JP5343680B2 - Encoder - Google Patents

Description

  The present invention relates to an encoder used as, for example, a position sensor or a rotation angle sensor in an industrial robot.

  An example of an encoder is an absolute encoder. As a basic operation of a conventional absolute encoder and a technique for detecting an error of an absolute angular position, one described in Patent Document 1 is known. In such a conventional absolute encoder, the M-sequence pattern is scanned by a plurality of bits when the power is turned on from the code board on which the M-sequence pattern is recorded in advance. Since the scanned data is M-sequence data, the absolute angle position can be determined after conversion to binary data. After the absolute value is determined, the counting operation is performed by the change of the incremental signal. An example of a circuit block for performing a conventional counting operation is shown in FIG.

  For example, data obtained by scanning a plurality of bits of the M-sequence pattern at power-on is copied (stored) as information (plural bits) on the M-sequence pattern into a shift register in the circuit. The M-sequence data stored in the circuit generates the next data (1 bit) by a polynomial such as an M-sequence generation polynomial while changing the shift direction according to the change of the incremental signal.

  On the other hand, 1 bit is detected from the M-sequence pattern after the absolute angle position is determined for error detection of the absolute angle position.

  Then, one bit scanned from the M-sequence pattern is compared with one bit generated in the circuit, and if they match, no abnormality is detected, and if they do not match, an abnormality is detected. As a cause of detecting an error in the absolute value in this case, for example, there may be a case where there is a foreign object on the code board or a case where noise is superimposed.

  The timing of comparison between the two signals is from the rising edge of the A phase when the B phase of the incremental signal is “H”, or from the falling edge to the rising or falling edge of the A phase when the B phase is “L”. If the two do not match and do not match for two cycles of the incremental signal (continuous twice), it is detected as an error in the absolute angular position. FIG. 6 shows detection timing as an example.

Japanese Patent Laid-Open No. 5-118872

  In recent years, there has been an increasing demand for absolute encoders with higher safety performance in industrial robots. However, in the conventional absolute encoder described above, if an incremental signal is not output at all (does not change), it may not be possible with conventional absolute angular position error detection. This is because the change of the incremental signal is used for error detection of the absolute angular position.

  That is, the conventional encoder has a problem in that when the incremental signal is not output, the abnormality may not be detected even if there is an error in the absolute angular position.

  The present invention has been made in view of such circumstances, and its purpose is to detect whether or not there is an error in absolute angular position information even when an incremental signal is not output at all. It is to provide a safer encoder.

The present invention has been made to solve the above-described problems, and an encoder according to an embodiment of the present invention is based on a code read from a code board on which a code indicating an absolute angular position of a rotary shaft is recorded. An absolute angle position generation unit that calculates one absolute angle position, an update unit that updates the first absolute angle position based on an incremental signal input in response to the rotation of the code board, and the code board A first abnormality detector that determines whether or not the second absolute angle position based on the read code matches the first absolute angle position; a rotational speed detector that detects the rotational speed of the code board; A reading determination unit that determines whether or not the code is normally read from the code board, and the first abnormality detection unit is a rotation speed at which the rotation speed detected by the rotation speed detection unit is predetermined. Whether or not the second absolute angle position matches the first absolute angle position when it is determined that the code is normally read from the code board by the reading determination unit. Determine.
An encoder according to an embodiment of the present invention includes an absolute angle position generation unit that calculates a first absolute angle position based on a code read from a code board on which a code indicating the absolute angle position of the rotating shaft is recorded; A plurality of elements for reading a code recorded on the code board; a code reading unit for reading a plurality of codes recorded on the code board by each of the plurality of elements; and the code board rotating The first absolute angle position is updated based on an incremental signal input in response to the signal, and is read by a plurality of elements included in the code reading unit in response to a change in the incremental signal. A code for updating the plurality of codes based on a plurality of codes and a change in the incremental signal, the plurality of elements included in the code reading unit An update unit that generates a first code corresponding to a code read by some of the elements, and the generated first code and the code in response to the update unit generating the first code A second abnormality detection unit that determines whether or not a second code read by a part of the plurality of elements of the reading unit matches .

  According to the present invention, even when no incremental signal is output, it is possible to detect whether or not there is an error in the absolute angular position information, and there is an effect that is more secure.

It is a block diagram which shows the structure of the encoder by one Embodiment of this invention. It is a schematic diagram which shows the operation | movement as an example of the shift register part and code | symbol production | generation part of FIG. It is a 1st flowchart which shows operation | movement of the encoder by this embodiment. It is a 2nd flowchart which shows operation | movement of the encoder by this embodiment. It is a block diagram which shows an example of the circuit block which performs the conventional count operation | movement. FIG. 6 is a timing chart showing detection timing as an example by the circuit block performing the conventional counting operation shown in FIG. 5.

<Principle of Encoder according to this Embodiment>
First, the principle of the encoder according to the present embodiment will be described. When the power is turned on, the M-sequence pattern is scanned by a plurality of bits to determine the absolute angular position. At the same time as determining the absolute angular position, information (a plurality of bits) on the M-sequence pattern is copied to the shift register in the circuit. After the absolute angle position is determined, the counting operation is performed by changing the incremental signal.

  The M-sequence pattern after the absolute angle position is determined detects only one bit for detecting an absolute angle position error. The M-sequence data stored in the circuit generates the next data (1 bit) by a polynomial while changing the shift direction according to the change of the incremental signal.

  Here, let us consider a case where the incremental signal is not output due to some influence. For example, it is assumed that a circuit that detects an incremental signal fails or a circuit that amplifies an incremental signal fails.

  When the power is turned on, the absolute angle position is determined by reading the M series pattern, and then the above-described counting operation is performed by the change of the incremental signal. However, when the incremental signal is not output, the incremental signal is not output (changed) even though the code board is rotating, so the circuit side has stopped rotating the code board (and thus the rotation shaft). Misidentified as a condition. In other words, the first absolute angular position obtained by counting according to the change in the incremental signal should change, but always maintains the same value.

  Since this state is an error as absolute angle position information, it must be detected as an abnormality. However, in the conventional detection, an error in the absolute angle position is detected using the incremental signal as described above. If is not output, there is a problem that it may not be detected correctly.

  Here, as a means for solving the above-described problem, the same scan operation as when the power is turned on, even when the power is turned on, so that it can be detected that there is an error in the absolute angular position even when the incremental signal is not output. When the absolute angle position that is updated when the power is turned on and updated according to the change in the incremental signal is compared with the absolute angle position that is obtained by scanning other than when the power is turned on. A comparison circuit (a first abnormality detection unit to be described later) is added to determine that if is normal (there is no error in the absolute angle position) and does not match (there is an error in the absolute angle position).

  In other words, the first absolute angle position obtained by scanning when the power is turned on and obtained by changing the incremental signal after the power is turned on, and the second absolute angle position obtained by scanning other than when the power is turned on to be added this time By comparing, it can be determined whether there is an error in the absolute angular position information.

  In the above comparison circuit, it is not necessary to provide comparison timing as in the case of conventional error detection of absolute angular position information, and it is only necessary to perform comparison at the time when the scanning operation is completed, so that an incremental signal is not required for error detection. . Further, since there is no need to change the direction of the shift register as in the conventional error detection of absolute angle position information, this also does not require an incremental signal.

  When the scan operation is performed at times other than when the power is turned on, the code board may be rotating, so that it is relatively difficult to perform the scan operation normally while the code board is rotating at high speed. Therefore, it is desirable to monitor the incremental signal and perform the scanning operation when the code board is rotating at a low speed.

  By doing so, the first absolute angle position information obtained by scanning when the power is turned on matches the absolute angle position information obtained by scanning other than when the power is turned on.

  In the case of an abnormality, let us consider a case where the code board is rotating at a high speed and no incremental signal is output. Since the incremental signal is not output, the scan operation is performed by misinterpreting it as a stop, but the M-sequence pattern data cannot be normally scanned because the code board is rotating at high speed, and there is an error in the absolute angular position information. to decide.

  Next, let us consider a case where an incremental signal is not output when the code board rotates at a low speed or is stopped after the code board has rotated to some extent. The absolute angle position obtained by scanning when the power is turned on does not change from the absolute angle position scanned when the power is turned on because no incremental signal is output. On the other hand, the absolute angle position obtained by scanning other than when the power is turned on is after the code board has already rotated. Therefore, unlike the scanned absolute angle position when the power is turned on, they do not match and the absolute angle position information is incorrect. It can be judged that there is.

  As described above, in the above-described embodiment, even if the incremental signal is not output, the scan is executed after the power is turned on, and the absolute angle position information is obtained by comparing with the obtained absolute angle position when the power is turned on. It becomes possible to detect whether or not there is an error, and a safer absolute encoder can be provided.

<Configuration as an example of the principle of the encoder according to the present embodiment>
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing a configuration of an encoder 100 according to an embodiment of the present invention.

  Here, the code indicating the absolute angle position of the rotation axis recorded on the code board is an M-sequence pattern, and it is assumed that the absolute angle position can be obtained by converting 8 consecutive bits of this M-sequence pattern. . In addition, the encoder 100 is controlled by the host control device, and description will be made assuming that the detected absolute angle position is output to the host control device.

  The encoder 100 includes an incremental signal input unit 1, a code reading unit 2, a rotation speed detection unit 3, a reading determination unit 4, an update unit 5, an absolute angular position generation unit 6, and a first abnormality detection unit 8. A second abnormality detection unit 9, an initial setting unit, and a control unit.

  The absolute angle position generation unit 6 obtains a first absolute angle position based on a code read from a code board on which a code indicating the absolute angle position of the rotating shaft is recorded, and updates the absolute angle position based on the incremental signal. .

  The incremental signal input unit 1 receives an incremental signal from the code board in response to the rotation of the code board, and outputs the input incremental signal. For example, when an incremental track is recorded on the code board, the incremental signal input unit 1 reads the incremental track and outputs an incremental signal. In addition, when a magnet is attached to the code board, the incremental signal input unit 1 causes the magnet attached to the code board to be rotated by a detection device such as a magnetic detection element (eg, Hall element). In response, an incremental signal is output. This incremental signal is, for example, a two-phase rectangular wave signal of A phase and B phase (see FIG. 6).

  The code reading unit 2 has a plurality of elements for reading the codes recorded on the code board, and reads the plurality of codes recorded on the code board by each of the plurality of elements. The plurality of elements are arranged in advance so that a plurality of codes recorded on the code board can be read. Each of the elements is, for example, a light receiving sensor.

  The code reading unit 2 can read a plurality of codes (a plurality of bits) corresponding to the absolute angle position from the code board by using a plurality of elements arranged in sequence.

  In addition, the code reading unit 2 is configured so that a part of a plurality of codes corresponding to the absolute angle position is obtained by a predetermined part of the plurality of elements arranged in order. A code (for example, a code for 1 bit) can be read from the code board as a second code. For example, among the plurality of elements arranged in order, the element disposed at the first end and the element disposed at the second end are the specific part of the elements. Correspond.

  In addition, as will be described later, as described later, an incremental signal is used to determine which element of the element disposed at the first end and the element disposed at the second end. It is determined by the direction of rotation of the base code board.

  The rotational speed detector 3 detects the rotational speed of the code board. For example, the rotation speed detection unit 3 detects the rotation speed of the code board based on the number of changes in the incremental signal output from the incremental signal input unit 1 in unit time or the cycle in which the incremental signal changes.

  The reading determination unit 4 determines whether or not the code has been normally read from the code board. For example, the code reading unit 2 reads a plurality of codes (a plurality of bits) from a code board, and the plurality of codes have a predetermined polynomial relationship. The reading determination unit 4 determines whether or not a plurality of codes (a plurality of bits) read from the code board by the code reading unit 2 satisfy a predetermined polynomial relationship. Determines whether the code has been successfully read from the code board.

  Further, the reading determination unit 4 determines whether or not the code has been normally read from the code reading unit 2 and the code board when the rotation speed detected by the rotation speed detection unit 3 is slower than a predetermined rotation speed. .

  The update unit 5 causes the absolute angle position generation unit 6 to update the first absolute angle position based on the incremental signal input in response to the rotation of the code board.

  In addition, the update unit 5 receives a plurality of codes based on a plurality of codes read by a plurality of elements included in the code reading unit 2 and changes in the incremental signals in response to a change in the incremental signal. Is generated, and a first code corresponding to a code read by a part of the plurality of elements of the code reading unit 2 is generated. Then, the update unit 5 causes the absolute angle position generation unit 6 to update and store the first absolute angle position based on the generated first code. That is, the update unit 5 outputs the first sign to the absolute angular position generation unit 6.

  The absolute angle position generation unit 6 reads the first absolute angle position read by the code reading unit 2 (the first absolute angle position stored in the absolute angle position generation unit 6 or the first absolute angle position based on the first code). Based on the incremental signal input from the incremental signal input unit 1, an absolute angular position is generated and output to the host controller.

  The first abnormality detection unit 8 determines whether or not the second absolute angle position based on the code read from the code board matches the first absolute angle position read from the absolute angle position generation unit 6.

  In addition, the first abnormality detection unit 8 detects the absolute value of the second absolute angular position based on the code read from the code board and the absolute value when the rotation speed detected by the rotation speed detection unit 3 is slower than a predetermined rotation speed. It is determined whether or not the first absolute angular position read from the angular position generation unit 6 matches.

  The first abnormality detection unit 8 is a case where the rotation speed detected by the rotation speed detection unit 3 is slower than a predetermined rotation speed, and the reading determination unit 4 correctly reads the code from the code board. When it is determined that the reading has been performed, it is determined whether or not the second absolute angle position based on the code read from the code board matches the first absolute angle position read from the absolute angle position generation unit 6.

  In addition, the first abnormality detection unit 8 determines whether or not it is a timing for determining an abnormality, and when it is a timing for determining an abnormality, the first absolute angle position and absolute value based on the code read from the code board are absolute. It is determined whether or not the first absolute angular position read from the angular position generation unit 6 matches.

  For example, the first abnormality detection unit 8 has a second absolute angle position based on a code read from the code board and a first absolute angle position read from the absolute angle position generation unit 6 at predetermined intervals. You may make it determine whether it corresponds. In this case, it is determined whether or not the determination of whether or not the predetermined cycle is a predetermined timing.

  Further, based on the input incremental signal, the determination as to whether or not the number of times the first absolute angle position of the absolute angle position generation unit 6 has been updated by the update unit 5 has exceeded a predetermined value is as described above. The timing may be determined.

  In response to the first code being generated by the updating unit 5, the second abnormality detection unit 9 is a part of the plurality of elements included in the generated first code and the code reading unit 2. It is determined whether or not the second code read by the above matches.

  In addition, the second abnormality detection unit 9 responds that the first code is generated by the code generation unit 52 when the rotation speed detected by the rotation speed detection unit 3 is faster than a predetermined rotation speed. It is determined whether or not the generated first code matches the second code read by some of the plurality of elements of the code reading unit 2.

  When the encoder 100 main body is activated, or when a control signal indicating that the first absolute angle position is stored in the absolute angle position generation unit 6 is input from the host controller, the initial setting unit starts from the code board. The absolute angle position generation unit 6 stores the first absolute angle position based on the read code.

  The initial setting unit performs the same processing as that of the updating unit 5 when the main body of the encoder 100 is activated or when a control signal indicating that the first absolute angle position is stored in the absolute angle position generation unit 6 is input. do. Therefore, the update unit 5 may have the function of an initial setting unit. In the configuration diagram of FIG. 1, a configuration in which the updating unit 5 and the initial setting unit are integrated is shown.

  The control unit controls each component included in the encoder 100. That is, the control unit controls the entire encoder 100.

<Configuration of update unit 5>
Next, a configuration as an example of the update unit 5 will be described. The update unit 5 includes a shift register unit 51, a code generation unit 52, and a second conversion unit 53.

  The shift register unit 51 stores a plurality of codes read from the code board by the code reading unit 2. Here, the shift register unit 51 stores a code for 8 bits.

  The code generation unit 52 includes a plurality of codes based on a plurality of codes read by a plurality of elements included in the code reading unit 2 and changes in the input incremental signals in response to changes in the incremental signal. A first code corresponding to a code read by a part of the plurality of elements of the code reading unit 2 is generated.

  Further, the code generation unit 52 reads a plurality of codes stored in the shift register unit 51 in response to a change in the incremental signal, and based on the read plurality of codes and a change in the incremental signal. Then, the first code described above is calculated and generated by a predetermined polynomial based on a plurality of codes among the plurality of read codes. Note that whether the first code is calculated based on any of the plurality of codes read out by the code generation unit 52 is determined based on the rotation direction of the code board based on the input incremental signal. .

  Then, the code generation unit 52 updates the plurality of codes stored in the shift register unit 51 based on the generated code. For example, the code generation unit 52 updates a plurality of codes stored in the shift register unit 51 by shifting right or left, based on the generated code. Whether the code generation unit 52 shifts to the right or left is determined based on the rotation direction of the code board based on the input incremental signal.

  The second conversion unit 53 converts the plurality of codes read from the shift register unit 51 into the first absolute angle position, and causes the absolute angle position generation unit 6 to store the converted first absolute angle position. The first absolute angle position stored in the absolute angle position generation unit 6 is updated. For example, the second conversion unit 53 converts M-sequence data that is a plurality of codes read from the shift register unit 51 into first absolute angle positions that are binary data.

<Configuration of first abnormality detection unit 8>
Next, a configuration as an example of the first abnormality detection unit 8 will be described. The first abnormality detection unit 8 includes a buffer unit 81, a first conversion unit 82, and a determination unit 83.

  The buffer unit 81 stores a plurality of codes read by a plurality of elements included in the code reading unit 2.

  The first conversion unit 82 includes a plurality of codes read by a plurality of elements included in the code reading unit 2, and converts the plurality of codes stored in the buffer unit 81 into the second absolute angle position. Convert. For example, like the second conversion unit 53, the first conversion unit 82 converts M-sequence data that is a plurality of codes stored in the buffer unit 81 into a second absolute angular position that is binary data. .

  The determination unit 83 determines whether or not the second absolute angle position converted by the first conversion unit 82 matches the first absolute angle position read from the absolute angle position generation unit 6.

<Specific example as an example of a code | cord | chord board, the code reading part 2, and the update part 5>
Next, a specific example as an example of the code board, the code reading unit 2 and the updating unit 5 will be described with reference to FIG. In the figure, portions corresponding to the respective portions in FIG.

  On the code board, for example, codes “Z, A, B, C, D, E, F, G, I, J” are sequentially recorded as M-sequence patterns. Each symbol indicates “0” or “1”, and the value is distinguished by a color or the like. This one code corresponds to 1 bit.

  Each code has a polynomial relationship. For example, a code generated by a predetermined polynomial from the code A, the code B, and the code D has a relationship that matches the code G. Assuming that the relative relationship in the code order is constant, all codes recorded on the code board have a relationship based on this polynomial.

  The code reading unit 2 includes eight elements as an element m1, an element m2, an element m3, an element m4, an element m5, an element m6, an element m7, and an element m8 as a plurality of elements arranged in order. ing. Each element reads an M-sequence pattern code of 1 bit recorded on the code board corresponding to the position where each element is arranged.

  Here, when the main body of the encoder 100 is activated, the code read by each element of the code reading unit 2 is stored corresponding to the plurality of storage units included in the shift register unit 51. For example, the code A read by the element m1 of the code reading unit 2 is stored in the first storage unit included in the shift register unit 51.

  Similarly, the code B read by the element m2 of the code reading unit 2 is stored in the second storage unit included in the shift register unit 51. The codes read by the eight elements of the code reading unit 2 in this way are stored in the eight storage units included in the shift register unit 51.

  Thereafter, the code generator 52 is a code for updating a plurality of codes in response to the code board rotating and the A-phase and B-phase incremental signals being input. A first code corresponding to a code read by a part of the plurality of elements is generated.

  For example, when an incremental signal indicating that the code board has rotated in the first direction is input, the code to be read next is J. In this case, the code generation unit 52 generates the first code corresponding to the code J by the above-described polynomial based on the code stored in the shift register unit 51 that can generate the code J. Based on the generated first code, the code generation unit 52 shifts and updates the plurality of codes stored in the shift register unit 51 in the case of FIG.

  In addition, the code reading unit 2 is a specific element that is predetermined among a plurality of elements in response to the input of an incremental signal indicating that the code board has rotated in the first direction. The code J is read from the code board by a certain element m8.

  Thereafter, the second abnormality detection unit 9 determines whether or not the first code generated by the code generation unit 52 of the update unit 5 matches the code read by the element m8 of the code reading unit 2. .

  On the contrary, for example, when the code board rotates in the second direction, if the code to be read next is code Z, the code generation unit 52 can similarly generate the code Z by the above-described polynomial. Based on the code stored in the unit 51, a first code corresponding to the code Z is generated. Then, the code generation unit 52 updates the plurality of codes stored in the shift register unit 51 by shifting to the right in the case of FIG. 2 based on the generated first code.

  In addition, the code reading unit 2 is a specific element that is predetermined among a plurality of elements in response to the input of an incremental signal indicating that the code board has rotated in the second direction. The code Z is read from the code board by a certain element m1.

  Thereafter, the second anomaly detection unit 9 detects the first code generated by the code generation unit 52 of the update unit 5 and the element m1 of the code reading unit 2 in the same manner as when the code board rotates in the first direction. It is determined whether or not the code read by the above matches.

  In this way, the second abnormality detection unit 9 similarly detects an abnormality in the detected absolute angular position regardless of whether the code board rotates in the first direction or the second direction. can do.

  As described above, all codes recorded on the code board have a polynomial relationship. Therefore, the reading determination unit 4 can determine whether or not the code can be normally read from the code board by determining whether or not the read code satisfies the relationship of this polynomial.

<Operation as an Example of Principle of Encoder according to this Embodiment>
Next, the operation when detecting an abnormality in the encoder 100 will be described with reference to FIGS. Here, it is assumed that the encoder 100 has already been activated and the first absolute angle position is stored in the absolute angle position generation unit 6 in advance. Further, the update unit 5 will be described as updating the first absolute angle position stored in the absolute angle position generation unit 6 based on an incremental signal input in response to the rotation of the code board.

  First, the rotational speed detector 3 detects the rotational speed of the code board (step S101). Next, the rotation speed detector 3 determines whether or not the detected rotation speed is faster than a predetermined rotation speed (step S102).

  If it is determined in step S102 that the rotational speed detected by the rotational speed detection unit 3 is slower than a predetermined rotational speed, it is time to determine abnormality by the first abnormality detection unit 8 Is determined (step S103). For example, the control unit determines whether or not it is time to determine abnormality by the first abnormality detection unit 8.

  If it is determined in step S103 that the first abnormality detector 8 does not determine the abnormality, the process from step S101 is repeated.

  On the other hand, when it is determined in step S103 that the first abnormality detection unit 8 determines the timing for abnormality, the code reading unit 2 reads a plurality of codes recorded on the code board (step S103). S104). The plurality of codes read by the code reading unit 2 are stored in the buffer unit 81 of the first abnormality detection unit 8 and are output to the reading determination unit 4.

  Next, the reading determination unit 4 determines whether or not the code has been normally read from the code board (step S105). In step S105, when the reading determination unit 4 determines that the code has not been read normally from the code board, the reading determination unit 4 detects an abnormality (step S109). For example, when the reading determination unit 4 detects an abnormality, the reading determination unit 4 outputs an error signal indicating that the code cannot be normally read from the code board to the host control device.

  On the other hand, if the reading determination unit 4 has successfully read the code from the code board in step S <b> 105, a plurality of first conversion units 82 of the first abnormality detection unit 8 are stored in the buffer unit 81. Is converted into the second absolute angle position (step S106).

  Next, the determination unit 83 of the first abnormality detection unit 8 reads the first absolute angle position based on the code read from the code board from the absolute angle position generation unit 6 (step S107).

  Next, the determination unit 83 of the first abnormality detection unit 8 determines the second absolute angle position converted by the first conversion unit 82 of the first abnormality detection unit 8 in step S106 and the absolute angle in step S107. It is determined whether or not the first absolute angle position read from the position generator 6 matches (step S108).

  In this step S108, when the first abnormality detection unit 8 determines that the second absolute angle position based on the code read from the code board does not match the first absolute angle position read from the absolute angle position generation unit 6 First, the first abnormality detection unit 8 detects an abnormality (step S109). For example, the first abnormality detection unit 8 controls the error signal indicating that the second absolute angle position based on the code read from the code board and the first absolute angle position read from the absolute angle position generation unit 6 do not coincide with each other. Output to the device.

  On the other hand, in step S108, the first abnormality detection unit 8 determines that the second absolute angle position based on the code read from the code board matches the first absolute angle position read from the absolute angle position generation unit 6. In that case, the processing from step S101 is repeated.

  On the other hand, in step S102 described above, if it is determined that the rotation speed detected by the rotation speed detection unit 3 is not slower (faster) than a predetermined rotation speed, the incremental signal input unit 1 outputs the rotation speed. It is determined whether or not the incremental signal has changed (step S120). The determination in step S120 is performed by a control unit (not shown), for example.

  If it is determined in step S120 that the incremental signal output from the incremental signal input unit 1 has not changed, the processing from step S101 is repeated.

  On the other hand, if it is determined in step S120 that the incremental signal output from the incremental signal input unit 1 has changed, the code reading unit 2 uses a part of the absolute angular position information (for example, 1). The code for bits) is read from the code board as the second code (step S122).

  Next, the code generation unit 52 reads a plurality of codes stored in the shift register unit 51 in response to a change in the incremental signal (step S123).

  The code generation unit 52 calculates and generates the first code described above using a predetermined polynomial based on the plurality of codes read out in step S123 and the change in the incremental signal (step S124). .

  Next, the second abnormality detection unit 9 matches the second code read by the code reading unit 2 in step S122 with the first code generated by the code generation unit 52 included in the update unit 5 in step S124. It is determined whether or not to perform (step S124).

  If the read second code does not match the generated first code in step S124, the second abnormality detection unit 9 detects an abnormality (step S126). For example, the second abnormality detection unit 9 outputs an error signal indicating that the read second code and the generated first code do not match to the host controller.

  On the other hand, if the read second code matches the generated first code in step S124, the processing from step S101 is repeated.

  Further, even when the incremental signal is not output by the processing from step S103 to step S109 described above, that is, by the processing when the rotation speed of the code board is low, the encoder 100 according to the present embodiment performs the first operation. It is determined whether or not the absolute angle position matches the second absolute angle position, and when both do not match, it can be determined that there is an abnormality.

  That is, when the incremental signal is not output, the first absolute angle position obtained by scanning at power-on does not change from the first absolute angle position scanned at power-on. On the other hand, since the second absolute angle position obtained by scanning other than when the power is turned on changes according to the rotation of the code board, it is determined that the encoder 100 in this embodiment is abnormal. Is possible.

  Further, the encoder 100 according to the present embodiment performs the first code generated by the incremental signal and the code reading unit 2 by the processing from step S121 to step S126 described above, that is, by the processing when the rotation speed of the code board is high. By determining whether or not the second code read by some of the plurality of elements coincides, it is possible to detect an abnormality in the detected absolute angular position.

  As described above, the encoder 100 according to the present embodiment is capable of detecting the abnormality of the detected absolute angular position even when the rotation speed of the code board is low or the rotation speed of the code board is high so that an incremental signal is not output. Can be detected.

  When the rotation speed of the code board is fast, the encoder 100 according to the present embodiment determines whether or not the first absolute angle position and the second absolute angle position match by the processing from step S103 to step S109 described above. The reason for not doing so is as follows.

  As a first reason, when the rotation speed of the code board is fast, there is a possibility that the code reading unit 2 cannot normally read a plurality of codes from the code board.

  As a second reason, even if the code reading unit 2 can normally read a plurality of codes from the code board when the rotation speed of the code board is high, the first conversion unit 82 can read the plurality of codes read out. May take a long time to convert to the second absolute angular position. Generally, a predetermined time is required for the conversion to the second absolute angle position by the first conversion unit 82. For this reason, when the rotation speed of the code board is fast, there is a possibility that the first conversion unit 82 cannot convert the second absolute angle position before the determination unit 83 executes the determination. In this case, the determination unit 83 cannot determine whether the second absolute angle position converted by the first conversion unit 82 matches the first absolute angle position read from the absolute angle position generation unit 6.

  For the above reason, the code reading unit 2 reads only a part of the absolute angle position information (for example, a code for one bit) from the code board when the rotation speed of the code board is fast, and from step S121. Abnormality of the absolute angular position is detected by the processing when the rotation speed of the code board described in step S126 is high.

  As described above, the encoder 100 according to the present embodiment limits the reading performance of the code reading unit 2 regardless of whether the code board rotation speed is low or the code board rotation speed is high so that an incremental signal is not output. And the abnormality of the detected absolute angular position can be detected without depending on the limit of the conversion process of the first conversion unit 82.

  In the above description, the first conversion unit 82 outputs the converted second absolute angle position directly to the determination unit 83. However, the present invention is not limited to this, and the first conversion unit 82 may temporarily store the converted second absolute angle position in a storage circuit such as a buffer circuit. Then, after the determination unit 83 reads the second absolute angle position from the storage circuit, whether the read second absolute angle position matches the first absolute angle position read from the absolute angle position generation unit 6 or not. It may be determined.

  By the way, at the timing when the incremental signal changes, the updating unit 5 described above updates the first absolute angular position stored in the absolute angular position generating unit 6. Therefore, even if it is the timing determined in step S103 of FIG. 3, the first abnormality detection unit 8 has the second absolute angle position and the second absolute angle position at the timing when the incremental signal changes at the timing when the incremental signal changes. It is desirable not to determine whether or not one absolute angle position matches.

  That is, the first abnormality detection unit 8 determines whether or not it is a determination timing, determines whether or not the incremental signal is changed, and determines whether or not the incremental signal is changing. If not, it is desirable to determine whether or not the second absolute angle position based on the code read from the code board matches the first absolute angle position read from the absolute angle position generation unit 6.

  It should be noted that if the incremental signal changes by determining whether the incremental signal changes immediately before or after step S103 or step S103 in FIG. 3, the absolute angular position generation is performed according to the change of the incremental signal. Considering that the first absolute angle position stored in the unit 6 is updated, the first abnormality detection unit 8 determines whether or not the second absolute angle position matches the first absolute angle position. You may make it determine.

  In the description of the above embodiment, the case where the code indicating the absolute angular position of the rotating shaft recorded on the code board is an M-sequence pattern has been described, but the present invention is not limited to this. The code indicating the absolute angular position of the rotating shaft recorded on the code board may be a binary code or a gray code.

  As for the incremental signal, each incremental code corresponding to a code indicating the absolute angular position of the rotating shaft recorded on the code board may be used. In addition, regardless of which series or code the code indicating the absolute angle position is, a magnet is attached to the code board, and a magnetic detection element (eg, Hall element or magnetoresistive element) is detected. An incremental signal may be generated and output by the device in response to rotation of the code board to which the magnet is attached.

  The incremental code desirably has a finer pitch than the code indicating the absolute angular position of the rotating shaft recorded on the code board. Moreover, the update part 5 and the 2nd abnormality detection part 9 may perform the same determination as a prior art.

  The absolute angle position generation unit 6 includes a nonvolatile memory such as a flash memory, a volatile memory such as a RAM (Random Access Memory), a hard disk device, a magneto-optical disk device, or a combination thereof. The structure which has a memory | storage part may be sufficient.

  In addition, the rotation speed detection unit 3, the reading determination unit 4, the update unit 5, the absolute angle position generation unit 6, the first abnormality detection unit 8, the second abnormality detection unit 9, the initial setting unit, or the control unit in FIG. Each configuration may be realized by dedicated hardware, or may be realized by a memory and a microprocessor.

  In addition, each of these configurations may be configured by a computer such as a memory and a microprocessor, and the function may be realized by loading a program for realizing the function of each configuration into the memory and executing the program. .

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design and the like within a scope not departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Incremental signal input part, 2 ... Code reading part, 3 ... Rotation speed detection part, 4 ... Reading determination part, 5 ... Update part, 6 ... Absolute angle position generation part, 8 ... 1st abnormality detection part, 9 ... 2nd abnormality detection part, 51 ... Shift register part, 52 ... Code generation part, 53 ... 2nd conversion part, 81 ... Buffer part, 82 ... 1st conversion part, 83 ... Determination part, 100 ... Encoder

Claims (7)

An absolute angle position generator that calculates a first absolute angle position based on a code read from a code board on which a code indicating the absolute angle position of the rotation axis is recorded;
An update unit for updating the first absolute angle position based on an incremental signal input in response to the rotation of the code board;
A first abnormality detection unit that determines whether or not the second absolute angle position based on the code read from the code board matches the first absolute angle position;
A rotational speed detector for detecting the rotational speed of the code board;
A reading determination unit for determining whether or not the code is normally read from the code board;
With
The first abnormality detector is
When the rotation speed detected by the rotation speed detection unit is slower than a predetermined rotation speed, and when the reading determination unit determines that the code is normally read from the code board, the first It is determined whether 2 absolute angle position and said 1st absolute angle position correspond. Encoder characterized by the above-mentioned. The reading determination unit
When the rotation speed detected by the rotation speed detection unit is slower than a predetermined rotation speed, it is determined whether or not the code is normally read from the code board,
The encoder according to claim 1. A plurality of elements for reading a code recorded on the code board; and a code reading unit for reading a plurality of codes recorded on the code board by each of the plurality of elements,
The first abnormality detector is
A first converter that converts a plurality of codes read by a plurality of elements of the code reader into the second absolute angle position;
3. The determination unit according to claim 1, further comprising: a determination unit that determines whether or not the second absolute angle position converted by the first conversion unit matches the first absolute angle position. The described encoder. The update unit
A code for updating the plurality of codes based on a plurality of codes read by a plurality of elements included in the code reading unit and changes in the incremental signals in response to a change in the incremental signal. And generating a first code corresponding to a code read by a part of the plurality of elements of the code reading unit,
In response to the generation of the first code by the updating unit, the generated first code and a second code read by some of the plurality of elements of the code reading unit A second abnormality detector for determining whether or not they match,
The encoder according to claim 3, further comprising: The second abnormality detector is
Wherein when the rotational speed of the rotation speed detection unit detects is faster than the rotational speed is predetermined, said in response to the first code is generated by the update unit, the first code and the code is the generated The encoder according to claim 4, wherein it is determined whether or not the second code read by a part of the plurality of elements of the reading unit matches. When the encoder body is activated or when a control signal indicating that the first absolute angle position is stored in the absolute angle position generation unit is input, the first absolute based on the code read from the code board The encoder according to claim 1, further comprising an initial setting unit that stores an angular position in the absolute angular position generation unit. An absolute angle position generator that calculates a first absolute angle position based on a code read from a code board on which a code indicating the absolute angle position of the rotation axis is recorded;
A plurality of elements for reading a code recorded on the code board; a code reading unit for reading a plurality of codes recorded on the code board by each of the plurality of elements;
A plurality of elements included in the code reading unit in response to the first absolute angle position being updated based on an incremental signal input in response to rotation of the code board and the incremental signal being changed. A code for updating the plurality of codes on the basis of the plurality of codes read by and a change in the incremental signal, and a part of the plurality of elements of the code reading unit An updating unit for generating a first code corresponding to the code read by
In response to the generation of the first code by the updating unit, the generated first code and a second code read by some of the plurality of elements of the code reading unit A second abnormality detection unit that determines whether or not they match,
An encoder comprising:

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