JPH04104007A - Monitoring method for rotation step of rotary encoder - Google Patents

Abstract

PURPOSE:To identify the rotating direction and the number of the rotating steps accurately even if the change is quick by discriminating and storing the rotating direction at the low-speed rotation of a rotary encoder. CONSTITUTION:Whether a rotary encoder is rotated at a high speed or a low speed is discriminated with the rotary encoder 11 and a high- and low-speed discriminating part 12. Namely, when the level states of the signals in a phase A and in a phase B which are read at a specified sampling period are at the level states which are to be generated at the next time of the level states of the signals in the phase A and the phase B which have been read at the time one sampling before, the low speed is judged. When the level state is the level which is skipped by n(>=2) steps, the high speed is judged.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a rotation step monitoring method for a rotary encoder, particularly when the rotary encoder rotates at a high speed compared to the level reading speed of the A-phase and B-phase signals. , relates to a rotation step monitoring method that can correctly monitor rotation steps.

<Prior art> When a rotary encoder rotates, it generates two signals, A phase and B phase, with a predetermined phase difference (for example, 90') (see Figure 4).The levels of these A phase and B phase signals are In the case of rotation (Fig. 4(a)).

It changes periodically as 11 → 01 → OO → 10 → 11 → (1), and the phase of the 8 signal changes ahead of the phase of the B-phase signal. In addition, in the case of left rotation (Fig. 4 (b)), A
The level of phase and B phase signals is 11→10→O0-)01→1
1→...(2), and the phase of the A-phase signal changes later than the phase of the B-phase signal.

From the above, by monitoring whether the level status of the A phase and B8 signals is changing according to (1) or (2), the rotation direction of the rotary encoder can be identified, and the number of level changes can be counted. By doing so, the number of rotation steps can be identified.

<Problems to be Solved by the Invention> The periods of the A-phase and B-phase signals become shorter as the rotational speed of the rotary encoder becomes faster. For this reason.

While the rotary encoder is rotating at a low speed, the level state read at each sampling period will be as shown in (1) or (2) above, and each time the level state changes (
The number of rotational steps can be reliably recognized by counting +1 or -1 for each step.

However, the rotation of the rotary encoder becomes faster and A
When the change in the level state of the phase and B phase signals is shorter than the sampling period, the read level state will be (1) or (2).
The result is not as shown in Figure 2, and n steps are skipped.

For this reason, conventionally, when the rate of state change of the A-phase and B-phase signals is faster than the sampling rate, in other words, when the rotary encoder rotates at high speed, the rotation direction cannot be identified, and the number of rotation steps increases. There was also a problem that it could not be identified.

From the above, it is an object of the present invention to
To a certain extent, even if the state changes of phase and B phase signals are rapid,
It is an object of the present invention to provide a rotation step monitoring method for a rotary encoder that can correctly identify the rotation direction and the number of rotation steps.

Means for Solving the Problems> In the present invention, the above problems are solved by: means for determining the rotational direction of the rotary encoder at low speed; means for storing the rotational direction; and counting means for counting the number of rotational steps. means for determining whether it is rotating at low speed or high speed; and if it is a level state that should occur next, the count value of the counting means is increased by +1 or -1 depending on the rotation direction;
A level state skipped by n steps is achieved by means of increasing the count value by +n or -n depending on the direction of rotation.

Function: When the rotary encoder rotates at low speed, the direction of rotation is determined and memorized, and the level states of the A-phase and B-phase signals are read at a predetermined sampling period.

If the level is the level that should occur next to the state of the A-phase and B-phase signals read one sampling ago, the count value is increased by +1 or -1 depending on the direction of one rotation, and if the level is skipped by n steps, it is stored. The number of rotational steps of the rotary encoder is monitored by increasing the count value by +n or -n depending on the direction of rotation.

<Embodiment> FIG. 1 is a block diagram of an apparatus that implements a rotation step monitoring method for a rotary encoder according to the present invention. Reference numeral 11 denotes a rotary encoder, and 12 a high-speed/low-speed discrimination section, which discriminates whether the rotary encoder is rotating at a high speed or at a low speed. That is, the level state of the A-phase and B-phase signals read at a predetermined sampling period is 1.
If the level state should occur next to the level state of the A-phase and B-phase signals read before sampling, it is determined to be low speed, and if the level state is skipped by n (≧2) steps, it is determined to be high speed. The high speed/low speed discrimination section may be configured to set the speed to low when the number of A-phase signals or B-phase signals generated within a predetermined time is greater than or equal to a set value or less than high speed.

Reference numeral 13 denotes a rotational direction determining section, which determines the rotational direction of the rotary encoder 11 during low-speed rotation based on the level states of the A-phase and B-phase signals. That is, when the level states of phase A and phase B change in the order shown in (1) (11
→01 or 01→O0 or Oo→10 or 10→
If the rotation direction changes to 11), it is determined that the direction of one rotation is clockwise rotation, and if the rotation direction changes in the order shown in (2) (if the rotation changes from 11 to 10 or 10 to 00 or OO to 01 or 01 to 11), It is determined that the rotation is to the left.

Reference numeral 14 denotes a rotation direction storage unit that stores the rotation direction determined at low speed, and is configured to turn on the right rotation flag Fn when the vehicle is rotating clockwise, and turn on the left rotation flag Fr when the vehicle rotates counterclockwise. .

15 is a low speed table that is referred to when updating the count value at low speed, 16 is a high speed right rotation table that is referred to when high speed right rotation, and 17 is a high speed left rotation table that is referred to when high speed left rotation. It has the contents shown in FIG.

That is, during low-speed clockwise rotation, the level states of A phase and B phase read at a predetermined sampling period change in the order shown in (1), and during low-speed counterclockwise rotation, the level states of A phase and B phase are shown in (2). change in order. Therefore, the low speed table 15 is 11→O1 or 01-+00 or OO+1
When changing from 0 or 10 to 11, add the count value Cs to +
1 (Cs + 1 → Cs), and when it changes from 11 → 10 or 10 → oO or oo → 01 or 01 → 11, it instructs to decrease the count value Cs by 1 (
Cs-1→Cs).

Also, during high speed rotation, the level status of A phase and B phase is (1)
, does not change in the order shown in (2), but skips n steps. Therefore, the table 16 for high-speed clockwise rotation instructs Cs+n-+C to increase the count value C5 by n steps when the level states of the A phase and B phase jump by n steps during high-speed clockwise rotation.
s) The table 17 for high-speed left rotation changes the count value when the level status of phase A and phase B jumps n steps during high-speed left rotation.
It is designed to instruct to decrease Cs by -n (Cs-n-+Cs).The level states of the A phase and B phase return to their original state in 4 steps. Therefore, in the present invention, the number of rotational steps cannot be counted correctly in the case of high-speed rotation such as n≧4. In other words, if the number of steps is N, the number of rotation steps can be correctly monitored if the rotation is at a high speed up to (N-1) times the sampling speed, but if it is higher than that, the number of rotation steps cannot be monitored correctly. .

18 is a sub-counter that counts the number of rotational steps of the rotary encoder, and 19 is a rotational step monitoring control unit, which updates the count @ Cs using the low-speed table 15 during low-speed rotation, and uses the table 16 during high-speed clockwise rotation. Update count value Cs, and table 1 during high speed left rotation.
7 to update the count value Cs. Incidentally, the rotation step monitoring control section 19 stores the level states of the A-phase and B-phase signals one sampling ago.

FIG. 3 is a flowchart of the rotation step monitoring process according to the present invention, and the overall operation of FIG. 1 will be explained below in accordance with this flowchart.

At every predetermined period, the high speed/low speed discriminator 12 reads the A phase and B phase of the rotary encoder 11 (step 101),
Identify whether it is rotating at high speed or rotating at low speed (step 10)
2).

During low-speed rotation, the rotation step monitoring control unit 19
A phase before one sampling and at the current sampling time,
Counting processing (+1 processing, -
1 processing) from the low-speed table 15, and if +1 is specified, the count value Cs of the sub-counter 18 is incremented by +1, and -1
is specified, the count value Cs of the sub-counter 18 is -
1 (step 103).

Thereafter, the one-rotation direction determining unit 13 determines the rotation direction (step 104), and if it is a right rotation, turns on the right rotation flag Fn of the rotation direction storage unit 14 and turns off the left rotation flag Fr (step 105).

If the rotation is to the left, the left rotation flag is turned on and the right rotation flag is turned off (step 106).

Once the processing in step 105 or 106 is completed, the processing from step 101 onwards is repeated at every sampling time.

On the other hand, if it is rotating at high speed, the rotation step monitoring control section 19
In step 107), check whether the clockwise rotation flag Fn or the counterclockwise rotation flag Fr is on. The number n (=1 to 3) to be added is determined by referring to the level state of the signal, and the count [Cs of the sub-counter 18 is +counted (step 108
), and for left rotation, a high speed left rotation table 17,
A phase before one sampling and at the current sampling time,
With reference to the level state of the B-phase signal, the number to be subtracted n(
=1 to 3), and the count value Cs of the sub-counter 18 is incremented by -n (step 109).

Once the processing at step 108 or 109 is completed, the processing from step 101 onward is repeated at every sampling time.

<Effects of the Invention> According to the present invention, the rotation direction of the rotary encoder is determined and stored when the rotary encoder rotates at low speed.

The level state of the A-phase and B-phase signals read at a predetermined sampling period is the same as that of the A-phase and B-phase signals read one sampling ago.
If it is a level state that should occur next to the state of the phase signal, the count value will be increased by +1 or -1 depending on the direction of one rotation, and if it is a level state that has skipped n steps, the count value will be increased according to the memorized direction of rotation. Since the configuration is configured to monitor the number of rotational steps of the rotary encoder by setting +n or -n, it is possible to correctly identify the rotational direction and number of rotational steps even if the state changes of the A-phase and B-phase signals are faster than the sampling speed. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a device that implements the rotary encoder rotation step monitoring method according to the present invention, and FIG. 2 is a diagram showing the contents of a low-speed table, a high-speed clockwise rotation table, and a high-speed counterclockwise rotation table. FIG. 3 is a flowchart of rotation step monitoring processing according to the present invention, and FIG. 4 is a waveform diagram of A-phase and B-phase signals output from the rotary encoder. 11... Rotary encoder 12... High speed/low speed discrimination unit, 13... Rotation direction discrimination unit, 14... Rotation direction storage unit. 15...Low speed table. 16...Table for high-speed clockwise rotation, 17...Table for high-speed counterclockwise rotation 18...Sub counter 19...Rotation step monitoring control unit.

Claims (1)

[Claims] In a rotation step monitoring method for a rotary encoder that generates two signals of A phase and B phase that are out of phase with each other due to rotation, the rotation direction is determined and stored when the rotary encoder rotates at a low speed. The level states of the A-phase and B-phase signals read at the predetermined sampling period are the same as the A-phase and B-phase signals read one sampling ago.
If it is a level state that should occur next to the state of the phase signal, the count value is +1 or -1 depending on the rotation direction, and if it is a level state that has skipped n steps, the count value is counted according to the memorized rotation direction. A method for monitoring rotational steps of a rotary encoder, characterized in that the rotational steps of the rotary encoder are monitored by increasing a value by +n or -n.