# US 10,500,734 B1 · Servo assembly, robot joint and robot

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- Number: US 10,500,734 B1
- Document ID: US10500734B1
- Status: Granted
- Kind: B1
- Application number: 16/226,663
- Filed: 2018-12-20
- Granted: 2019-12-10
- Earliest claimed: 2018-10-31
- Assignees: Ubtech Robotics Corp Ltd
- Applicants: UBTECH Robotics Corp
- Inventors: Youjun Xiong; Youpeng Li; Hongyu Ding; Wenhua Fan; Jianxin Pang
- Web page: https://patentgrep.com/patent/US10500734B1

## CPC

- B25J 13/088: {with position, velocity or acceleration sensors}
- B25J 9/1025: {Harmonic drives (in general: F16H49/001)}
- B25J 9/108: {Bearings specially adapted therefor (bearings in general F16C)}
- B25J 9/126: {Rotary actuators}
- B25J 17/00: Joints
- H02K 1/2781: Magnets shaped to vary the mechanical air gap between the magnets and the stator
- H02K 5/161: {radially supporting the rotary shaft at both ends of the rotor (H02K5/165, H02K5/167, H02K5/173 take precedence)}
- H02K 7/116: with gears
- H02K 11/215: Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements
- B25J: MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES ({manipulators specially adapted for use in surgery A61B34/70; manipulators used in cleaning hollow articles B08B9/04}; manipulators associated with rolling mills B21B39/20; manipulators associated with forging machines B21J13/10; {manipulators associated with picking-up and placing mechanisms B23P19/007}; means for holding wheels or parts thereof B60B30/00; {vehicles with ground-engaging propulsion means, e.g. walking members B62D57/02, B62D57/032; devices for picking-up and depositing articles or materials between conveyors B65G47/90, B65G47/91; manipulators with gripping or holding means for transferring packages B65H67/065}; cranes B66C; {manipulators used in the protection or supervision of pipe-line installations F17D5/00; walking equipment adapted for nuclear steam-generators F22B37/006}; manipulators specially adapted for, or associated with, nuclear reactors G21C; {apparatus used for handling wafers during manufacture or treatment of semiconductor H10P72/50})
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})

## Abstract

A servo includes a casing, a motor assembly arranged within the casing and including a hollow output shaft, a harmonic drive including a flex spline, a wave generator arranged and a circular spline that comprises, a first bearing to rotatably connect the flex spline to the circular spline so as to enable one of the flex spline and the circular spline to serve as an output member, and enable the other one to serve as a fixed member, a post fixed to the output member and received in the output shaft, a first source member arranged at one end of the post that is away from the output member; and a control circuit board having a first sensing member. The first sensing member and the first source member corporately constitute a rotation sensor to detect rotation of the output member.

## Claims

### Claim 1

A servo comprising:
a casing;
a motor assembly arranged within the casing, the motor assembly comprising a hollow output shaft extending within the casing;
a harmonic drive comprising a flex spline, a wave generator arranged at one end of the output shaft and a circular spline that comprises a inner ring gear, the flex spline comprising a hollow cylindrical member and an annular portion connected to one end of the cylindrical member, the cylindrical member being arranged around the wave generator and comprising an outer ring gear on an outer lateral surface thereof, which is engaged with the inner ring gear;
a first bearing configured to rotatably connect the flex spline to the circular spline so as to enable one of the flex spline and the circular spline to serve as an output member, and enable the other one to serve as a fixed member;
a post fixed to the output member and received in the output shaft;
a first source member arranged at one end of the post that is away from the output member; and
a control circuit board arranged under the end of the post that includes the first source member, the control circuit board comprising a first sensing member, the first sensing member and the first source member corporately constituting a first rotation sensor that is configured to detect rotation of the output member.

### Claim 2 (depends on 1)

The servo according to claim 1, wherein the motor assembly comprises a stator assembly and a rotor assembly, the stator assembly comprises a stator arranged within the casing, and a retaining ring for fixing the stator to the casing, the rotor assembly comprises a rotor received in the stator and fixed to the output shaft; the rotor comprises a rotor core and a plurality of magnets evenly fixed to an outer surface of the rotor core.

### Claim 3 (depends on 2)

The servo according to claim 2, wherein the rotor assembly further comprises a connection member configured to connect the rotor core to the output shaft.

### Claim 4 (depends on 1)

The servo according to claim 1, wherein the first source member is a magnet, and the first sensing member is configured to detect a change of magnetic field caused by rotation of the first source member.

### Claim 5 (depends on 1)

The servo according to claim 1, further comprising a second source member and a second sensing member, wherein the second source member is arranged on an end of the output shaft that is away from the output member, the second sensing member is arranged on the control circuit board, the second sensing member and the second source member corporately constituting a second rotation sensor that is configured to detect rotation of the output shaft.

### Claim 6 (depends on 5)

The servo according to claim 5, wherein the second source member comprises a holder fixed to an end of the output shaft that is away from the harmonic drive and a magnet fixed to the holder, the control circuit board is spaced apart from the magnet, the second sensing member is configured to detect a change of magnetic field caused by rotation of magnet.

### Claim 7 (depends on 1)

The servo according to claim 1, wherein the casing comprises a hollow main body, a first cap connected to one end of the main body and a second cap that is connected to the main body and opposite the first cap, the first cap defines a first through hole, the second cap defines a second through hole, and the output shaft extends through the first through hole and the second through hole.

### Claim 8 (depends on 7)

The servo according to claim 7, wherein when the flex spline serves the fixed member and the circular spline serves as the output member, the annular portion is fixed to the casing, the first bearing comprises an inner ring fixed to the circular spline and an outer ring fixed to the annular portion.

### Claim 9 (depends on 8)

The servo according to claim 8, further comprising an output plate connected to the circular spline, wherein one end of the post that is opposite the source member is fixed to the output plate.

### Claim 10 (depends on 9)

The servo according to claim 9, further comprising a second bearing fit in the first through hole of the first cap for supporting the output shaft, and a third bearing connected to the output plate for supporting the harmonic drive.

### Claim 11 (depends on 10)

The servo according to claim 10, wherein a height of the third bearing is less than a height of the wave generator.

### Claim 12 (depends on 7)

The servo according to claim 7, wherein when the circular spline serves the fixed member and the flex spline serves as the output member, the circular spline is fixed to the casing, the first bearing comprises an inner ring fixed to the annular portion and an outer ring fixed to the casing.

### Claim 13 (depends on 12)

The servo according to claim 12, further comprising a disc member connected to the annular portion, wherein one end of the post that is opposite the source member is fixed to the disc member.

### Claim 14 (depends on 12)

The servo according to claim 12, further comprising a support bearing arranged within the output shaft for supporting the post.

### Claim 15 (depends on 12)

The servo according to claim 12, further comprising a second bearing received in the first through hole of the first cap and a third bearing received in the second through hole of second cap, both of which are configured to support the output shaft.

### Claim 16 (depends on 7)

The servo according to claim 7, further comprising a fourth bearing, wherein the casing further comprises a third cap connected to an end of the main body that is opposite the first cap, the third cap defines a receiving space to receive the fourth bearing.

### Claim 17

A robot comprising a servo, the servo comprising:
a casing;
a motor assembly arranged within the casing, the motor assembly comprising a hollow output shaft extending within the casing;
a harmonic drive comprising a flex spline, a wave generator arranged at one end of the output shaft and a circular spline that comprises a inner ring gear, the flex spline comprising a hollow cylindrical member and an annular portion connected to one end of the cylindrical member, the cylindrical member being arranged around the wave generator and comprising an outer ring gear on an outer lateral surface thereof, which is engaged with the inner ring gear;
a first bearing configured to rotatably connect the flex spline to the circular spline so as to enable one of the flex spline and the circular spline to serve as an output member, and enable the other one to serve as a fixed member;
a post fixed to the output member and received in the output shaft;
a first source member arranged at one end of the post that is away from the output member; and
a control circuit board arranged under the end of the post that includes the first source member, the control circuit board comprising a first sensing member, the first sensing member and the first source member corporately constituting a first rotation sensor that is configured to detect rotation of the output member.