Drive actuators and robots

Abstract

To provide a drive actuator and a robot that can reduce an impact of magnetism on a sensor mounted on a decelerator while being downsized.SOLUTION: A drive actuator 20 comprises: a motor 21 including a rotor 32 and a stator 33 used for rotating a revolving shaft 31 by a magnetic field generated by the rotor 32 and the stator 33; a decelerator 23 for decelerating the rotation of the revolving shaft 31; a brake device 22 for stopping the rotation of the revolving shaft 31; and an encoder 24 for detecting the position of the rotation of the revolving shaft 31. A strain sensor 68 is mounted on the decelerator 23. The rotor 32 and stator 33 of the motor 21, the decelerator 23, the brake device 22, and the encoder 24 are aligned in the axial direction of the revolving shaft 31. The brake device 22 is arranged between the rotor 32 and stator 33, and the decelerator 23.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a drive actuator and a robot.

Background Art

[0002] Articulated robots are each provided with a drive actuator that rotationally drives the corresponding joint. The drive actuator includes a motor that rotates a rotating shaft. The motor has a rotor fixed to the outer peripheral side of the rotating shaft, and a stator disposed on the outer peripheral side of the rotor. The rotor is configured to include, for example, a permanent magnet, and the stator is configured to include, for example, an electromagnet. When electricity is supplied to the stator, a rotating magnetic field is generated, the rotating magnetic field causes the rotor to rotate, and consequently the rotating shaft rotates.

[0003] In addition to the motor, the drive actuator further includes a speed reducer that reduces the rotational speed of the rotating shaft, a brake device that stops the rotation of the rotating shaft, and an encoder that detects the rotational position of the rotating shaft. In the drive actuator of Patent Document 1, the rotor and stator of the motor, the speed reducer, the brake device, and the encoder are arranged side by side in the axial direction of the rotating shaft. Specifically, along the axial direction of the rotating shaft from the output side toward the opposite output side, the speed reducer, the rotor and stator, the brake device, and the encoder are arranged in this order.

[0004] Further, a sensor such as a strain sensor may be attached to the speed reducer of the drive actuator (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of Invention

Problem to be Solved by Invention

[0006] By the way, there is a need to miniaturize drive actuators in order to save space in robots. In the drive actuator described in Patent Document 1, the rotor and stator of the motor and the reduction gear are arranged adjacent to each other. Therefore, if the drive actuator is to be miniaturized, the rotor and stator and the reduction gear will be placed in close proximity. However, if they are placed in close proximity, and a sensor is attached to the reduction gear, the sensor may be affected by the magnetism generated from the rotor and stator. For example, electromagnetic induction may occur due to the influence of magnetism, which may cause noise in the output value of the sensor.

[0007] This invention has been made in view of the above circumstances, and its main objective is to provide a drive actuator that can reduce the influence of magnetism on a sensor attached to a reduction gear while achieving miniaturization, and a robot equipped with the drive actuator. [Means for solving the problem]

[0008] To solve the above problems, the drive actuator of the first invention comprises a motor having a rotor and a stator, which rotates a rotating shaft by a magnetic field generated by the rotor and the stator, a reduction gear that reduces the rotation of the rotating shaft, a braking device that stops the rotation of the rotating shaft, and an encoder that detects the rotational position of the rotating shaft, wherein a sensor is attached to the reduction gear, and the rotor and the stator, the reduction gear, the braking device and the encoder are arranged in the axial direction of the rotating shaft, and at least one of the brake device and the encoder is located between the rotor and the stator and the reduction gear.

[0009] According to the first invention, at least one of a brake device and an encoder is arranged between the rotor and stator of the motor and the reduction gear. In this case, the rotor and stator, which are sources of magnetic fields, can be separated from the reduction gear, thereby reducing the magnetic influence on a sensor attached to the reduction gear.

[0010] Furthermore, even if adjacent components of the rotor and stator, the reduction gear, the braking system, and the encoder are placed close together, the rotor and stator and the reduction gear can be placed far apart. This allows for miniaturization of the drive actuator while reducing the magnetic influence on the sensors.

[0011] The drive actuator of the second invention has an electromagnetic brake device, which has a housing made of a magnetic material and which houses a brake coil inside, and the brake device is positioned between the rotor and the stator and the reduction gear.

[0012] In electromagnetic brake systems, the housing that houses the brake coil is made of a magnetic material such as iron or steel to prevent the magnetic flux generated when the brake coil is energized from leaking to the outside of the brake system. Therefore, in the second invention, the electromagnetic brake system is placed between the rotor and stator and the reduction gear. In this case, the effect of blocking the magnetism generated from the rotor and stator by the housing of the brake system (i.e., a magnetic shielding effect) can be obtained. As a result, the influence of magnetism on the sensor attached to the reduction gear can be further reduced.

[0013] Incidentally, it is possible to obtain the above effects by separately arranging a magnetic shielding member between the rotor and stator and the reduction gear. However, in that case, adding the magnetic shielding member may lead to increased costs or hinder the miniaturization of the drive actuator. In this respect, the above-described configuration makes it possible to obtain the above effects without causing such inconveniences.

[0014] The drive actuator of the third invention has a reduction gear formed in an annular shape centered on the rotation axis, and a housing formed in an annular shape surrounding the rotation axis, which overlaps with the sensor when viewed from the axial direction.

[0015] According to the third invention, the housing of the brake device is formed in an annular shape surrounding the rotating shaft. Furthermore, the housing overlaps with the sensor attached to the annular reduction gear when viewed from the axial direction of the rotating shaft. In this case, a magnetic shielding effect by the housing can be suitably obtained.

[0016] Furthermore, when the gearbox rotates in the circumferential direction of the rotation shaft, the sensor also rotates in the same direction. In this respect, with the above configuration, the sensor and the housing overlap in the axial direction of the rotation shaft regardless of the position of the sensor in the rotation direction. Therefore, a stable magnetic shielding effect from the housing can be obtained.

[0017] The robot of the fourth invention is equipped with a drive actuator of any of the first to third inventions that rotates the joints.

[0018] According to the fourth invention, the effects of the first invention can be obtained in a drive actuator that rotates the joints of a robot. Furthermore, by miniaturizing the drive actuator, the robot can be made more space-saving. [Brief explanation of the drawing]

[0019] [Figure 1] A side view showing the robot's overview. [Figure 2] A cross-sectional view showing the internal structure of the drive actuator. [Modes for carrying out the invention]

[0020] An embodiment of the present invention will be described below with reference to the drawings.

[0021] As shown in Figure 1, the robot 10 is a 6-axis vertical articulated robot having six joints K1 to K6. The robot 10 includes a base 11 installed on a predetermined installation surface (such as a floor surface), and a plurality (six) of arms 12 to 17 supported by the base 11. The plurality of arms 12 to 17 include a shoulder portion 12, a lower arm 13, a first upper arm 14, a second upper arm 15, a wrist portion 16, and a flange 17.

[0022] The shoulder portion 12 is supported by the base 11 so as to be rotatable in the horizontal direction (J1 axis). The lower arm 13 is supported by the shoulder portion 12 so as to be rotatable in the vertical direction (J2 axis). The first upper arm 14 is supported by the lower arm 13 so as to be rotatable in the vertical direction (J3 axis). The second upper arm 15 is supported by the first upper arm 14 so as to be torsionally rotatable (J4 axis). The wrist portion 16 is supported by the second upper arm 15 so as to be rotatable in the vertical direction (J5 axis). The flange 17 is supported by the wrist portion 16 so as to be torsionally rotatable (J6 axis). Although not illustrated, an end effector is attached to the flange 17.

[0023] Each of the joints K1 to K6 of the robot 10 is provided with a drive actuator 20 that rotationally drives the joints K1 to K6. The arms 12 to 17 are caused to perform rotational operations as the joints K1 to K6 are rotationally driven by the drive actuator 20.

[0024] Next, the configuration of the drive actuator 20 will be described based on Figure 2. Note that the drive actuators 20 for each of the joints K1 to K6 basically have the same structure.

[0025] As shown in Figure 2, the drive actuator 20 includes a motor 21, a brake device 22, a speed reducer 23, and an encoder 24. The motor 21 has a rotary shaft 31, a rotor 32, and a stator 33. One side in the axial direction of the rotary shaft 31 is an output side from which the rotation of the rotary shaft 31 is output, and in Figure 2, this output side is the upper side.

[0026] The rotor 32 is formed in an annular shape by permanent magnets and is fixed to the outer circumference of the rotating shaft 31. More specifically, the rotating shaft 31 has a large-diameter portion 31a with a larger outer diameter than other parts, and the rotor 32 is fixed to this large-diameter portion 31a. The stator 33 includes an electromagnet composed of coils and a core, and is formed in an annular shape. The stator 33 is positioned on the outer circumference of the rotor 32, surrounding the rotor 32. In this case, the rotor 32 and the stator 33 are arranged coaxially with the rotating shaft 31.

[0027] The stator 33 is housed inside the casing 25 together with the rotor 32. The casing 25 has a cylindrical casing body 26 and a pair of roughly disc-shaped covers 27 and 28 that are provided to close the openings at both ends of the casing body 26. The casing body 26 (corresponding to the cylindrical part) is arranged coaxially with the rotating shaft 31, and the covers 27 and 28 are fixed to the casing body 26. The rotating shaft 31 also passes through the center of each cover 27 and 28. Of the covers 27 and 28, cover 27 is positioned on the output side in the axial direction of the rotating shaft 31, and cover 28 is positioned on the opposite side from the output side, the anti-output side (the lower side in Figure 2).

[0028] The stator 33 is press-fitted into the casing body 26 and is fixed to the casing body 26 by this press-fitting. When current is supplied to the coils of the stator 33, a rotating magnetic field is generated, and this rotating magnetic field causes the rotor 32 to rotate, which in turn causes the rotating shaft 31 to rotate. In other words, the rotating shaft 31 rotates due to the magnetic fields generated by the rotor 32 and the stator 33.

[0029] The rotating shaft 31 is rotatably supported by a plurality of bearings 36, 37 that are spaced apart in the axial direction. Of the bearings 36, 37, the bearing 36 located on the output side in the axial direction is supported by the cover 27 of the casing 25. The bearing 37 located on the non-output side in the axial direction is supported by the cover 28 of the casing 25.

[0030] The brake device 22 stops the rotation of the rotating shaft 31 and consists of an electromagnetic brake device. The brake device 22 is formed in an annular shape as a whole, and the rotating shaft 31 is inserted inside it. Furthermore, the brake device 22 is positioned on the output side of the rotor 32 and stator 33 of the motor 21 in the axial direction of the rotating shaft 31.

[0031] The brake device 22 is housed within the casing 25 together with the rotor 32 and stator 33. The brake device 22 is secured to the cover 27 of the casing 25, for example, by bolts.

[0032] The brake device 22 includes a brake coil 51, a housing 52 that houses the brake coil 51, a movable plate 53, a friction plate 54, and a fixed plate 55. The housing 52 is formed in an annular shape, and a rotating shaft 31 is inserted through its interior. In this case, the housing 52 is arranged coaxially with the rotating shaft 31. The housing 52 is made of a magnetic material such as iron or steel, for example, low-carbon steel. The brake coil 51 is wound around the circumferential direction of the housing 52, and the entire coil is covered by the housing 52. This creates a path for the magnetic flux generated when the brake coil 51 is energized, and prevents the magnetic flux from leaking out of the housing 52.

[0033] The movable plate 53, friction plate 54, and fixed plate 55 are formed in a disc shape and are positioned on the side opposite to the output side of the housing 52 (i.e., the side of the rotor 32 and stator 33). The movable plate 53, friction plate 54, and fixed plate 55 are aligned in the direction of the axis of the rotation shaft 31, with their thickness direction facing the axis of the rotation shaft 31, in the order described above, from the housing 52 side (output side) to the opposite side. The rotation shaft 31 also passes through the center of each of these plates 53 to 55.

[0034] The movable plate 53 is provided so as to be displaceable in the axial direction of the rotating shaft 31. The movable plate 53 is constantly biased toward the friction plate 54 by a spring material (not shown). The movable plate 53 is made of a magnetic material such as iron or steel. The friction plate 54 is fixed to the rotating shaft 31 at its inner circumference. The fixed plate 55 is fixed to the housing 52 at its outer circumference via a spacer (not shown).

[0035] In the brake device 22 with the above configuration, when the brake coil 51 is energized, a magnetic field is generated, which causes the movable plate 53 to be pulled towards the housing 52 against the biasing force of the spring material. In this case, the movable plate 53 and the friction plate 54 move apart from each other. As a result, the friction plate 54 becomes rotatable, and consequently, the rotating shaft 31 becomes rotatable. Therefore, this state is the brake-off state (the state in Figure 2).

[0036] Conversely, when the brake coil 51 is not energized, no magnetic field is generated, so the movable plate 53 is pressed against the friction plate 54 by the biasing force of the spring material, and the friction plate 54 is sandwiched between the movable plate 53 and the fixed plate 55. In this case, a frictional force is generated against the friction plate 54, and this frictional force applies a braking force to the friction plate 54. As a result, the rotation of the friction plate 54 is prohibited, and consequently, the rotation of the rotating shaft 31 is prohibited. Therefore, this state is the brake-on state.

[0037] The reduction gear 23 reduces the rotation of the rotating shaft 31 by a predetermined reduction ratio and outputs the result. The reduction gear 23 is formed in an annular (cylindrical) shape and is arranged coaxially with the rotating shaft 31. The reduction gear 23 is positioned on the output side of the braking device 22 in the axial direction of the rotating shaft 31 and is adjacent to the braking device 22, separated by the cover 27 of the casing 25.

[0038] The reducer 23 is a harmonic drive reducer and has, for example, a harmonic drive (registered trademark) structure. Specifically, the reducer 23 has a wave generator 61, a flexspline 62, and a circular spline 63. The wave generator 61 is constructed by assembling ball bearings on the outer circumference of an elliptical cam. The wave generator 61 is fixed to the output end of the rotating shaft 31.

[0039] The flexspline 62 is formed thinly from an elastic material. The flexspline 62 has a cylindrical body portion 62a and an annular flange portion 62b extending outward from one end of the body portion 62a in the axial direction. The body portion 62a is positioned on the outer circumference side of the wave generator 61, and in this arrangement, the flange portion 62b is located on the opposite side of the body portion 62a from the output side (in other words, the brake device 22 side). The body portion 62a is also bent in an elliptical shape by the wave generator 61.

[0040] The circular spline 63 is formed in an annular shape from a rigid body and is positioned on the outer circumference of the body 62a of the flexspline 62. Numerous external teeth (not shown) are formed on the outer circumference of the body 62a, and numerous internal teeth (not shown) are formed on the inner circumference of the circular spline 63. The number of internal teeth is predetermined (for example, 2) greater than the number of external teeth. The internal teeth of the circular spline 63 and the external teeth of the body 62a engage only at the major axis of the ellipse, due to the elliptical bending of the body 62a.

[0041] A bearing 65 is provided on the outer circumference of the circular spline 63. The bearing 65 consists of a cross roller bearing and is fixed to the cover 27 of the casing 25.

[0042] In the reduction gear 23 with the above configuration, when the rotating shaft 31 rotates, the wave generator 61 rotates together with the rotating shaft 31. This rotation is then transmitted to the circular spline 63 via the flexspline 62. As a result, the circular spline 63 rotates at a predetermined reduction ratio in relation to the rotation of the rotating shaft 31. This reduced rotation is then output to the output destination.

[0043] A strain sensor 68 (strain gauge) is attached to the flexspline 62 of the reduction gear 23. Torsional deformation occurs in the flexspline 62 due to the transmission torque transmitted from the wave generator 61 to the circular spline 63. The strain sensor 68 (equivalent to a sensor) detects the strain that occurs in the flexspline 62 due to this torsional deformation.

[0044] The strain sensor 68 is attached to the flange portion 62b of the flexspline 62. In this case, the strain sensor 68 is attached to the outer circumference of the reduction gear 23 and to the end of the reduction gear 23 on the brake device 22 side. Multiple strain sensors 68 are arranged at predetermined intervals (e.g., equal intervals) in the circumferential direction of the flange portion 62b. Each strain sensor 68 is connected to a control device (not shown) built into the robot 10. The detection result from the strain sensor 68 is output to the control device, and the control device detects the transmission torque and, consequently, the output torque based on the output detection result (amount of strain).

[0045] The encoder 24 detects the rotational position of the rotating shaft 31 and consists of, for example, an optical rotary encoder. The encoder 24 is positioned on the non-output side of the rotor 32 and stator 33 in the axial direction of the rotating shaft 31. The encoder 24 has an encoder disk 71 attached to the non-output end of the rotating shaft 31 and a cover portion 72 that surrounds the encoder disk 71. The encoder disk 71 is formed in a disc shape and is positioned coaxially with the rotating shaft 31.

[0046] In the configuration described above, the reduction gear 23, the braking device 22, the rotor 32 and stator 33 of the motor 21, and the encoder 24 are arranged in this order along the axial direction of the rotating shaft 31, from the output side to the non-output side. In this case, the braking device 22 is positioned between the reduction gear 23 and the rotor 32 and stator 33. Therefore, the reduction gear 23 and the rotor 32 and stator 33 are spaced apart from each other with the braking device 22 in between.

[0047] The housing 52 of the brake device 22 is interposed between the rotor 32 and stator 33 and each strain sensor 68 attached to the reduction gear 23 (flexspline 62). The outer circumferential surface of the housing 52 is located radially outward from each strain sensor 68, and the inner circumferential surface is located radially inward from each strain sensor 68. Therefore, each strain sensor 68 overlaps with the housing 52 when viewed from the axial direction of the rotation axis 31.

[0048] As described in detail above, the configuration of this embodiment provides the following excellent effects.

[0049] A braking device 22 is positioned between the rotor 32 and stator 33 of the motor 21 and the reduction gear 23. In this case, the rotor 32 and stator 33, which are sources of magnetic fields, can be moved away from the reduction gear 23. Therefore, the influence of magnetism on the strain sensor 68 attached to the reduction gear 23 can be reduced.

[0050] Furthermore, even if adjacent components of the rotor 32 and stator 33, the reduction gear 23, the braking device 22, and the encoder 24 are placed close together, the rotor 32 and stator 33 and the reduction gear 23 can be placed far apart from each other. Therefore, the influence of magnetism on the strain sensor 68 can be reduced while miniaturizing the drive actuator 20.

[0051] Incidentally, the above effect can also be achieved by placing the encoder 24 between the rotor 32 and stator 33 and the reduction gear 23, thereby increasing the distance between the rotor 32 and stator 33 and the reduction gear 23. However, since the rotor 32, stator 33, and reduction gear 23 are all heat sources that generate heat, in a configuration where the encoder 24 is placed between the rotor 32 and stator 33 and the reduction gear 23, the encoder 24 may be affected by heat, potentially leading to problems such as false detections. In this respect, the above configuration, in which the brake device 22 is placed between the rotor 32 and stator 33 and the reduction gear 23, makes it possible to achieve the above effect while avoiding such problems.

[0052] Furthermore, by miniaturizing the drive actuator 20, advantages such as saving space in the robot 10 can be obtained.

[0053] In the electromagnetic brake device 22, the housing 52 that houses the brake coil 51 is made of a magnetic material such as iron or steel to prevent the magnetic flux generated when the brake coil 51 is energized from leaking to the outside of the brake device 22. Therefore, in the above embodiment, this point is taken into consideration, and the electromagnetic brake device 22 is placed between the rotor 32 and stator 33 and the reduction gear 23. In this case, the effect of blocking the magnetism generated from the rotor 32 and stator 33 by the housing 52 of the brake device 22 (i.e., a magnetic shielding effect) can be obtained. As a result, the influence of magnetism on the strain sensor 68 attached to the reduction gear 23 can be further reduced. Furthermore, since this effect can be obtained without adding a separate magnetic shielding member, there is also the advantage of reducing costs compared to when a separate magnetic shielding member is added.

[0054] The housing 52 of the brake device 22 is formed in an annular shape that surrounds the rotating shaft 31. Furthermore, when viewed from the axial direction of the rotating shaft 31, the housing 52 overlaps with the strain sensor 68 attached to the annular reduction gear 23. In this case, a magnetic shielding effect by the housing 52 can be suitably obtained.

[0055] Furthermore, when the reduction gear 23 rotates in the circumferential direction of the rotating shaft 31, the strain sensor 68 also rotates in the same direction. In this respect, with the above configuration, the strain sensor 68 and the housing 52 overlap in the axial direction of the rotating shaft 31, regardless of the position of the strain sensor 68 in the rotational direction. Therefore, the magnetic shielding effect of the housing 52 can be reliably obtained.

[0056] In the reduction gear 23, the flexspline 62, which transmits torque from the wave generator 61 to the circular spline 63, undergoes torsional deformation due to the transmitted torque. Therefore, a strain sensor 68 is often attached to the flexspline 62 to detect the strain caused by this torsion. Specifically, the flexspline 62 has a cylindrical body 62a that is coaxial with the rotating shaft 31, and a flange portion 62b that extends laterally from the end of the body 62a on the brake device 22 side (in other words, the rotor 32 and stator 33 side) (in the axial direction of the rotating shaft 31), and the strain sensor 68 is often attached to the flange portion 62b.

[0057] However, in the mounting configuration of the strain sensor 68 described above, in the conventional configuration where the rotor 32 and stator 33 and the reduction gear 23 are arranged adjacent to each other (the configuration described in Patent Document 1 above), the strain sensor 68 is positioned in extremely close proximity to the rotor 32 and stator 33. Therefore, there is a risk that the strain sensor 68 will be greatly affected by magnetism from the rotor 32 and stator 33. In this respect, in the above embodiment, in the mounting configuration of the strain sensor 68, a brake device 22 is placed between the rotor 32 and stator 33 and the reduction gear 23, thereby moving the rotor 32 and stator 33 and the reduction gear 23 further apart. Therefore, even in this mounting configuration of the strain sensor 68, it is possible to suitably reduce the influence of magnetism on the strain sensor 68.

[0058] The present invention is not limited to the embodiments described above, and may be implemented, for example, as follows.

[0059] In the above embodiment, a brake device 22 is placed between the rotor 32 and stator 33 of the motor 21 and the reduction gear 23. However, this can be changed, and an encoder 24 may be placed between the rotor 32 and stator 33 and the reduction gear 23. In this case as well, the rotor 32 and stator 33, which are sources of magnetic fields, and the reduction gear 23 can be moved further apart, thereby reducing the magnetic influence on the strain sensor 68 attached to the reduction gear 23.

[0060] In this case, the encoder disk 71 of the encoder 24 may be formed from a magnetic material such as iron. In that case, a magnetic shielding effect can be obtained from the encoder disk 71, thereby further reducing the influence of magnetism on the strain sensor 68.

[0061] The brake device 22 and encoder 24 may be placed between the rotor 32 and stator 33 and the reduction gear 23, respectively. In that case, the rotor 32 and stator 33 and the reduction gear 23 can be moved further apart.

[0062] The gearbox 23 may be fitted with sensors other than the strain sensor 68, such as an acceleration sensor or a temperature sensor. In such cases, the present invention can be applied to reduce the magnetic influence on the sensors. The sensors may also be attached to components other than the flexspline 62 in the gearbox 23, such as a wave generator 61 or a circular spline 63.

[0063] In the above embodiment, the present invention was applied to a drive actuator 20 that rotates the joints K1 to K6 of the robot 10, but the present invention may also be applied to a drive actuator used in a vehicle other than the robot 10, such as a drive actuator that rotates a rotating stage.

[0064] In the above embodiment, the present invention was applied to a 6-axis robot having 6 joints K1 to K6, but the present invention may also be applied to robots with 5 or fewer axes or 7 or more axes. Furthermore, the present invention may also be applied to a 1-axis robot having only one joint. Moreover, the present invention is not limited to vertical articulated robots, but may also be applied to horizontal articulated robots. [Explanation of Symbols]

[0065] 10...Robot, 20...Drive actuator, 21...Motor, 22...Brake device, 23...Gear reducer, 24...Encoder, 31...Rotating shaft, 32...Rotor, 33...Stator, 51...Brake coil, 52...Housing, 68...Strain sensor (sensor), K1~K6...Joint (joint part).

Claims

1. A motor having a rotor and a stator, which rotates a rotating shaft by the magnetic field generated by the rotor and the stator, A reduction gear for reducing the rotation of the aforementioned rotating shaft, A braking device for stopping the rotation of the aforementioned rotating shaft, The system includes an encoder for detecting the rotational position of the rotational shaft, The aforementioned reduction gear is a drive actuator to which a sensor is attached, The rotor and stator, the reduction gear, the braking device, and the encoder are arranged in the axial direction of the rotating shaft, and the braking device is positioned between the rotor and stator and the reduction gear. The aforementioned brake device is electromagnetic and has a housing made of a magnetic material that houses a brake coil inside. The reduction gear is formed in an annular shape with respect to the rotation axis, The housing is formed in an annular shape surrounding the rotating shaft and overlaps with the sensor when viewed from the axial direction. The aforementioned reduction gear is a harmonic drive gear reduction gear, which is a drive actuator.

2. A robot comprising a drive actuator according to claim 1 for rotationally driving a joint.

3. The robot according to claim 2, which is a vertically articulated type.

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