Device for detecting the end position of a servomotor and robot joint servomotor

Abstract

Device for detecting the end position of a servomotor and a robot joint servomotor. The present invention relates to a device for detecting the end position of a servomotor and a robot joint servomotor. The servomotor comprises a motor stator, a motor rotor (1), and a motor housing. The detection device comprises: a first gear (2), a second gear (4), a first magnetic encoder (3), and a second magnetic encoder (5). The first gear (2) is fixedly connected to the end of the motor rotor (1), and the first gear (2) rotates with the motor rotor (1). The second gear (4) is mounted on the motor housing. The second gear (4) and the first gear (2) mesh, and the second gear (4) rotates under the drive of the first gear (2). Figure to be published with the abstract: Figure 1

Description

Title of the invention: Device for detecting the end position of a servomotor and robot joint servomotor technical field

[0001] The present invention relates to the field of detection, in particular a device for detecting the end position of a servomotor and a robot joint servomotor. Technology context

[0002] With the development of industrial techniques, robots have been widely used in various fields such as industrial production, detection, medical services, etc. Robots used in fields such as industrial production, detection, etc., must have mobile robotic arms in order to perform relatively complex tasks, but a relatively large number of degrees of freedom of the robotic arms is achieved through the robot joints.

[0003] Generally, it is the servo motor that controls the joints of a robot. The servo motor is the motor that controls the operation of the mechanical elements in the servo system; it is an auxiliary device for indirect speed change of the motor. In order to better control the micromovements of the robot's joints, it is necessary to accurately detect the end position of the servo motor. Existing technologies generally employ the use of a hollow magnetic encoder or a hollow inductive encoder at the output end of the servo motor's harmonic speed reducer to ensure that the end position of the servo motor can still be recorded after a power outage affecting the electric motor. In this method, if the servo motor rotates more than one revolution, the total angle of rotation cannot be recorded, which will lead to relatively large errors in the detection results.

[0004] It can be seen that the end position of the servomotor cannot be exactly detected with existing technologies. Contents of the invention

[0005] In order to solve the above technical problem or to solve at least part of the above technical problem, the present invention provides a device for detecting the end position of a servomotor and a robot joint servomotor.

[0006] On the one hand, the present invention provides a device for detecting the end position of a robot joint servomotor, said servomotor comprising a motor stator, a motor rotor, an internal support structure and a motor housing, said motor stator is fixedly connected to said internal support structure, said motor housing encloses the outside of said internal support structure, said motor rotor is movably connected to said internal support structure, said motor rotor is capable of rotating relative to said motor stator.

[0007] Said detection device comprises: a first gear, a second gear, a first magnetic encoder and a second magnetic encoder,

[0008] Said first gear is fixedly connected to the end of said motor rotor and said first gear rotates with said motor rotor;

[0009] Said second gear is installed on said motor housing, said second gear and said first gear mesh and said second gear rotates under the drive of said first gear;

[0010] Said first magnetic encoder is installed on said first gear and is used to detect a first angle of said first gear.

[0011] Said second magnetic encoder is installed on said second gear, to detect a second angle of said second gear;

[0012] In which, the number of teeth of said first gear is not equal to the number of teeth of said second gear;

[0013] Said first angle, second angle and the difference in number of teeth between the first gear and the second gear are used to obtain the end position of said servomotor.

[0014] Optionally, the end surface of said first gear is fixedly connected to the end of said motor rotor.

[0015] Optionally, said first gear comprises a first gear disc and a first gear shaft, said first gear shaft is installed in the center of said first gear disc, said first gear shaft is fixedly connected to said first gear disc, said first gear shaft is fixedly connected to the end of said motor rotor.

[0016] Optionally, said first gear includes a third gear disc and a third sleeve, said third sleeve is arranged concentrically with said third gear disc, said third sleeve is fixedly connected to said third gear disc, the inner wall of said third sleeve is fixedly connected to the outer wall of the end of said motor rotor.

[0017] Optionally, said first magnetic encoder includes:

[0018] A first magnetic unit, said first magnetic unit is fixedly connected to said first gear, said first magnetic unit rotates with the rotation of the first gear, a first variable magnetic field is generated during the rotation of said first magnetic unit;

[0019] A first inductor, which is used to detect the variations of said first magnetic field, and outputs a first electrical signal that varies according to the variations of said first magnetic field;

[0020] A first output device, which is used to output said first angle corresponding to the angle of rotation of said first gear as a function of said first electrical signal.

[0021] Optionally, said first magnetic unit is glued to the end surface of said first gear furthest from the motor housing, or

[0022] Said first magnetic unit is embedded in the end surface of said first gear away from the motor housing.

[0023] Optionally, said second gear includes a second gear disc and a second gear shaft, said second gear shaft is installed in the center of said second gear disc, said second gear shaft rotates around said second gear shaft, said second gear shaft is fixedly connected to said motor housing.

[0024] Optionally, said second magnetic encoder includes:

[0025] A second magnetic unit, said second magnetic unit is fixedly connected to said second gear, said second magnetic unit rotates with the rotation of said second gear, a second variable magnetic field is generated during the rotation of said second magnetic unit;

[0026] A second inductor, which is used to detect variations in said second magnetic field, and outputs a second electrical signal that varies according to the variations in said second magnetic field;

[0027] A second output device, which is used to output said second angle corresponding to the angle of rotation of said second gear as a function of said second electrical signal.

[0028] Optionally, said second magnetic unit is glued to the end surface of said second gear furthest from the motor housing, or

[0029] Said second magnetic unit is embedded in the end surface of said second gear away from the motor housing.

[0030] On the other hand, the present invention provides a robot articulation servomotor, which includes a motor stator, a motor rotor, an internal support structure and a motor housing, said motor stator is fixedly connected to said internal support structure, said motor housing encloses the outside of said internal support structure, said motor rotor is movably connected to said internal support structure, said motor rotor is capable of rotating relative to said motor stator, said robot articulation servomotor also includes the sensing device described above.

[0031] The present invention relates to a device for detecting the end position of a servomotor and a robot articulation servomotor. Said servomotor comprises a motor stator, a motor rotor, an internal support structure, and a motor housing. Said motor stator is fixedly connected to said internal support structure. Said motor housing encloses the exterior of said internal support structure. Said motor rotor is movably connected to said internal support structure. Said motor rotor is capable of rotating relative to said motor stator. Said detection device comprises: a first gear, a second gear, a first magnetic encoder, and a second magnetic encoder. Said first gear is fixedly connected to the end of said motor rotor, and said first gear rotates with said motor rotor. Said second gear is installed on said motor housing.said second gear and said first gear mesh, and said second gear rotates under the drive of said first gear; said first magnetic encoder is installed on said first gear and is used to detect the first angle of said first gear. Said second magnetic encoder is installed on said second gear to detect the second angle of said second gear; wherein the number of teeth of said first gear is not equal to the number of teeth of said second gear; said first angle, second angle, and the difference in the number of teeth between the first gear and the second gear are used to obtain the end position of said servomotor. In the present invention, the first angle of the first gear and the second angle of the second gear are detected, and the number of complete revolutions of the motor rotor can be obtained using the first angle.From the second angle and the difference in the number of teeth between the first and second gears, the actual rotation angle of the motor rotor can be obtained. This solves the problem of inaccurate detection of the servo motor's end angle caused by the impossibility of precise counting if the motor rotor rotation exceeds one full revolution, according to existing technologies. It can improve the accuracy of servo motor end angle detection, thus allowing for more precise control of robot joints. Description of the attached figures

[0032] The accompanying figures illustrate one embodiment of the present invention and are used together with the description to explain the principles of the present invention.

[0033] In order to more clearly explain the embodiments of the present invention or the technical programs in existing technologies, the accompanying figures to be used in the descriptions of the embodiment or existing technologies will be briefly described below; obviously, for ordinary technicians in this field, they can obtain other attached figures from these attached figures without any creative work.

[0034] [Fig. 1] shows the cross-sectional diagram of the servomotor of the embodiment of the present invention;

[0035] [Fig.2] shows the diagram of the structure of the servomotor of the embodiment of the present invention;

[0036] In which, 1. Motor rotor; 2. The first gear; 3. The first magnetic encoder; 4. The second gear; 5. The second magnetic encoder; 6. Harmonic speed reducer. Specific implementation method

[0037] To make the objective, technical programs, and advantages of the present embodiment of the invention clearer, the technical programs in the present embodiment of the invention are described clearly and completely in conjunction with the figures attached to the present embodiment of the invention below. Obviously, the embodiments described are only some of the embodiments of the present invention and do not represent all of them. Based on the embodiments of the present invention, all other embodiments that ordinary technicians in this field can obtain without any creative work are within the scope of the present invention.

[0038] With reference to Figures 1 and 2, in the present embodiment of the present invention, said servomotor comprises a motor stator, a motor rotor 1, an internal support structure and a motor housing, said motor stator is fixedly connected to said internal support structure, said motor housing encloses the outside of said internal support structure, said motor rotor 1 is movably connected to said internal support structure, said motor rotor 1 can rotate relative to said motor stator.

[0039] Said detection device comprises: a first gear 2, a second gear 4, a first magnetic encoder 3 and a second magnetic encoder 5,

[0040] Said first gear 2 is fixedly connected to the end of said motor rotor 1 and said first gear 2 rotates with said motor rotor 1;

[0041] Said second gear 4 is installed on said motor housing, said second gear 4 and said first gear 2 mesh and said second gear 4 rotates under the drive of said first gear 2;

[0042] Said first magnetic encoder 3 is installed on said first gear 2 and is used to detect the first angle of said first gear 2.

[0043] Said second magnetic encoder 5 is installed on said second gear 4, to detect the second angle of said second gear 4;

[0044] In which, the number of teeth of said first gear 2 is not equal to the number of teeth of said second gear 4;

[0045] Said first angle, second angle and the difference in number of teeth between the first gear 2 and the second gear 4 are used to obtain the end position of said servomotor.

[0046] In the embodiment of the present invention, said motor rotor 1 can rotate relative to said motor stator, this rotation can be the rotation of the motor rotor 1 inside the motor stator, or the rotation of the motor rotor 1 outside the motor stator at that time, the motor stator is inside.

[0047] The end position of the servomotor which functions as a joint which the present invention detects generally designates the end position of the harmonic speed reducer 6, the harmonic speed reducer 6 is connected to the motor rotor 1, the turned angle of the motor rotor 1 corresponds to the turned angle of the harmonic speed reducer 6, therefore the detection of the end position of the servomotor which functions as a joint in the present invention is effectively the detection of the angle of the motor rotor 1.

[0048] In the embodiment of the present invention, the motor rotor 1 is connected to the flexible wheel of the harmonic speed reducer. When the motor rotor 1 rotates one revolution, the flexible wheel of the harmonic speed reducer 6 oscillates one tooth. The number of teeth of the harmonic speed reducer 6 is related to the reduction ratio of the harmonic speed reducer 6. The reduction ratio of the harmonic speed reducer 6, which is defined at the time of delivery, is a characteristic of the harmonic speed reducer 6.

[0049] According to existing technologies, the magnetic encoder can detect the difference in angle of the motor rotor 1 relative to its starting position when it stops. However, if the rotation of the motor rotor 1 exceeds one full revolution, accurate counting will be impossible, resulting in inaccurate detection. For example, if the magnetic encoder detects that the motor rotor 1 rotates 90 degrees relative to its starting position when it stops, we cannot confirm whether the motor rotor 1 rotates 90 degrees or one full revolution plus 90 degrees; that is, we cannot confirm whether it rotates 90 degrees or 450 degrees. Furthermore, the servomotor may need to rotate more degrees to achieve the target, especially with the increasing complexity of the robot's joints, in order to control the movements of the robot's joints.Based on existing technologies, if we simply adopt the magnetic encoder to detect the rotor angle of motor 1, it is difficult to achieve high accuracy, and therefore, this also makes precise control of the robot's joints difficult.

[0050] In the embodiment of the present invention, when the motor rotor 1 rotates by one revolution, the first gear 2 installed on the motor rotor 1 also rotates by one revolution, for example, both rotate by 360 degrees, but as the number of teeth of the first gear 2 and the number of teeth of the second gear 4 are not equal and the first gear 2 and the second gear 4 mesh and rotate, therefore the second gear 4 also rotates, but the degree of rotation is not equal to 360 degrees.

[0051] If the number of teeth of the first gear 2 and the number of teeth of the second gear 4 are known, the angle of rotation of the second gear 4 can be obtained. Assuming that the number of teeth of the first gear 2 is A and that the number of teeth of the second gear 4 is B, then if the first gear 2 rotates by M degrees and the second gear 4 rotates by M*A / B degrees.

[0052] Since the number of teeth of the first gear 2 and the number of teeth of the second gear 4 are known, each time the rotor of the motor 1 turns one revolution, the difference between the angle of rotation of the first gear 2 and the angle of rotation of the second gear 4 can be obtained, if the angle of rotation of the first gear 2 and the angle of rotation of the second gear 4 can be detected, the difference between the angle of rotation of the first gear 2 and the angle of rotation of the second gear 4 can be obtained, then the number of complete revolutions by which the rotor of the motor 1 has turned can be obtained.

[0053] In the embodiment of the present invention, said first angle, second angle and the difference in number of teeth between the first gear 2 and the second gear 4 are used to obtain the end position of said servomotor.

[0054] In the embodiment of the present invention, the first gear 2 is installed at the end of the motor rotor 1, the second gear 4 is installed on the motor housing, the first gear 2 is installed at the end of the motor rotor 1, the second gear 4 is installed on the motor housing, the first gear 2 and the second gear 4 have different numbers of teeth and mesh. The first angle of the first gear 2 and the second angle of the second gear 4 are detected, and the number of complete revolutions of the rotation of the motor rotor 1 can be obtained using the first angle, the second angle and the difference in the number of teeth between the first gear 2 and the second gear 4, thus, the actual angle of rotation of the motor rotor 1 can be obtained.This solves the problem of inaccurate detection of the servo motor end angle caused by the impossibility of precise counting if the rotation of motor rotor 1 exceeds one full revolution according to existing technologies, can improve the accuracy of the detection of the servo motor end angle, thus the robot joints can be controlled more precisely.

[0055] In the embodiment of the present invention, said first angle, second angle and the difference in number of teeth between the first gear 2 and the second gear 4 are used to obtain the end position of said servomotor.

[0056] In the embodiment of the present invention, assuming that the number of teeth of the first gear 2 is A, at the initial moment, the first angle output at the initial moment by said first magnetic encoder 3 is El_Zero, the first angle output at the stopping moment by the first magnetic encoder 3 is El, thus the first angle of rotation is El- El_Zero.

[0057] Similarly, if we assume that the difference between the number of teeth of the first gear 2 and the number of teeth of the second gear 4 is X, that is to say that the number of teeth of the second gear 4 is A+X. At the initial moment, the second angle output at the initial moment by said second magnetic encoder 5 is E2_Zero, the second angle output at the stopping moment by the second magnetic encoder 5 is E2, thus the first angle of rotation is E2- E2_Zero.

[0058] Ea is a parameter of the first magnetic encoder.

[0059] Thus, the first reference value Q1 = ((El- El_Zero) - (E2- E2_Zero) / (Ea / A / X).

[0060] The value Q1 rounded down to the nearest integer is Q, i.e. the said number of complete turns of the rotation.

[0061] The total rotor angle of the motor rotor E = Q* Ea + EL

[0062] The reduction ratio of the harmonic speed reducer 6 is P, so the value of the end angle of the harmonic speed reducer 6 is W = E / P.

[0063] The number of complete revolutions of the motor rotor 1 can be obtained using the first angle, the second angle, and the difference in the number of teeth between the first gear 2 and the second gear 4, which can be obtained using simple elementary arithmetic such as addition, subtraction, multiplication, division, etc., in the formula above. Further elementary arithmetic calculations can be performed by subsequent calculation circuits. These calculation circuits can be composed of basic circuit devices such as AND gates, NOT gates, amplifiers, counters, triggers, etc., or composed of other devices that can complete arithmetic operations, such as addition, subtraction, multiplication, division, or these calculation circuits may be integrated circuit chips in existing technologies, or these calculation circuits may be composed of several integrated circuit chips in existing technologies, or these calculation circuits may be certain calculation modules in the main control chips of the robot in existing technologies, these contents will not be repeated here. .

[0064] In the embodiment of the present invention, this subsequent calculation process is not carried out by computer software or a computer program.

[0065] In other embodiments of the present invention, this subsequent calculation process can be carried out using existing computer software. The sole purpose of this process is to calculate the end position of the servomotor using the data detected in the embodiments of the present invention. The present invention protects the structure of the above-mentioned hardware and its improvements, but these subsequent calculations, which may be performed by computer software using existing technologies, are not improved by the present invention.

[0066] In the embodiment of the present invention, the difference between the number of teeth of said first gear 2 and the number of teeth of said second gear 4 is 1.

[0067] The embodiment of the present invention has provided several structures of the first gear 2, the end surface of said first gear 2 is fixedly connected to the end of said rotor of the motor 1.

[0068] In the embodiment of the present invention, said first gear 2 comprises a first gear disc and a first gear shaft, said first gear shaft is installed in the center of said first gear disc, said first gear shaft is fixedly connected to said first gear disc, said first gear shaft is fixedly connected to the end of said motor rotor 1.

[0069] In the embodiment of the present invention, said first gear 2 comprises a third gear disc and a third sleeve, said third sleeve is arranged concentrically with said third gear disc, said third sleeve is fixedly connected to said third gear disc, the inner wall of said third sleeve is fixedly connected to the outer wall of the end of said motor rotor 1.

[0070] In the embodiment of the present invention, the structure of the first gear 2 also has several other forms, the fixed link between the first gear 2 and the rotor of the motor 1 also has several forms, these contents will not be repeated here.

[0071] In the embodiment of the present invention, said first magnetic encoder 3 comprises:

[0072] A first magnetic unit, said first magnetic unit is fixedly connected to said first gear 2, said first magnetic unit rotates with the rotation of the first gear 2, a first variable magnetic field is generated during the rotation of said first magnetic unit;

[0073] A first inductor, which is used to detect the variations of said first magnetic field, and outputs the first electrical signal which varies according to the variations of said first magnetic field;

[0074] A first output device, which is used to output said first angle corresponding to the angle of rotation of said first gear 2 as a function of said first electrical signal.

[0075] For the first magnetic encoder 3, we can adopt a magnetic encoder in existing technologies; also, devices having other forms and identical or similar functions can be adopted as well; these contents will not be repeated here.

[0076] In the embodiment of the present invention, as shown in [Fig. 2], said first magnetic unit is glued to the end surface of said first gear 2 away from the motor housing, or

[0077] Said first magnetic unit is embedded in the motor end surface of said first gear 2 away from the motor housing.

[0078] In the embodiment of the present invention, said second gear 4 comprises a second gear disc and a second gear shaft, said second gear shaft is installed in the center of said second gear disc, said second gear shaft rotates around said second gear shaft, said second gear shaft is fixedly connected to said motor housing.

[0079] In the embodiment of the present invention, the structure of the second gear 4 also has several other forms, the link between the second gear 4 and the motor housing also has several forms, these contents will not be repeated here.

[0080] In the embodiment of the present invention, said second magnetic encoder 5 comprises:

[0081] A second magnetic unit, said second magnetic unit is fixedly connected to said second gear 4, said second magnetic unit rotates with the rotation of said second gear 4, a second variable magnetic field is generated during the rotation of said second magnetic unit;

[0082] A second inductor, which is used to detect the variations of said second magnetic field, and outputs the second electrical signal which varies according to the variations of said second magnetic field;

[0083] A second output device, which is used to output said second angle corresponding to the angle of rotation of said second gear 4 as a function of said second electrical signal.

[0084] For the second magnetic encoder 5, we can adopt a magnetic encoder from existing technologies; also, devices having other Identical or similar forms and functions may also be adopted; this content will not be repeated here.

[0085] In the embodiment of the present invention, as shown in [Fig. 2], said second magnetic unit is glued to the end surface of said second gear 4 away from the motor housing, or

[0086] Said second magnetic unit is embedded in the end surface of said second gear 4 away from the motor housing.

[0087] In the embodiment of the present invention, the number of complete revolutions of the motor rotor 1 can be precisely detected using a pair of gears with different numbers of teeth that mesh together. Thus, the end position of the servomotor, which acts as a joint, can be precisely detected. This has several advantages, such as high accuracy, a simple structure, and low cost. Furthermore, in the embodiment of the present invention, a pair of gears with different numbers of teeth that mesh together and a magnetic encoder are used for detection; no additional sensors are required, which can reduce interference in the system.

[0088] The present invention also provides a robot articulation servomotor, which includes a motor stator, a motor rotor 1, an internal support structure and a motor housing, said motor stator is fixedly connected to said internal support structure, said motor housing encloses the outside of said internal support structure, said motor rotor is movably connected to said internal support structure, said motor rotor 1 can rotate relative to said motor stator, said robot articulation servomotor also includes the sensing device described above.

[0089] It is necessary to clarify that, in this document, relational terms such as "the first," "the second," etc., are used only to distinguish one entity or operation from another; these relational terms do not require or certainly do not imply any actual relationship or order among these entities or operations. Furthermore, the terms "include," "comprise," or any other variants thereof are intended to cover non-exclusive inclusion; thus, a process, method, object, or piece of equipment that comprises a series of elements includes not only those elements, but also other elements not explicitly listed or inherent elements of that process, method, object, or piece of equipment. Unless otherwise restricted, the elements defined by the phrase "includes a...""do not exclude the presence of other identical elements in the processes, methods, objects or equipment that include said elements."

[0090] The above description is merely one specific embodiment of the present invention, intended to enable technicians in this field to understand or implement the present invention. For technicians in this field, modifications to several types of these embodiments are obvious; the general principles defined in this document can be implemented in other embodiments without departing from the scope of the present invention.

Claims

Demands

1. Device for detecting the end position of a robot articulation servomotor, characterized in that said servomotor comprises a motor stator, a motor rotor (1), an internal support structure and a motor housing, said motor stator is fixedly connected to said internal support structure, said motor housing encloses the outside of said internal support structure, said motor rotor (1) is movably connected to said internal support structure, said motor rotor (1) is capable of rotating relative to said motor stator, said detection device comprises: a first gear (2), a second gear (4), a first magnetic encoder (3) and a second magnetic encoder (5), said first gear (2) is fixedly connected to the end of said motor rotor (1) and said first gear (2) rotates with said motor rotor (1);said second gear (4) is installed on said motor housing, said second gear (4) and said first gear (2) mesh and said second gear (4) rotates under the drive of said first gear (2); said first magnetic encoder (3) is installed on said first gear (2) and is used to detect a first angle of said first gear (2); said second magnetic encoder (5) is installed on said second gear (4), to detect a second angle of said second gear (4); wherein the number of teeth of said first gear (2) is not equal to the number of teeth of said second gear (4); said first angle, second angle and the difference in number of teeth between the first gear (2) and the second gear (4) are used to obtain the end position of said servomotor.

2. Detection device according to claim 1, characterized in that the end surface of the first gear (2) is fixedly connected to the end of the motor rotor (1).

3. A detection device according to claim 1, characterized in that said first gear (2) comprises a first gear disc and a first gear shaft, said first gear shaft gear is installed in the center of said first gear disc, said first gear shaft is fixedly connected to said first gear disc, said first gear shaft is fixedly connected to the end of said motor rotor (1).

4. Detection device according to claim 1, characterized in that said first gear (2) comprises a first gear disc and a sleeve, said sleeve is arranged concentrically with said first gear disc, said sleeve is fixedly connected to said first gear disc, the inner wall of said sleeve is fixedly connected to the outer wall of the end of said motor rotor (1).

5. A detection device according to claim 1, characterized in that said first magnetic encoder (3) comprises: a first magnetic unit, said first magnetic unit is fixedly connected to said first gear (2), said first magnetic unit rotates with the rotation of the first gear (2), a first variable magnetic field is generated during the rotation of said first magnetic unit; a first inductor, which is used to detect the variations of said first magnetic field, and outputs a first variable electrical signal as a function of the variations of said first magnetic field; a first output device, which is used to output said first angle corresponding to the angle of rotation of said first gear (2) as a function of said first electrical signal.

6. Detection device according to claim 5, characterized in that said first magnetic unit is glued to the end surface of said first gear (2) away from the motor housing, or said first magnetic unit is embedded in the end surface of said first gear (2) away from the motor housing.

7. Detection device according to claim 1, characterized in that said second gear (4) comprises a second gear disc and a second gear shaft, said second gear shaft is installed in the center of said second gear disc, said second gear shaft rotates around said second gear shaft, said second gear shaft is fixedly connected to said motor housing.

8. A detection device according to claim 1, characterized in that said second magnetic encoder (5) comprises: a second magnetic unit, said second magnetic unit is fixedly connected to said second gear (4), said second magnetic unit rotates with the rotation of said second gear (4), a second variable magnetic field is generated during the rotation of said second magnetic unit; a second inductor, which is used to detect the variations of said second magnetic field, and outputs a second variable electrical signal as a function of the variations of said second magnetic field; a second output device, which is used to output said second angle corresponding to the angle of rotation of said second gear (4) as a function of said second electrical signal.

9. Detection device according to claim 8, characterized in that said second magnetic unit is glued to the end surface of said second gear (4) away from the motor housing, or said second magnetic unit is embedded in the end surface of said second gear (4) away from the motor housing.

10. Robot articulation servomotor, characterized in that it comprises a motor stator, a motor rotor (1), an internal support structure and a motor housing, said motor stator is fixedly connected to said internal support structure, said motor housing encloses the outside of said internal support structure, said motor rotor (1) is movably connected to said internal support structure, said motor rotor (1) is capable of rotating relative to said motor stator, said robot articulation servomotor also comprises a sensing device according to any one of claims 1 to 9.

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