JPS6249513A - Automatic control method for robot machine constant - Google Patents

Abstract

PURPOSE:To measure automatically the machine constant of robot set under an assembling state and to improve the absolute positioning accuracy, by using a correlative equation between the machine constant and the angle data to obtain the machine constant. CONSTITUTION:The three different postures are given against the reference position through operations of a robot. A machine constant arithmetic means 41 calculates a reference machine constant li based on the angle data phiij on each posture detected by an angle sensor 5 and by means of a prescribed correlative equation. Then a comparison arithmetic means 42 obtains the difference DELTAli between the constant li and a reference machine constant. An appropriate state is decided when the difference DELTAli is kept within an allowable error epsiloni. Thus, it is possible to measure the machine constant of the robot while the robot is working. This can improve the absolute positioning accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for automatically managing robot mechanical constants, and relates to a method suitable for controlling the quality of robots, particularly the operation accuracy.

[Conventional technology]

In general, position repeatability and absolute positioning accuracy are used to express the operational accuracy of a robot, and in the past, the former was mainly considered important in controlling the performance and quality of the robot.

[Problem that the invention seeks to solve]

However, as the application of robots has expanded, absolute positioning accuracy for a desired position has become more important, and at the same time, it has become necessary to ensure compatibility between robots of the same model. Absolute positioning accuracy is related to the so-called mechanical constants of the shapes and dimensions of the parts constituting the robot arm, and compatibility is also related to the mechanical constants.

However, since one mechanical constant is determined during manufacturing and assembly, its value is unique to each robot, and if there is a large variation in the mechanical constant, compatibility will be impaired.

Additionally, since the mechanical constants fluctuate due to changes in the operating environment conditions (e.g. temperature), there is a problem in that the robot's motion may err in relation to the desired motion, resulting in poor absolute positioning accuracy. . Moreover, there is a problem in that the error varies depending on various conditions.

However, in the past, the only way to measure mechanical constants was to directly measure them using gauges, etc., which was impossible without disassembling the robot, so mechanical constants were usually measured after assembly or during use. nothing has been done,
There was no management of absolute positioning accuracy, let alone compatibility management.

An object of the present invention is to provide an automatic control method for robot mechanical constants that can automatically measure the mechanical constants of a robot in an assembled state and improve absolute positioning accuracy.

[Means for solving problems]

In order to achieve the above object, the present invention drives a robot to set a plurality of different postures with respect to a predetermined reference position,
The present invention is characterized in that angular data consisting of the rotation angle of each axis of the arm configuration in each posture and the angle with respect to the coordinate axis is detected, and the mechanical constants of the robot are determined using a correlation equation between the mechanical constants and the angular data.

[Effect]

That is, the present invention takes into consideration that there is a certain correlation between the mechanical constants of the robot and the control position and angle data of the arm.
The control position is kept constant by setting a reference position, and the angular data is detected by an angle sensor mounted on the robot to obtain mechanical constants.

Therefore, by setting a number of different postures corresponding to the number of unknown mechanical constants, a simultaneous correlation equation corresponding to the number of unknown mechanical constants can be obtained, and by solving this equation, all mechanical constants can be found. be able to.

〔Example〕

Hereinafter, the present invention will be explained based on the implementation side.

FIG. 1 shows a flowchart of the management procedure of an embodiment in which the present invention is applied to the six-axis articulated robot shown in FIG.

As shown in the schematic diagram of FIG. 3, the robot main body 1 shown in FIG. 2 has six axes Li (i=1 to 6) and a joint Jk (k=1 -6). The robot main body 1 is driven and operated by a robot control device 2. A reference pillar 3 is installed within the operating range of the robot body 1, and the reference pillar 3 is formed in the shape of a spire, and the coordinates of the tip position P are set to (Xo +10 +Zo). Note that the reference column 3 is desirably formed of a material that is less affected by changes in environmental conditions such as temperature changes, such as ceramic.

The robot control device 2 incorporates a mechanical constant management device 4 having the configuration shown in FIG. The mechanical constant management device 4 is
Angle data ψ1j (j=1
-6) and the reference position coordinate P (xo.

ya+Za), a mechanical constant calculation means 41 calculates the mechanical constant 11, a comparison calculation means 42 calculates the difference Δli by comparing the calculated mechanical constant 11 and the reference mechanical constant 11', an error determining means 43 that determines whether or not the tolerance is within the tolerance ε; and outputs an alarm signal when the error is negative; and a control calculation parameter correction means that corrects the control calculation parameters related to robot control according to 1i. 44. In addition, the obtained mechanical constant 1i and the difference Δli are displayed on a display device 6 such as a monitor.
It is now displayed in the output.

A specific example of the configuration of the comparison calculation means 42 and error determination means 43 is shown in FIG. As shown in the figure, a buffer Bi is provided corresponding to the number of each mechanical constant 11, and the mechanical constant 1i obtained by the mechanical constant calculating means 41 is stored in the corresponding buffer B.
It is distributed and stored in i. The processing means after each buffer Bi have the same configuration for each constant 11, and illustrations other than i=1 are omitted. The contents of buffer B1 are the reference mechanical constant 11' set in setter S and comparator C.
1□, and the difference Δ1□ is calculated by setting device Sa1.
The comparator C2□ compares and determines the tolerance error ε set in ing.

The control calculation parameter correction means 44, as shown in FIG. Ten contents obtained by the mechanical constant calculation means 41 are rewritten.

The operation of the embodiment configured as described above will be described next with reference to the flowchart of FIG. 1 and FIG. 3.

The correlation between the axis Li, the angle data ψij, and the reference position (XoyloyZa) in the arbitrary state diagram shown in Fig. 3 is calculated from i = 1 to i The composite matrix Mi up to is expressed by the following equation (1) (for example, M, = T1 umbrella T2
Umbrella...Umbrella T6).

Mi=Mi-, skewer Ti・ ・ ・ ・ ・ ・ ・ ・
・ ・ (1) However, 1≦i≦6 i=integer M. =1 From equation (1), a forward transformation determinant shown in equation (2) below is constructed.

When formula (2) is expanded, it becomes a three-dimensional linear system of equations, but the unknowns are 1, 1, ... IIGIX
There are 9 OIyo+Zo. Since ψsjsψzjs...ψ6j are determined by teaching one posture, three equations including the nine unknowns are established. Therefore, if three or more postures are taught with j=1 to 3, nine equations will be established, and all the desired unknowns 11 will be found.

Therefore, in step 101 of FIG. 1, FIG.
As shown in C), the robot is operated to teach three different postures relative to the reference position P. These three postures may be taught in any posture as long as P (XD Hy6 HZ6 ) is constant. Then, in step 102, the angle data φ1j (i=1 to 6. (mechanical constant calculation means 41). Next, in step 104, the reference mechanical constant 11
’ by subtracting the mechanical constant 11 found, the difference Δ1i
=1i'-1i (comparison calculation means), step 10
Proceed to step 5 and compare the absolute value of the difference Δ11 with the allowable error εi, and if 1Δliil≦εi, it is determined to be appropriate, and 1Δ1
If 11>εi, it is determined to be inappropriate (error determination means).

Then, in step 106, the determined mechanical constant 11
The difference Δli and the determination result are output and displayed on the display device 6. As a result, the mechanical constant of the robot is 11 while in use.
It can also be measured.

The difference Δli from the reference mechanical constant 1i' is immediately displayed as an output, and it can be easily determined whether the difference Δ11 is within the allowable error range εi.

By managing the robot based on the results, it is possible to improve absolute positioning accuracy, and it is also possible to easily determine whether or not there is compatibility.

On the other hand, based on the mechanical constants 10 determined in step 103, in step 107, the contents of mechanical constants 11 in the data table DT related to robot control calculation parameters are rewritten. As a result, the mechanical constants used for robot control calculations are corrected to accurate actual measured values.
It can respond to changes in environmental conditions and changes over time, and can always guarantee movement to a desired position and path, improving absolute positioning accuracy.

The above explanation was based on an example applied to a 6-axis articulated robot with 6 degrees of freedom. However, since the difference in degrees of freedom is related to the number of equations in equation (2), The method can be applied to any robot, and in that case, the number of postures may be selected to obtain simultaneous equations according to the unknowns.

Further, although the comparison calculation means 42 and the error determination means 43 shown in FIG. 5 are configured to process the mechanical constants 1i related to each axis Li in parallel, they may also be processed in series using the 1 time division method.
It is also possible to incorporate the functions of the machine constant management installation 4 into the CPU of the robot control device 2.

〔Effect of the invention〕

As explained above, according to the present invention, a robot is driven to set a plurality of different postures with respect to a predetermined reference position, angle data in each posture is detected, and a correlation equation between mechanical constants and angle data is calculated. Since the mechanical constants are determined by using the robot, the mechanical constants can be easily and accurately automatically measured while the robot is in use without disassembling the robot, thereby improving the absolute positioning accuracy of the robot. It has the effect of being able to

[Brief explanation of drawings]

Fig. 1 is a flowchart showing the management procedure of an embodiment of the present invention, Fig. 2 is an overall configuration diagram of an embodiment to which the present invention is applied, and Fig. 3 is a schematic diagram of the robot arm of the embodiment of Fig. 2. Figure 4 is a block configuration diagram of the main part of the embodiment shown in Figure 2, Figures 5 and 6 are detailed views of the main part of Figure 4, and Figure 7 is a schematic diagram illustrating a plurality of different postures. be. DESCRIPTION OF SYMBOLS 1... Robot body, 3... Reference column, 4... Mechanical constant management device, 5... Angle sensor, 6... Display device, 41... Mechanical constant calculation means, 42... Comparison calculation means. 43...Error determination means, 44...Control calculation parameter correction means, LL...axis, ψij...angle data,
Jk...Joint, 11...Mechanical constant, li'...Reference mechanical constant.

Claims (3)

[Claims] (1) Drive the robot to set multiple different postures with respect to a predetermined reference position, detect the angle data consisting of the rotation angle of each axis of the arm configuration and the angle with respect to the coordinate axes in each posture, and calculate the mechanical constants and angles. 1. A method for automatically managing mechanical constants of a robot, comprising determining mechanical constants of the robot using a correlation equation with data. (2) The method for automatically managing robot mechanical constants according to claim 1, characterized in that it is determined whether the difference between the determined mechanical constants and a reference mechanical constant is within an allowable range. (3) The method for automatically managing robot mechanical constants according to claim 1, characterized in that control parameters of the robot are corrected based on the determined mechanical constants.