JPS625755B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a joint structure of a robot arm.

In general, the joints of a robot's arm, etc., have the ability to perform tasks without being affected by this drag and shifting from the specified position, even when it receives external resistance, such as when transporting objects or deburring objects. ,
There are two types of robots: those with so-called "highly rigid control functions," and those with so-called "flexible control functions," such as assembly robots, which have flexible joints and can follow external drag forces. It can be broadly classified into those that have.

Conventionally, the above-mentioned "highly rigid control function" and "flexible control function" require contradictory movements, so there has been no joint that has both functions.

An object of the present invention is to provide a robot arm joint that has both "highly rigid control function" and "flexible control function".

According to the present invention, a joint structure for angularly displacing an arm of a robot includes a drive motor that outputs a predetermined driving force, a wave generator to which the driving force is input, and an outer side of the wave generator. a flex spline located at the flex spline, a circular spline disposed outside the flex spline, and a shaft shaft connected to the flex spline, the rotational driving force of the motor being connected to the circular spline. It has a harmonic drive that transmits to the arm, a buffer member connected to the shaft shaft, and an electromagnetic brake provided around the shaft shaft for switching the shaft shaft between a fixed state and a movable state. When the buffer member is substantially separated from the shaft shaft by the electromagnetic brake, the arm is supported with high rigidity by the harmonic drive, and on the other hand, the buffer member is substantially connected to the shaft shaft. In this state, the robot joint structure is characterized in that the arm is supported with low rigidity via the buffer member and the harmonic drive.

Embodiments of the present invention will be described below with reference to the drawings. The illustrated joint is used to connect multiple arms, here fixed to the body of the i-th arm section and angularly displacing the (i+1)-th arm section (not shown). shall be taken as a thing. The driving force for driving the (i+1)th arm is the motor 1 fixed to the i-th arm.
given from. The motor 1 is connected via a chain 2 to an input shaft 4 of a so-called harmonic drive 3.
is connected to. This harmonic drive 3
The so-called wave generator 5 is composed of an elliptical cam and a ball bearing fitted on its outer periphery, and the so-called flex generator 5 is located outside the wave generator and is made of a thin, cup-shaped metal elastic body. It has a spline 6. The outer periphery of the flexspline 6 is provided with involute teeth. Furthermore, the harmonic drive 3 is a rigid body and has a ring shape,
A so-called circular spline 7 having the same pitch as the flex spline 6 and having more teeth than the flex spline 6 is provided on the inner periphery. The (i+1)th arm section (hereinafter simply referred to as an arm section) is connected to the circular spline 7 of the harmonic drive 3. Further, a shaft shaft 9 is connected to the flex spline 6 of the harmonic drive 3, and a spring 8 connected to the arm body 11 is connected to the shaft shaft 9. Further, the shaft shaft 9 can be switched between a fixed state and a movable state by an electromagnetic brake 10.

Next, the operation of this joint structure will be explained.
When the shaft shaft 9 is fixed by the electromagnetic brake 10 and the arm is positioned at an arbitrary angle by the motor 1, and an external force is applied to the arm, the shaft shaft 9 is fixed. The flexspline 6 connected to the shaft 9 cannot undergo rotational displacement. Therefore, the angle of the arm portion does not change from the initially positioned angle.

When the shaft shaft 9 is in a movable state by the electromagnetic brake 10 and the arm part is positioned at an arbitrary angle by the motor 1, when an external force is applied to the arm part, the circular spline 7 and the flex spline 6 are Therefore, the displacement of the arm portion due to the external force becomes a rotational displacement and is transmitted to the shaft shaft 9. However, in the shaft axis 9,
Since the spring 8 coupled to the arm body 11 is connected, the spring 8 deflects in response to external force applied to the arm portion. The angular displacement of the arm portion is kept stable at a position where the resistance of the spring 8 and the external force applied to the arm portion are balanced.

As explained above, in the present invention, in a joint structure for angularly displacing an arm of a robot, a drive motor that outputs a predetermined driving force, a wave generator to which the driving force is input, and a The wave generator includes a flex spline located outside the wave generator, a circular spline located outside the flex spline, and a shaft shaft coupled to the flex spline. A harmonic drive that transmits transmission to an arm connected to a spline, a buffer member connected to the shaft shaft, and an electromagnetic brake provided around the shaft shaft for switching the shaft shaft between a fixed state and a movable state. have. With this electromagnetic brake, when the buffer member is separated from the shaft shaft, the arm is supported with high rigidity by the harmonic drive, and when the buffer member is substantially connected to the shaft shaft, the arm is supported by the shock absorber. and is supported with low rigidity via a harmonic drive. Therefore, if this joint structure is used in a robot arm, it will provide "highly rigid control functions."
and "flexible control function", so it can be controlled according to the nature of the work, unlike conventional methods.
Switch the rigidity of the joint structure of the robot arm depending on the content of the work without using a separate robot arm with a "highly rigid control function" or a robot arm with a "flexible control function" This allows the same robot arm to perform both rigid and flexible tasks.

In addition, in the example, explanation was given assuming a case where multiple arm sections are connected in series, but when a joint is provided on a fixed support base and a single arm section is connected to this joint, The present invention is also applicable.

[Brief explanation of the drawing]

The drawing shows one of the robot joint structures according to the present invention.
It represents the principle diagram which is an example. 1... Motor, 2... Chain, 3... Harmonic drive, 4... Input shaft, 5... Wave generator, 6... Flex spline, 7...
...Circular spline, 8...Spring, 9...Shaft axis, 10...Electromagnetic brake, 11...Arm body.

Claims (1)

[Claims] 1 A joint structure for angularly displacing a robot arm includes a drive motor that outputs a predetermined drive force, a wave generator to which the drive force is input, and a frame located outside the wave generator. The motor includes a flex spline, a circular spline disposed outside the flex spline, and a shaft shaft coupled to the flex spline, and transmits the rotational driving force of the motor to an arm connected to the circular spline. It has a harmonic drive, a buffer member connected to the shaft shaft, and an electromagnetic brake provided around the shaft shaft for switching the shaft shaft between a fixed state and a movable state, and by the electromagnetic brake, When the buffer member is substantially disconnected from the shaft shaft, the arm is supported with high rigidity by the harmonic drive, while when the buffer member is substantially connected to the shaft shaft, the arm is supported by the harmonic drive with high rigidity. A joint structure for a robot, wherein the arm is supported with low rigidity via the buffer member and the harmonic drive.