JP2007263731A - Absolute angle detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absolute angle detector having high resolution utilizing a chain code such as an M code. <P>SOLUTION: An incremental signal string 2 and first and second digital signal strings 3, 4 are formed on a code plate 1, and four detection elements 5, 6, 7, 8 corresponding to respective signal strings are arranged. The first and second digital signal strings 3, 4 are formed so that a prescribed number of chain codes are generated when an inversion number of times of a first digital signal C1 detected from the first digital signal string 3 within a pulse width (between adjacent bits) of an A-phase pulse and an inversion number of times of a second digital signal C2 detected from the second digital signal string 4 within a pulse width of a B-phase pulse whose phase is delayed by 90° from that of the A-phase pulse. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an absolute angle detection device, and more particularly to means for improving the resolution of an absolute angle detection device using a chain code such as an M code.

  Conventionally, as an absolute angle detection device used for a steering angle detection device of an automobile, a plurality of detection elements are arranged in a predetermined arrangement along a signal train formed on a code plate that rotates integrally with a rotating body such as a steering shaft. And detecting the absolute rotational position of the rotating body by generating a digital code from each pulse signal output from each detecting element as the code plate rotates.

  FIG. 5 and FIG. 6 are diagrams showing an example of this type of absolute angle detecting device known conventionally, FIG. 5 is a schematic diagram showing the distribution of tracks on the code plate, and FIG. 6 shows individual detecting elements. It is explanatory drawing of the 8-bit code word produced | generated from the output signal output from each of these output signals. As shown in FIG. 5, in the absolute angle detection device of this example, an incremental track 101 and a code track 102 for indicating an absolute value code are formed concentrically on a code plate 100, and two pieces are formed along the incremental track 101. The detection elements 103 and 104 are disposed, and one detection element 105 is disposed along the code track 102 (see, for example, Patent Document 1).

  As shown in FIGS. 6A and 6B, the two detection elements 103 and 104 arranged along the incremental track 101 have an A-phase pulse whose phase is shifted by 90 ° as the code plate 100 rotates. A B-phase pulse is output. In addition, as shown in FIG. 6C, a code pulse is output from one detection element 105 arranged along the code track 102 as the code plate 100 rotates.

As shown in FIGS. 6C and 6D, the code track 102 has a rise of the code pulse between the rise of the A-phase pulse and the rise of the B-phase pulse whose phase is delayed by 90 °. Is assigned a code “1” and a code “0” is assigned when no code pulse rises, a 6-bit chain code is obtained as the code plate 100 rotates, and the rise of the A-phase pulse and B When the rising edge of the phase pulse is added as a code “1”, an 8-bit chain code is obtained. Thereby, in the absolute angle detection apparatus of this example, 240 different angle values can be defined.
JP 2000-504409 A

  However, the absolute angle detection device according to the conventional example detects whether or not there is a code pulse rise from the rise of the A phase pulse to the rise of the B phase pulse whose phase is delayed by 90 °. There is a problem that it is difficult to perform high-resolution angle detection.

  That is, as shown by hatching in FIG. 7, the rise and fall of the pulse signal output from the detection element includes a track manufacturing error, a detection element arrangement error during assembly, and a code plate or detection element during use. Usually, a certain amount of fluctuation is caused by the vibration of the. Therefore, in order to reliably detect the presence or absence of the rise of the code pulse between the rise of the A phase pulse and the rise of the B phase pulse whose phase is delayed by 90 °, the pulses of the A phase pulse and the B phase pulse are detected. The width must be set sufficiently large, and it is structurally difficult to increase the resolution of the detection angle.

  The present invention has been made to solve such deficiencies of the prior art, and an object of the present invention is to provide an absolute angle detection device having a high resolution using a chain code such as an M code.

  In order to solve the above problems, the present invention firstly corresponds to the code plate, the incremental signal sequence formed on the code plate, the first and second digital signal sequences, and each of these signal sequences. And the first and second digital signal sequences are within the pulse width of the A-phase pulse detected from the incremental signal sequence, that is, between adjacent bits (rising edge). The number of inversions of the first digital signal detected from the first digital signal sequence between the bit and the falling bit or between the falling bit and the rising bit) and the detection from the incremental signal sequence When the inversion times of the second digital signal detected from the second digital signal sequence are arranged in order within the pulse width of the B phase pulse whose phase is delayed by 90 ° from the A phase pulse, a predetermined bit is obtained. And the configuration that the number of chain codes are formed so as to be generated.

  In addition, the present invention secondly, a code plate, an incremental signal sequence formed on the code plate, first and second digital signal sequences, and a plurality of signals arranged corresponding to each of these signal sequences. A detection element; and an arithmetic processing unit that takes in signals output from the plurality of detection elements and outputs a rotation angle signal corresponding to the rotation angle of the code plate, and the first and second digital signal sequences are , The number of inversions of the first digital signal detected from the first digital signal sequence within the pulse width of the A phase pulse detected from the incremental signal sequence, and the phase detected from the incremental signal sequence and from the A phase pulse. When the inversion count of the second digital signal detected from the second digital signal sequence is arranged in order within the pulse width of the B-phase pulse delayed by 90 °, a chain of a predetermined number of bits A code is generated, and the arithmetic processing unit generates a chain code having a predetermined number of bits by sequentially combining the inversion number of the first digital signal and the inversion number of the second digital signal. The chain code is compared with a table stored in advance in the arithmetic processing unit, and an absolute angle signal corresponding to each chain code is output.

  According to this configuration, the number of inversions of the first digital signal is detected within the pulse width of the A-phase pulse, and the number of inversions of the second digital signal within the pulse width of the B-phase pulse whose phase is delayed by 90 ° from the A-phase pulse. Therefore, the first and second digital signals are compared with the case where the presence or absence of the rise of the code pulse is detected between the rise of the A-phase pulse and the rise of the B-phase pulse whose phase is delayed by 90 °. The formation margin of the signal string can be increased.

  In the first or second absolute angle detection device according to the present invention, the first digital signal is not inverted at the timing of the rising bit and the falling bit of the A-phase pulse, and the B-phase pulse is not inverted. The second digital signal is not inverted at the timing of the rising and falling bits.

  According to this configuration, the first digital signal is not inverted at the timing of the rising and falling bits of the A-phase pulse, and the second digital signal is generated at the timing of the rising and falling bits of the B-phase pulse. Since it is not inverted, the number of inversions of the first digital signal within the pulse width of the A-phase pulse and the number of inversions of the second digital signal within the pulse width of the B-phase pulse can be reliably detected.

  Further, in the second absolute angle detection device according to the present invention, the arithmetic processing unit includes angle information based on the absolute angle signal corresponding to the chain code immediately after the absolute angle signal corresponding to the chain code is determined. It is desirable to compare the rotation angle of the code plate calculated by counting the number of pulses of the A-phase pulse or the B-phase pulse and output the absolute angle signal when they coincide.

  According to such a configuration, an error in the absolute angle signal can be detected, so that the fail-safe property of the absolute angle detection device can be ensured.

  The absolute angle detection device of the present invention detects the number of inversions of the first digital signal within the pulse width of the A-phase pulse, and the second digital signal within the pulse width of the B-phase pulse delayed by 90 ° from the A-phase pulse. Since the number of inversions of the signal is detected, the first and the second are compared with the case where the presence or absence of the rise of the code pulse is detected between the rise of the A-phase pulse and the rise of the B-phase pulse whose phase is delayed by 90 °. 2 can increase the formation margin of the digital signal sequence, improve the resolution by narrowing the pulse width of the A-phase pulse and the B-phase pulse, or within the pulse width of the A-phase pulse and the pulse width of the B-phase pulse. The resolution can be improved by increasing the number of inversions of the first digital signal and the second digital signal.

  Hereinafter, an embodiment of an absolute angle detection device according to the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a configuration diagram of an absolute angle detection device according to the embodiment, FIG. 2 is an explanatory diagram illustrating a principle of chain code generation in the absolute angle detection device according to the embodiment, and FIG. 3 is generated by the absolute angle detection device according to the embodiment. FIG. 4 is a waveform diagram showing the effect of the absolute angle detection device according to the embodiment. FIG. 4 is a table showing the relationship between the chain cord and the absolute rotation angle of the code plate.

    As shown in FIG. 1, the absolute angle detection device of this example includes a code plate 1, an incremental signal sequence 2 formed on the code plate 1, first and second digital signal sequences 3 and 4, and these Four detection elements 5, 6, 7, and 8 arranged corresponding to each signal sequence 2, 3, 4, and each detection signal SignalA, output from the plurality of detection elements 5, 6, 7, 8 It comprises an arithmetic processing unit 9 that takes in SignalB, SignalC1, and SignalC2 and outputs an absolute angle signal corresponding to the rotation angle of the code plate.

  The code plate 1 is connected to a rotating body (not shown) such as a steering shaft and is rotated integrally with the rotating body.

  As shown in FIG. 2, the incremental signal sequence 2 and the two detection elements 5 and 6 arranged corresponding thereto are composed of an A phase signal (Signal A) and a B phase that are 90 ° out of phase with the incremental signal sequence 2. A signal (SignalB) is output. In addition, the first digital signal sequence 3 and the detection elements 7 arranged corresponding to the first digital signal sequence 3 generate a first digital signal (SignalC1) that is inverted a predetermined number of inversions within the pulse width of the A-phase signal. Configured to output. Further, the second digital signal sequence 4 and the detection element 8 arranged corresponding thereto, a second digital signal (SignalC2) that is inverted a predetermined number of inversions within the pulse width of the B phase signal. Configured to output. Here, the pulse width refers to the width of a pulse between adjacent bits (between a rising bit and a falling bit or between a falling bit and a rising bit).

  That is, in the example of FIG. 2, the first digital signal is inverted three times within the pulse width from the rising edge to the falling edge of the first A-phase signal after the code plate 1 starts rotating. The second digital signal is not inverted within the pulse width from the rising edge to the falling edge of the B phase signal whose phase is shifted by 90 ° from the rising edge of the A phase signal. Next, the first digital signal is inverted twice within the pulse width from the falling edge of the first A-phase signal to the rising edge, and the phase B is shifted by 90 ° from the rising edge of the second A-phase signal. The second digital signal is not inverted even within the pulse width from the fall of the signal to the rise. Next, the first digital signal is inverted twice within the pulse width from the rising edge to the falling edge of the second A-phase signal, and the phase B is shifted by 90 ° from the rising edge of the second A-phase signal. The second digital signal is inverted twice within the pulse width from the rising edge to the falling edge of the signal. Next, the first digital signal is inverted four times within the pulse width from the falling edge to the rising edge of the second A-phase signal, and the phase is shifted by 90 ° from the falling edge of the second A-phase signal. The second digital signal is inverted twice within the pulse width from the falling edge to the rising edge of the phase signal. Further, as is clear from this figure, in this example, the first digital signal is not inverted at the rising and falling timings of the A-phase pulse, and the second digital signal at the rising and falling timings of the B-phase pulse. The digital signal is not inverted.

  The arithmetic processing unit 9 arranges the number of inversions of the first digital signal C1 and the number of inversions of the second digital signal C2 output from the detection elements 7 and 8 in order, and stores them by three steps. In the example of FIG. 2, since the number of inversions of each digital signal changes to (3, 0, 2, 0, 2, 2, 4, 2), storing for three steps (3, 0, 2) , (0,2,0), (2,0,2), (0,2,2), (2,2,4), (2,4,2) .

  As shown in FIG. 3, the arithmetic processing unit 9 stores a table indicating the relationship between the step number, the absolute angle of the code plate 1, the detection code, and the three-step chain code. Every time a three-step chain code is detected, the unit 9 compares the table in FIG. 3 and outputs an absolute angle signal of the code plate 1 corresponding to the three-step chain code. In FIG. 3, only a table for 120 steps (180 °) is shown, but for steps 121 to 240, steps 1 to 120 are repeated, and the first digital signal C1 and the second digital signal are displayed. Because the position of the signal C2 is reversed. Absolute angles up to 360 ° can be detected.

  The absolute angle detection device of this example detects the number of inversions of the first digital signal C1 within the pulse width of the A phase pulse, and the second within the pulse width of the B phase pulse whose phase is delayed by 90 ° from the A phase pulse. Since the number of inversions of the digital signal C2 is detected, as shown in FIG. 4, the presence / absence of the rise of the code pulse is detected between the rise of the A phase pulse and the rise of the B phase pulse whose phase is delayed by 90 °. Compared to the case, the formation margin of the first and second digital signal sequences C1 and C2 can be increased, the resolution is improved by narrowing the pulse width of the A-phase pulse and the B-phase pulse, or the A-phase pulse The resolution can be improved by increasing the number of inversions of the first digital signal C1 and the second digital signal C2 within the pulse width and within the pulse width of the B-phase pulse.

Further, the absolute angle detection device of this example does not invert the first digital signal C1 at the timing of the rising and falling bits of the A phase pulse, and the rising and falling bits of the B phase pulse. Since the second digital signal C2 is not inverted at the timing, the number of inversions of the first digital signal C1 within the pulse width of the A-phase pulse and the number of inversions of the second digital signal C2 within the pulse width of the B-phase pulse are reliably detected. In the absolute angle detection device, the angle information based on the absolute angle signal corresponding to the chain code immediately after the absolute angle signal corresponding to the chain code is determined (a predetermined number of bits is stored). And the rotation angle of the code plate 1 calculated by counting the number of pulses of the A-phase pulse or the B-phase pulse, and match The absolute angle detection signal may be output when the signal is output. In this way, since an error in the absolute angle signal can be detected, the fail-safe property of the absolute angle detection device can be ensured.

  In the above embodiment, an example of a code when one sector is 180 ° and the resolution is 1.5 ° is shown. However, the gist of the present invention is not limited to this, and the angle allocated to one sector is shown. Of course, the code can be appropriately set according to the resolution.

It is a block diagram of the absolute angle detection apparatus which concerns on embodiment. It is explanatory drawing which shows the production | generation principle of the chain code in the absolute angle detection apparatus which concerns on embodiment. It is a table | surface figure which shows the relationship between the chain cord produced | generated with the absolute angle detection apparatus which concerns on embodiment, and the absolute rotation angle of a code board. It is a wave form diagram which shows the effect of the absolute angle detection apparatus which concerns on embodiment. It is the schematic which shows distribution of the track | truck on the code | cord board of the absolute angle detection apparatus concerning a prior art example. It is explanatory drawing of the 8-bit code word produced | generated from each output signal and the output signal output from each detection element in the absolute angle detection apparatus which concerns on a prior art example. It is a wave form diagram which shows the problem of the absolute angle detection apparatus which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Code board 2 Incremental signal sequence 3 1st digital signal sequence 4 2nd digital signal sequence 5, 6, 7, 8 Detection element 9 Arithmetic processing part SignalA A phase signal SignalB B phase signal SignalC1 1st digital signal SignalC2 2nd Digital signal

Claims (4)

A code plate, an incremental signal sequence and first and second digital signal sequences formed on the code plate, and a plurality of detection elements arranged corresponding to each of these signal sequences,
The first and second digital signal sequences include the number of inversions of the first digital signal detected from the first digital signal sequence within the pulse width of the A-phase pulse detected from the incremental signal sequence, and the incremental signal. A predetermined bit when the inversion count of the second digital signal detected from the second digital signal sequence is arranged in order within the pulse width of the B phase pulse detected from the sequence and delayed in phase by 90 ° from the A phase pulse. An absolute angle detecting device, wherein a number of chain codes are generated. A code plate, an incremental signal sequence formed on the code plate, first and second digital signal sequences, a plurality of detection elements arranged corresponding to each of these signal sequences, and a plurality of detection elements An arithmetic processing unit that captures an output signal and outputs a rotation angle signal corresponding to the rotation angle of the code plate;
The first and second digital signal sequences include the number of inversions of the first digital signal detected from the first digital signal sequence within the pulse width of the A-phase pulse detected from the incremental signal sequence, and the incremental signal. A predetermined bit when the inversion count of the second digital signal detected from the second digital signal sequence is arranged in order within the pulse width of the B phase pulse detected from the sequence and delayed in phase by 90 ° from the A phase pulse. Formed to generate a number of chain codes,
The arithmetic processing unit generates a chain code having a predetermined number of bits by sequentially combining the inversion number of the first digital signal and the inversion number of the second digital signal, and the generated chain code is stored in the arithmetic processing unit. An absolute angle detection device that outputs an absolute angle signal corresponding to each chain cord in contrast to a table stored in advance.   The first digital signal is not inverted at the rising and falling timings of the A-phase pulse, and the second digital signal is not inverted at the rising and falling timings of the B-phase pulse. The absolute angle detection device according to claim 1 or 2.   The arithmetic processing unit counts the angle information by the absolute angle signal corresponding to the chain code and the number of pulses of the A-phase pulse or the B-phase pulse immediately after the absolute angle signal corresponding to the chain code is determined. 3. The absolute angle detection device according to claim 2, wherein the absolute angle signal is output when the code angle and the rotation angle of the code plate calculated as described above coincide with each other.

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