JPS59169787A - Actuator for joint of multi-joint robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention (d) relates to a joint actuator for an industrial multi-joint robot.

Conventional series, Mizonari and its problems Conventionally, this type of D robot joint is disclosed in Japanese Patent Application Laid-open No. 56-1, for example.
As seen in Japanese Patent No. 57494, etc., it has been proposed that one electric fold is built into the inside of the rectangular joint. However, in vertically articulated robots used for industrial purposes,
Since it is necessary to handle a heavy object over a certain level at a speed above a certain level, an electric motor with a large torque is required, and therefore, in order to directly drive it with the output 11IlII of the electric motor, the electric motor is too large and the K is too large. - The structure of the hemorrhoid (Japanese Unexamined Patent Publication No. 55-157494) is not practical as a joint for a vertically articulated robot. For this reason, JP-A-57-
As seen in Japanese Patent No. 114051, efforts have been made to reduce the rotational speed of the electric motor and increase the torque so as to use the motor efficiently. However, in this patent, a harmonic drive reduction gear is used as the reduction gear, but because it uses a short type of flexible spline, which is generally called a flat type, the deflection per unit length is The disadvantages are that the amount is too large, causing large stress on the flexible spline, short service life, and low load capacity. On the other hand, if the so-called cup type shown in Figure 1 is used, the flexible spline is long, so the amount of deflection per unit length is small for the same amount of deflection, and the stress is also small. Although it is possible to increase the load capacity and extend the life of the i4, it has the disadvantage of being large in size.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a joint actuator for an articulated robot that solves the above-mentioned drawbacks, has a large load capacity, has a long life, and has a small, lightweight, and compact overall structure.

Structure of the Invention The present invention provides an electric motor, a brake, a rotation angle detection device, and an electric motor, brake, rotation angle detection device, etc.
A combination of two or more rotational speed detection devices is housed and arranged to increase volumetric efficiency and constitute a joint actuator that is compact, lightweight, and compact as a whole.

DESCRIPTION OF EMBODIMENTS FIG. 2 shows an embodiment of the present invention, and the present invention will be described below with reference to FIG.

The pair of frameworks 1 and 2 have a cylindrical fulcrum shaft 5° 6 fixed to bearings 3 and 4 mounted on both ends of one framework 1 and coaxially fixed to both sides of the other U-shaped framework 2. By fitting the tips of the bearings into the inner rings of the bearings 3 and 4, the bearings are assembled to be able to swing relative to each other about the fulcrum shafts 5 and 6 at 0T. As a g-motion source for imparting ultra-swing motion to the framework, an electric motor is rotatably supported at both ends of its shaft 7 by bearings 8 and 9.

One of the bearings 8 is attached to the center of the fulcrum shaft 6, and the other bearing 9 is held by a bearing case 10 attached to the center of the fulcrum shaft 6.

A heavy machine 11 is fixed to the center of the shaft 7 of the electric motor, and an appropriate number of permanent magnets 12 are arranged around it in opposition to it, and the permanent magnets 12 are fixed to a holder 13 having a yoke function. The holder 13 is fastened to the fulcrum shaft 6 so as to be coaxial, and a minute gap is formed between the outer periphery of the iron core of the armature 11 and the inner periphery of the permanent magnet 12. A commutator 13 is fixed on the motor shaft 7 in 11J contact with the heavy machine 11, and a brush 14 sliding in contact with the outer periphery of the commutator 13 is mounted in a brush holder 15 fixed on the fulcrum shaft 6. A suitable number of these members are attached and are urged by a spring 16 so as to be able to slide and come into contact with the commutator 13 with an appropriate contact pressure. Although a reduction gear 5 and a gear device are required to reduce the rotation speed of the electric motor and transmit it to the framework 1, in this embodiment, a harmonic drive reduction device is used as the reduction device.・
- Since the monic drive speed reduction device is already universal, explanation of its structure and operating principle will be omitted.

A wave generator 17 is fixed on the motor shaft γ on the opposite side of the commutator 13 and adjacent to the armature 11, and a ball bearing 18 having thin and flexible inner and outer rings on the outside thereof. The ball bearing 18 has an elliptical outer circumference that follows the shape of the wave generator 17. Furthermore, the outer periphery of the ball bearing 18 is fitted into the inner periphery of the flexible spline 19. The flexible spline 19 is usually a particularly flexible thin-walled metal cylinder formed into a cup shape as shown in FIG. It is formed into a ring shape by extending it out. The flexible spline 19 is fixed to the flange portion of the holder 13 of the permanent magnet 12, and is located on the outer periphery of the armature 11 and the permanent magnet 12, and is shaped like a built-in electric motor.

The teeth of the flexible spline 19 are connected to the frame 1.
It is engaged with a circular spline 20 fixed to Ii1. On the side surface of the wave generator 17 opposite to the armature 11, a disc 21 for detecting rotational angle and rotational speed is fixed concentrically with the motor shaft 7. In the case of this embodiment, an extremely thin light-absorbing film having narrow radial slits formed at equal intervals in the radial direction is closely attached to the light-reflecting glossy side surface of the disc 21. Next to the disk 21 are a light projecting section 22 and a light receiving section 23.
is fixed to the fulcrum shaft 5 with an L-shaped holder 24, and the light emitted from the light projecting section 22 is reflected on the side surface of the disc 21,
The light projecting section 2 is placed in a positional relationship such that it enters the light receiving section 23.
2. The light receiving section 23 is attached to the curved holder 24 at an appropriate angle.

A friction disk 25 made of a highly wear-resistant material with a large coefficient of friction is fixed to the shaft end of the motor shaft 7 by a key 26 at 77, but it is slidable in the axial direction. It is movably mounted. A brake disk 27 made of a magnetic material is attached to the side surface of the friction disk 25 so as to be movable in the axial direction, with its outer periphery guided by an electromagnetic case 28. The brake disc 27 is mounted in such a position that a slight gap is formed between the brake disc 27 and the friction disc 25 when the brake disc 27 is attracted to the electromagnet. The electromagnet is constructed by winding a coil 30 around a ring-shaped iron core 29 having a U-shaped surface, and its outer periphery is fixed to the case 28 and is fixed to the side of the fulcrum shaft 5 concentrically with the brake disc 27. has been done. A compression coil spring 31 is installed inside the iron core 29 of the electromagnet, and the brake disc 27
is pressed against the friction disk 25. The compression coil spring 31
For example, it has sufficient force to prevent the frameworks 1 and 2 from moving relative to each other due to external loads during a power outage.

Next, the operation of the above embodiment will be explained.

Now by turning on the power the coil 3o of said electromagnet
When energized, the brake plate 27 is attracted to the iron core against the biasing force of the compression coil spring 31, and a gap is created between the brake plate 27 and the friction plate 25, so that the motor shaft 7 You will be able to move around freely. Now, when the glyph frame 2 is fixed in this state and a command is input to a control circuit (not shown), the brush 14. A current flows through the armature 11 through the commutator 13, and the motor shaft 7
starts rotating. Since the wave generator 17 is fixed to the motor shaft 7, it rotates together with the shaft, and causes the outer periphery of the flexible spline 19 to bend via the ball bearing inserted on the outside thereof. Due to the bending, the meshing between the teeth of the flexible spline 19 and the circular spline 2o shifts by the difference in the number of teeth per rotation of the wave generator 17, causing a gap between the flexible spline 19 and the circular spline 2o. A relative rotation occurs, and the rotational speed is reduced from the rotational speed of the motor shaft 7.

Now, the flexible spline is connected to the hole 91.
Fern13. It is fixed to the glyph frame 2 via the fulcrum shaft 6, while the circular spline 20 is fixed to the frame 1, so that the frame 1 swings.

At the same time, the disk 21 also rotates as the motor shaft 70 rotates, and the light emitted from the light projecting section 22 is reflected by the reflective surface of the disk 21 and enters the light receiving section 23. Since the light absorption film is formed in the shape of a slit on the reflective surface, the light received by the light receiving section 23 is in the form of a 1d pulse, and this pulse signal enters the control section (not shown) and is processed and rotated. Converted to angle and rotational speed values. Since the motor shaft 7 is rotating relative to the U-shaped framework 2, each value is the swing angle value of the framework 1, which is transmitted without slipping and at a reliable deceleration. There is a one-to-one correspondence with the speed value. In this manner, when the amount of swing of the framework 1 approaches a pre-commanded value, the speed is decelerated in accordance with the detected amount and controlled to stop at a predetermined position. Normally, the motor is energized even when it is stopped, so the motor is servo-locked, but in the event of a power outage, etc., when the power stops, the brake plate 27 is released from the adsorption force of the iron core 29. Forced by the force of the compression coil spring 31, the friction disk 26 is pressed against the side surface of the support shaft 5. Since the friction disk 25 is fixed to the electric rear shaft 7 with the key 26 in the rotational direction,
The framework 1 will be locked without moving even if an external force is applied.

FIG. 3 shows another embodiment of the present invention. In this embodiment, an axial gap type motor, a so-called flat type motor, is used in place of the radial gap type motor of the previous embodiment.
An integrated rotation angle detection device and rotation speed detection device is arranged in the inner space of the flexible spline. Since the structure and operation are almost the same as those of the previous embodiment, only the outline of the main parts will be explained.

A pair of frames, l+J132, 33, is a U-shaped frame fIi3
2 and the other framework 33 located between the two side walls, and bearings 34 and 35 mounted on both frameworks 32 and 33.
Therefore, it is configured to be able to swing relative to the curvature of its axis. The tortoise mechanism 117,-ヮ, which serves as a driving source for rocking, has both ends of its shaft 36 supported by bearings 37, 38 mounted on the framework 33, and an armature 39 formed in a disc shape on the shaft. A commutator 4o is fixed, and a yoke 41 and a plurality of permanent magnets 42, facing the armature 39 and separated from each other by a minute gap in the axial direction, are in contact with the outer periphery of the commutator 40 to hold the brush 43. A plurality of brush holders 44 are fixed to the framework 33. A wave generator 45 of a monic drive speed reduction device is fixed to the end of the motor shaft 36, and is in contact with a flexible spline 47 via a ball bearing 46 installed on the outside thereof. The flexible spline 47 is molded in the same shape as that of the previous embodiment. The teeth of the flexible spline 47 are engaged with the teeth of a circular spline 48 fixed to the framework 33. In the inner space of the flexible spline 47, a position/speed detection device 6o is located, which is an integrated rotary encoder and tacho generator fixed to the U-shaped framework by a holder 49, and its input shaft 61 is connected to a cup. It is coupled to the motor shaft 36 via a ring 52.

In the first embodiment and the second embodiment, the electric motor and the position/speed detection device are arranged in the inner space of the flexible spline, but other components such as a brake may also be arranged. Needless to say, it is possible to arrange a combination of the following by making simple changes.

Furthermore, in this implementation, a harmonic drive vehicle reduction device was used as the speed reduction device, but it is also possible to configure and arrange other speed reduction devices to be hollow, and place the element unit of the actuator in the hollow portion. be.

Effects of the Invention As described above, the present invention provides an electric motor, a brake, a rotation angle detection device, a rotation speed detection device, or a combination of two or more thereof, in the inner hollow part of a reduction gear device constructed in a hollow manner. It is possible to construct an actuator that is compact and light as a whole.Furthermore, when using a harmonic drive device as a reduction gear, the total length of the flexible spline can be made longer, and the per unit length If the amount of deflection can be reduced, stress can be reduced, load capacity can be increased, and life can be extended, which has great practical effects.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a cup-shaped flexible spline of a monic reducer, Fig. 2 is a sectional view of a joint actuator of an articulated robot according to an embodiment of the present invention, and Fig. 3 is a sectional view of a joint actuator of an articulated robot according to an embodiment of the present invention. It is a sectional view of an example. 11... Motor armature, 19... Flexible spline, 21... Rotation angle/speed detection disc, 27... Brake plate, 30... Electromagnetic coil, 39... Motor armature, 47-...
・Flexible spline, 50- ・・Rotation angle・
Speed detection device. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3

Claims (1)

[Claims] A deceleration device having a hollow space is arranged in the joint part of the multi-joint robot, and one or more of the following are installed in the hollow part of the deceleration device: an electric motor, a brake, a rotation angle detection device, and a rotation speed detection device. A joint actuator for an articulated robot consisting of arranging legs.