JPS6377678A - Method of controlling operation of robot - Google Patents

Abstract

(57) [Abstract] 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 a method of controlling the motion of a robot, and particularly to a method of controlling the motion of a robot that performs work while changing its relative position to a workpiece.

[Prior Art] A robot is generally fixedly installed, and performs work on a workpiece set within the operating range of the robot. In this case, a so-called teaching/reproduction control method is employed, which is a control system in which the robot is taught and memorized the content of the motion prior to the robot's work, and the stored content is reproduced to cause the robot to perform the work.

On the other hand, in recent years, with the diversification of robots, there has been a demand for the application of robots to work on large-scale sweepers, atomic couplants, etc. where human intervention is not possible. In order to meet this demand, mobile robots that perform work while moving themselves are essential. However, the position and posture of mobile robots change relative to the work object during the execution of the work. For this reason, it has been impossible to have the robot perform work along a predetermined trajectory based on numerical values based on teaching or design data. Examples close to this include JP-A-57-182205 and JP-A-57-182205.
As described in Japanese Patent No. 9-189415, there is a system that detects the relative relationship between a robot and an object by teaching a plurality of representative points and corrects the work content.

[Problem that the invention seeks to solve]

However, the above-mentioned conventional technology cannot cope with a situation where the relative relationship between the robot and the object changes during execution of one task.

The first object of the present invention is 5. Operation of the robot that allows the robot to execute pre-given work contents in real time even if the relative relationship between the position and posture of the work object and the robot changes during the work execution. The objective is to provide a control method.

A second object of the present invention is to control the motion of a robot that can execute pre-given work contents in real time even if the relative relationship between the position and posture of the work object and the robot changes during the execution of the work. The goal is to provide equipment.

[Means for solving problems]

The first object of the present invention is to represent and memorize the work content given in advance in a coordinate system fixed to the target object, and to sequentially correct it based on the relative relationship between the robot and the target object detected by a sensor, etc. This is achieved by controlling the robot's movement along the trajectory of the robot.

A second object of the present invention is to detect the relative relationship between a work object and the robot in a robot that performs work in a situation where the relative relationship of the position and posture of the work object to the work object changes during the execution of the work. A detection means, a means for storing the robot's work data, a means for converting an arbitrary work point on the object into the robot's coordinate system, and a means for doubling the robot's work data using information from the converting means are installed. Achieve it by doing.

[Effect]

Even if the relative relationship between the position and posture of the robot changes due to movement of the robot, etc., the relative relationship is detected by a sensor or the like. Based on the relative relationships at this time, the work contents given in advance are sequentially corrected by coordinate transformation. By operating the robot according to the corrected work content, the robot can be controlled to move along a predetermined trajectory of the object.

〔Example〕

The present invention will be described in detail below with reference to the drawings.

First, before giving a detailed explanation of the present invention, the principle of the present invention will be explained with reference to FIG.

Let P be the position of the robot R at a certain moment during work, and Q be the position it moves to the next moment. Now, the coordinate system fixed on the work target W^ to be worked by the robot is 0^, XA as shown in Fig. 2.

YA, ZA, the coordinate system on the robot at the position of P is Op r xp typ + zp, and similarly the coordinate system on the robot at the position of Q is Oe, X
Q.

Let yQ and ZQ.

First, regarding the work content, a coordinate system 0^, X^, Y^ is fixed on the work target location W^ based on data taught in advance or design data.

It is given based on ZA.

Next, when performing work at the robot position P,
It is necessary to express the data of the work content in the robot's coordinate system Op 9 XP + yP tzp.

Similarly, when the robot performs work at position Q, the coordinate system Oe at position Q of the robot.

It needs to be expressed as XQ, yQ, and ZQ.

Here, let A be an arbitrary work point in the work content data, and let the coordinate values of point Δ in the coordinate system OA, XA, YA, Z^ be (X
a, Ya, Za). Also, the coordinate system Op + XPv 3'P+zp at the robot position P
The coordinate values of point A (7) in (Xp, Yp, Z
p) and the coordinate system Oe at the robot position Q.

XQ v ye t The coordinate value of point A in ZQ is (X
, t.

Yq , Zq ) then (Xa , Ya , Za
) and (XP, Yp, ZP) and (Xq,
If we give the relational expression for converting Yq, Zq),
Robots can be made to perform tasks while converting taught data.

Therefore, the above-mentioned coordinate transformation relationship will be explained. Now, the 1@ mark of any point A shown in Fig. 1 is the coordinate system O^.

When expressed by XA, YA, ZA, (Xa, Ya,
Za ), and the coordinate system OP * XP p 3'P
It is assumed that when expressed as tZP, it becomes (Xp, Yp, Zp). If the transformation matrix between these is T1, the relationship holds true, where the transformation matrix T1 is the coordinate system 0^
, XA, YA, ZA coordinate system Op
, xp , yp F zp is obtained by expressing it from above. Therefore, the coordinate system Op, xp.

The coordinate system 0^ is determined by visual sensors on yp and zp.
, XA, YA, and ZA, if multiple reference points are detected,
A transformation matrix T1 can be obtained.

In addition, by the same method as above, the coordinate system O^.

XA, YA, ZA and coordinate systems Oe, Xe, YG
A transformation matrix TZ with I and Ze can also be obtained.

As is clear from the above explanation, no matter how the relative relationship between the robot and the work object changes, the transformation matrix is determined from the sensor information at each time, and the robot moves any work point on the work object. It is possible to perform a predetermined work by converting the coordinate system into the coordinate system of

Next, an embodiment of the motion control device of the present invention will be described with reference to FIG. 1 based on the principle of motion control of the present invention described above. In this figure, R is a mobile robot, and S is a sensor that photographs the work object.

102 is a motion path storage device, and this device 102 has a workpiece coordinate system 0^, XA as shown in FIG. 2, for example.

Store it as work data on YA and ZA.

This basic work data is given from a design data storage device 101 that stores numerical data obtained by a computer or the like based on the teaching motion of the robot R or design data. 107 is a correction point data storage device, and this device 107 stores the aforementioned workpiece coordinate system and robot coordinate system Op.
tXP! Standard reference point data for giving a relative relationship with yP rzp is detected by the sensor S and stored.

The standard reference point data can be detected by the sensor S and rewritten as the relative relationship between the robot R and the workpiece A changes. For example, as shown in FIG. 4, this correction point data changes from point Al l Ax v As to point A as the relative relationship between the robot and workpiece changes.
It is rewritten as I', A2', Aa'.

106 is a device that calculates a transformation matrix using the correction point data from the device 107;
) is used to calculate the transformation matrix TI. 103 uses the correction transformation matrix T1 of the device 106 to convert the device 102
This is a device that calculates the work movement path of the robot R from the robot R as data in the robot coordinate system. The corrected motion path data of the robot R obtained by the arithmetic unit 103 is corrected as the relative relationship between the work W^ and the robot R changes. This data is stored in the storage device 104 and sequentially sent to the motion command generation device 105 of the robot R. The operation command generating device 105 drives the robot R based on the data described above, and causes the robot R to perform the correct work regardless of changes in the relative relationship between the robot R and the workpiece W^.

Note that when the relative relationship between the robot R and the workpiece W^ changes from time to time, the storage device 104 can be omitted because the calculations are performed by the calculation device 103 at high speed in real time.

Next, an example in which the present invention is applied to an example of work performed by a mobile robot will be described. As an example of the work, as shown in FIG.
, 1 is an example of moving inside.

In the above-described robot work, the robot R approaches the door 11 and while moving, grasps the knob 12 using the hand 13 and opens it. When opening the door 11, the relative relationship between the knob 12 of the door 11 and the robot R changes from moment to moment as the robot R moves. For this reason, visual sensors 14 and 15 attached to the robot R detect reference points Ar, A2, and A2 on the door 11. As is detected, and based on the results, the relative relationship between the robot R and the object door 11 is detected moment by moment, and the first hand 13 is controlled, the knob 12 is moved, and the door 11 is opened.

In this case, the standard reference points Ax, Ax, and As are generally black marks, but as long as they can be recognized by the visual sensors 14 and 15, they can have nine different shapes.

In the door opening operation by robot R shown in FIG. 3, robot R moves from point α to point β as shown in FIG.
In the meantime, the door 11 moves from the position indicated by the symbol WB to the symbol WB.
' Move to the position indicated by '. The work data given here is the trajectory of the knob 12 shown in FIG. 3, in which it moves from point B to B'. below,
The operation control method will be explained using FIG.

The coordinate system at point α of robot R is 0α, Xa.

Let Ya and Zα be the coordinate systems of the door WB, which is the object at that time, as OB and XFI + YB + ZB. next,
The coordinate system at point β of robot R is 0β, XB.

YB and Zn, and the object at that time is the door W B'
OR the coordinate system of * XB' + Ya' l ZB
shall be.

Here, the robot's work point B is in the coordinate system Oa, XB
.

Ya, Zn, and B' is the coordinate system OB.
+ Xl: I'HYa' l Za' d. First, at point α, the robot R uses the visual sensors 14 and 15 shown in FIG.
.

A2. Detect As. Based on this data, the transformation matrix calculation device 1.06 calculates the coordinate systems OB, Xa t YB.

Transformation matrix T from za to coordinate system Oα, Xα, Yα, Zα
Find α and set the data of point B to the coordinate system 0α.

Convert to data on Xa, Ya, and Zα. Similarly, point β
The transformation matrix Tβ at the reference point A 1 ′ HA 2
It is obtained by detecting '+As' and converts the data at point B' into data on the coordinate system Oβ, Xβ, Yβ, Zβ.

By performing the same method as above, the data of the working point knob 12 of the robot R and the target object, the door 11, can be given in the robot's coordinate system as the robot R moves, and the first hand 13 can be guided. , work can be done.

Next, another embodiment of the present invention will be described using FIGS. 5 and 6.

In the example shown in FIG. 5, a steel plate member 44 is flowing on a belt conveyor 4, and a pen 4 attached to the tip of a robot 40 is attached to the steel plate member 44.
3 shows an example of writing characters. In this example, the member 44 is
The edge of the image is detected as a reference point. The operation control method in this example will be explained using FIG. 6. The robot is installed at point E, and the coordinate system of the robot is Op, XE.
.

Let Ya, ZE. Let the coordinate system at point C of the member 44 be Oct Xc + Yc t Zc, and let the coordinate system at the point be On, Xo t Yo e Zo J knee. Further, the data representing the work contents is expressed in the coordinate system of the work object.

Here, the member 44 at the zero point is detected by the sensor 42 in FIG.
Detect the upper reference point AC11ACll, ACll and change the coordinate system Oc? Xc + Yc * Zc and coordinate system OE
tXF! A transformation matrix TC between yYE and ZE is determined. In this example, since the robot is fixedly installed, the sensor 42, which is fixed in absolute space, can be expressed as the robot's coordinate system 0 + = + XE r YEt Za te. 44
By detecting only the reference point of , the transformation matrix Tc can be obtained.
It can be expressed as p t Zp, and by moving the pen 43 attached to the tip of the robot 40 to a predetermined position on the member 44, a predetermined work can be performed.

In the above embodiment, the reference points were three points, but depending on the changing conditions of the relative relationship between the robot and the workpiece, two points,
Alternatively, even if one point, a straight line, etc. is detected, the transformation matrix can be obtained in the same way.

Furthermore, it is obvious that even if a reference point on the robot is detected by a sensor fixed to the object, it can be converted to the robot coordinate system by obtaining an inverse transformation matrix.

Furthermore, a case where the sensor is fixed in absolute space and the robot and the object move together will be explained using FIG.

The absolute coordinate system in which the sensor is fixed is Oo, Xo.

To, 7. o, and the coordinate system of the object is Ow HXw g
Yw, OR the coordinate system of the 2w robot + Xs v Y
RrZR, where, as mentioned above, by detecting the reference point of the object-H with a sensor, the transformation matrix T
V is determined, and a transformation matrix TFI-' is determined by detecting a reference point on the robot. Here, TR-'' is the inverse coordinate transformation matrix of the transformation matrix TR from the robot coordinate system to the absolute coordinate system. Based on the above results, the coordinate system Ow of the object is
Robot coordinate system OR, XR from Xw, Yw, Zw
, YR, and the transformation matrix for converting to ZFI is T = T w−T R−” −−
Determined by (2).

Here, if only the robot moves, the transformation matrix T can be found by simply finding TR-'', and if only the object moves, the transformation matrix T can be found by just finding Tw.

In the above description, a visual sensor is used to detect the reference point, but a tactile sensor or the like may also be used for detection.

Furthermore, if the object or robot rotates, detection using an encoder or the like is also possible.

In addition, in the above explanation, the transformation of position data at the robot's work point was shown, but the posture of the robot's hand tool is transformed into an angular component (Euler angle) with respect to the coordinate system of the target object.
By expressing it using the direction cosine of the coordinate system of the tool principal axis and the object, etc., using a transformation matrix like position data,
It can be converted as robot coordinate system data. That is, the present invention can be applied to cases where it is necessary to accurately control not only the position of the hand but also the posture of the hand relative to the work object even if the relative relationship between the robot and the work object changes. .

In addition, as is clear from the above explanation, by providing the work content data in advance in the coordinate system of the work object, the work data in the robot coordinate system can be transformed by simply performing a transformation matrix obtained from sensor information. Because it can be converted to
This method is advantageous in that it can speed up calculation time, respond in real time to changes in relative relationships caused by movement of robots and work objects, and achieve predetermined motion control.

〔Effect of the invention〕

According to the present invention, even if the relative relationship between the work object and the robot changes from moment to moment, it is possible to correct the pre-stored data and control the movement of the robot's hands along a predetermined trajectory. Become.

[Brief explanation of the drawing]

Fig. 1 is a circuit configuration diagram showing one embodiment of the device of the present invention, Fig. 2 is a diagram for explaining the operating principle of the present invention, and Fig. 3 is a diagram showing the present invention in a door opening operation by a mobile robot. FIG. 4 is a perspective view showing an example of the application, FIG. 5 is a perspective view showing another example of application of the present invention, FIG. 6 is an illustration of the operation, and FIG. FIG. 7 is an explanatory diagram of operation in another example. 11...door, 14,15.42...visual sensor,
R940...Robot 544...Work object.

Claims (1)

[Claims] 1. In a robot that performs work in a situation where the relative relationship between the position and posture of the work object changes during the execution of the work, means for detecting the relative relationship between the work object and the robot. Based on this detection result, the robot's work content is sequentially corrected, and the work tool fixed to the robot's hand is driven and controlled along a required trajectory predetermined on the work object. A robot motion control method characterized by: 2. The robot operation control method according to claim 1, wherein the relative relationship is determined by detecting the object with a sensor fixed to the robot. 3. The robot operation control method according to claim 1, wherein the relative relationship is determined by detecting the robot and the object using a sensor fixed in absolute space. 4. The robot operation control method according to claim 1, wherein the relative relationship is determined by detecting the robot with a sensor fixed to the object. 5. The robot motion control method according to claim 3, wherein only the robot is detected when only the robot moves. 6. The robot motion control method according to claim 3, wherein only the target object is detected when only the target object moves. 7. Operation control of the robot according to claim 1, characterized in that the work content of the robot is represented by a coordinate system fixed with respect to the object, and correction is performed based on the relative relationship detection result. Method. 8. A patent claim characterized in that the work content of the robot is represented by a coordinate system fixed to the object, and correction is performed by converting this into the robot coordinate system based on the relative relationship detection result. A method for controlling the motion of a robot according to item 1. 9. In a robot that performs work in a situation where the relative relationship between the position and posture of the work object changes during the execution of the work, a detection means for detecting the relative relationship between the work object and the robot; The present invention is characterized by comprising means for storing work data, means for converting an arbitrary work point on the object into the robot's coordinate system, and means for correcting the robot's work data using information from the converting means. robot motion control device.