JPS62148175A - Industrial 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 relates to industrial robots, and particularly to a position detection mechanism suitably used in a power transmission mechanism of an industrial robot.

"Prior Art" Conventionally, industrial robots are known that are equipped with wrist mechanisms that rotate around a plurality of axes oriented in mutually orthogonal directions.

FIG. 3 shows a conventional example of the above-mentioned wrist mechanism.

The symbol l in the figure is a pipe-shaped arm, and this arm 1
Inside, there is a pipe-shaped transmission shaft 2A that transmits rotational force.
2B and the solid transmission shaft 2C have the same axis,
Moreover, it is provided rotatably about the axis and constitutes a transmission shaft called a so-called torque tube. A gear 3 is provided at the base end of each of the transmission shafts 2A, 2B, and 2C, and these gears 3 are connected to a speed reducer 5A that is directly connected to a drive source 4A, 4B, and 4C such as a DC motor. - It meshes with the gear 6 provided on the output shaft of 5B and 5C, and is driven respectively. Note that the rotation angles of the output shafts of the reduction gears 5A, 5B, and 5C are detected by position detectors 7A, 7B, and 7C, respectively.

On the other hand, a wrist mechanism 8 is attached to the tip of the outermost transmission shaft 2A, and the wrist mechanism 8 includes a support frame 9 that rotates together with the transmission shaft 2A, and a A hollow operating shaft IOA and a solid operating shaft 10B are provided in a direction perpendicular to the transmission shafts 2A, 2B, and 2C and have the same axis, and are fixed to the lower end of the operating shaft IOA. and a wrist frame II that rotates as a unit. Said operating shaft l0A-
10B are both rotatably supported by the support frame 9, and one end of the operation shaft 10A is connected to the transmission shaft 2.
B via bevel gears (transmission mechanism) 12, 12, and one end of the operating shaft 10B is connected to the transmission shaft 2C via bevel gears (transmission mechanism) 13, 13.
They are designed to rotate in conjunction with each other.

The wrist frame II is rotatably supported by a support frame 9, and the transmission shaft 10A-1 is provided inside the wrist frame II.
013 (that is, the transmission shafts 2Δ, 2B,
A working shaft 14 (parallel to 2C) is rotatably supported. The working shaft 14 is connected to the operating shaft 10B via bevel gears (transmission mechanism) 15, and rotates in conjunction with the operating shaft 10B.

"Problems to be Solved by the Invention" By the way, in the above wrist mechanism, for example, the drive source 4A
When the support frame 9 (hereinafter referred to as the first driven shaft 9) is rotated, the first driven shaft 9 becomes the transmission shaft 2.
B and 2C rotate relative to each other, and this relative rotation is transmitted to the transmission shafts 10A and IOB through power transmission mechanisms consisting of bevel gears I2 and 13, respectively, and as a result, the wrist frame (second driven shaft) 11 and the working axis (third driven axis)! 4 will be rotated in conjunction with each other.

Therefore, in the above-mentioned wrist mechanism, a control mechanism as shown in FIG. 4 is used to correct the rotation angle of each axis.

In other words, the ratio of each gear and bevel gear, A is l=1
Assuming that, the absolute rotation angle (after deceleration) of each drive source 4A to 4C is 01
01710 between M・02M・03M and the absolute rotation angle θITθ2T・63 of each transmission shaft 2A to 2C.
The following relationships hold: 1M θ2T=02M θ3T=03M, and furthermore, the rotation angle of each part of the wrist mechanism is
If the rotation angle of the support frame (first driven shaft) 9 is θl, the rotation angle of the wrist frame (second driven shaft) 11 is 02, and the rotation angle of the work shaft (third driven shaft) 14 is 03. , θl=θIT θ2=02T−θIT θ3=03T−02T hold true. From these relational expressions, in order to rotate each part of the wrist mechanism by θ1, θ2, and 033, respectively, θ1M=θl...
(1) 2〇2M−θ2+θIT=θ2+θl ・
...(2) 2〇3M-θ3+θ2T-θ3+θ2+θ
1. It is necessary to control the absolute amount of the rotation angle of each drive source 4A to 4C so as to satisfy the three equations (3).

Next, the control operation of the wrist mechanism will be explained.

That is, when a command is issued to rotate the first driven shaft 9 by an angle of 01, this angle signal θl is subtracted from the feedback data from the vertical position detection Th57A in the adder 21, and then the rotation of the drive source 4A is determined. The signal is input to the drive source 4A via the amplifier 22, the adder 23, and the amplifier 24, and the drive source 4A is rotated by a predetermined angle.

Further, the detection signal of the rotational speed of the drive source 4A is
When the signal is fed back to the adder 23 via the tacho generator 25 built in the IA, it is further fed back to the adder 21 via the position detector 7A and after inversion. There is.

The control mechanism of the drive source 4B is such that an adder 26 is added to the input side of the control mechanism of the drive source 4A. The data θ2 and the data θl of the angle at which the first driven shaft 9 should be rotated are added, and this calculation result is manually input to the adder 21 as the rotation angle signal 02M of the drive source 4B.Hereinafter, the drive source= It is configured to perform control consisting of processes similar to LA.

Furthermore, the control mechanism of the drive source 4C adds the data θ3 of the angle at which the third driven shaft 14 should be rotated and the output of the adder 26 in an adder 27, and uses this calculation result as the rotation angle of the drive source 4C. It is input to the adder 21 as a signal 03M, and is thereafter controlled through the same process as the drive sources 4A and 4B.

In the above control mechanism, Fig. 4 θl to θIM, 02
In each section of ~02M and 03~03M, the above (1)
A correction process based on formula (3) is performed, and this process adjusts the first driven shaft 9, second driven shaft 11, and third driven shafts 1 and 1 by 01, θ2, and 03 degrees, respectively. It is designed so that it can be rotated.

However, in the above Nli positive operation, if the operating ranges of the first driven shaft 9, second driven shaft It, and third driven shaft 14 are respectively θIE, θ2E, and 03E, then 1 θ 11 ≦ θ IE 1021 ≦ 02E 1 θ 31 ≦ 032, and therefore, the operating range of each drive source 4A to 4C is [IMl≦θIE 102Ml≦oIE+θ2E 103Ml≦θIE+θ2E+ 03E, so the first driven shaft 9→second driven shaft 11−th As the operating range of the third driven shaft 14 increases, errors tend to accumulate and the positioning accuracy tends to decrease.

The present invention was proposed in view of the above circumstances, and an object of the present invention is to improve the positioning accuracy of a wrist mechanism.

"Means for Solving the Problems" In order to achieve the above object, the present invention provides an angle detector between rotating transmission shafts connected to a plurality of drive sources.

"Operation" The detector detects the difference in the rotation angle of each drive source from the detection result of the relative rotation angle of the transmission shaft, and feeds back data of this difference to each drive source, so that each drive source The absolute value of the angle to be rotated can be directly specified.

2. Embodiment 2 An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Components in the figure that are common to those in FIGS. 3 and 4 are designated by the same reference numerals, and the explanation thereof will be simplified.

This wrist mechanism connects position detectors 28A, 28B, and 28G between arm l and transmission shaft 2A, and between transmission shafts 2A and 2B.
What is the basic structure of the transmission shafts 2B and 2C, respectively?

In this embodiment, the position detection i! S28 A.2
So-called hollow resolvers (synchronized oscillators) are used as 8B and 28G, and these detectors 28A and 2
813 and 28G both have a function of converting the angle of relative rotation between the inner ring 29 and the outer ring 30 into an electrical signal.

Next, the configuration of the control mechanism will be explained.

In other words, the rotation angle signal of the drive source 4A for the first driven shaft 9 is input to the position detector 28A, and after inversion, the rotation angle signal is input to the adder 2.
The second driven shaft II
An inverted state is input manually to an adder 32 provided on the output side of the control mechanism. In this adder 32, the inverted signal is added to the rotation angle signal of the drive source 4B of the second driven shaft 11, and then manually inputted to the position detector 28I3. Be it. The rotation angle signal of the drive source 4B of the second driven shaft 11 is transmitted to the third driven shaft 14.
The adder 32 provided on the output side of the control mechanism is manually inputted in an inverted state. In this adder 32, the inverted signal is added to the rotation angle signal of the drive source 4C of the third driven shaft 14, then manually inputted to the position detector 28C, and after inverted, is fed back to the adder 21. Ru.

In the control mechanism configured in this way, the first and second
・The rotation angles of the third driven shafts 9, 11, and 14 are respectively θ
1, θ2, θ3, and the rotation angles of the respective transmission shafts 2A, 2B, and 2C are respectively θIT, 02T, and 03, then the angles θIR, θ2R, θ3R detected by each position detector 28A, 28B, and 28C, and each of the above Transmission shaft 2A/2B/2
Between the rotation angle of C and the rotation angle, 01R=θlT=θ1...(4) formula
2R-θ2T-θlT=θ2...(5) Formula 0
3R-03-θ2T=θ3 Each of the equations (6) holds true. Therefore, each position detector 28A.
The detected angles of 8B and 28C are equal to the wrist movement angle.

As long as the above formulas (4) to 6) are satisfied,
By inputting a signal indicating the angle at which each of the driven shafts 9 and 11-14 should be rotated, each drive source 4A to 4C can be directly controlled without performing a correction operation.

Note that the technology of the present invention can be applied not only to a wrist mechanism that operates three axes as in the above embodiment, but also to a wrist mechanism that operates two axes or even more axes. In addition, the transmission mechanism between each drive source and each transmission shaft, or the transmission mechanism between the transmission shaft and the driven shaft, is limited to that of the above example. Of course, it may be changed as appropriate depending on the function.

Furthermore, if the reduction ratio of the transmission system from each drive source to the driven shaft is different for each axis, the output of each detector is multiplied by a coefficient corresponding to the reduction ratio to determine the rotational speed of one drive source. Accurate control can be performed by converting this value into , and processing this converted value in the same way.

"Effects of the Invention" As is clear from the above explanation, the present invention provides a position detector for measuring the relative rotation angle between the transmission shafts that are provided with the same axis. , each position detector measures the relative rotation angle of the transmission shaft, and by feeding back this rotation angle to the drive sources, these drive sources can be rotated by a predetermined amount without the need for special correction. Therefore, it is possible to minimize the rotation angle of each drive source, reduce the accumulation of errors that cannot be avoided in the correction operation, and achieve more accurate positioning.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention,
Figure 1 is a transmission system diagram, Figure 2 is a block diagram of the control mechanism,
3 and 4 show a conventional example of a robot wrist control mechanism, with FIG. 3 being a transmission system diagram and FIG. 4 being a block diagram of the control mechanism. 2A, 2B, 2C...Transmission shaft, 3...
Gear, 4A, 4B, 4C... Drive source, 5A, 5B, 5
C...Reducer, 6...Gear, 8...
... Wrist mechanism, 9... Support frame (first driven shaft), II... Wrist frame (second driven shaft)
, 14... Working axis (third driven axis), 12・I
3.15...Bevel gear. Figure 4Figure 2

Claims (1)

[Claims] a plurality of transmission shafts arranged parallel to each other; a plurality of drive sources connected to one end of the transmission shafts to individually rotate the transmission shafts; and oriented in a direction intersecting the axes of the plurality of transmission shafts, one driven shaft that is connected to one of the plurality of transmission shafts and rotates in conjunction; and one driven shaft that is rotatably supported by the one driven shaft and connected to another transmission shaft that is different from the one transmission shaft. a position detector that is provided between each of the plurality of transmission shafts and detects a relative rotation angle thereof; and a position detector that feeds back the detected angle of the position detector to each drive source. An industrial robot characterized by comprising a control mechanism that adjusts the rotation angle by rotating the robot.