Wrist-shaped device of mechanical arm

Abstract

A wrist-shaped device of a mechanical arm comprises a first rotating unit, a second rotating unit and a first brake unit. The first rotating unit comprises a first motor, a first rotating shaft capable of rotating around a first axis, and a first encoder used for measuring the rotating angle of the first rotating shaft and capable of feeding back and controlling the first motor. The second rotating unit comprises a second motor and a working platform capable of rotating around a second axis. The first brake unit comprises a first brake pad connected with the first rotating shaft and a first brake disc. When the first brake disc is driven to be close to and abut against the first brake pad, rotation of the first rotating shaft can be stopped. The rotation angle of the first rotating shaft is measured through the first encoder, and the first brake unit is matched to stop rotation of the first rotating shaft, so that the rotation precision can be improved.

Description

Technical Field

[0001] The present invention relates to a device cooperating with a robotic arm, and particularly to a wrist device of a robotic arm. Background Art

[0002] Referring to Figure 1 , a wrist joint structure of a robotic arm disclosed in a Chinese Taiwan patent No. I418452B includes a forearm body 91, a first rotating assembly 92, a wrist body 93, and a second rotating assembly 94. The first rotating assembly 92 is disposed within the forearm body 91 and has a first motor 921, a first speed reducer 922, and a transmission mechanism 923. The first motor 921 has an output shaft 924. The first speed reducer 922 has an input shaft 925 and an output shaft 926. The transmission mechanism 923 has a first pulley 927, a second pulley 928, and a belt 929. The first pulley 927 is mounted on the output shaft 924 of the first motor 921, the second pulley 928 is mounted on the input shaft 925 of the first speed reducer 922, and the belt 929 is sleeved on the first pulley 927 and the second pulley 928 to transmit the rotational power of the first motor 921 to the first speed reducer 922. The wrist body 93 is mounted on the forearm body 91 and connected to the output shaft 926 of the first speed reducer 922, so that the wrist body 93 is driven by the output shaft 926 of the first speed reducer 922 to rotate about a first rotation axis L1. The second rotating assembly 94 has a second motor 941, a base 942, and a second speed reducer 943. The second motor 941 is mounted within the wrist body 93 and has an output shaft 944. The base 942 is used to connect the second motor 941 and the second speed reducer 943. The rotational power of the second motor 941 is transmitted to the second speed reducer 943, so that the second speed reducer 943 can drive a workpiece (not shown) mounted thereon to rotate about a second rotation axis L2.

[0003] However, since the existing wrist joint structure of the robotic arm is driven by the first pulley 927, the second pulley 928, and the belt 929, the belt 929 may become loose or slip during transmission, and due to factors such as its elasticity, tightness, wear, or uneven distribution of tensile force, the belt 929 is prone to problems of poor transmission accuracy, affecting the accuracy of the wrist body 93 when rotating about the first rotation axis L1. Moreover, the structures of the first pulley 927, the second pulley 928, the belt 929, the first speed reducer 922, and the second speed reducer 943 make the overall device relatively large in volume, thus unable to meet the application scenarios with high-precision and miniaturization requirements. Summary of the Invention

[0004] The object of the present invention is to provide a wrist-type device for a robotic arm that is miniaturized and can improve rotational accuracy.

[0005] The wrist-type device of the robotic arm of the present invention includes a housing unit, a first rotation unit, a second rotation unit, and a first braking unit. The first rotation unit includes a first motor disposed within the housing unit, a first rotating shaft connected to the first motor, and a first encoder for measuring the rotation angle of the first rotating shaft. The first motor is used to drive the first rotating shaft to rotate about a first axis. The first encoder can feedback and control the first motor. The second rotation unit is disposed on the first rotating shaft and can rotate about the first axis along with the first rotating shaft. The second rotation unit includes a second motor and a working platform connected to the second motor. The second motor is used to drive the working platform to rotate about a second axis perpendicular to the first axis. The first braking unit includes a first brake pad connected to the first rotating shaft and a first braking disc that can be driven to move along the first axis to approach or move away from the first brake pad. When the first braking disc is driven to approach and abut against the first brake pad along the first axis, the rotation of the first rotating shaft can be stopped.

[0006] In the wrist-type device of the robotic arm of the present invention, the first braking unit further includes a first coil located on a side of the first braking disc opposite to the first brake pad, and a plurality of first elastic members that elastically abut against the first braking disc and constantly push it towards the first brake pad. When the first coil is energized, it can attract the first braking disc away from the first brake pad and compress the first elastic members. When the first coil is not energized, the first braking disc is pushed by the first elastic members to approach and abut against the first brake pad along the first axis.

[0007] In the wrist-type device of the robotic arm of the present invention, the first braking unit further includes a first mounting seat fixed to the housing unit, a first fixing disc fixed to the first mounting seat at intervals along the first axis, and a plurality of first guiding columns abutted between the first mounting seat and the first fixing disc. The first mounting seat is used to accommodate the first coil and the first elastic members. The first brake pad is located between the first fixing disc and the first braking disc, and the first brake pad is spaced apart from the first fixing disc. The first braking disc has a plurality of first grooves for the first guiding columns to penetrate through.

[0008] In the wrist-type device of the robotic arm of the present invention, the first encoder has a first code disc that rotates with the first rotating shaft, and a first reading head disposed on the housing unit and used to detect the rotation of the first code disc.

[0009] For the wrist-type device of the robotic arm according to the present invention, the housing unit further includes a base, a first side seat and a second side seat spaced apart on a first side of the base. The first motor is disposed on the first side seat. The first rotating shaft penetrates through the first side seat and the second side seat along the first axis. The first encoder is connected to the first rotating shaft and is located within the second side seat.

[0010] The wrist-type device of the robotic arm according to the present invention further includes a second braking unit. The second rotating unit further includes a hollow shaft tube connected to the second motor and fixedly penetrating through the first rotating shaft along the second axis, a second rotating shaft connected to the working platform and rotatably penetrating through the hollow shaft tube, and a second encoder for measuring the rotation angle of the second rotating shaft. The second encoder can feedback and control the second motor. The second braking unit is located at an end of the hollow shaft tube opposite to the second motor and includes a second brake pad connected to the second rotating shaft, and a second braking disc that can be driven to move along the second axis to approach or move away from the second brake pad. When the second braking disc is driven to approach and abut against the second brake pad along the second axis, the rotation of the second rotating shaft can be stopped.

[0011] For the wrist-type device of the robotic arm according to the present invention, the second braking unit further includes a second coil connected to the hollow shaft tube, and a plurality of second elastic members that elastically abut against the second braking disc and constantly push it towards the second brake pad. The second coil and the second elastic members are located on a side of the second braking disc opposite to the second brake pad. When the second coil is energized, it can attract the second braking disc away from the second brake pad and compress the second elastic members. When the second coil is not energized, the second braking disc is pushed by the second elastic members to approach and abut against the second brake pad along the second axis.

[0012] For the wrist-type device of the robotic arm according to the present invention, the second braking unit further includes a second mounting seat fixedly connected to the hollow shaft tube, a second fixed disc fixedly connected to the second mounting seat at intervals along the second axis, and a plurality of second guiding columns abutting between the second mounting seat and the second fixed disc. The second mounting seat is used to accommodate the second coil and the second elastic members. The second brake pad is located between the second fixed disc and the second braking disc, and the second brake pad is spaced from the second fixed disc. The second braking disc has a plurality of second grooves for the second guiding columns to penetrate through.

[0013] For the wrist-type device of the robotic arm according to the present invention, the second encoder has a second code disc disposed at an end of the second rotating shaft opposite to the working platform, and a second reading head disposed on the second fixed disc and used for detecting the rotation of the second code disc.

[0014] The beneficial effects of the present invention are as follows: The rotation angle of the first rotating shaft can be measured by the first encoder, and the first motor can be feedback-controlled, which can improve the rotation accuracy of the first rotating shaft around the first axis. When the first rotating shaft rotates to the target position, the first braking disc is driven to approach and abut against the first brake pad to stop the rotation of the first brake pad around the first axis, and at the same time, the rotation of the first rotating shaft is also stopped, which can further improve the rotation accuracy of the first rotating shaft around the first axis. In addition, through the control of the first motor in combination with the first encoder and the structural design of the compact arrangement of the first braking unit, the pulley, belt, and speed reducer used in the prior art are omitted, making the overall device smaller in size. Description of the Drawings

[0015] Figure 1 is an exploded perspective view of a wrist joint structure of an existing robotic arm;

[0016] Figure 2 is a perspective view of an embodiment of the wrist-type device of the robotic arm of the present invention;

[0017] Figure 3 is a partial exploded perspective view of a first rotating unit and a first braking unit of the embodiment;

[0018] Figure 4 is similar to Figure 3 a partial exploded perspective view;

[0019] Figure 5 is another partial exploded perspective view of the first rotating unit and the first braking unit of the embodiment;

[0020] Figure 6 is similar to Figure 5 a partial exploded perspective view;

[0021] Figure 7 is a partial exploded perspective view of a second rotating unit and a second braking unit of the embodiment;

[0022] Figure 8 is similar to Figure 7 a partial exploded perspective view;

[0023] Figure 9 is a cross-sectional view of the embodiment;

[0024] Figure 10 is a partial enlarged cross-sectional view of the first braking unit of the embodiment;

[0025] Figure 11 is similar to Figure 10 a partial enlarged cross-sectional view;

[0026] Figure 12 is a partial enlarged cross-sectional view of the second braking unit of the embodiment; and

[0027] Figure 13 is similar to Figure 12 a partial enlarged cross-sectional view of. Detailed implementation manners

[0028] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0029] Refer to Figure 2 and Figure 3 For an embodiment of the wrist device 1 of the robotic arm of the present invention, it is adapted to be mounted on a robotic arm (not shown in the figure) and can be controlled by a signal from a servo (not shown in the figure). The wrist device 1 of the robotic arm includes a housing unit 2, a first rotating unit 3, a first braking unit 4, a second rotating unit 5, and a second braking unit 6.

[0030] The housing unit 2 includes a base 21, a first side seat 22 and a second side seat 23 that are spaced apart and disposed on a first side of the base 21. The first side seat 22 has a first side shell portion 221 connecting the base 21, and a first cover plate 222 covering one side of the first side shell portion 221. The second side seat 23 has a second side shell portion 231 connecting the base 21, and a second cover plate 232 covering one side of the second side shell portion 231.

[0031] Refer to Figures 3 to 5 For, the first rotating unit 3 includes a first motor 31 disposed between the first side seat 22 and the second side seat 23 and signal-connected to the servo, a first rotating shaft 32 connected to the first motor 31 and extending through the first side seat 22 and the second side seat 23 along a first axis B, a first ring connection seat 33 fixed to one end of the first rotating shaft 32 and located within the first side shell portion 221, a second ring connection seat 34 fixed to the other end of the first rotating shaft 32 and located within the second side shell portion 231, a first bearing 35 rotatably abutted between the first ring connection seat 33 and the first side shell portion 221, a second bearing 36 rotatably abutted between the second ring connection seat 34 and the second side shell portion 231, a first circuit board 37 fixed to the second cover plate 232, and a first encoder 38 located within the second side shell portion 231.

[0032] Refer to Figures 4 to 6, the first motor 31 can be controlled by the signal of the servo to drive the first rotating shaft 32 to rotate around the first axis B. The first encoder 38 is used to measure the rotation angle of the first rotating shaft 32, and has a first code disk 381 fixedly arranged on the second connecting seat 34 to rotate around the first axis B with the first rotating shaft 32, and a first reading head 382 electrically connected to the first circuit board 37. The first reading head 382 is arranged on one side of the first circuit board 37 facing the first code disk 381.

[0033] It should be noted that, in this embodiment, the first motor 31 is a disc motor. The first encoder 38 is a reflective photoelectric encoder, and a plurality of alternately arranged reflective areas and non-reflective areas (not shown in the figure) are provided on the first code disk 381. When the first code disk 381 rotates with the second connecting seat 34 and the first rotating shaft 32, the first reading head 382 continuously emits light sources towards the first code disk 381. The light sources are reflected by the reflective areas and received by the first reading head 382. Combining with the fact that the first reading head 382 does not receive the reflected light source when the light source irradiates the non-reflective areas, the first reading head 382 can encode according to the time interval of receiving and not receiving the light source reflection, and then calculate the rotation angle of the first rotating shaft 32. The first encoder 38 feedback-controls the first motor 31 through the servo to improve the accuracy of the first motor 31 driving the first rotating shaft 32 to rotate.

[0034] Refer to Figure 3 , Figure 4 and Figure 9 , the first brake unit 4 is located in the first side seat 22, and includes a first brake mounting disc 41 fixedly connected to the first rotating shaft 32, two first brake pads 42 embedded in the first brake mounting disc 41, a first mounting seat 43 fixedly arranged on the first cover plate 222, a first coil 44 accommodated in the first mounting seat 43, four first elastic members 45 accommodated in the first mounting seat 43, a first braking turntable 46 that can be driven to move along the first axis B to approach or separate from the first brake pads 42, a first fixing disc 47 fixedly connected to the first mounting seat 43 at intervals along the first axis B, and four first guiding columns 48 abutted between the first mounting seat 43 and the first fixing disc 47.

[0035] The first brake mounting disc 41 can carry the first brake pads 42 to rotate around the first axis B with the first rotating shaft 32. The first brake mounting disc 41 is located between the first fixing disc 47 and the first braking turntable 46, and the first brake pads 42 and the first fixing disc 47 always maintain a gap (refer to Figure 10 ).

[0036] Reference Figure 9 , the first coil 44 is located on a side of the first turntable 46 opposite to the first brake mounting plate 41, and can be powered on or off under the control of the servo. The first elastic member 45 elastically abuts against the first turntable 46 and constantly moves it towards the first brake pad 42. Refer to Figure 10 , when the first coil 44 is powered on, it can attract the first turntable 46 away from the first brake pad 42 and compress the first elastic member 45. At this time, a gap is maintained between the first turntable 46 and the first brake pad 42; Refer to Figure 11 , when the first coil 44 is not powered on, the first turntable 46 is pushed by the first elastic member 45 to approach and abut against the first brake pad 42.

[0037] Refer to Figure 3 and Figure 4 , four screws 49 pass through the first fixing plate 47 and the first guiding column 48 and are screwed to the first mounting seat 43, so that the first fixing plate 47 is fixedly connected to the first mounting seat 43. The first turntable 46 has four first grooves 461 that are spaced apart around the first axis B and through which the first guiding column 48 extends. Through the limiting cooperation between the first grooves 461 and the first guiding column 48, the first guiding column 48 becomes the track for the first turntable 46 to move along the first axis B, ensuring that the first turntable 46 can move stably along the first axis B between the first mounting seat 43 and the first fixing plate 47.

[0038] Refer to Figures 7 to 9 , the second rotating unit 5 is disposed on the first rotating shaft 32 and can rotate around the first axis B with the first rotating shaft 32. The second rotating unit 5 includes a second motor 51 signal-connected to the servo, a working platform 52 connected to the second motor 51, a hollow shaft tube 53 connected to the second motor 51 and fixedly passing through the first rotating shaft 32 along a second axis T perpendicular to the first axis B, a second rotating shaft 54 connected to the working platform 52 and rotatably extending through the hollow shaft tube 53, an end seat 55 connected to an end of the second rotating shaft 54 opposite to the working platform 52, a second circuit board 56, and a second encoder 57 for measuring the rotation angle of the second rotating shaft 54.

[0039] The second motor 51 is an outer-rotating motor and has an outer rotor 511 that can be controlled by the signal of the servo to rotate around the second axis T. The working platform 52 is connected to the top of the outer rotor 511 and can thus rotate around the second axis T with the outer rotor 511. The working platform 52 is used to mount the workpiece or the processing tool to be processed. One end of the second rotating shaft 54 is connected to the working platform 52 and can rotate around the second axis T with the working platform 52. The other end of the second rotating shaft 54 is connected to the end seat 55, and the end seat 55 can rotate around the second axis T with the second rotating shaft 54.

[0040] The second encoder 57 is used to measure the rotation angle of the second rotating shaft 54 and has a second code disk 571 disposed on the end seat 55 and a second reading head 572 electrically connected to the second circuit board 56. The second reading head 572 is disposed on the side of the second circuit board 56 facing the second code disk 571.

[0041] It should be noted that the second encoder 57 and the first encoder 38 are both reflective photoelectric encoders, so the detailed structure and sensing principle of the second encoder 57 will not be described in detail. When the second code disk 571 rotates with the end seat 55 and the second rotating shaft 54, the second reading head 572 can perform encoding, and then calculate the rotation angle of the second rotating shaft 54. The second encoder 57 can feedback-control the second motor 51 through the servo to increase the accuracy of the second motor 51 in driving the working platform 52 and the second rotating shaft 54 to rotate.

[0042] The second braking unit 6 includes a second brake mounting disk 61 connected to the second rotating shaft 54, two second brake pads 62 embedded in the second brake mounting disk 61, a second mounting seat 63 fixedly connected to the end of the hollow shaft tube 53 opposite to the second motor 51, a second coil 64 accommodated in the second mounting seat 63, four second elastic members 65 accommodated in the second mounting seat 63, a second braking disk 66 that can be driven to move along the second axis T to approach or depart from the second brake pads 62, a second fixing disk 67 fixedly connected to the second mounting seat 63 at intervals along the second axis T, and four second guiding columns 68 abutted between the second mounting seat 63 and the second fixing disk 67.

[0043] The second brake mounting disk 61 can carry the second brake pads 62 to rotate around the second axis T with the second rotating shaft 54, and the second brake mounting disk 61 is located between the second fixing disk 67 and the second braking disk 66. The second brake pads 62 and the second fixing disk 67 always maintain a gap (see Figure 12 ).

[0044] Refer to Figure 9 , the second coil 64 is located on a side of the second braking disc 66 opposite to the second brake pad 62, and can be powered on or off under the signal control of the servo. The second elastic member 65 elastically abuts against the second braking disc 66 and constantly moves it towards the second brake pad 62. Refer to Figure 12 , when the second coil 64 is powered on, it can attract the second braking disc 66 away from the second brake pad 62 and compress the second elastic member 65. At this time, a gap is maintained between the second braking disc 66 and the second brake pad 62; Refer to Figure 13 , when the second coil 64 is not powered on, the second braking disc 66 is pushed by the second elastic member 65 to approach and abut against the second brake pad 62.

[0045] Refer to Figure 9 , the second circuit board 56 is fixedly connected to the second fixed plate 67.

[0046] Refer to Figure 7 、 Figure 8 And Figure 12 , four screws 69 pass through the second fixed plate 67 and the second guiding column 68 and are screwed to the second mounting seat 63, so that the second fixed plate 67 is fixedly connected to the second mounting seat 63. The second braking disc 66 has four second grooves 661 that are spaced apart and surround the second axis T and through which the second guiding column 68 extends. Through the limiting cooperation between the second groove 661 and the second guiding column 68, the second guiding column 68 becomes the track for the second braking disc 66 to move along the second axis T, ensuring that the second braking disc 66 can stably move along the second axis T between the second mounting seat 63 and the second fixed plate 67.

[0047] Refer to Figures 9 to 11, when the wrist device 1 of the robotic arm of the present invention is in use, the first motor 31 can be controlled by the servo to drive the first rotating shaft 32 to rotate around the first axis B. The first encoder 38 is used to measure the rotation angle of the first rotating shaft 32 and feedback to control the first motor 31 through the servo, so as to increase the rotation accuracy of the first motor 31 in driving the first rotating shaft 32. The first rotating shaft 32 drives the second rotating unit 5 and the first brake mounting disc 41 to rotate around the first axis B together. When the servo controls the first motor 31 to drive the first rotating shaft 32 to rotate, the servo synchronously controls the first coil 44 to be energized, so that the first control disc 46 is attracted by the first coil 44 and compresses the first elastic member 45 to move away from and not contact the first brake pad 42, ensuring that the first brake mounting disc 41 can rotate around the first axis B with the first rotating shaft 32. When the first rotating shaft 32 rotates to the target position, the servo immediately controls the first coil 44 to be powered off, so that the first control disc 46 is no longer attracted by the first coil 44, and the first elastic member 45 springs the first control disc 46 to approach and abut against the first brake pad 42 to stop the first brake mounting disc 41 from rotating around the first axis B, and at the same time stop the first rotating shaft 32 from rotating around the first axis B. Therefore, the first brake unit 4 can further improve the rotation accuracy and stability of the first rotating shaft 32.

[0048] Similarly, refer to Figure 9 , Figure 12 and Figure 13, the second motor 51 can be controlled by the servo to drive the working platform 52 to rotate around the second axis T. The second rotating shaft 54 rotates together with the working platform 52, and the second brake mounting disc 61 rotates together with the second rotating shaft 54. The second encoder 57 is used to measure the rotation angle of the second rotating shaft 54 and feedback to control the second motor 51 through the servo, so as to improve the rotation accuracy of the second rotating shaft 54. When the servo controls the second motor 51 to drive the working platform 52 to rotate, the servo synchronously controls the second coil 64 to be energized, so that the second control disc 66 is attracted by the second coil 64 and compresses the second elastic member 65 to move away from and not contact the second brake pad 62, ensuring that the second brake mounting disc 61 rotates together with the second rotating shaft 54. When the second rotating shaft 54 rotates to the target position, the servo controls the second coil 64 to be powered off in real time, so that the second control disc 66 is no longer attracted by the second coil 64, and the second elastic member 65 springs the second control disc 66 to move close to and abut against the second brake pad 62 to stop the second brake mounting disc 61 from rotating around the second axis T, and at the same time stop the second rotating shaft 54 and the working platform 52 from rotating around the second axis T. Thereby, the second brake unit 6 can further improve the rotation accuracy and stability of the second rotating shaft 54 and the working platform 52.

[0049] In summary, for the wrist device 1 of the robotic arm of the present invention, the first encoder 38 can measure the rotation angle of the first rotating shaft 32, the second encoder 57 can measure the rotation angle of the second rotating shaft 54, and the servo feedback controls the first motor 31 and the second motor 51, which can improve the rotation accuracy of the first rotating shaft 32, the second rotating shaft 54 and the working platform 52. When the first rotating shaft 32 and the second rotating shaft 54 rotate to the target position, the servo controls the first brake unit 4 and the second brake unit 6 to stop the rotation of the first rotating shaft 32 and the second rotating shaft 54 in real time, which can further improve the rotation accuracy of the first rotating shaft 32 and the second rotating shaft 54. In addition, through the control of the first motor 31 with the first encoder 38, the control of the second motor 51 with the second encoder 57, and the structural design of the compact arrangement of the first brake unit 4 and the second brake unit 6, the belt pulleys, belts and speed reducers used in the prior art are omitted, making the overall device smaller in size. Therefore, the object of the present invention can be truly achieved.

[0050] However, the above are only the embodiments of the present invention, and the scope of implementation of the present invention cannot be limited thereby. That is, all simple equivalent changes and modifications made according to the claims and the content of the specification of the present invention still belong to the scope of the present invention.

Claims

1. A wrist device of a robotic arm, characterized in that: Comprising: A housing unit; A first rotating unit, including a first motor disposed within the housing unit, a first rotating shaft connected to the first motor, and a first encoder for measuring the rotation angle of the first rotating shaft, the first motor being configured to drive the first rotating shaft to rotate about a first axis, and the first encoder being capable of providing feedback control to the first motor; A second rotating unit disposed on the first rotating shaft and capable of rotating about the first axis with the first rotating shaft, the second rotating unit including a second motor and a working platform connected to the second motor, the second motor being configured to drive the working platform to rotate about a second axis perpendicular to the first axis; and A first braking unit, including a first brake pad connected to the first rotating shaft and a first braking disc that can be driven to move along the first axis to approach or move away from the first brake pad, and when the first braking disc is driven to approach and abut against the first brake pad along the first axis, the rotation of the first rotating shaft can be stopped.

2. The wrist-type device of the robotic arm according to claim 1, characterized in that: The first braking unit further includes a first coil located on a side of the first braking disc opposite to the first brake pad, and a plurality of first elastic members that elastically abut the first braking disc and constantly urge it to move towards the first brake pad. When the first coil is energized, it can attract the first braking disc away from the first brake pad and compress the first elastic members. When the first coil is not energized, the first braking disc is pushed by the first elastic members to approach and abut against the first brake pad along the first axis.

3. The wrist-type device of the robotic arm according to claim 2, characterized in that: The first braking unit further includes a first mounting seat fixed to the housing unit, a first fixing disc fixed to the first mounting seat at intervals along the first axis, and a plurality of first guiding columns abutting between the first mounting seat and the first fixing disc. The first mounting seat is used to accommodate the first coil and the first elastic members. The first brake pad is located between the first fixing disc and the first braking disc, and the first brake pad is spaced apart from the first fixing disc. The first braking disc has a plurality of first grooves for the first guiding columns to pass through.

4. The wrist-type device of the robotic arm according to claim 1, characterized in that: The first encoder has a first code disc that rotates with the first rotating shaft, and a first reading head disposed on the housing unit and configured to detect the rotation of the first code disc.

5. The wrist device of the robotic arm according to claim 1, characterized in that: The housing unit further includes a base, a first side seat and a second side seat spaced apart on a first side of the base. The first motor is disposed on the first side seat. The first rotating shaft extends through the first side seat and the second side seat along the first axis. The first encoder is connected to the first rotating shaft and is located within the second side seat.

6. The wrist device of the robotic arm according to claim 1, characterized in that: It further includes a second braking unit. The second rotating unit further includes a hollow shaft tube that connects the second motor and is fixedly disposed along the second axis through the first rotating shaft, a second rotating shaft that connects the working platform and rotatably extends through the hollow shaft tube, and a second encoder for measuring the rotation angle of the second rotating shaft. The second encoder can feedback and control the second motor. The second braking unit is located at an end of the hollow shaft tube opposite to the second motor and includes a second brake pad connected to the second rotating shaft and a second braking disc that can be driven to move along the second axis to approach or away from the second brake pad. When the second braking disc is driven to approach and abut against the second brake pad along the second axis, the rotation of the second rotating shaft can be stopped.

7. The wrist device of the robotic arm according to claim 6, characterized in that: The second braking unit further includes a second coil connected to the hollow shaft tube and a plurality of second elastic members that elastically abut the second braking disc to constantly move towards the second brake pad. The second coil and the second elastic members are located on a side of the second braking disc opposite to the second brake pad. When the second coil is energized, it can attract the second braking disc away from the second brake pad and compress the second elastic members. When the second coil is not energized, the second braking disc is pushed by the second elastic members to approach and abut against the second brake pad along the second axis.

8. The wrist-type device of the robotic arm according to claim 7, characterized in that: The second braking unit further includes a second mounting seat fixedly connected to the hollow shaft tube, a second fixing disc fixedly connected to the second mounting seat at intervals along the second axis, and a plurality of second guiding columns abutted between the second mounting seat and the second fixing disc. The second mounting seat is used to accommodate the second coil and the second elastic members. The second brake pad is located between the second fixing disc and the second braking disc, and the second brake pad is spaced from the second fixing disc. The second braking disc has a plurality of second grooves for the second guiding columns to penetrate.

9. The wrist-type device of the robotic arm according to claim 8, characterized in that: The second encoder has a second code disc disposed at an end of the second rotating shaft opposite to the working platform and a second reading head disposed on the second fixing disc for detecting the rotation of the second code disc.

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