JPH02237783A - Industrial robot - Google Patents

Abstract

PURPOSE:To make the centroid of an arm coincident with the axial position of a rotating joint and to constrain the generation of a centrifugal torque, etc., by installing a motor for removing an interference torque on a robot arm and at the opposite side to the other axial driving motor for the rotating joint thereof. CONSTITUTION:The stator side of a 2nd motor 3 is fixed in parallel axially to a 1st motor to the 1st arm driven by a 1st motor 1. By this 2nd motor 3 a 2nd arm 4 or wrist axis is driven. Moreover, the stator side of a 3rd motor 7 is fixed to the 1st arm 2 in parallel axially to the 1st motor 1 and the torque for offsetting the interference torque which the 1st motor 1 receives by the driving of the 2nd motor 3 is generated by this 3rd motor 7. The 3rd motor 7 is arranged at the opposite side to the 2nd motor 3 in relation to the shaft of the 1st motor 1 and the centroid of the 1st arm 2 is made coincident with the shaft of the 1st motor 1. Consequently, the variation in the load inertias due to the attitude variation of a robot is eliminated and the generation of a centrifugal torque, etc., is restrained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to multi-jointed robots, and in particular, the present invention relates to multi-joint robots, and in particular, the present invention relates to multi-joint robots, and particularly to the interference that motors disposed at each joint of robot arms connected in series receive when the other motors operate. This article relates to an industrial robot with a mechanism for removing torque. [Prior art] A mechanism for eliminating interference between the main axis and the lower axis of the wrist of a conventional horizontal articulated robot is disclosed in Japanese Patent Application Laid-Open No. 63-77673.
As described in the publication, there is an example in which the wrist vertical axis drive motor is arranged in the longitudinal direction of the robot arm, and the power transmission system is configured so that there is no rotating axis parallel to the main axis. In addition, as an example of using a control method, as discussed in Proceedings of the Institute of Electrical Engineers of Japan, Volume D, Vol. 107, No. 1 (1986), pages 1-8, torque that can eliminate interference between shafts is There is an example of removing interference between the hair by generating it on each axis of the hair. [Problems to be Solved by the Invention] The conventional technology disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 63-77673 uses only the vertical axis in a wrist device that normally requires two-axis movement, vertical and rotational. However, it is not possible to configure such a power transmission mechanism for something with a wrist rotation function. Furthermore, in power transmission between the vertical shafts, since the vertical shafts are directly moved using a belt, the vertical rigidity is low and the positioning accuracy is poor.

In addition, in the conventional technology discussed in the above-mentioned Proceedings of the Institute of Electrical Engineers of Japan,
Since complex calculations need to be performed in real time, there is a problem in that the load on the robot controller increases.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a robot arm disposed at each joint of robot arms connected in series, or at each joint of a robot arm and a wrist axis. By equipping the arm with a mechanism that removes the interference torque that each motor receives when the other motors operate, the required torque of the motor for each axis can be reduced.
The purpose is to speed up robot movement. [
Means for Solving the Problem] The above object is to provide a first robot arm that is directly driven by a first motor, and a second motor that is fixed to the first robot arm on the stator side with its axis parallel to the first motor. and,
A second robot arm or a wrist shaft directly driven by the second motor, and a third motor whose stator side is fixedly attached to the first robot arm in parallel with the axis of the first motor, and the third motor is fixed to the first robot arm. This is achieved by an industrial robot whose motor generates a torque that cancels out the interference torque experienced by the first motor due to the operation of the second motor. Preferably, the third motor is located on the opposite side of the second motor with respect to the axis of the first motor, and the center of gravity of the first robot arm is aligned with the axis of the first motor. Further, it is preferable that the first robot arm is provided with a rotational angular acceleration detector.

Furthermore, the above object includes a first robot arm that is directly driven by a first motor, a second motor whose stator side is fixed to the first robot arm with its axis parallel to the first motor; a second robot arm or wrist shaft directly driven by two motors; a third motor whose stator side is fixedly attached to the first robot arm in parallel with the axis of the first motor; and a third motor that is axially coupled to the third motor. and a reducer having a seat fixed to the first robot arm, and a weight coupled to an output shaft of the reducer, and the third motor, the reducer, and the weight are activated by the operation of the second motor. This is achieved by an industrial robot that generates a torque that cancels out the interference torque received by one motor. Also in this case, the third motor is located on the opposite side of the second motor with respect to the axis of the first motor, and the center of gravity of the first robot arm is located at a position that coincides with the axis of the first motor. It is preferable that the first robot arm is provided with a rotational angular acceleration detector.

[Effect]

In order to eliminate interference by 1-lux, we will explain the case where a reducer and a weight are attached to the third motor as an example. When the second motor provided on the first robot arm and driving the second robot arm or wrist axis transmits a torque of τ, the first robot arm receives a counter torque of −τ. In order to prevent the first motor that rotationally drives the first robot arm from being interfered with by the second motor that drives the second robot arm or the wrist axis, the first robot arm must be rotated when the third motor rotationally drives the weight. This is possible because the reaction torque T received coincides with .

Since the fixed side of the reducer is connected to the first robot arm, when current flows to the third motor, the counter torque multiplied by the reduction ratio of the reducer is transmitted to the first robot arm.

Furthermore, by providing the third motor and the speed reducer on the side opposite to the second motor with respect to the rotary joint of the first robot arm, the center of gravity of the first robot arm can be aligned with the rotary joint axis of the first robot arm. , it is possible to eliminate the change in the attitude of the load initial as seen from the axis of the first motor,
The generation of inertial torque, centrifugal torque, and Coriolis torque of the first robot l-arm can be suppressed.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3. 1 shows a perspective view of the horizontal articulated direct drive robot of this embodiment, FIG. 2 shows a cross-sectional perspective view of the first arm of the robot of FIG. 1, and FIG. 3 shows a perspective view of the robot of FIG. 1. The model was shown. First, the structure of the robot of this embodiment will be explained using the first direct drive motor 1. The first direct drive motor 1 has its stator fixed to the base and its rotor fixedly connected to the bottom of the first arm 2. , the first arm 2 is provided with a second direct drive motor 3, a first interference torque removal motor 7, and a first reduction gear 8. A weight 16 is provided at the tip of the output shaft of this reducer 8.

Second direct drive motor 3 and first interference torque removal motor 7
is provided on the first arm 2 on the opposite side to the first direct drive motor 1, and the center of gravity of the first arm coincides with the axial position of the first direct drive motor 1. Further, the rotor of the second direct drive motor 3 is fixedly coupled to the bottom of the second arm 4, and the second arm 4 has wrist shaft drive motors 5, 6.
, a wrist device 11, a second interference torque removal motor 9, a second accelerator 10, and a weight. Wrist axis 12
performs vertical movement and rotational movement by the rotation of wrist drive motors 5 and 6, respectively. The second interference torque removal motor 9 is located on the second arm 4 on the opposite side of the wrist device 11 with respect to the second direct drive motor 3, and the center of gravity of the entire second arm 4 is the axis of the second direct drive motor 3. consistent with the location. Further, in the above description, the interference torque removal motor is configured to multiply the output torque by being directly connected to the reduction gear, but it may be configured with only a direct drive motor. Furthermore, rotational angular acceleration detectors 13a and 13b are provided on the side surface of each arm tip.

Next, the method of attaching the interference torque removing motor, reducer, and weight will be explained using FIG. 2, taking the first arm as an example. A fixed side of the first speed reducer 8 that is directly connected to the first interference torque removing motor 7 is connected to a span plate 14 provided on the first arm 2 . Reducer output shaft 15 is weight 1
6 and is rotatable. By adopting such a structure, the static torque TL' generated by the first interference torque removal motor 7 can be reduced by the first reduction ratio n
1, robot arm 2 has anti-Katork TI”
: ntT% is transmitted to the bottom of the robot arm, and when the torque τ2 of the second direct drive motor 3 is generated, the torque combined with the reaction force torque 2 provided by the base part 18 causes the first direct drive motor 1 to engage. 17 to the first direct drive motor 1. The same function can be obtained by attaching the second interference torque removing motor 9, the second reduction gear 10, and the weight in the same manner.

Next, we will discuss the effect of interference torque cancellation based on the equation of motion of this robot. When the robot is treated as a rigid body model, the equations of motion become as shown in equations (1) and (2). The meanings of the symbols used here are shown in Figure 3.8 cx=Jzx θz+Jxx θx−2mzaiQz
sin θ2θ1θ2−m2az! ). x sin θ
2θx2Tt - (1)? z=Jtz゜θ1
1+J2■”o'2+ m2a t Q 2 sj.n
θ2θ, 2+τ8+τ first T2
...(2) J 11=mxQx"+mz (a
t”+12z2+2 atl2t cogθ2.)
+■Work x+Izz J 12= mz (Q 2”+ a t n 2
Cogθ2)+IzzJ 22: m 2Q 2”+
I zx Here, if the center of gravity position of each arm matches the rotation axis position of the drive motor of each arm, Qx=:Qz=0
Then, the third and fourth terms of the first equation and the third term of the second equation are O
Therefore, centrifugal torque and Coriolis torque become 0, and there is no change in inertia JIJ due to attitude θ2. J1z
=Jzx always holds true. Therefore, equations (1) and (2) are simplified as (3) and (4), respectively. τ1= (mz a. t”+ I tz+ I zz
) θ1+Izzθ2-Ti...(3) τz=I2zθ1+Izzθ2+τδ+τ4-T2 mountain (
4) Here, for the following four cases, the interference torque (return motor, reducer output torque T, and direct drive motor required torque τJ) are shown below.

(A) When only the wrist axis operates Tt=0, Tz=t+s+τ<, τl=:Q,
τ2=0(B) When only 2# is operating Tz=tx, Tz= τs+ τat τz=0+τ
z=lzzθ2 (C) When only 1@ operates Tx=Ixzθz + T x = T z + τ3 + τ
4, τ1=(I rz+mza 12) θ1, τ
2-0(D) 1.2 axis and wrist movement Tz=I2xθx, Tz== Izz B 1+τ
3+τ4prz= (Itz+I2x+mzaIQ
θl, τx=Izzθ2 From the above results, by providing the first and second interference torque removal motors 7 and 9, the required 1-rook of the first and second direct drive motors 1 and 3 can be made non-interfering. be done. In addition, both the interference torque removal hexameter and the direct drive motor required torque are given by the product of the constant inertia value and the joint rotational angular acceleration regardless of the robot's posture, so the rotational angular acceleration detection shown in Figure 1 is Vessel J. By amplifying the outputs of 3a and 13b with an operational amplifier or the like and giving a torque command to each motor controller, non-interfering operation between the axes becomes possible. [Effects of the Invention] Since the present invention is configured as explained above, it produces the effects as described below. First, by installing the interference torque removal motor on the robot arm on the opposite side of the rotary joint from the other axis drive motor, the center of gravity of the arm can be aligned with the rotary joint axis position, and the robot There is no change in load inertia due to changes in posture, and the generation of centrifugal torque, etc. can be suppressed. Motor control becomes easier.

Second, by generating an interference torque removal torque using an interference torque removal motor. The required torque of the robot 1-arm rotation drive motor is reduced, allowing the robot to operate at high speed. Third, since the required torque for each motor is expressed as the product of a constant value of inertia and joint rotational angular acceleration, an analog torque command signal can be easily generated using an acceleration detector and an operational amplifier.

[Brief explanation of drawings]

1 is a perspective view of an industrial robot according to an embodiment of the present invention, FIG. 2 is a perspective sectional view of the first arm of FIG. 1, and FIG. 3 is a perspective view of the first arm of FIG.
FIG. 2 is a diagram showing a model of the robot shown in the figure. 1...First direct drive motor, 2...First arm:
3... Second direct drive motor, 4... Second arm, 5
, 6... Wrist shaft drive motor, 7, 9... Motor for removing interference torque, 8, 10... Reduction gear, 11... Wrist device, 12... Wrist shaft, 13... Rotation Angular acceleration detector, ] 4... gangboard. 1, 5...Reducer output shaft, 1
6...Weight, 17 case concave

Claims (1)

[Claims] 1. A first robot arm directly driven by a first motor, a second motor whose stator side is fixed to the first robot arm so as to be axially parallel to the first motor, a second robot arm or wrist shaft directly driven by two motors, and a third motor whose stator side is fixedly attached to the first robot arm in parallel with the axis of the first motor, the third motor being An industrial robot that generates torque that cancels the interference torque that the first motor receives due to the operation of the second motor. 2. The third motor is located on the opposite side of the second motor with respect to the axis of the first motor, and the center of gravity of the first robot arm is located at a position that coincides with the axis of the first motor. The industrial robot according to claim 1. 3. The industrial robot according to claim 1 or 2, wherein the first robot arm is provided with a rotational angular acceleration detector. 4. A first robot arm that is directly driven by a first motor; a second motor that is fixed to the first robot arm on the stator side with its axis parallel to the first motor; and a second motor that is directly driven by the second motor. a second robot arm or wrist shaft; a third motor whose stator side is fixedly attached to the first robot arm in axis parallel to the first motor; and a third motor which is axially coupled to the third motor and the first robot arm. a reducer having a seat fixed thereto, and a weight coupled to an output shaft of the reducer, wherein the third motor, the reducer, and the weight have an interference torque that the first motor receives due to the operation of the second motor. An industrial robot that generates torque that cancels out the 5. The third motor is located on the opposite side of the second motor with respect to the axis of the first motor, and the center of gravity of the first robot arm is located at a position that coincides with the axis of the first motor. The industrial robot according to claim 4. 6. The industrial robot according to claim 4 or 5, wherein the first robot arm is provided with a rotational angular acceleration detector.