Dual-disc encoder and servo joint using the same

Abstract

This invention relates to the field of encoder technology, specifically to a dual-code-disk encoder and a servo joint using this dual-code-disk encoder. The dual-code-disk encoder includes a first code disk for measuring the rotation angle of a reducer, a second code disk for measuring the rotation angle of a motor, a first reading head and a second reading head for reading data, and a circuit board for fixing the first and second reading heads. The first and second code disks are coaxial and nested in the same plane. By coaxially and nesting the first and second code disks for measuring the rotation angle of the reducer and motor in the same plane, compared to the prior art of using two encoders vertically, the size of the servo joint is reduced, and the load-bearing capacity of the joint is improved. The servo joint using this dual-code-disk encoder has a compact structure, reduced production costs, and reduced size and weight, making it convenient for application in robots.

Description

Technical Field

[0001] The present invention relates to the technical field of encoders, and in particular to a dual-code disc encoder and a servo joint using the dual-code disc encoder. Background Art

[0002] With the rapid development of industrial automation technology, robots, as an important industrial automation equipment, are gaining more and more attention and are being used more and more widely. Among the robot-related technologies, the control of robot joints and other moving parts is the most important and critical.

[0003] In the servo reducer, the robot's joints and other moving parts can be powered by the motor, and the motion posture of the robot's motor and joints and other moving parts can be measured by the encoder, thereby achieving full closed-loop control of the robot's joints and other moving parts.

[0004] In the prior art, such as Patent 201620077231.7, in a servo reducer, if two encoders are set up one above the other to measure the rotation angles of the motor and the reducer respectively, this setting method will result in a large number of parts in the entire joint, increased production costs, and a large joint volume and weight, thereby reducing the load-bearing capacity of the joint. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a dual-disc encoder in view of the above-mentioned defects of the prior art, so as to solve the defects in the prior art that the servo joint needs to be provided with two encoders respectively at the upper and lower parts, and has a large number of parts.

[0006] The technical solution adopted by the present invention to solve its technical problem is: a dual-code disc encoder, including a first code disc for measuring the rotation angle of a reducer, a second code disc for measuring the rotation angle of a motor, and a first reading head and a second reading head for reading, and a circuit board for fixing the first reading head and the second reading head, wherein the first code disc is coaxial with the second code disc and is nested in the same plane.

[0007] A further preferred solution of the present invention is that the first reading head and the second reading head are arranged on the same circuit board.

[0008] A further preferred solution of the present invention is that the first reading head is provided with two first reading chips, and the two first reading chips are centrally symmetrically arranged about the axis of the first code disk.

[0009] A further preferred solution of the present invention is that the second reading head is provided with two second reading chips, and the two second reading chips are centrally symmetrically arranged about the axis of the second code disk.

[0010] A further preferred embodiment of the present invention is that the dual code disc encoder adopts a magnetic absolute encoder, and the first code disc and the second code disc are provided with dual magnetic tracks.

[0011] In view of the defects of existing joints being large in size, using two encoders which are large in size and weight, having poor load capacity and high production cost, the present invention also provides a servo joint, comprising a housing, a reduction unit and a motor unit, and also comprising a dual-code disc encoder as described in any of the above schemes, the circuit board being fixed to the housing through a base, and the reduction gear, motor unit and dual-code disc encoder being coaxially arranged.

[0012] In the servo joint provided by the present invention, a preferred solution is that pin holes are provided at corresponding positions of the base and the circuit board.

[0013] In the servo joint provided by the present invention, a preferred solution is: the deceleration part includes an output end cover, a reducer and an output shaft, and the output shaft is transmission-connected to the first code disc.

[0014] In the servo joint provided by the present invention, a further preferred solution is: the servo joint also includes a brake retainer, and the brake retainer is arranged on the side of the dual-code disc encoder close to the motor part.

[0015] In the dual-disc encoder provided by the present invention, the first and second code discs for measuring the rotation angles of the reducer and the motor are coaxially and nested in the same plane. Compared with the prior art in which two encoders are arranged up and down, the volume of the corresponding servo joint is reduced, the number of parts is reduced, and the load capacity of the joint is improved. In addition, the present invention also uses two reading chips that are symmetrical with the axis center of the code disc to read the rotation angle of the code disc, thereby eliminating the measurement error caused by the coaxiality error between the central axis of the code disc and the corresponding rotation central axis of the measured object, and improving the reading accuracy of the encoder. At the same time, the present invention also provides a servo joint using the dual-disc encoder, which has a compact structure and is convenient for application on robots. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0017] Figure 1 It is a schematic diagram of the structure of the dual-code disc encoder of the present invention;

[0018] Figure 2 It is a schematic diagram of the optimized structure of the dual-code disc encoder of the present invention;

[0019] Figure 3 It is a schematic diagram of the optimized structure of the reading head of the present invention;

[0020] Figure 4 It is a schematic diagram of the structure of the servo joint without the outer shell of the present invention;

[0021] Figure 5 It is a cross-sectional view of the servo joint of the present invention.

[0022] In the figure: encoder 1, first code disc 10, second code disc 11, first reading chip 10a, second reading chip 11a, circuit board 12, base 13, pin hole 14; housing 2; motor part 3, stator assembly 31, rotor 32; reduction part 4, reducer 41, output end cover 42, output shaft 43; connecting flange 5, transmission seat 6, brake retainer 7, motor driver 8. DETAILED DESCRIPTION

[0023] Now, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0024] like Figure 1-5 As shown, the present invention provides a dual-code disc encoder 1, comprising a first code disc 10 for measuring the rotation angle of a reducer, a second code disc 11 for measuring the rotation angle of a motor, a first reading head and a second reading head for reading, and a circuit board 12 for fixing the first reading head and the second reading head, wherein the first code disc 10 and the second code disc 11 are coaxial and nested in the same plane. By using the coaxial and horizontal nesting method of the first code disc 10 and the second code disc 11, compared with the prior art in which two encoders are arranged up and down, the number of parts can be reduced and the volume of the corresponding servo joint can be reduced.

[0025] Specifically, the first code disc 10 is used to measure the reducer angle in the servo joint, and the second code disc 11 is used to measure the motor angle in the servo joint. The inner diameter of the second code disc 11 is larger than the outer diameter of the first code disc 10. The first code disc 10 is nested in the hollow shaft of the second code disc 11, and the two are located in the same horizontal plane. In this embodiment, the first reading head and the second reading head are arranged on the same circuit board 12. The use of a circuit board 12 can reduce production costs and make the structure more compact. Compared with fixing the first reading head and the second reading head to different circuit boards respectively, the need to fix the first reading head circuit board located on the inner side to the servo motor will increase the difficulty of assembly. Of course, in other embodiments, separate fixing methods can also be used.

[0026] Combination Figure 2 , Figure 3In order to further optimize the above scheme and increase the measurement accuracy of the dual-code disc encoder 1, the first reading head used is provided with two first reading chips 10a, and the two first reading chips 10a are centrally symmetrically arranged about the axis of the first code disc 10. When the first code disc 10 rotates, the reading error amplitudes of the two centrally distributed first reading chips 10a are equal and opposite in direction, and the errors can be offset after addition. The digital signal processor of the first reading head collects and sums the information of the two first reading chips 10a at the same time, and then converts the processing results into encoder angular position information, accurately reflecting the reducer angle corresponding to the first code disc 10, and improving the measurement accuracy of the reducer angle. Furthermore, the second reading head used is also provided with two second reading chips 11a, wherein the two second reading chips 11a are centrally symmetrically arranged about the axis of the second code disc 11. Similarly, when the second code disk 11 rotates, the reading error amplitudes of the two centrally distributed second reading chips 11a are equal and opposite in direction, and the errors can cancel each other out after addition. The digital signal processor of the second reading head collects and sums the information of the two second reading chips 11a at the same time, and then converts the processing result into encoder angular position information, accurately reflecting the motor angle corresponding to the second code disk 11, and ensuring the accuracy of the motor angle reading. Compared with a single reading chip, the use of two centrally symmetrical reading chips can eliminate the measurement error caused by the coaxiality error between the central axis of the code disk and the corresponding rotational central axis of the measured object, improve the reading accuracy of the encoder, and reduce the coaxiality requirements of the code disk installation.

[0027] In order to optimize the dual-disc encoder 1 of the present invention, the present invention adopts a magnetic absolute encoder, which can directly obtain the absolute position of the joint compared to the incremental encoder. Compared with the photoelectric encoder, it is resistant to oil and dust pollution and has higher reliability. At the same time, the first code disk 10 and the second code disk 11 are both provided with dual magnetic tracks. Among them, the outer circle magnetic track of the code disk is provided with 2n pairs of magnetic poles, and the inner circle magnetic track is provided with 2n-1 pairs of magnetic poles, and the N pole and the S pole are alternately formed on the magnetic track. A dual-track format is adopted. For example, when n=6, the outer circle track is divided into 64 pairs of magnetic pole pairs, and the inner circle is 63 pairs of magnetic pole pairs. The starting points of the inner circle track and the outer circle track are the same. When measuring the angle, the angle position is accurately obtained by reading the information on the two tracks to improve the accuracy. The track n of the first code disk 10 of the present invention is 1 less than the track n' of the second code disk 11. For example, when the outer circle track of the second code disk 11 is 64 pairs of magnetic pole pairs, the outer circle track of the first code disk 10 is generally 32 pairs of magnetic pole pairs. Since the track pole pairs are affected by the corresponding code disk size and the encoder accuracy, no strict regulations are made here.

[0028] Combination Figure 4 , Figure 5As shown in the figure, the present invention also provides a servo joint, including a housing 2, a motor part 3 and a speed reduction part 4, and also includes the double disc encoder 1 described in the above embodiment, wherein a circuit board 12 is fixed to the housing 2 through a base 13, and the speed reduction part 4, the motor part 3 and the double disc encoder 1 are coaxially arranged, and the double disc encoder 1 is arranged on the side of the motor part 3 away from the speed reduction part 4. With the above double disc encoder 1, the servo joint has a compact structure, reduced volume and weight, fewer parts, and lower production costs, and will be better applied to robots.

[0029] Further, such as Figure 1 As shown, pin holes 14 are provided at corresponding positions on the base 13 and the circuit board 12. During assembly, the two are first preliminarily fixed with pins, and then fixed and locked with screws. The use of pins for preliminarily fixing can effectively improve the assembly accuracy of the circuit board 12, thereby reducing errors. The pins used can be one or more, and are not limited here.

[0030] Specifically, the motor part 3 is connected to the reduction part 4 through the connecting flange 5, and the reduction part 4 includes a reducer 41, an output shaft 43 and an output end cover 42, wherein the output shaft 43 is connected to the first code disc 10 in a transmission manner, and the movement of the reducer 41 is transmitted to the first code disc 10 through the output shaft 43, so as to measure the rotation angle of the reducer 41. The motor part 3 includes a stator assembly 31, a rotor 32 and a motor driver 8, and the servo joint also includes a transmission seat 6 arranged between the motor part 3 and the second code disc 11, one end of the transmission seat 6 is connected to the rotor 32, and the other end is connected to the second code disc 11, and the movement of the rotor 32 is transmitted to the second code disc 11 through the action of the transmission seat 6, so as to measure the rotation angle of the motor. Furthermore, the servo joint used in the present invention also includes a brake retainer 7, which is arranged on the side of the dual code disc encoder 1 close to the motor part 3, and can provide braking in power failure or emergency situations to prevent the robot from falling or losing control due to power failure.

[0031] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A servo joint, comprising a housing, a speed reduction unit, a motor unit and a dual-disc encoder, characterized in that: The dual-code disc encoder includes a first code disc for measuring the rotation angle of the reducer, a second code disc for measuring the rotation angle of the motor, and a first reading head and a second reading head for reading, and a circuit board for fixing the first reading head and the second reading head, wherein the first code disc is coaxial with the second code disc and nested in the same plane, wherein the inner diameter of the second code disc is larger than the outer diameter of the first code disc, and the first code disc is nested in the hollow shaft of the second code disc, the first code disc is used to measure the rotation angle of the reducer in the servo joint, and the second code disc is used to measure the rotation angle of the motor in the servo joint; the first reading head and the second reading head are arranged on the same circuit board; the first reading head is provided with two first reading chips, and the two first reading chips are centrally symmetrically arranged about the axis of the first code disc; the second reading head is provided with two second reading chips, and the two second reading chips are centrally symmetrically arranged about the axis of the second code disc, wherein, when the first code disc rotates, the reading error amplitude of the two centrally distributed first reading chips The two first reading chips are equal and opposite in direction, and the errors can be offset after addition. The digital signal processor of the first reading head collects and sums the information of the two first reading chips at the same time, and then converts the processing result into the encoder angular position information; the second reading head is provided with two second reading chips, and the two second reading chips are centrally symmetrically arranged about the axis of the second code disk; the double code disk encoder adopts a magnetic absolute encoder, the first code disk and the second code disk are provided with double tracks, and the number of magnetic pole pairs on the outer circle track of the first code disk is 1 / 2 of the number of magnetic pole pairs on the outer circle track of the second code disk, the circuit board is fixed to the housing through the base, and the speed reduction part, the motor part and the double code disk encoder are coaxially arranged; the base and the circuit board are provided with pin holes at corresponding positions; the speed reduction part includes an output end cover, a speed reducer and an output shaft, and the output shaft is transmission-connected with the first code disk; the servo joint also includes a brake retainer, and the brake retainer is arranged on the side of the double code disk encoder close to the motor part; Wherein, it also includes a transmission seat arranged between the motor part and the second code disk, one end of the transmission seat is connected to the rotor of the motor part, and the other end is connected to the second code disk.

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