JPH11148843A - Detection method for bit skip in sampling encoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of sampling data by always comparing previous sampling data and the present sampling data, comparing the absolute value of the difference and a set value and detecting a bit skip. SOLUTION: This sampling encoder 1 has a rotary detector 1a outputting an encoder signal 1aA, sampling data 2 is output from a sampling pulse detector 1d and an abnormal signal 3 form a bit skip detector 1g. That is, in the bit skip detector 1g, previous sampling data 2 and the present sampling data 2 are always compared and the difference is obtained as an absolute value. This absolute value is compared with a set value formed by maximum bit number in the same sampling angle range as the preset sampling data 2. When this absolute value is larger than the maximum bit number, an abnormal signal 3 indicating that the sampling encoder 1 is abnormal is output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bit skip detection method in a sampling encoder, and more particularly, to a method of constantly comparing previous sampling data with current sampling data and comparing the absolute value of the difference with a preset value. And a new improvement for detecting bit skipping of sampling data.

[0002]

2. Description of the Related Art Conventionally, in this type of sampling encoder used, only a function of outputting sampling data, and no function of detecting bit skipping has been employed.

[0003]

The conventional sampling type encoder has the following problems because it is configured as described above. That is, since the bit skipping detection function was not provided, even if bit skipping occurred in the sampling data, it could not be detected, and there was a problem in the reliability of the sampling data, and the accuracy of the control system using this sampling data deteriorated. There was something to do.

[0004] The present invention has been made to solve the above problems, and in particular, always compares the previous sampling data with the current sampling data, and compares the absolute value of the difference with a preset value in advance. It is an object of the present invention to provide a bit skipping detection method in a sampling type encoder which detects bit skipping of sampling data.

[0005]

According to the present invention, there is provided a bit skip detection method in a sampling encoder according to the present invention, which samples an encoder signal obtained from a rotation detector at regular time intervals to obtain an output of sampling data. In the encoder, the previous sampling data and the current sampling data are constantly compared, the difference is obtained as an absolute value, and the absolute value is set in advance to a set value including the maximum number of bits in the same sampling angle range as the sampling data. And outputting an abnormal signal indicating that the sampling encoder is abnormal when the absolute value is larger than the maximum number of bits.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a bit skip detection method in a sampling encoder according to the present invention will be described below with reference to the drawings. In FIG. 1, what is indicated by reference numeral 1 is a sampling encoder. The sampling encoder 1 includes a rotation detector 1a that outputs an encoder signal 1aA, an optical connector 1b,
It comprises a waveform shaping circuit 1c, a sampling pulse detector 1d, a clock generator 1e, a synchronizing circuit 1f, and a bit skip detection unit 1g. The sampling pulse detector 1d outputs sampling data 2, and the bit skip detection unit 1g outputs An abnormal signal 3 is output.

The bit skip detector 1g is configured as shown in FIG. That is, the sampling data 2 is input to the first comparator 12 via the first and second latch circuits 10 and 11, and the output of each of the latch circuits 10 and 11 is directly input to the third latch circuit 13 and the first comparator The output of the third latch circuit 1 is also transmitted through the first gate circuit 14 to the third latch circuit 1.
3 has been entered. The output of the third latch circuit 13 is subjected to subtraction processing by a subtracter 17 via second and third gate circuits 15 and 16 and is input to a second comparator 18. The set value 19a from the memory 19 in which the maximum number of bits at the same sampling angle (that is, the same time length) as the sampling data is stored as the set value 19a is constantly input. The second comparator 18
Is input to a fifth gate circuit 21 via a fourth gate circuit 20. The fifth gate circuit 21 has a fourth latch circuit 23 to which a sampling clock 22 is input.
From the latch output 23a.

Therefore, the sampling data 2 is supplied to the first latch circuit 10, the second latch circuit 11, the third latch circuit 13, and the first comparator 12 at a predetermined interval by a sampling operation.
The first sampling data A and the subsequent sampling data B are compared by the first comparator 12, and the third latch circuit 13 outputs the data to each of the gate circuits 15, 1.
The signal is input to the subtractor 17 through 6. In the subtracter 17, the data A and B are subtracted as A 'and B', and the difference is input to the second comparator 18 as an absolute value and compared with the set value 19a. The result of this comparison processing is that when A '<B', A 'is the set value 19a (B').
, The fifth gate circuit 21 becomes “HIGH” and an abnormal signal 3 is output, and when A ′ = B′K, the fifth gate circuit 21
The gate circuit 21 becomes "LOW" to indicate that it is normal, and the abnormal signal 3 is not output. Although the bit skip detection unit 1g in FIG. 2 is shown by hardware, it may be realized by software by CPU program processing.
In FIG. 1, the case of the optical fiber encoder has been described, but a known optical type or magnetic type may be used.

[0009]

The bit skip detection method in the sampling type encoder according to the present invention is configured as described above, so that the following effects can be obtained. That is, if there is a bit skip in the sampling data, an abnormal signal is output. Therefore, the control state of the control system can be changed using the abnormal signal, and the reliability of the sampling data can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a bit skip detection method in a sampling encoder according to the present invention.

FIG. 2 is a circuit diagram showing a bit skip detector of FIG. 1;

[Explanation of symbols]

 1a Rotation detector 1aA Encoder signal 2 Sampling data 3 Abnormal signal 19a Set value

Claims (1)

[Claims] 1. A sampling encoder in which an encoder signal (1aA) obtained from a rotation detecting section (1a) is sampled at regular intervals to obtain an output of sampling data (2). Always compare the current sampling data, find the difference as an absolute value, and compare the absolute value with a preset value (19a) consisting of the maximum number of bits in the same sampling angle range as the previously set sampling data (2). A bit skip detection method in the sampling encoder, wherein when the absolute value is larger than the maximum number of bits, an abnormal signal (3) indicating that the sampling encoder is abnormal is output.