JP5731022B1 - Absolute position detector - Google Patents

Abstract

In an absolute position detection device, the structure is simplified, the size is reduced, and the cost is reduced. In an absolute position detection device that detects an absolute angle of a rotation angle of a motor based on output signals of a plurality of magnetic sensors S1, S2, S3, S4, the rotation axis of the motor or the rotation axis of the motor The two gears 2 and 3 having different number of teeth are meshed with the gear 1 of the output shaft of the connected speed reducer, and the rotation angle of the two gears 2 and 3 is detected. Based on this, the absolute angle of the rotating shaft of the motor or the output shaft of the speed reducer connected to the rotating shaft of the motor is detected. [Selection] Figure 1

Description

  The present invention relates to an absolute position detection device that detects an absolute angle of a rotating shaft of a motor, an output shaft of a reduction gear, or a position of a rack based on output signals of a plurality of magnetic sensors.

  Patent Document 1 proposes an absolute position detection device using a reluctance resolver.

Japanese Patent No. 3704462

  However, an absolute position detection device using a reluctance resolver as shown in Patent Document 1 has a complicated structure and is not suitable for miniaturization.

  As described above, in the absolute position detection device, it is an issue to simplify the structure, to reduce the size and to reduce the cost.

  The present invention has been devised in view of the above-described conventional problems. One aspect of the present invention is based on output signals of a plurality of magnetic sensors, and a reduction gear connected to a motor rotation shaft or a motor rotation shaft. An absolute position detecting device for detecting an absolute angle of an output shaft of a machine, wherein a first gear having a different number of teeth is provided on a gear of an output shaft of a speed reducer connected to a rotation shaft of a motor or a rotation shaft of a motor. The angle difference between the first gear and the second gear is calculated based on the two 90 ° phase difference detection signals for each of the gears that have engaged the two gears and detected the rotation angles of the first gear and the second gear. The angle difference between the first gear and the second gear, the number of teeth of the first gear, the number of teeth of the second gear, the number of teeth of the rotating shaft of the motor, or the output of the speed reducer connected to the rotating shaft of the motor From the number of teeth on the shaft gear, connected to the motor rotation shaft or motor rotation shaft And detecting the absolute angle of the output shaft of the speed machine.

  According to another aspect, there is provided an absolute position detection device for detecting an absolute position of a rack based on output signals of a plurality of magnetic sensors installed in gears meshing with teeth formed on the rack. The first gear and the second gear with different number of teeth are meshed, and the first gear and the second gear are detected based on the two 90 ° phase difference detection signals of the respective gears that detect the rotation angle of the first gear and the second gear. The angle difference between the two gears is calculated, and the absolute position of the rack is determined from the angle difference between the first gear and the second gear, the number of teeth of the first gear, the number of teeth of the second gear, and the number of teeth of the rack. It is characterized by detecting.

  Also, as one aspect thereof, magnetic sensors are arranged on the gears at intervals of 120 °, and the difference between two different sensor output signals is calculated using three-phase sensor output signals with different 120 ° phases output from the magnetic sensor. To generate a three-phase sine wave signal from which harmonic distortion has been removed, add or subtract two-phase sine wave signals from the three-phase sine wave signals, and generate a composite signal; A phase difference signal is generated using a sine wave signal that was not used to generate a combined signal, and the combined signal and the phase difference signal are used as the two 90 ° phase difference detection signals. It is characterized by that.

  The two gears may be formed of a magnetizable member.

  According to the present invention, it is possible to simplify the structure, reduce the size, and reduce the cost in the absolute position detection device.

FIG. 2 is a plan view showing the absolute position detection device according to the first embodiment. FIG. 2 is a side view showing the absolute position detection device according to the first embodiment. The side view which shows the gearwheel and magnet in Embodiment 1. FIG. The top view and side view which show the gearwheel in Embodiment 2. FIG. Schematic which shows the gearwheel in Embodiment 3. FIG. Schematic which shows the position of the magnetic sensor in Embodiment 4. FIG. The time chart which shows the distorted sensor output signal. The time chart which shows a synthetic | combination signal and a phase difference signal. Schematic which shows a rack and a pinion.

  Embodiments 1 to 5 of the absolute position detection device according to the present invention will be described below in detail with reference to FIGS.

[Embodiment 1]
As shown in FIGS. 1 to 3, the absolute position detection device according to the first embodiment has a gear 1 having a number of teeth L on the rotation shaft of the motor to be detected or the output shaft of the reduction gear connected to the rotation shaft of the motor. Is provided. A gear 2 having the number of teeth M is rotatably supported on the shaft 2a so as to mesh with the gear 1, and a gear 3 having a number N of teeth different from the number M of teeth is rotatable on the shaft 3a so as to mesh with the gear 1. Is pivotally supported.

  It arrange | positions so that the magnet 4 of a pair of magnetic pole (S, N) may overlap with the gearwheels 2 and 3, respectively. In addition, a magnetic sensor such as a Hall element or a magnetoresistive effect element is provided so that the rotation angle of each of the gears 2 and 3 is detected on the fixed side of the motor, and a detection signal having a phase difference of 90 ° in electrical angle is obtained. S1, S2, S3 and S4 are arranged. Thereby, the rotation angle of the rotating shaft of the motor or the output shaft of the speed reducer is detected over multiple rotations from the phase difference of the sensor output signals (voltage signals) of the magnetic sensors S1, S2, S3, S4.

  Assuming that the rotation angle of the rotating shaft of the motor is α, as shown in the following equation (1), the magnetic sensor S1 to Xs, the magnetic sensor S2 to Xc, the magnetic sensor S3 to Ys, and the magnetic sensor S4 to Yc sensor An output signal is obtained.

  Here, when sin θ is the following equation (2), the following equation (3) is obtained from the addition theorem of trigonometric functions. Further, the angle difference θ between the gear 2 and the gear 3 can be calculated from the equation (4).

  On the other hand, the following (6) can be derived from the following equation (5), and the relationship between the angular difference θ and α between the gear 2 and the gear 3 can be understood from the equation (6).

  As a result, the rotation angle can be detected even if the rotation angle α of the rotation shaft of the motor is one rotation or more.

  As described above, according to the first embodiment, the mechanical position (absolute angle) of the rotating shaft of the motor can be detected as an absolute value with a very simplified structure. As a result, the cost of the device can be reduced and the size can be reduced.

  Further, according to the first embodiment, since the absolute angle is calculated based on the rotation angles of the two gears 2 and 3, it is not necessary to store the absolute angle even when the apparatus is turned off. Furthermore, even after the power is turned off, even if the rotation shaft of the motor is rotated by an external force, the rotation angle can be detected after the power is turned on.

[Embodiment 2]
FIG. 4 is a plan view and a side view showing the gears 2 and 3 in the second embodiment. As shown in FIG. 4, in the second embodiment, the gears 2 and 3 are made of a magnetizable material such as a plastic magnet, and the N and S poles are magnetized directly on the gears 2 and 3. . Thus, the gears 2 and 3 and the magnet are made into one component and integrated, so that it is not necessary to provide the magnet 4 separately.

  Further, according to the second embodiment, the same effects as those of the first embodiment can be obtained.

[Embodiment 3]
FIG. 5 is a schematic diagram showing the gears 1, 2, 3 in the third embodiment. In the first embodiment, the gears 2 and 3 are arranged to mesh with the gear 1. In the third embodiment, the gear 2 is meshed with the gear 1 and the gear 3 is meshed with the gear 2. Thus, the gears 2 and 3 are not necessarily meshed with the gear 1.

  According to the third embodiment, the same effects as those of the first embodiment are obtained.

[Embodiment 4]
The sin signal and the cosine signal obtained from the magnetic sensors S1, S2, S3, and S4 such as Hall elements and magnetoresistive elements often have a distorted waveform including a lot of third harmonics. Detection error increases.

  Therefore, in the fourth embodiment, as shown in FIG. 6, the magnetic sensors SX1, SX2, SX3 are arranged at intervals of 120 °. It calculates the two-phase accurate sine wave of 90 ° phase difference from the analog three-phase sensor output signals U0, V0, W0 of 120 ° phase difference, respectively, and detects the absolute angle of the motor rotation shaft. is there.

  Hereinafter, a method of calculating a two-phase accurate sine wave from the three-phase sensor output signals U0, V0, and W0 having a 120 ° phase difference will be described.

  As shown in FIG. 7, the three-phase sensor output signals U0, V0, W0 are not substantially sine waves that are substantially trapezoidally distorted.

  From these three-phase sensor output signals U0, V0, and W0, sine wave signals U1, V1, and W1, which are differences between two different-phase signals (U0−V0, V0−W0, and W0−U0), are calculated. . The three-phase sine wave signals U1, V1, and W1 are accurate sine waves from which harmonic distortion has been removed.

  Further, two phases of the three-phase sine wave signals U1, V1, and W1 are added or subtracted to generate a composite signal Rx. Also, a sine wave signal that is not used to generate the composite signal Rx from among the sine wave signals U1, V1, and W1 is referred to as a phase difference signal Ry.

  As shown in FIG. 8, the combined signal Rx is a signal having a phase difference of 90 ° from the phase difference signal Ry (sine wave signal W1). The two-phase combined signal Rx and phase difference signal Ry are used in place of the sensor output signals Xs, Xc or Ys, Yc output from the magnetic sensors S1, S2 or S3, S4 in the first embodiment. It is also possible to use the three-phase sine wave signals U1, V1, and W1 from which harmonic distortion has been removed as the rectification signal of the motor, and it can be easily applied to a drive circuit using a conventional three-phase sensor output signal. Can be applied.

  Next, an example of a method for calculating the composite signal Rx and the phase difference signal Ry from the sensor output signals U0, V0, W0 will be described.

  First, sensor output signals U0, V0, and W0 distorted in a substantially trapezoidal shape as shown in FIG.

  Next, the sine wave signal U1 is expressed by the following equation (8).

  Similarly, the sine wave signals V1 and W2 are expressed by the following equation (9).

  The above equations (8) and (9) indicate that the sine wave signals U1, V1, and W1 are shifted from each other by 30 ° from the original sensor output signals U0, V0, and W0 and are 120 ° out of phase with each other. It shows that a sine wave of only the fundamental wave from which the second harmonic is removed can be obtained.

  Also, a synthesized signal Rx and a phase difference signal Ry having a 90 ° phase difference are generated from the sine wave signals U1, V1, and W1 having a 120 ° phase difference by the following equation (10).

  The phase difference signal Ry is a sine wave signal W1 multiplied by √3. The phase difference signal Ry is a sine wave having the same peak value as the synthesized signal Rx and a phase difference of 90 °.

  In this way, from the substantially trapezoidal sensor output signals U0, V0, W0 including the three-phase harmonics, the combined signal Rx having a phase difference of 90 degrees with the three-phase rectifying sine wave signals U1, V1, W1. It can be seen that the phase difference signal Ry is obtained.

  As described above, according to the motor rotation angle detection device of the fourth embodiment, the 90 ° phase difference obtained by removing harmonics from the three-phase sensor output signals U0, V0, and W0 having an electrical angle of 120 °. It becomes possible to generate the two-phase composite signal Rx and the phase difference signal Ry. As a result, the absolute angle or angle control on the rotation shaft of the motor can be accurately performed using the two-phase composite signal Rx and the phase difference signal Ry having the 90 ° phase difference.

  Further, since the three-phase sine wave signals U1, V1, and W1 can be used as the rectification signal of the motor, it can be easily connected to a conventional driving circuit.

  In addition, since it is not necessary to use an expensive encoder or resolver, the cost can be reduced.

[Embodiment 5]
FIG. 9 is a schematic diagram illustrating an absolute position detection apparatus according to the fifth embodiment. As shown in FIG. 9, the absolute position detection apparatus according to the fifth embodiment includes a rack 5 that translates linearly and pinions (gears) 2 and 3 as detection units. In the absolute position detection apparatus according to the fifth embodiment, the pinions (gears) 2 and 3 rotate with the parallel movement of the rack 5. The pinions (gears) 2 and 3 are provided with magnetic sensors S1 to S4. The absolute position of the rack can be detected from the sensor output signals Xs, Xc, Ys, and Yc of the magnetic sensors S1 to S4 as in the first to fourth embodiments.

  As shown in the fifth embodiment, it is possible to detect not only the absolute angle of the rotating shaft of the motor but also the absolute position of the rack.

S1-S4 ... Magnetic sensor SX1, SX2, SX3 ... Magnetic sensor 1-3 ... Gear 2a, 3a ... Shaft 4 ... Magnet 5 ... Rack

Claims (2)

An absolute position detection device that detects an absolute angle of a rotating shaft of a motor or an output shaft of a reduction gear connected to the rotating shaft of a motor based on output signals of a plurality of magnetic sensors,
The first gear and the second gear with different number of teeth are meshed with the gear of the rotating shaft of the motor or the output shaft of the speed reducer connected to the rotating shaft of the motor,
Magnetic sensors are arranged at 120 ° intervals on the first gear and the second gear, and a difference between two different sensor output signals is obtained by using three-phase sensor output signals with different 120 ° phases output from the magnetic sensor. To generate a three-phase sine wave signal from which harmonic distortion has been removed,
Adding or subtracting two-phase sine wave signals from the three-phase sine wave signals to generate a composite signal;
Among the three-phase sine wave signals, a phase difference signal is generated using a sine wave signal that was not used to generate a composite signal,
The combined signal and the phase difference signal are used as the two 90 ° phase difference detection signals,
Based on the two 90 ° phase difference detection signals for each of the gears that detected the rotation angles of the first gear and the second gear, the angle difference between the first gear and the second gear is calculated,
The angle difference between the first gear and the second gear, the number of teeth of the first gear, the number of teeth of the second gear, the number of teeth of the rotating shaft of the motor, or the output of the speed reducer connected to the rotating shaft of the motor An absolute position detecting device for detecting an absolute angle of a rotating shaft of a motor or an output shaft of a speed reducer connected to the rotating shaft of a motor from the number of teeth in a shaft gear. An absolute position detection device that detects the absolute position of a rack based on output signals of a plurality of magnetic sensors installed in gears meshing with teeth formed on the rack,
The first gear and the second gear with different number of teeth are meshed with the teeth of the rack,
Magnetic sensors are arranged at intervals of 120 ° on the first gear and the second gear, and the difference between two different sensor output signals is calculated using three-phase sensor output signals with different 120 ° phases output from the magnetic sensor. To generate a three-phase sine wave signal from which harmonic distortion has been removed,
Adding or subtracting two-phase sine wave signals from the three-phase sine wave signals to generate a composite signal;
Among the three-phase sine wave signals, a phase difference signal is generated using a sine wave signal that was not used to generate a composite signal,
The combined signal and the phase difference signal are used as the two 90 ° phase difference detection signals,
Based on the two 90 ° phase difference detection signals for each of the gears that detected the rotation angles of the first gear and the second gear, the angle difference between the first gear and the second gear is calculated,
The absolute position of the rack is detected from the angle difference between the first gear and the second gear, the number of teeth of the first gear, the number of teeth of the second gear, and the number of teeth of the rack. Detection device.

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