolute position of the rotating shaft is detected based on a rotating angle of the rotating shaft and a rotating angle of an output shaft of the reducer.
A first rotation angle detector for detecting a first rotation angle between the pitches of gears attached substantially coaxially to the rotation shaft;
A second rotation angle detector for detecting a second rotation angle within one rotation of the rotation shaft;
A third rotation angle detector for detecting a third rotation angle within one rotation of the output shaft according to multiple rotations of the rotation shaft;
An arithmetic processing unit that calculates an absolute position of the rotating shaft at the time of starting based on the first to third rotational angles detected by the first to third rotational angle detectors at the time of starting the position detecting device; ,
Based on the first rotation angle detected by the first rotation angle detector and the absolute position of the rotation shaft at the time of start-up during rotation of the rotation shaft by driving the rotating body, the current rotation shaft A current position detector for detecting the absolute position of
A position detecting device comprising: The position detection device according to claim 1,
The first rotation angle detector is configured such that when a spur gear made of a magnetic material attached substantially coaxially to the rotation shaft and the tooth tip of the spur gear are set to one cycle, the phases are shifted by 90 ° from each other. Two first magnetic sensing elements arranged opposite to the gear, and a first bias magnet,
Each of the first magnetic detection elements outputs a first analog signal corresponding to the first rotation angle and having a phase shifted by 90 ° from each other. The position detection device according to claim 2,
The second rotation angle detector includes a ring-shaped second bias magnet attached substantially coaxially to the rotation shaft and the first rotation angle of the second rotation magnet when the rotation of the rotation shaft is one cycle. Two second magnetic sensing elements disposed opposite to the two-bias magnet,
Each of the second magnetic detection elements outputs a second analog signal corresponding to the second rotation angle and having a phase shifted by 90 ° from each other. The position detection device according to claim 3, wherein
The third rotation angle detector includes a ring-shaped third bias magnet attached substantially coaxially to the output shaft, and the first rotation of the output shaft in one cycle, the phases being shifted by 90 ° from each other. Two third magnetic sensing elements arranged opposite to a three-bias magnet,
Each of the third magnetic detection elements outputs a third analog signal corresponding to the third rotation angle and having a phase shifted by 90 ° from each other. The position detection device according to claim 4, wherein
An interpolator for converting each first analog signal output from each first magnetic detection element into a two-phase first pulse signal;
The arithmetic processing unit calculates the absolute position of the rotating shaft at the time of activation based on the first to third analog signals output from the first to third magnetic detection elements, respectively. Output a second pulse signal according to the absolute position,
The current position detection unit detects the current absolute position of the rotating shaft based on each first pulse signal output from the interpolator and the second pulse signal output from the arithmetic processing unit. A position detecting device characterized by that. The position detection device according to claim 5, wherein
The position detection device, wherein the arithmetic processing unit transmits the second pulse signal to the current position detection unit as a serial signal having a pulse number corresponding to the absolute position of the rotating shaft at the time of activation. The position detection device according to claim 6, wherein
A multiplier circuit that generates a multiplied pulse signal obtained by multiplying each of the first pulse signals and outputs the multiplied pulse signal to the current position detector;
The current position detection unit presets the number of pulses according to the serial signal at the time of starting, and counts the number of pulses according to the multiplied pulse signal from the preset number of pulses during rotation of the rotating shaft, A position detection device comprising a current position counter for detecting a current absolute position of the rotating shaft. The position detection device according to claim 7,
The multiplication circuit compares the first pulse signals to determine normal rotation or reverse rotation of the rotating shaft, and generates the determined normal rotation or reverse rotation pulse signal. . The position detection device according to claim 7 or 8,
The position detection device further comprising: a rotating body drive control unit that drives the rotating body to rotate the rotating shaft when the number of pulses corresponding to the serial signal is preset in the current position counter. In a position detection device in which a speed reducer is connected to a rotating shaft of a rotating body, and an absolute position of the rotating shaft is detected based on a rotating angle of the rotating shaft and a rotating angle of an output shaft of the reducer.
A first rotation angle detector for detecting a first rotation angle within one rotation of the rotation shaft;
A second rotation angle detector for detecting a second rotation angle within one rotation of the output shaft according to multiple rotations of the rotation shaft;
Based on the first rotation angle and the second rotation angle detected by the first rotation angle detector and the second rotation angle detector, respectively, at the time of starting the position detection device, An arithmetic processing unit for calculating an absolute position;
Based on the first rotation angle detected by the first rotation angle detector and the absolute position of the rotation shaft at the time of start-up during rotation of the rotation shaft by driving the rotating body, the current rotation shaft A current position detector for detecting the absolute position of
Have
The first rotation angle detector includes a columnar bias magnet attached substantially coaxially to the rotation shaft, and a magnetic detection element disposed opposite to the bias magnet,
The magnetic detection element outputs a serial signal corresponding to the first rotation angle to the arithmetic processing unit, and on the other hand, a two-phase pulse signal corresponding to the first rotation angle and having a phase shifted by 90 ° from each other. A position detection apparatus that outputs to the current position detection unit. The position detection device according to claim 10.
A rotation transmission mechanism for transmitting the rotational force of the rotation shaft to the input shaft of the speed reducer;
The position detection device, wherein the rotation shaft, the input shaft, and the output shaft are arranged substantially coaxially. In a position detection device in which a speed reducer is connected to a rotating shaft of a rotating body, and an absolute position of the rotating shaft is detected based on a rotating angle of the rotating shaft and a rotating angle of an output shaft of the reducer.
A first rotation angle detector for detecting a first rotation angle within one rotation of the rotation shaft;
A first speed reducer that decelerates and outputs the rotational speed of the rotating shaft;
An input shaft connected to the first speed reducer, a second speed reducer that further reduces the rotational speed of the rotary shaft decelerated by the first speed reducer and outputs it to the output shaft;
A second rotation angle detector for detecting a second rotation angle within one rotation of the input shaft according to multiple rotations of the rotation shaft;
A third rotation angle detector for detecting a third rotation angle within one rotation of the output shaft according to multiple rotations of the rotation shaft;
An arithmetic processing unit that calculates the absolute position of the rotating shaft at the time of starting based on the first to third rotating angles detected by the first to third rotating angle detectors at the time of starting the position detecting device. When,
Based on the first rotation angle detected by the first rotation angle detector and the absolute position of the rotation shaft at the time of start-up during rotation of the rotation shaft by driving the rotating body, the current rotation shaft A current position detector for detecting the absolute position of
Have
The first rotation angle detector includes a columnar bias magnet attached substantially coaxially to the rotation shaft, and a magnetic detection element disposed opposite to the bias magnet,
The magnetic detection element outputs a serial signal corresponding to the first rotation angle to the arithmetic processing unit, and on the other hand, a two-phase pulse signal corresponding to the first rotation angle and having a phase shifted by 90 ° from each other. A position detection apparatus that outputs to the current position detection unit.

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