A magnetic encoder

Abstract

The application discloses a magnetic encoder, comprising a rear bearing, a stator shell, a circular Hall circuit board, a shaft, a shaft disc, a rotor, an end cover, a front bearing and an outer ring magnetic ring, the stator shell is arranged at the front end of the end cover, the shaft penetrates the stator shell and the end cover, the shaft end of the shaft located at one side of the stator shell is limited by the rear bearing, and the shaft end of the shaft located at one side of the end cover is limited by the front bearing; the circular Hall circuit board, the outer ring magnetic ring, the shaft disc and the rotor are all arranged in the stator shell and penetrate the shaft in sequence along the direction from the rear bearing to the front bearing, the circular Hall circuit board is fixedly connected with the stator shell, the shaft disc and the rotor are both fixedly connected with the shaft, and the outer ring magnetic ring is sleeved with the outer ring of the shaft disc. The magnetic encoder has the characteristics of low cost, high resolution, high precision, high-speed measurement, flexible installation and no need of magnetic field calibration.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of magnetic encoding, and specifically relates to a magnetic encoder. BACKGROUND

[0002] A magnetic encoder is a common position sensor used to measure the position and movement of an object. It utilizes the characteristics of magnetic fields to achieve accurate position detection. A magnetic encoder typically consists of two parts: a magnetic scale and a sensor head. The magnetic scale in a magnetic encoder usually has fixed magnetic poles, while the sensor head contains magnetic field sensing elements such as Hall effect sensors or magnetoresistive sensors. When the magnetic poles on the magnetic scale pass through the sensor head, the magnetic field sensing elements will be affected by the magnetic field, generating corresponding electrical signals.

[0003] A Hall effect sensor is a sensor based on the Hall effect, which uses the deflection of charge carriers caused by a magnetic field to measure the strength and direction of a magnetic field. When the magnetic poles on the magnetic scale pass through the Hall effect sensor, it will sense the change in the magnetic field and generate a voltage or current output related to the strength of the magnetic field.

[0004] Magnetoresistive sensors, on the other hand, use the influence of a magnetic field on the electrical resistance of a material to measure the strength and direction of a magnetic field. When the magnetic poles on the magnetic scale pass through the magnetoresistive sensor, the external magnetic field will exert pressure on the material's magnetic domains, changing the electrical resistance. When the rotor magnetic pole passes through the sensor array, the resistance changes in a sinusoidal manner. The sensor head converts the sensed electrical signals into digital signals, which are then processed and decoded by the processing circuit. The decoding process converts the electrical signals into corresponding position information, such as angle or linear position.

[0005] However, existing magnetic encoders have the following problems in actual application:

[0006] (1) Low precision: compared with the same level of encoder, its detection precision is not as high as that of an optical encoder;

[0007] (2) High cost: the manufacturing and installation cost of a magnetic encoder is relatively high, especially in applications requiring high precision and high resolution;

[0008] (3) Temperature influence: temperature changes can affect the performance of a magnetic encoder, and the working temperature range of a magnetic encoder is relatively narrow. When the temperature exceeds the range, it may cause measurement deviation;

[0009] (4) Installation restrictions: the installation process of a magnetic encoder is relatively complex and requires proper installation conditions to work normally;

[0010] In addition, the existing magnetic encoder in actual application needs to be improved in terms of signal processing speed and positioning accuracy. SUMMARY

[0011] In view of the problems in the prior art, the present application provides a magnetic encoder with the characteristics of low cost, high resolution, high precision, high-speed measurement, flexible installation and no need for magnetic field calibration.

[0012] To achieve the above technical purpose, the present application adopts the following technical scheme: a magnetic encoder, comprising: a rear bearing, a stator shell, a circular Hall circuit board, a shaft, a shaft disc, a rotor, an end cover, a front bearing and an outer ring magnetic ring, the stator shell is arranged at the front end of the end cover, the shaft penetrates the stator shell and the end cover, the shaft end of the shaft located at one side of the stator shell is limited by the rear bearing, and the shaft end of the shaft located at one side of the end cover is limited by the front bearing; the circular Hall circuit board, the outer ring magnetic ring, the shaft disc and the rotor are all arranged in the stator shell and penetrate the shaft in turn along the direction from the rear bearing to the front bearing, the circular Hall circuit board is fixedly connected with the stator shell, the shaft disc and the rotor are both fixedly connected with the shaft, and the outer ring magnetic ring is sleeved on the outer ring of the shaft disc.

[0013] Further, the outer ring magnetic ring is composed of a plurality of magnetic strips arranged along the circumference.

[0014] Further, the side of the circular Hall circuit board close to the outer ring magnetic ring is provided with a first linear Hall element and a second linear Hall element; the other side of the circular Hall circuit board is provided with an embedded microprocessor and a baseband signal conditioning circuit, the input end of the baseband signal conditioning circuit is connected with the output end of the first linear Hall element and the output end of the second linear Hall element respectively, and the output end of the baseband signal conditioning circuit is connected with the A / D conversion input end of the embedded microprocessor.

[0015] Further, the first linear Hall element and the second linear Hall element are arranged at intervals along the circumference of the outer ring magnetic ring, and the interval is 1.5 times the length of the magnetic strip.

[0016] Further, the baseband signal conditioning circuit comprises: an inverting input proportional operational amplifier OP1, an adder OP2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6, one end of the first resistor R1 is connected with one end of the third resistor R3 and the inverting end of the inverting input proportional operational amplifier OP1 respectively, the non-inverting end of the inverting input proportional operational amplifier OP1 is connected with one end of the second resistor R2, the other end of the second resistor R2 is grounded, the output end of the inverting input proportional operational amplifier OP1 is connected with the other end of the third resistor R3 and one end of the fourth resistor R4 respectively, the other end of the fourth resistor R4 is connected with the inverting end of the adder OP2, one end of the fifth resistor R5 and one end of the sixth resistor R6 respectively, the other end of the fifth resistor R5 is connected with a power supply, the output end of the adder OP2 is connected with the other end of the sixth resistor R6, and the non-inverting end of the adder OP2 is grounded.

[0017] Further, the fourth resistance R4, the fifth resistance R5, and the sixth resistance R6 have equal resistance values, the ratio of the third resistance R3 to the first resistance R1 is an amplification factor, and the resistance value of the second resistance R2 is the inverse of the amplification factor.

[0018] Further, the baseband signal conditioning circuit conditions and amplifies the bipolar signal output by the first linear Hall element into a unipolar signal Further, the baseband signal conditioning circuit conditions and amplifies the bipolar signal output by the second linear Hall element into a unipolar signal Further, the baseband signal conditioning circuit conditions and amplifies the bipolar signal output by the second linear Hall element into a unipolar signal Further, the baseband signal conditioning circuit conditions and amplifies the bipolar signal output by the second linear Hall element into a unipolar signal Further, the baseband signal conditioning circuit conditions and amplifies the bipolar signal output by the second linear Hall element into a unipolar signal Further, the baseband signal conditioning circuit conditions and amplifies the bipolar signal output by the second linear Hall element into a unipolar signal

[0019] Further, the baseband signal conditioning circuit conditions and amplifies the bipolar signal output by the second linear Hall element into a unipolar signal

[0020] Further, the baseband signal conditioning circuit conditions and amplifies the bipolar signal output by the second linear Hall element into a unipolar signal

[0021] wherein VCC represents the voltage of a power supply.

[0022] Further, the embedded microprocessor comprises a baseband signal amplitude judging link, a correction integral link, and a sine and cosine lookup table link.

[0023] Further, the processing procedure of the embedded microprocessor is as follows:

[0024] Step S1: the A / D conversion port of the embedded microprocessor reads the unipolar signal output by the baseband signal conditioning circuit

[0025] Step S2: the signal sinθ (i) and cosθ (i) are constructed by querying the sine and cosine table with the current output position angle θ

[0026] Step S3: the angle swing quantity

[0027] Step S4: the angle swing quantity ε (i) is subjected to proportional integral processing to obtain an integral processing result wherein K P is a proportional coefficient, K I is an integral coefficient, j is the index of i, and k is the index of j.

[0028] Step S5: the integral processing result is accumulated to obtain the current rotation angle position θ(i) = θ (i-1) + Δθ (i) .

[0029] Compared with the prior art, the magnetic encoder has the following beneficial effects: the magnetic encoder has the characteristics of low cost due to its relatively simple structure design and commonly used hardware circuit; compared with the traditional encoder, by setting the baseband signal amplitude discrimination link, the correction integral link and the sine and cosine lookup table link, the magnetic encoder can provide higher precision, more reliable position measurement and feedback in application, and can also make up for the disadvantages that the photoelectric encoder cannot work in high temperature, humidity and severe vibration environment; in addition, the magnetic encoder has small size and weight, and is relatively simple to install and set, and is widely used in many applications, such as mechanical engineering, automation control, robot technology and medical equipment, etc., to provide accurate and reliable position feedback and help realize accurate motion control and positioning. The magnetic encoder can realize non-contact measurement without physical contact, thereby reducing the risk of wear and failure, and increasing its reliability and durability. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of the magnetic encoder of the present application;

[0031] Figure 2 It is an exploded view of the magnetic encoder of the present application;

[0032] Figure 3 It is a schematic diagram of the structure of the circular Hall circuit board in the present application;

[0033] Figure 4 It is a schematic diagram of the outer ring magnetic ring in the present application;

[0034] Figure 5 It is a schematic diagram of the baseband signal amplitude discrimination link of the present application;

[0035] Figure 6 It is a flow chart of the baseband signal amplitude discrimination link of the present application;

[0036] Figure 7 It is a signal conditioning circuit diagram in the present application;

[0037] Figure 8 It is a schematic diagram of the linear Hall signal corresponding to the magnetic pole in the present application;

[0038] 1 - rear bearing, 2 - stator housing, 3 - circular Hall circuit board, 4 - shaft, 5 - shaft disc, 6 - rotor, 7 - end cover, 8 - front bearing, 9 - first linear Hall element, 10 - outer ring magnetic ring, 11 - second linear Hall element, 12 - embedded microprocessor, 13 - baseband signal conditioning circuit. DETAILED DESCRIPTION

[0039] The technical solutions of the present application are further explained in combination with the drawings.

[0040] As Figures 1-2 The present application provides a magnetic encoder, comprising: a rear bearing 1, a stator housing 2, a circular Hall circuit board 3, a shaft 4, a shaft disc 5, a rotor 6, an end cover 7, a front bearing 8 and an outer ring magnetic ring 10, the stator housing 2 is arranged at the front end of the end cover 7, the shaft 4 penetrates the stator housing 2 and the end cover 7, the shaft end of the shaft 4 on one side of the stator housing 2 is limited by the rear bearing 1, and the shaft end of the shaft 4 on one side of the end cover 7 is limited by the front bearing 8; the circular Hall circuit board 3, the outer ring magnetic ring 10, the shaft disc 5 and the rotor 6 are all arranged in the stator housing 1 and penetrate the shaft 4 in turn along the direction from the rear bearing 1 to the front bearing 8, the circular Hall circuit board 3 is fixedly connected with the stator housing 2, the shaft disc 5 and the rotor 6 are both fixedly connected with the shaft 4, and the outer ring magnetic ring 10 is sleeved on the outer ring of the shaft disc 5. The magnetic encoder of the present application has the characteristics of low cost, small size and light weight, and is easy to install.

[0041] As Figure 4 In the present application, the outer ring magnetic ring 10 is composed of multiple magnetic strips arranged along the circumference, which can achieve higher resolution, each magnetic strip represents a discrete position, and more accurate position measurement can be achieved by detecting the change of each magnetic strip; at the same time, since the outer ring magnetic ring is composed of multiple magnetic strips, even if one of the magnetic strips is damaged or fails, position measurement can still be performed through other magnetic strips, this design improves the fault tolerance of the system and reduces the position measurement error caused by single point failure; it can provide more magnetic field change information, thereby enhancing the resistance to external interference, even in the presence of interference, the position can still be accurately measured; in addition, the number, size and arrangement of the magnetic strips can be adjusted according to the specific application requirements to meet different accuracy and resolution requirements.

[0042] As Figure 3 In the present application, the side of the circular Hall circuit board 3 close to the outer ring magnetic ring 10 is provided with a first linear Hall element 9 and a second linear Hall element 11, the first linear Hall element 9 and the second linear Hall element 11 are arranged at intervals along the circumference of the outer ring magnetic ring 10, and the interval is 1.5 times the length of the magnetic strip, as shown in Figure 8 As shown in the figure, one period of the signal corresponds to two pairs of polarity, in order to make the output signals of the two linear Halls differ by 90°, that is, and The linear Hall elements are arranged at a distance of 1 / 2 of the pole distance, and the distance between the linear Hall elements is 1.5 times the length of the magnetic stripe. The other side of the circular Hall circuit board 3 is provided with an embedded microprocessor 12 and a baseband signal conditioning circuit 13. The input end of the baseband signal conditioning circuit 13 is connected with the output end of the first linear Hall element 9 and the second linear Hall element 11 respectively, and the output end of the baseband signal conditioning circuit 13 is connected with the A / D conversion input end of the embedded microprocessor 12. The baseband signal conditioning circuit 13 is used to amplify and level up the sine and cosine signals of the linear Hall elements to make them single polarity signals, and then the embedded microprocessor 12 is used to judge the position and speed of the magnetic stripe through the steps of signal amplitude discrimination, correction integration and sine and cosine table lookup.

[0043] As Figure 7 In the present application, the baseband signal conditioning circuit comprises: an inverting input proportional operational amplifier OP1, an adder OP2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6. One end of the first resistor R1 is connected with one end of the third resistor R3 and the inverting end of the inverting input proportional operational amplifier OP1 respectively. The non-inverting end of the inverting input proportional operational amplifier OP1 is connected with one end of the second resistor R2. The other end of the second resistor R2 is grounded. The output end of the inverting input proportional operational amplifier OP1 is connected with the other end of the third resistor R3 and one end of the fourth resistor R4 respectively. The other end of the fourth resistor R4 is connected with the inverting end of the adder OP2, one end of the fifth resistor R5 and one end of the sixth resistor R6 respectively. The other end of the fifth resistor R5 is connected with a power supply. The output end of the adder OP2 is connected with the other end of the sixth resistor R6. The non-inverting end of the adder OP2 is grounded. In addition, the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6 have the same resistance value. The ratio of the third resistor R3 to the first resistor R1 is the amplification coefficient. The resistance value of the second resistor R2 is the inverse of the amplification coefficient. The circuit is a reverse amplification circuit. The ratio of R3 to R1 is the amplification coefficient. R2 is a balance resistor, which makes the static resistance of the input end to the ground equal. The circuit is a reverse addition circuit. R4, R5 and R6 have the same resistance value, which can perform addition operation. V0 = -(V a + VCC). V0 is the output voltage of the proportional operational amplifier OP1. V0 is the output voltage of the adder OP2. a

[0044] As Figure 5 The baseband signal conditioning circuit 13 conditions and amplifies the bipolar signal output by the first linear Hall element 9 into a single polarity signal The baseband signal conditioning circuit 13 conditions and amplifies the bipolar signal output by the second linear Hall element 11 into a single polarity signal The baseband signal conditioning circuit 13 conditions and amplifies the bipolar signal output by the second linear Hall element 11 into a single polarity signal The baseband signal conditioning circuit 13 conditions and amplifies the bipolar signal output by the second linear Hall element 11 into a single polarity signal ​Unipolar signal The unipolar signal of the first linear Hall element 9 and the unipolar signal of the second linear Hall element 11 are both input into the embedded microprocessor 12 by the A / D conversion input end. The unipolar signal of the second linear Hall element 11 Wherein, VCC represents the voltage of the power supply, so as to move the level up and make the signal unipolar.

[0045] The embedded microprocessor 12 in the application includes a baseband signal amplitude judgment link, a correction integral link and a sine and cosine lookup table link, so that the magnetic encoder can provide higher precision and more reliable position measurement and feedback in application, and can also make up for the disadvantages of the photoelectric encoder that cannot work in high temperature, humidity and severe vibration environment. As shown in FIG. 6, the processing process of the embedded microprocessor 12 is as follows:

[0046] Step S1, reading the unipolar signal output by the baseband signal conditioning circuit 13 by the A / D conversion port of the embedded microprocessor 12

[0047] Step S2, constructing the signal sinθ by querying the sine and cosine table with the current output position angle θ (i) and cosθ (i) , i is the current calculation period number, i = 1, 2, 3…;

[0048] Step S3, calculating the angle rotation amount Since is approximately equal to θ, so

[0049] Step S4, performing proportional integral processing on the angle rotation amount ε (i) to obtain the integral processing result Wherein, K P is the proportional coefficient, K I is the integral coefficient, j is the index of i, and k is the index of j.

[0050] Step S5, accumulating the integral processing result to obtain the current rotation angle position θ (i) = θ (i-1) + Δθ (i) .

[0051] The magnetic encoder of the application is widely used in many applications, such as mechanical engineering, automation control, robot technology and medical equipment, etc., and provides accurate and reliable position feedback to help realize precise motion control and positioning; and the magnetic encoder of the application can realize non-contact measurement without physical contact, thereby reducing the risk of wear and failure, and increasing its reliability and durability.

[0052] The above merely is the preferred embodiment of the present application, the protection scope of the present application is not limited to the above-mentioned embodiment, and the technical scheme belonging to the idea of the present application is all the protection scope of the present application. It should be pointed out that, for the ordinary skilled in the art, some improvements and decorations without departing from the principle of the present application should be regarded as the protection scope of the present application.

Claims

1. A magnetic encoder, characterized by The application relates to a circular Hall circuit board (3), a rear bearing (1), a stator shell (2), a shaft (4), a shaft disc (5), a rotor (6), an end cover (7), a front bearing (8) and an outer ring magnetic ring (10), the stator shell (2) is arranged at the front end of the end cover (7), the shaft (4) penetrates through the stator shell (2) and the end cover (7), the shaft end of the shaft (4) located at one side of the stator shell (2) is limited by the rear bearing (1), and the shaft end of the shaft (4) located at one side of the end cover (7) is limited by the front bearing (8); the circular Hall circuit board (3), the outer ring magnetic ring (10), the shaft disc (5) and the rotor (6) are all arranged in the stator shell (2) and penetrate through the shaft (4) in sequence along the direction from the rear bearing (1) to the front bearing (8), the circular Hall circuit board (3) is fixedly connected with the stator shell (2), the shaft disc (5) and the rotor (6) are both fixedly connected with the shaft (4), and the outer ring magnetic ring (10) is sleeved on the outer ring of the shaft disc (5). The side, close to the outer ring magnetic ring (10), of the circular Hall circuit board (3) is provided with a first linear Hall element (9) and a second linear Hall element (11); the other side of the circular Hall circuit board (3) is provided with an embedded microprocessor (12) and a baseband signal conditioning circuit (13), the input end of the baseband signal conditioning circuit (13) is connected with the output end of the first linear Hall element (9) and the second linear Hall element (11) respectively, and the output end of the baseband signal conditioning circuit (13) is connected with the A / D conversion input end of the embedded microprocessor (12). The embedded microprocessor (12) comprises a baseband signal amplitude judging link, a correction integral link and a sine and cosine look-up table link. The processing procedure of the embedded microprocessor (12) is as follows: The outer ring magnetic ring (10) is composed of a plurality of magnetic strips arranged along the circumference. Step S1, reading the single polarity signal outputted by the baseband signal conditioning circuit (13) from the A / D conversion port of the embedded microprocessor (12) , ; Step S2, constructing the signal with the current output position angle θ by querying the sine-cosine table and , i is the current calculation cycle number, i = 1, 2, 3…; Step S3, calculating the angular spin ; Step S4, angle gyro carries out proportional integral processing to obtain an integral processing result wherein K P is a proportional coefficient, K I is an integral coefficient, j is an index of i , k is an index of j ; Step S5, accumulate the integration processing result to obtain the current rotation angle position .

2. A magnetic encoder according to claim 1, characterised in that, The first linear Hall element (9) and the second linear Hall element (11) are arranged at intervals along the circumference of the outer ring magnetic ring (10), and the interval is 1.5 times the length of the magnetic strip.

3. A magnetic encoder according to claim 1, wherein, The baseband signal conditioning circuit comprises an inverting input proportional operational amplifier OP1, an adder OP2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6, one end of the first resistor R1 is connected with one end of the third resistor R3 and the inverting end of the inverting input proportional operational amplifier OP1 respectively, the non-inverting end of the inverting input proportional operational amplifier OP1 is connected with one end of the second resistor R2, the other end of the second resistor R2 is grounded, the output end of the inverting input proportional operational amplifier OP1 is connected with the other end of the third resistor R3 and one end of the fourth resistor R4 respectively, the other end of the fourth resistor R4 is connected with the inverting end of the adder OP2, one end of the fifth resistor R5 and one end of the sixth resistor R6 respectively, the other end of the fifth resistor R5 is connected with a power supply, the output end of the adder OP2 is connected with the other end of the sixth resistor R6, and the non-inverting end of the adder OP2 is grounded.

4. A magnetic encoder according to claim 1, characterised in that, ​ 5. A magnetic encoder according to claim 4, characterised in that, The fourth resistance R4, the fifth resistance R5 and the sixth resistance R6 have the same resistance value, the ratio of the third resistance R3 to the first resistance R1 is an amplification factor, and the second resistance R2 has a resistance value which is the inverse of the amplification factor.

6. A magnetic encoder according to claim 4, characterised in that, The baseband signal conditioning circuit (13) conditions and amplifies the bipolar signal output by the first linear Hall element (9) into a unipolar signal A conditions and amplifies the bipolar signal output by the second linear Hall element (11) into a unipolar signal B conditions and amplifies the bipolar signal output by the second linear Hall element (11) into a unipolar signal 、 are input into the embedded microprocessor by the A / D conversion input end.​​ 7. A magnetic encoder according to claim 6, characterised in that, The unipolar signal of the first linear Hall element (9) , The unipolar signal of the second linear Hall element (11) ; wherein V represents the voltage of the power supply.

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