CN114754803A

CN114754803A - Through-hole type encoder safety redundancy system and method

Info

Publication number: CN114754803A
Application number: CN202110020748.8A
Authority: CN
Inventors: 魏花
Original assignee: Wuxi Demochuan Electronic Technology Co ltd
Current assignee: Wuxi Demochuan Electronic Technology Co ltd
Priority date: 2021-01-08
Filing date: 2021-01-08
Publication date: 2022-07-15

Abstract

The invention relates to the technical field of encoders, in particular to a safety redundancy system and method for a through-hole encoder. After the system is powered on, the invention divides the encoder into several large intervals to obtain coarse codes; The phase difference with the main code channel M is used to obtain the secondary coarse code and the fine code, and form the current position; the eddy current induction signal of the inductance coil is solved by the inductance-digital converter to obtain the current absolute position; the absolute position of S3 is used for error correction, Correct the wrong position information calculated by the optical vernier; connect with the multi-turn signal, and output a digital signal with high safety redundancy through the RS485 bus protocol. The invention exerts the high precision and anti-magnetic properties of the optical encoder, and avoids the encoder safety risk caused by pollution. The eddy current inductive encoder is used to correct and correct the error of the optical encoder, which reduces the loss of encoder precision caused by the aging of the LED light source and improves the service life of the encoder.

Description

Through-hole type encoder safety redundancy system and method

Technical Field

The invention relates to the technical field of encoders, in particular to a through hole type encoder safety redundancy system and a through hole type encoder safety redundancy method.

Background

The encoder can be classified into an optical type, a magnetic type, an inductive test type and a capacitive type according to the detection principle, and in short, the optical encoder is composed of a slotted code wheel and an LED light source on the photoelectric and magnetic reverse side of one side. When the code wheel rotates, the light path is projected to photocell through the code wheel, and the photocell outputs digital quantity information in certain rule when the code wheel rotates in different positions.

An alternating magnetic field is generated when an alternating current flows through the inductor. If a conductive material, such as a metal object, is brought into proximity with the inductor, the magnetic field will induce circulating currents (eddy currents) at the surface of the conductor as shown in FIG. 1.

The eddy currents generate their own magnetic field, which is opposite to the original magnetic field generated by the inductor coil. This effect is equivalent to a set of coupled inductors, where the inductor coil is the primary winding and the eddy currents in the object under test are the secondary inductances. The resistance and inductance of the secondary winding caused by eddy currents can be equated to distance-dependent resistance and inductance components on the primary side (coil). Figure 2 shows a simplified circuit of the sensor and the target as a coupling coil.

Eddy currents are a function of the conductor distance, size and shape composition. The larger the area of the code wheel shape covering the coil, the larger the intercepted electromagnetic field. As more magnetic field flux is intercepted, the eddy currents increase, the effective inductance of the coil generating the magnetic field decreases, and the LC oscillation frequency increases.

The tested code disc is designed into an eccentric circle, and the coil groups A and B are placed under the rotary code disc at 90 degrees to each other as shown in figure 3. A positive and residual signal A and B shown in figure 4 can be obtained by rotating the code wheel, and the absolute rotation angle of 360 degrees can be measured by resolving the signal A and the signal B.

Taking the vernier principle design scheme of the most representative optical encoder chip manufacturer iC-HAUS as an example, three code channel vernier principles are adopted, namely a main code channel M, a vernier code channel N and a segment code channel S. The phase shift of these three positive signals is used to calculate the angle of the absolute position by interpolating the subdivision, and the angle is defined as shown in fig. 5.

According to the non-integrated design scheme, the output signals of the photocells shown in the figure 6 are processed by an analog circuit and then are processed by an MCU (microprogrammed control unit) to calculate the absolute position of the encoder, and the MCU carries out orthogonal counting to calculate Hall signals to obtain multi-turn information of the encoder. Finally, multi-circle absolute position coding information is synthesized. And sending the data to the control equipment in an RS485 communication output mode.

The existing optical encoder has high precision and small volume, and is widely applied in China for years. There is still a disadvantage that in dusty and dirty environments such as industrial applications, contaminants can accumulate on the code wheel, preventing the transmission of LED light to the photocell, thus greatly affecting the accuracy and reliability of the optical encoder.

The service life of the LED light source is limited, and the light source gradually weakens along with the prolonging of the service life and finally can be damaged. Resulting in encoder failure.

The traditional magnetic encoder design structure is formed by mounting magnetic steel at the center of the tail end of a mechanical shaft and a PCB with a magnetic induction chip at the upper end of the magnetic steel. This structure is limited in the design of the center hole of the through-hole type encoder, and the accuracy of the magnetic encoder itself is not high. Therefore, the design of the through-hole type encoder mostly adopts the design scheme of the optical encoder, and even if the design scheme of the optical encoder is adopted, the influence of dust and dirt cannot be avoided, so that the high protection requirement is provided for outdoor and severe environment, the service life cost is high, the safety redundancy is poor, and the application in many industries is limited.

Disclosure of Invention

Aiming at the defects of the prior art, the invention discloses a through hole type encoder safety redundancy system and a method, aiming at ensuring that an optical encoder can not only exert high-precision characteristics, but also can safely operate in dust, dirt and severe environments.

The invention is realized by the following technical scheme:

in a first aspect, the invention discloses a safety redundancy method for a through hole type encoder, which comprises the following steps:

The S1 system is electrified, and the encoder is divided into a plurality of large intervals to obtain coarse codes;

s2, obtaining secondary coarse codes and fine codes by using the phase difference between the cursor code channel N and the main code channel M, and forming the current position;

s3, resolving the eddy current induction signal of the inductance coil through an inductance digital converter to obtain the current absolute position;

s4, correcting errors through the absolute position of S3, and correcting error position information calculated by the optical vernier;

and S5 is connected with the multi-turn signal and outputs a digital signal with high safety redundancy through an RS485 bus protocol.

Furthermore, in the method, the processor divides the encoder into a plurality of large intervals by the periodic phase difference of the segment code channel S to the main code channel M to obtain the coarse code.

Furthermore, in the method, the processor calculates the eddy current induction signals of the two induction coils a and B through the inductance-to-digital converter to obtain the current absolute position.

In a second aspect, the invention discloses a safety redundancy system of a through hole type encoder, which is used for executing the safety redundancy method of the through hole type encoder in the first aspect, and is characterized by comprising a power management circuit, a photocell, an analog input circuit, a Hall quadrature counting circuit, an inductance digital conversion module, an RS485 output circuit and an MCU.

Furthermore, the MCU includes a memory storing execution instructions, and when the system executes the execution instructions stored in the memory, the system executes the method for safely redundancy through-hole encoder according to the first aspect.

The beneficial effects of the invention are as follows:

the invention gives play to the high precision and diamagnetism of the optical encoder, and avoids the safety risk of the encoder caused by pollution. The eddy current induction type encoder is used for correcting and correcting the error of the optical encoder, so that the accuracy loss of the encoder caused by the aging of the LED light source is reduced, and the service life of the encoder is prolonged.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is an eddy current induction schematic;

FIG. 2 is an equivalent circuit diagram;

FIG. 3 is a view of coil sets A and B positioned 90 degrees from each other below the rotating code wheel;

FIG. 4 is a diagram of the positive and negative signals A and B;

FIG. 5 is a diagram of an integrated circuit design;

FIG. 6 is a diagram of a non-integrated circuit design;

fig. 7 is a circuit diagram of a safety redundancy system of a through-hole type encoder.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The embodiment discloses a through hole type encoder safety redundancy method, which comprises the following steps:

And S5 is connected with the multi-turn signal, and outputs a digital signal with high safety redundancy through an RS485 bus protocol.

In this embodiment, the processor divides the encoder into a plurality of large intervals by the periodic phase difference of the segment code channel S to the main code channel M to obtain the coarse code.

In this embodiment, the processor obtains the current absolute position by resolving the eddy current induction signals of the two inductor coils a and B through the inductance-to-digital converter.

This embodiment adopts the optical encoder principle and combines together with the electric eddy current sensing principle in order to let optical encoder can be in the safe operation under dust, dirt and adverse circumstances, and the design rotational position sensor is designed to the utilization eddy current sensing principle, and the absolute position of optical encoder and rotational position sensor is solved out to rethread treater mixture. And correcting the code track information of the optical encoder by using the absolute position measured by the rotary position sensor.

Example 2

The embodiment discloses a safety redundancy system of a through-hole type encoder as shown in fig. 7, which comprises a power management circuit, a photocell, an analog input circuit, a hall quadrature counting circuit, an inductance digital conversion module, an RS485 output circuit and an MCU.

In this embodiment, the MCU includes a memory storing an execution instruction, and when the system executes the execution instruction stored in the memory, the system executes the pass-through encoder security redundancy method.

The redundant design of the optical encoder circuit and the eddy current induction type encoder circuit is not limited to the optical encoder circuit and the eddy current induction type encoder circuit, and can be any combination of other types of encoding circuits such as the optical encoder circuit, the inductive circuit, the capacitive circuit and the magnetic circuit.

The invention is applicable to a through hole type hardware circuit, and a non-through hole type hardware circuit.

In conclusion, the invention exerts the high precision and diamagnetism of the optical encoder and avoids the safety risk of the encoder caused by pollution. The eddy current induction type encoder is used for correcting and correcting the error of the optical encoder, so that the accuracy loss of the encoder caused by the aging of the LED light source is reduced, and the service life of the encoder is prolonged.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. a through-hole encoder safety redundancy method, is characterized in that, described method comprises the following steps:

The S1 system is powered on, and the encoder is divided into several large intervals to obtain the rough code;

S2 utilizes the phase difference of the vernier code track N and the main code track M to obtain the secondary coarse code and the fine code, and form the current position;

S3 obtains the current absolute position by solving the eddy current induction signal of the inductance coil through the inductance digital converter;

S4 performs error correction through the absolute position of S3, and corrects the wrong position information calculated by the optical vernier;

S5 connects with multi-turn signals and outputs digital signals with high safety redundancy through RS485 bus protocol.

2. through-hole encoder safety redundancy method according to claim 1, is characterized in that, in described method, processor divides encoder into several by the periodic phase difference of segment code channel S to main code channel M A large interval gets a coarse code.

3. The through-hole encoder safety redundancy method according to claim 1, wherein in the method, the processor calculates the eddy current induction signals of the two inductance coils A and B through an inductance-to-digital converter Get the current absolute position.

4. A through-hole encoder safety redundancy system, the system is used to implement the through-hole encoder safety redundancy method according to any one of claims 1-3, characterized in that, comprising a power management circuit , Photocell, analog input circuit, Hall quadrature counting circuit, inductance digital conversion module, RS485 output circuit and MCU.

5. The through-hole encoder safety redundancy system according to claim 4, wherein the MCU comprises a memory storing execution instructions, and when the system executes the execution instructions stored in the memory, The system implements the through-hole encoder safety redundancy method of any one of claims 1 to 3.