JP3377050B2 - Absolute position detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absolute position detecting device for detecting an absolute position of a multi-rotating actuator or the like, and more particularly to a device for backing up in case of power failure.

[0002]

2. Description of the Related Art Conventionally, when an absolute position detecting device such as a resolver is connected to a rotary shaft of an actuator for driving an arm of an articulated robot to detect the amount of rotation, and a multi-rotation absolute position of the actuator is obtained, a power failure occurs. There is also a method to obtain an absolute position by a resolver even at times. As an example thereof, as shown in FIG. 4, an excitation circuit 2 which is excited by a backup battery 9 connected in parallel with a main power source 8.
Pulse is supplied to the resolver 1, the output from the detection coil of the resolver 1 is held by the sample hold circuit 3, the detection signal is held, the A phase and B phase sine wave signals are output from the held detection signal, and the comparator 4 The rotation speed is detected via the R / D converter 5, the rotation angle is detected via the R / D converter 5, the rotation speed and the rotation angle are combined to obtain the absolute position of the rotation axis, and the excitation circuit 2 and the sample hold circuit 3 are detected. There is one in which the power consumption of the backup area A including the comparator 4 and the counter 5 is reduced (for example, Japanese Patent Laid-Open No. 5629/1993). A circuit for pulse-exciting the resolver to sample and hold the output thereof is shown in Japanese Patent Publication No. 2-55836. Also, when the actuator stops during a power failure, the excitation current pulse frequency is made lower than when the actuator operates to reduce the power consumption in the backup area and to output the number of revolutions from the detection coil. Is input to the microprocessor to detect the absolute position of the rotary shaft of the actuator (for example, Japanese Patent Laid-Open No. 2-257003, USP 5092051).

[0003]

By the way, in the structure of the above-mentioned Japanese Patent Laid-Open No. 5-5629, there is a problem that the output sine wave signal of the sample hold circuit is biased due to the temperature drift of the sample hold circuit and the detection accuracy is lowered. . In addition, even when the actuator is not operating at the time of a power failure, or when the actuator is operating by external force, for example, pulses of a constant frequency are output from the excitation circuit, so the backup battery is wasted and the backup battery is consumed. There was a problem of shortening the life of the. In addition, Japanese Patent Publication 2-558
No. 36 does not show the point of detecting the power failure and switching the excitation frequency. Further, JP-A-2-257003,
In the configuration of USP 5092051, when detecting the number of rotations from a high frequency resolver output pulse by a microprocessor or the like, high-speed digital synchronization processing is required for sampling, the processing becomes complicated, and the high-speed rotation of the resolver cannot be followed. Furthermore, in the case of digital synchronization processing, the microprocessor etc. is always in the operation mode,
There was a problem of high power consumption. It is an object of the present invention to provide an absolute position detection device capable of keeping high detection accuracy, following a high-speed rotation of a resolver, and suppressing power consumption of a backup circuit.

[0004]

In order to solve the above problems, the present invention provides a rotor provided with a one-phase exciting coil and 90 °
A resolver having a stator provided with two-phase detection coils (12a, 12b) having different phases, an exciting circuit for exciting the exciting coil, and a pulse output from the exciting circuit.
90 ° phase difference from the two-phase detection coil in synchronization with
A sample and hold circuit that obtains two sine wave signals
Rotation of the resolver from the output of the sample and hold circuit
Rotation speed detector for detecting the number and the two-phase detection coil
From the modulated wave amplitude-modulated by the rotation angle output from
The R / D converter (6) that detects the rotation angle and the main DC
An energization detector that detects whether the power source is in the energized state or a power failure state, and
In the backup area including the resolver and the excitation circuit
A backup device that supplies power by connecting in parallel with the main DC power supply.
In an absolute position detection apparatus and a flop cell, the detection
Connect one end of each coil (12a, 12b) in common.
Then, each of the detection coils (12a, 12b)
At the other end, a resolver is passed through a high pass filter (61).
/ A digital (R / D) converter (6) is connected , and a motion detector for detecting the operation state of the rotor, and a detection signal from the energization detector cause 1: when the rotor is stopped due to a power failure. The excitation circuit outputs a pulse with a duty ratio of n (n> 1) in response to a detection signal from the operation detector during a power failure and in an operating state with a duty pulse of 1: m (1 <m <n). And a pulse switching device for switching as described above. Further, the m is made variable according to the rotation speed of the rotor.

[0005]

[Function] During a power failure, a pulse having a constant pulse width having a frequency lower than that during energization is output from the exciting circuit to excite the exciting coil, and when the actuator operates during a power failure, the pulse width is lower than that during energization. Since the exciting coil is excited with a pulse having a higher frequency than that when the power supply does not operate, the duty of the exciting current at the time of power failure is lower than that at the time of energization, so that the power consumption of the backup battery is reduced. Further, the modulated wave signal amplitude-modulated by the rotation angle of the pulse output from the detection coil is input to the R / D converter via the high-pass filter, the modulated wave signal is converted into a digital signal, and the rotation angle signal θ is output. Therefore, the influence of the temperature drift of the sample hold circuit is eliminated, and the direct current component of the modulated wave signal is cut,
The influence of temperature drift of the sample and hold circuit is also eliminated, and the rotation angle detection accuracy can be kept high.

[0006]

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an embodiment of the present invention.
Is a rotor fixed to the detected rotary shaft and provided with a 1-phase exciting coil 11, and a 2-phase detecting coil 1 having a 90 ° phase difference.
And a stator provided with 2a and 12b. The exciting circuit 2 expands FIG. 2 (a) and the time axis through the pulse switching device 22 during energization by the detection signal from the energization detector 21 which detects whether the main DC power supply is in the energized state or the power failure state. As shown in FIG. 3A, a pulse having a high frequency such as 8 kHz is output with a constant pulse width, that is, a pulse with a constant on-time and a 50% duty. During a power failure, a pulse having a low frequency such as 1 kHz is output from the exciting circuit 2 via the pulse switch 22 as shown in FIG.
The duty coil is output to excite the exciting coil 11. Further, when the actuator operates during a power failure, for example, a pulse is generated by a detection signal from an operation detector 23 that detects an edge of an output of a comparator 4 to be described later to detect whether or not the rotating shaft is in a rotating state. Switch 22
3C, a pulse having an intermediate frequency such as 4 kHz is output through the pulse generator, and the pulse width is changed so that the duty is smaller than when energized and the minimum required when the actuator operates. The exciting coil 11 is excited by outputting with various duty. Note that the pulse width or the pulse frequency may be changed according to the rotation speed of the rotary shaft when the duty is reduced during a power failure and when the actuator operates. One end of each of the detection coils 12a and 12b is commonly connected,
A sample hold circuit 3 that operates in synchronization with the excitation circuit 2 is connected to the other end of each of the detection coils 12a, 12
The pulse detected in b is amplitude-modulated by the rotation angle,
The A-phase modulated wave signal V _ra and the B-phase modulated wave signal V _rb as shown in FIG. 2B are sampled and held, and sine wave signals V _{0a having} different 90 ° phases as shown in FIG. , V _0b are output. A rotation speed detector 10 including a comparator 4 and a counter 5 is connected to the sample hold circuit 3 and corresponds to the sine wave signals V _0a and V _0b (FIG. 2D).
The A and B phase signals V _a and V _b at the pulse positions as shown in ₍₁₎ are output, counted by the counter 5 connected to the comparator 4, and output as the rotation speed signal N.
A resolver / digital (R / D) converter 6 is connected to the other ends of the detection coils 12a and 12b via a high-pass filter 61, as shown in FIG.
The A-phase modulated wave signal V _ra and the B-phase modulated wave signal V _{rb in} which the pulses detected by the detection coils 12 a and 12 b as shown in FIG. 2 are amplitude-modulated by the rotation angle are input to the R / D converter 6 via the high-pass filter 61. Then, the modulated wave signal is converted into a digital signal and the rotation angle signal θ is output. The rotation speed signal N of the counter 5 and the rotation angle signal θ that is the output of the R / D converter 6 are input to the controller 7, and the rotation speed signal N and the rotation angle signal θ are combined to generate an absolute position signal of the resolver 1. Is obtained. To the R / D converter 6 and the controller 7, the + side of the main DC power source 8 for applying a DC voltage of ± 5 V or ± 12 V is connected by a connecting line 81, and the − side is connected by a connecting line 82. In addition, a main DC power supply 8 is provided in a backup area A including the excitation circuit 2, an energization detector 21, a pulse switch 22, an operation detector 23, a sample hold circuit 3, a comparator 4, and a counter 5, and a diode 83 is provided on the + side. The connection line 84 is connected via the diode 85 and the connection line 86 is connected to the negative side via the diode 85 to supply electric power. A backup battery 9 is provided in parallel with the main DC power supply 8, the + side of the backup battery 9 is connected to the connecting line 84 via the diode 91, and the − side is the diode 9
It is connected to the connection line 86 via 2. Normally, the DC voltage is applied to the backup area A by the main DC power supply 8, but when the main DC power supply 8 shuts down or drops in voltage during a power failure, the backup battery 9 applies the DC voltage to the backup area A to perform backup. Is done. As a result, when there is a power failure and the actuator is not operating, the output of the excitation circuit 2 is the A-phase and B-phase consisting of coarse-pitched pulses, as schematically shown in FIG. 4 (a). Modulated wave signals V _ra 'and V _rb ' are obtained, and the sine wave signals V _0a 'and V _0b ' output from the sample hold circuit 3 have the waveforms shown in FIG. 4B, and the actuator operates during a power failure. Although not shown, the output waveform has a duty in the middle of those in FIGS. 2 and 4.

As described above, during a power failure, a pulse having a constant pulse width having a lower frequency than that during energization is output from the exciting circuit to excite the exciting coil, and during a power failure and when the actuator operates, it is more than during energization. Is also low, the duty is reduced by exciting the exciting coil with a pulse of a higher frequency than when the actuator does not operate.
The power consumption is much smaller than the conventional constant frequency sinusoidal excitation. Therefore, by exciting the exciting circuit with a pulse, the life of the backup battery can be remarkably extended. Further, the detection coils 12a, 12
An R / D converter 6 is connected to each of the other ends of b via a high-pass filter 61, and a modulated wave signal whose pulse is amplitude-modulated by a rotation angle is input to the R / D converter via a high-pass filter to obtain a modulated wave. Since the signal is converted to a digital signal and the rotation angle signal θ is output, the influence of the temperature drift of the sample and hold circuit is eliminated, and the direct current component of the modulated wave signal is cut, which is used for the high pass filter. The influence of temperature drift of the existing amplifier is also eliminated, and the rotation angle detection accuracy can be maintained high. FIG. 3 is a block diagram showing another embodiment. When a plurality of resolvers 1 are backed up by a single backup battery 8, a multi-phase pulse generator is used to generate excitation pulses in the excitation circuit 2. Since pulse excitation is performed and each excitation coil 11 extracts and excites pulses having different phases, the voltage fluctuation of the power supply can be suppressed to a small level, and the life of the backup battery 8 serving as the power supply can be extended.

[0008]

As described above, the present invention has the following effects. (1) During a power failure, a pulse with a duty smaller than that during energization is output from the excitation circuit to excite the exciting coil, and during an electric power failure and when the actuator operates, it is lower than during energization and less than when the actuator does not operate. Since the exciting coil is excited by a pulse with a large duty, the power consumption is much smaller than the conventional constant duty excitation. (2) In order to detect the rotation angle, the modulated wave signal whose pulse is amplitude-modulated by the rotation angle is directly input from the output of the detection coil to the R / D converter through the high pass filter, and the modulated wave signal is converted into a digital signal. Convert and rotate angle signal θ
Is output, the direct current component of the modulated wave signal is cut off, the influence of the temperature drift of the sample hold circuit is eliminated, and the rotation angle detection accuracy can be maintained high. (3) Since the output of the resolver is sampled and held, the follow-up process can be performed with a simple analog circuit even at high speed rotation. (4) When the actuator does not operate due to a power failure, since the sample hold circuit is provided, the microprocessor does not need to operate for sampling processing or the like, and power consumption is low.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

[Fig. 2] Excitation pulse when energized, A, B phase modulated wave signal,
It is an explanatory view of an A and B phase sine wave signal.

FIG. 3 is an explanatory diagram of an excitation pulse with an expanded time axis.

FIG. 4 is an explanatory diagram of A and B phase modulated wave signals and A and B phase sine wave signals at the time of power failure.

FIG. 5 is a block diagram showing a conventional example.

[Explanation of symbols]

1 resolver 2 Excitation circuit 21 Current detector 22 pulse switch 23 Motion detector 3 sample and hold circuit 4 comparator 5 counter 6 R / D converter 61 High-pass filter 7 controller 8 Main DC power supply 9 backup battery 10 rpm detector

Front page continuation (72) Kenji Hara, No. 2 Kurosaki Shiroishi, Yawatanishi-ku, Kitakyushu City, Fukuoka Prefecture, Yasukawa Electric Co., Ltd. In-machine (72) Inventor Yukinori Sato No. 2 Kurosaki Shiroishi, Yawatanishi-ku, Kitakyushu, Fukuoka Yasukawa Electric Co., Ltd. (56) Reference JP-A-5-5629 (JP, A) JP-A-1-272914 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01D 5/00-5/62 G01B ⁷ /00-7/34

Claims (2)

(57) [Claims] 1. A rotor provided with a one-phase exciting coil and a rotor
° Resolver including a stator provided with two-phase detection coils (12a, 12b) having different phases, an exciting circuit for exciting the exciting coil, and a pulse output from the exciting circuit.
90 ° phase difference from the two-phase detection coil in synchronization with the
A sample and hold circuit that obtains two sinusoidal signals
From the output of the sample and hold circuit, the resolver
Rotation speed detector for detecting the rotation speed and the two-phase detection coil
Is the modulated wave amplitude-modulated by the rotation angle output from
R / D converter (6) that detects the rotation angle from the main DC
An energization detector that detects whether the power supply is in the energized state or the power failure state,
Backup area including the resolver and the excitation circuit
Is connected in parallel with the main DC power source to supply power.
In an absolute position detector including a battery pack, one end of each of the detection coils (12a, 12b) is
Connect in common and connect the detector coil (12a, 12b)
At the other end of each via a high pass filter (61)
Connect resolver / digital (R / D) converter (6)
And a motion detector for detecting a motion state of the rotor,
According to the detection signal from the energization detector, a pulse with a duty of 1: n (n> 1) when the rotor is stopped at the time of a power failure, and when there is a power failure and an operating state by the detection signal from the operation detector An absolute position detecting device, comprising: a pulse switch that switches a pulse having a duty of 1: m (1 <m <n) so that the exciting circuit outputs the pulse. 2. The absolute position detection device according to claim 1, wherein the m is variable according to the rotation speed of the rotor.