Patent Description:
A robot arm is formed by connecting a plurality of joints, such as a six-axis robot arm. The joints of the robot arm are connected in series through power cables and signal cables, so that each axis of the robot arm can be driven by electricity and complete predetermined actions in sequence according to input signals.

As disclosed in U. Patent Application Early Publication No. <CIT> titled "Assembly for a Robot, and Robot Device", the connection between two adjacent joints of the robot arm includes the following features:.

As disclosed in U. Patent Publication No. <CIT> titled "Actuator Unit and Multi-axis Robot", the connection of two adjacent joints of the robot arm includes the following features. As disclosed in the paragraph [<NUM>] of the description of this patent, referring to <FIG> of this patent, the wire harness <NUM> extending from the electrical contact <NUM> winds several turns around the output shaft <NUM>, and then is connected to the control board <NUM> in the actuator unit. Similarly, the wire harness (not shown) extending from the electrical contact <NUM> winds several turns around the output shaft <NUM>, and then is connected to the control board <NUM> in the actuator unit. As disclosed in the paragraph [<NUM>] of the description of this patent, the wire harness <NUM> winds several turns around the output shaft <NUM> connected to the motor to prevent the wire harness <NUM> from being cut in the range of rotation (about -<NUM> degrees to about +<NUM> degrees) of the output shaft <NUM>. Furthermore, this winding structure suppresses metal fatigue of the wire harness <NUM> even if the output shaft <NUM> rotates many times. That is to say, the invention disclosed in <CIT> utilizes the feature that "the wire harness <NUM> winds several turns around the output shaft <NUM>" to avoid metal fatigue of the wire harness <NUM>. However, such a feature still has the following defects:.

<CIT> discloses an arm module, modular robot arm or industrial robot having a housing with first and second connection sides. The first connection side has a first connection plate, a first fluid contact device and a first contact device. The second connection side is mechanically connected to the housing in a torque-proof manner, and has a second connection plate. The first fluid contact device and first contact device are arranged on the first connection plate, parallel to a mounting axis. The first connection side is connectable to another arm module. An external thread is arranged about the first mounting axis, on an outer circumferential side of the first connection plate. The second connection plate is circumferentially embraced by a fastening ring with an internal thread corresponding to the external thread. The fastening ring is connected to the housing in an axially fixed manner, rotatable about a second mounting axis.

<CIT> discloses an active arm module for the robot arm of a modular industrial robot having a first housing, first and connection sides arranged at an offset, and a drive device. The first connection side is mounted rotatably relative to the first housing, and is connected to the drive device in a torque-locking manner. The second connection side is connected to the first housing in a torque-proof manner, the drive device being arranged in the first housing and configured to rotate the first connection side relative to the first housing. A further module can be connected to the first and/or second connection side, where the first connection side is optically, electrically, power-electrically and/or fluidically connected to the second connection side, and an optical signal, electrical signal, electrical power, and/or a fluid can be exchanged with the further module via the and/or second connection side.

<CIT> discloses an arm module having a housing with a first connection side and a second connection side. The first connection side is embodied to be controllably rotatable about an axis of rotation relative to the second connection side. The first connection side has a rotatable first connection device and the second connection side has a second connection device fixed to the housing. A multifunctional rotation transfer system is provided for rotational transmission of data signals, electrical energy and fluid. A drive device is provided comprising a shaft assembly having an output shaft, which is connected to the rotatable first connection device of the first connection side in a torque-proof manner, wherein the shaft assembly forms a section of the multifunctional rotation transfer system.

<CIT> discloses an industrial robot comprising a modular robot arm having a plurality of arm modules, where a rotation transfer device for optical signal transmission is provided in an arm module or between a first and a second arm module. The rotation transfer device comprises an optomechanical rotation interface having a first interface side and a second interface side, which face each other and are substantially rotationally symmetrical and complementary. The first and second interface sides are configured to rotate relative to each other. The first and second interface sides are mechanically mounted with respect to each other, with a radial plain bearing on one interface side and a slide bearing shell complementary thereto on the other interface side. A gap is formed between the first and second interface sides, in the axial direction of the rotation transfer device, across which the optical signal transmission takes place.

The objective of the invention is achieved by the subject-matter of the independent claim. Advantageous embodiments are disclosed by the dependent claims.

According to one aspect of the present invention, a robot arm joint is provided. The robot arm joint comprises a joint body, a motor, a fixing end modular contact seat, a transmission end modular contact seat, and a joint wire assembly. The joint body includes a fixing end and a transmission end. The fixing end has a fixing end connecting surface. The transmission end has a transmission end connecting surface. The motor is fixed in the joint body and configured to output power to the transmission end. The fixing end modular contact seat is fixed to the fixing end connecting surface. The fixing end modular contact seat includes a plurality of fixing end power contacts and a plurality of fixing end signal contacts. The fixing end power contacts and the fixing end signal contacts are exposed on the fixing end connecting surface. The transmission end modular contact seat is fixed to the transmission end connecting surface. The transmission end modular contact seat includes a plurality of transmission end power contacts and a plurality of transmission end signal contacts. The transmission end power contacts and the transmission end signal contacts are exposed on the transmission end connecting surface. The joint wire assembly is disposed in the joint body. The joint wire assembly includes a plurality of joint wires. The plurality of joint wires extends on a preset connection path. The preset connection path includes a straight path. The joint wire assembly includes a torsion section and a fixed section. One end of the torsion section is connected to the transmission end modular contact seat. One end of the fixed section is connected to the fixing end modular contact seat. When the transmission end rotates, the torsion section is simultaneously driven to twist on the straight path.

Preferably, the transmission end includes a transmission member. The motor is connected to the transmission member through a transmission assembly. The transmission member is rotatable relative to the joint body. The transmission end connecting surface is located on the transmission member. The transmission end connecting surface is exposed on the joint body.

Preferably, the fixing end power contacts and the fixing end signal contacts are in the form of a plug pin. The transmission end power contacts and the transmission end signal contacts are in the form of a socket. The socket has an annular inner surface matched with the plug pin.

Preferably, opposite two ends of the straight path have two retaining members. The torsion section of the joint wire assembly is located between the two retaining members.

Preferably, a slip ring is provided in the joint body. The slip ring connects the torsion section and the fixed section, so that the torsion section is able to rotate relative to the fixed section.

Preferably, the transmission end rotates about a rotation axis. The transmission end has a wire hole along the rotation axis. The straight path is arranged on the rotation axis. The joint wire assembly passes through the wire hole and is connected to the transmission end modular contact seat.

Preferably, the robot arm joint further comprises an encoder and a driver. The motor is electrically connected to the encoder and the driver. The motor, the encoder and the driver are arranged on the rotation axis sequentially in a direction opposite to the transmission end. The straight path passes through the motor and the encoder.

Preferably, the fixing end has a fixing end coupling unit. The transmission end has a transmission end coupling unit. The fixing end and the transmission end each have a fool-proof unit.

According to an example not form part of but helpful for understanding the present invention, a connector for connecting the foregoing robot arm joint. The connector comprises a connector body and a connector wire assembly. The connector body includes a first end and a second end. The first end has a first end connecting surface and a first end modular contact seat fixed to the first end connecting surface. The first end modular contact seat includes a first end power contact and a first end signal contact that are exposed on the first end connecting surface. The second end has a second end connecting surface and a second end modular contact seat fixed to the second end connecting surface. The second end modular contact seat includes a second end power contact and a second end signal contact that are exposed on the second end connecting surface. The connector wire assembly is disposed in the connector body. The connector wire assembly includes a plurality of connector wires. One end of the connector wire assembly is connected to the first end modular contact seat. Another end of the connector wire assembly is connected to the second end modular contact seat.

Preferably, the first end power contact and the first end signal contact of the first end modular contact seat are in the form of a socket, and the socket has an annular inner surface. The second end power contact and the second end signal contact of the second end modular contact seat are in the form of a socket, and the socket has an annular inner surface.

Preferably, the first end power contact and the first end signal contact of the first end modular contact seat are in the form of a plug pin. The second end power contact and the second end signal contact of the second end modular contact seat are in the form of a socket, and the socket has an annular inner surface.

Preferably, the first end has a first end coupling unit, and the second end has a second end coupling unit.

According to a further aspect of the present invention, a robot arm is provided. The robot arm comprises the foregoing robot arm joint and the foregoing connector that are connected to each other.

The fixing end of the joint body has any of the following connection relationships:.

The transmission end of the joint body has any of the following connection relationships:.

The joint wire assembly and the connector wire assembly are connected in series with each other by means of the connection relationships.

Preferably, the connection relationship of the contacts is that a plug pin is inserted into a socket, and the socket has an annular inner surface matched with the plug pin.

According to the above-mentioned technical features, the following effects can be achieved:.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings.

As shown in <FIG>, a robot arm A according to an embodiment of the present invention is a six-axis robot arm, comprising six robot arm joints <NUM> and two connectors. The two connectors are defined as a first connector <NUM> and a second connector <NUM>. The structures of the first connector <NUM> and the second connector <NUM> are the same, but they have different shapes for constructing the six-axis robot arm of this embodiment. The robot arm joint <NUM> includes a joint body <NUM>. The joint body <NUM> includes a fixing end <NUM> and a transmission end <NUM>. The first connector <NUM> includes a first connector body <NUM>. The first connector body <NUM> includes a first end <NUM> and a second end <NUM>. The second connector <NUM> includes a second connector body <NUM>. The second connector body <NUM> also includes a first end <NUM> and a second end <NUM>.

The assembly method of the robot arm joints <NUM> and the connectors in this embodiment includes: for two adj acent j oint bodies <NUM>, the fixing end <NUM> of one j oint body <NUM> is connected to the transmission end <NUM> of the other joint body <NUM>; for adjacent joint bodies <NUM> and the first connector body <NUM>, the first end <NUM> and the second end <NUM> of the first connector body <NUM> are connected to the fixing ends <NUM> of the adjacent joint bodies <NUM>, respectively; for adjacent joint bodies <NUM> and the second connector body <NUM>, the first end <NUM> of the second connector body <NUM> is connected to the transmission end <NUM> of one adjacent joint body <NUM>, and the second end <NUM> of the second connector body <NUM> is connected to the fixing end <NUM> of the other adj acent j oint body <NUM>.

Referring to <FIG>, <FIG> and <FIG>, the fixing end <NUM> of the j oint body <NUM> has a fixing end power contact <NUM> and a fixing end signal contact <NUM>. Specifically, the fixing end power contact <NUM> and the fixing end signal contact <NUM> are integrated on a fixing end modular contact seat <NUM>. The transmission end <NUM> of the joint body <NUM> has a transmission end power contact <NUM> and a transmission end signal contact <NUM>. Specifically, the transmission end power contact <NUM> and the transmission end signal contact <NUM> are integrated on a transmission end modular contact seat <NUM>. The transmission end <NUM> includes a transmission member <NUM>. The transmission member <NUM> includes a transmission end connecting surface <NUM>. The transmission end connecting surface <NUM> is exposed on the joint body <NUM>. The transmission end modular contact seat <NUM> is fixed to the transmission end connecting surface <NUM>. The transmission end power contact <NUM> and the transmission end signal contact <NUM> are exposed on the transmission end connecting surface <NUM>. The fixing end <NUM> has a fixing end connecting surface <NUM>. The fixing end modular contact seat <NUM> is fixed to the fixing end connecting surface <NUM>. The fixing end power contact <NUM> and the fixing end signal contact <NUM> are exposed on the fixing end connecting surface <NUM>. In this embodiment, the fixing end <NUM> further has a fixing end coupling unit <NUM>. The transmission end <NUM> has a transmission end coupling unit <NUM>. The fixing end <NUM> and the transmission end <NUM> each have a fool-proof unit. Specifically, the fixing end coupling unit <NUM> is a recess portion. The transmission end coupling unit <NUM> is a protruding portion formed by the transmission member <NUM> protruding from the joint body <NUM>. The periphery of the fixing end coupling unit <NUM> and the periphery the transmission end coupling unit <NUM> have a plurality of pin holes <NUM>/<NUM>, respectively. The fool-proof unit of the fixing end <NUM> is a post <NUM>. The fool-proof unit of the transmission end <NUM> is a groove <NUM>. The fool-proof unit is configured to prevent the fixing ends <NUM> of the adj acent j oint bodies <NUM> from touching and to prevent the transmission ends <NUM> of the adj acent joint bodies <NUM> from touching.

The robot arm joint <NUM> further includes a motor <NUM>, a joint wire assembly <NUM>, an encoder <NUM>, and a driver <NUM>. The motor <NUM>, the encoder <NUM> and the driver <NUM> are electrically connected to each other. The motor <NUM> is fixed in the joint body <NUM> and connected to the transmission member <NUM> through a transmission assembly <NUM>. Thus, the motor <NUM> can output power to the transmission end <NUM>, so that the transmission member <NUM> can rotate relative to the joint body <NUM>. The joint wire assembly <NUM> is disposed in the joint body <NUM>. The joint wire assembly <NUM> includes a plurality of joint wires. One end of the joint wire assembly <NUM> is connected to the fixing end modular contact seat <NUM>, and the other end of the joint wire assembly <NUM> is connected to the transmission end modular contact seat <NUM>. The joint wires of the joint wire assembly <NUM> extend on a preset connection path. Preferably, the preset connection path includes a straight path S. Specifically, in this embodiment, the transmission member <NUM> of the transmission end <NUM> rotates about a rotation axis P. The transmission end <NUM> has a wire hole <NUM> along the rotation axis P. The straight path S is arranged on the rotation axis P. The joint wire assembly <NUM> passes through the wire hole <NUM> and is connected to the transmission end modular contact seat <NUM>. The transmission assembly <NUM>, the motor <NUM>, the encoder <NUM> and the driver <NUM> are arranged on the rotation axis P sequentially in a direction opposite to the transmission end <NUM>. The straight path S passes through the transmission assembly <NUM>, the motor <NUM> and the encoder <NUM>. Further, opposite two ends of the straight path S have two retaining members <NUM> for retaining the joint wire assembly <NUM>. The joint wire assembly passes through the two retaining member <NUM> to form a torsion section <NUM> and a fixed section <NUM>. The torsion section <NUM> is located between the two retaining members <NUM>. The torsion section <NUM> is substantially arranged along the straight path S. One end of the torsion section <NUM> is connected to the transmission end modular contact seat <NUM>. The fixed section <NUM> is located between the retaining member <NUM> away from the transmission end <NUM> and the fixing end <NUM><NUM><NUM>. One end of the fixed section <NUM> is connected to the fixing end modular contact seat <NUM>. The fixed section <NUM> is unable to move or twist inside the joint body <NUM>. Preferably, a slip ring <NUM> is provided in the joint body <NUM>. The slip ring <NUM> connects the torsion section <NUM> and the fixed section <NUM>. The slip ring <NUM> allows transmission of power and signals in a rotating state.

Referring to <FIG> and <FIG>, the first end <NUM> of the first connector body <NUM> has a first end power contact <NUM> and a first end signal contact <NUM>. Specifically, the first end power contact <NUM> and the first end signal contact <NUM> are integrated on a first end modular contact seat <NUM>. The second end <NUM> of the first connector body <NUM> has a second end power contact <NUM> and a second end signal contact <NUM>. Specifically, the second end power contact <NUM> and the second end signal contact <NUM> are integrated on a second end modular contact seat <NUM>. The first end <NUM> has a first end connecting surface <NUM>. The first end modular contact seat <NUM> is fixed to the first end connecting surface <NUM>. The first end power contact <NUM> and the first end signal contact <NUM> are exposed on the first end connecting surface <NUM>. The second end <NUM> has a second end connecting surface <NUM>. The second end modular contact seat <NUM> is fixed to the second end connecting surface <NUM>. The second end power contact <NUM> and the second end signal contact <NUM> are exposed on the second end connecting surface <NUM>. In this embodiment, the first end <NUM> further has a first end coupling unit <NUM>, and the second end <NUM> further has a second end coupling unit <NUM>. Specifically, the first end coupling unit <NUM> and the second end coupling unit <NUM> are each a protruding portion. The periphery of the first end coupling unit <NUM> and the periphery the second end coupling unit <NUM> have a plurality of pin holes <NUM>/<NUM>, respectively. The first end <NUM> and the second end <NUM> have a plurality of grooves <NUM>/<NUM> corresponding to the fool-proof unit (the post <NUM>) of the fixing end <NUM> of the joint body <NUM>.

The first connector <NUM> further includes a first connector wire assembly <NUM>. The first connector wire assembly <NUM> is disposed in the first connector body <NUM>. The first connector wire assembly <NUM> includes a plurality of connector wires. One end of the first connector wire assembly <NUM> is connected to the first end modular contact seat <NUM>, and the other end of the first connector wire assembly <NUM> is connected to the second end modular contact seat <NUM>.

Referring to <FIG>, the first end <NUM> of the second connector body <NUM> has a first end power contact <NUM> and a first end signal contact <NUM>. Specifically, the first end power contact <NUM> and the first end signal contact <NUM> are integrated on a first end modular contact seat <NUM>. The second end <NUM> of the second connector body <NUM> has a second end power contact <NUM> and a second end signal contact <NUM>. Specifically, the second end power contact <NUM> and the second end signal contact <NUM> are integrated on a second end modular contact seat <NUM>. The first end <NUM> has a first end connecting surface <NUM>. The first end modular contact seat <NUM> is fixed to the first end connecting surface <NUM>. The first end power contact <NUM> and the first end signal contact <NUM> are exposed on the first end connecting surface <NUM>. The second end <NUM> has a second end connecting surface <NUM>. The second end modular contact seat <NUM> is fixed to the second end connecting surface <NUM>. The second end power contact <NUM> and the second end signal contact <NUM> are exposed on the second end connection surface <NUM>. In this embodiment, the first end <NUM> further has a first end coupling unit <NUM>, and the second end <NUM> further has a second end coupling unit <NUM>. Specifically, the first coupling unit <NUM> is a recess portion, and the second coupling unit <NUM> is a protruding portion. The periphery of the first end coupling unit <NUM> and the periphery the second end coupling unit <NUM> have a plurality of pin holes <NUM>/<NUM>, respectively. The first end <NUM> has a plurality of posts <NUM> corresponding to the fool-proof unit (the groove <NUM>) of the transmission end <NUM> of the joint body <NUM>. The second end <NUM> has a plurality of grooves <NUM> corresponding to the fool-proof unit (the post <NUM>) of the fixing end <NUM> of the joint body <NUM>.

The second connector <NUM> further includes a second connector wire assembly <NUM>. The second connector wire assembly <NUM> is disposed in the second connector body <NUM>. The second connector wire assembly <NUM> includes a plurality of connector wires. One end of the second connector wire assembly <NUM> is connected to the first end modular contact seat <NUM>, and the other end of the second connector wire assembly <NUM> is connected to the second end modular contact seat <NUM>.

Referring to the foregoing figures and <FIG>, for two adjacent joint bodies <NUM>, the fixing end <NUM> of one joint body <NUM> is connected to the transmission end <NUM> of the other joint body <NUM>. Through the fixing end coupling unit <NUM> and the transmission end coupling unit <NUM>, the two adj acent joint bodies <NUM> are coupled accurately. Through a plurality of pins passing through the pin holes <NUM> on the periphery of the fixing end coupling unit <NUM> and the pin holes <NUM> on the periphery of the transmission end coupling unit <NUM>, the two coupled joint bodies <NUM> are fixedly connected to each other. Further, the fixing end power contact <NUM> and the fixing end signal contact <NUM> of one joint body <NUM> are connected to the transmission end power contact <NUM> and the transmission end signal contact <NUM> of the other joint body <NUM>, respectively. Referring to <FIG> and <FIG>, the fixing end power contact <NUM> and the fixing end signal contact <NUM> that are in the form of a plug pin are inserted into the transmission end power contact <NUM> and the transmission end signal contact <NUM> that are in the form of a socket. The annular inner surface of the socket matches and covers the plug pin. Therefore, the contacts have the largest contact area. When used to transmit signals, they have greater signal strength. When used to transmit current, they have less resistance to avoid overheating.

For adjacent joint bodies <NUM> and the first connector body <NUM>, the first end <NUM> and the second end <NUM> of the first connector body <NUM> are connected to the fixing ends <NUM> of the adj acent joint bodies <NUM>, respectively. Through the fixing end coupling unit <NUM>, the first end coupling unit <NUM> and the second end coupling unit <NUM>, the adj acent j oint bodies <NUM> and the first connector body <NUM> are coupled accurately. Through a plurality of pins passing through the pin holes <NUM> on the periphery of the fixing end coupling unit <NUM> and the pin holes <NUM> on the periphery of the first end coupling unit <NUM> as well as a plurality of pins passing through the pin holes <NUM> on the periphery of the fixing end coupling unit <NUM> and the pin holes <NUM> on the periphery of the second end coupling unit <NUM>, the joint body <NUM> and the first connector body <NUM> that are coupled together are fixedly connected to each other. Further, the first end power contact <NUM> and the first end signal contact <NUM> as well as the second end power contact <NUM> and the second end signal contact <NUM> are connected to the fixing end power contact <NUM> and the fixing end signal contact <NUM> of the adj acent joint body <NUM>, respectively. The connection of the contacts also uses a plug pin and a socket. The annular inner surface of the socket matches and covers the plug pin.

For adjacent joint bodies <NUM> and the second connector body <NUM>, the first end <NUM> of the second connector body <NUM> is connected to the transmission end <NUM> of one adjacent joint body <NUM>, and the second end <NUM> of the second connector body <NUM> is connected to the fixing end <NUM> of the other adjacent joint body <NUM>. Through the transmission end coupling unit <NUM> and the first end coupling unit <NUM> as well as through the fixing end coupling unit <NUM> and the second end coupling unit <NUM>, the adjacent joint bodies <NUM> and the second connector body <NUM> are coupled accurately. Through a plurality of pins passing through the pin holes <NUM> on the periphery of the transmission end coupling unit <NUM> and the pin holes <NUM> on the periphery of the first end coupling unit <NUM> as well as a plurality of pins passing through the pin holes <NUM> on the periphery of the fixing end coupling unit <NUM> and the pin holes <NUM> on the periphery of the second end coupling unit <NUM>, the joint body <NUM> and the second connector body <NUM> that are coupled together are fixedly connected to each other. Further, the first end power contact <NUM> and the first end signal contact <NUM> are connected to the transmission end power contact <NUM> and the transmission end signal contact <NUM> of the adjacent joint body <NUM>, respectively. The second end power contact <NUM> and the second end signal contact <NUM> are connected to the fixing end power contact <NUM> and the fixing end signal contact <NUM> of the adjacent joint body <NUM>, respectively. The connection of the contacts also uses a plug pin and a socket. The annular inner surface of the socket matches and covers the plug pin.

Accordingly, the robot arm joint <NUM>, the first connector <NUM> and the second connector <NUM> are assembled into the robot arm A. The joint wire assembly <NUM>, the first connector wire assembly <NUM> and the second connector wire assembly <NUM> are connected in series with each other through the above-mentioned connection relationship. In this way, power and commands can be received for the robotic arm A to complete expected actions.

Referring to <FIG> and <FIG>, when power and commands are input to the robot arm A for the transmission member <NUM> of the transmission end <NUM> to rotate relative to the joint body <NUM>, the transmission member <NUM> will simultaneously drive the torsion section <NUM> of the joint wire assembly <NUM> to generate a twist on the preset connection path. Specifically, the twist occurs on the straight path S on the rotation axis P of the transmission member <NUM>, and the joint wire assembly <NUM> will not be coiled. Referring to <FIG> and <FIG>, the torsional radius r of the torsion section <NUM> of the joint wire assembly <NUM> is much smaller than the winding radius R of the wire harness as disclosed in <CIT> (r<R). Therefore, it is applicable to the smaller joint body <NUM>. In this embodiment, through the retaining members <NUM>, the fixing end power contact <NUM>, the fixing end signal contact <NUM>, the transmission end power contact <NUM> and the transmission end signal contact <NUM> will not cause poor contact or breakage due to the stress when the transmission end <NUM> is rotated. If the slip ring <NUM> is not provided, since the torsion section <NUM> is substantially arranged along the straight path S, the torsion section <NUM> can provide enough torsion space and torsion margin for the joint wire assembly <NUM> to perform necessary forward rotation and reverse rotation. If the slip ring <NUM> is provided, the slip ring <NUM> allows the transmission end <NUM> to rotate without restriction. The rotation of the joint wire assembly <NUM> is completed in the slip ring <NUM>, which will not cause other part of the joint wire assembly <NUM> to be twisted under force.

Claim 1:
A robot arm joint (<NUM>), comprising:
a joint body (<NUM>), including a fixing end (<NUM>) and a transmission end (<NUM>), the fixing end (<NUM>) having a fixing end connecting surface (<NUM>), the transmission end (<NUM>) having a transmission end connecting surface (<NUM>); and
a motor (<NUM>), fixed in the joint body (<NUM>) and configured to output power to the transmission end (<NUM>),
the robot arm joint (<NUM>) further comprises:
a fixing end modular contact seat (<NUM>), fixed to the fixing end connecting surface (<NUM>), the fixing end modular contact seat (<NUM>) including a plurality of fixing end power contacts (<NUM>) and a plurality of fixing end signal contacts (<NUM>); the fixing end power contacts (<NUM>) and the fixing end signal contacts (<NUM>) being exposed on the fixing end connecting surface (<NUM>);
a transmission end modular contact seat (<NUM>), fixed to the transmission end connecting surface (<NUM>), the transmission end modular contact seat (<NUM>) including a plurality of transmission end power contacts (<NUM>) and a plurality of transmission end signal contacts (<NUM>); the transmission end power contacts (<NUM>) and the transmission end signal contacts (<NUM>) being exposed on the transmission end connecting surface (<NUM>); and
a joint wire assembly (<NUM>), disposed in the joint body (<NUM>), the joint wire assembly (<NUM>) including a plurality of joint wires, the plurality of joint wires extending on a preset connection path, the preset connection path including a straight path (S), characterized in that
the joint wire assembly (<NUM>) including a torsion section (<NUM>) and a fixed section (<NUM>), one end of the torsion section (<NUM>) being connected to the transmission end modular contact seat (<NUM>), one end of the fixed section (<NUM>) being connected to the fixing end modular contact seat (<NUM>); wherein when the transmission end (<NUM>) rotates, the torsion section (<NUM>) is simultaneously driven to twist on the straight path (S), wherein opposite two ends of the straight path (S) have two retaining members (<NUM>), the torsion section (<NUM>) of the joint wire assembly (<NUM>) is located between the two retaining members (<NUM>), the fixed section (<NUM>) is located between the retaining member (<NUM>) away from the transmission end (<NUM>) and the fixing end (<NUM>); wherein when the transmission end (<NUM>) rotates, the fixed section (<NUM>) is unable to twist inside the joint body (<NUM>).