JPH07132435A - Robot work computing-teaching method - Google Patents

Abstract

PURPOSE:To compute and teach the work of a robot simply and flexibly by computing the contact point position, on a work object, of an end effector set to a robot, and generating the control target value of a robot according to the target path of the work object and work specifications. CONSTITUTION:When an operator Q induces a robot arm A' to a work object C', the detection signal of at least a six-tension detector 9 is transmitted to a computer through an A/D converter so as to store the three-dimensional position-attitude and action force of an end effector B' in the robot arm A'. In the computer, the contact point position of the end effector B' on the work object C' is computed on the basis of stored information, and the target path of the work object C' is generated according to the contact point position. In addition, work specifications are stored, and the control target value of the robot arm A' is generated according to the target path and work specifications.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention calculates control target value motion information for a predetermined work in a robot used for various works such as polishing work and deburring work for working along the surface of a work object. The present invention relates to a robot work calculation teaching method used for teaching.

[0002]

2. Description of the Related Art A conventional technique of this kind will be described with reference to the drawings. FIG. 8 is a perspective view showing a work example, and FIG. 9 is a perspective view showing various robot control target values necessary for the work example. In the figure, A is a robot hand, B is an end effector, C is a work target, and D is a target route on the work C.

FIG. 8 shows an example of work in the technical field to which the present invention belongs. The work in such a form includes various works such as polishing, chamfering, deburring and the like. In order to teach the robot such a work, FIG.
, The target contact force F _r , the significant velocity V _r ,
It is necessary to generate a robot control target value that realizes the contact point position P _r , the contact attitude a _{r, and the} like.

As a conventional technique relating to such a work teaching method, for a commonly used industrial robot, the robot is operated on the route of the work target object by remote control using a teaching box or the like. However, there is a method of storing the joint angle information at that time.

In addition, "Journal of the Robotics Society of Japan, Vol. 9, No. 3, 35"
"Page 4" shows a method of teaching by the joint angle information when the operator directly guides the robot to follow the work target. And regarding the method of teaching the posture,
For example, Japanese Patent Laid-Open No. 4-609 discloses a method of generating a robot control target value by designating a posture or the like from target route information on a work target based on CAD data.

[0006]

However, in the method of operating the robot on the path of the work object by remote control and storing the joint angle information at that time, in the case of a complicated work object, one A large number of teaching points are required for the path of the work object, and the contact point position and contact attitude at that time must be remotely controlled according to the desired contact point position and contact attitude. In addition to this, even when changing only the tool posture or the contact position for one work object, it is difficult to perform a flexible operation, and there is a problem that re-teaching is required.

In addition, "Journal of the Robotics Society of Japan, Vol. 9, No. 3, 35"
The method described in "Page 4" basically generates a control target value by playing back the joint angle at the time of teaching based on the force control law, that is, essentially teaches the work path. However, there is a problem in that when the operator guides the robot, it is necessary to guide the robot so as to achieve a desired contact point position and contact posture. Also in this case, there is a problem that a flexible operation is difficult even when changing only the tool posture or the contact position with respect to one work object, and re-teaching is required.

In the method disclosed in Japanese Patent Laid-Open No. 4-609, since the route information is acquired based on the CAD system, the operator preliminarily works on each work object. There is a problem that the shape needs to be memorized and it cannot be realized without introducing a costly CAD system.

In view of the above-mentioned problems of the prior art, the present invention omits the complicated procedure of operating or guiding so as to realize a desired contact point position and contact attitude at the time of teaching, and yet another one. It is intended to provide a robot work calculation teaching method that can be flexibly operated even when only the tool posture or the contact position is changed with respect to the work object and does not require CAD data of the work object. Is.

[0010]

The above-mentioned problems can be solved by the present invention by adopting the following novel characteristic construction method. That is, a feature of the present invention is that a robot having a function of detecting and calculating the three-dimensional position / orientation of the set end effector and a function of detecting and calculating the acting force applied to the end effector When calculating and teaching control target value motion information for a predetermined work directed to an object, the three-dimensional position of the end effector when the operator guides the robot to the work object is calculated.
An information storing procedure for storing a posture and an acting force; a contact point calculating procedure for calculating a contact point position of the end effector on the work object from the three-dimensional position / posture and the acting force of the end effector; A route generation procedure for generating a target route on the work target from the contact point position, a procedure for storing work specifications, and a target value generation for generating a robot control target value from the target route on the work target and the work specifications It is a robot work calculation teaching method which is step by step.

[0011]

According to the present invention, since the method as described above is adopted, the information necessary for path generation is stored by the information storing procedure for storing the three-dimensional position / posture and the acting force of the end effector when the operator guides the robot. Since the information is acquired, the teaching can be performed in a short time, and the information necessary for the route generation can be acquired without the CAD data.

Further, in order to carry out a procedure for storing the work specification, a target path on the work object, and a target value generation procedure for generating a robot control target value from the work specification, information on the work specification and the target path. Can be specified independently, eliminating the complicated procedure of operating or guiding to achieve the desired contact point position and contact posture during teaching, and further Even when only the contact position is changed, there is a difference from the conventional technique in that it is not necessary to re-teach the target route by only designating necessary change points.

[0013]

Embodiments of the present invention will be described with reference to the drawings. Figure 1
Is a schematic diagram showing the degrees of freedom of each joint and each link length of the robot arm to which the embodiment of the present invention is applied, FIG. 2 is a control system configuration diagram of the robot arm, and FIG. 3 is a flowchart showing a work procedure in this embodiment. FIG. 4 is a diagram illustrating an example of guiding the robot arm by an operator in the present embodiment, and FIG.
(A) (b) (c) (d) is a figure which shows each setting example of the coordinate system in a present Example.

In the figure, A'is a robot arm having three rotary shafts and three rotary shafts each having a total of 6 degrees of freedom, B'is an end effector set at the end of the robot arm A'and is replaceable, and C'is a work. A barrel work object, D ′ is a target path on the work object C ′, 1 to 6 are joints from the base of the robot arm A ′ in sequence, 7 is an encoder attached to each joint 1 to 6 of the robot arm A ′, 8 is an up / down counter, 9 is a 6-axis force detector attached to the hand of the robot arm A ', 10 is an A / D converter, 11 is D /
An A converter, 12 is a servo amplifier, 13 is a direct drive type actuator, and 14 is a computer for controlling the operation of the entire robot arm A'and performing calculations necessary for this embodiment.

Robot arm A'to which this embodiment is applied
Shows such a concrete embodiment, but next, the procedure for carrying out the present embodiment will be described with reference to the drawings, taking a copying operation such as polishing and deburring work as shown in FIG. 7 as an example. .

[Information Storage Procedure] (Step 1 in FIG. 3) First, as shown in FIG. 4, the operator Q guides the robot arm A '. The signal of the encoder 7 during this operation is stored in the computer 14 via the up / down counter 8, and the signal of the 6-axis force detector 9 is stored in the computer 14 via the A / D converter 10. At this time, it is also possible to store the joint angle information of the robot arm A'necessary for approaching the work object C'and leaving the work object C'as shown by the dotted arrow in FIG. Is.

[Contact Point Calculation Procedure] (Step 2 in FIG. 3) Next, an example of a procedure for calculating the contact point based on the stored information will be described. For example, among the candidate points provided on the surface of the end effector B ′ sufficiently finely, the external force direction of the 6-axis force detector 9 is 90 degrees or more with the outward normal line of the candidate point, and the following equation (1) is used. The point that minimizes the evaluation function H shown may be the contact point.

H = δ | V _(pi) · N _(pi) | + ε‖ (u · pi) u + b−pi‖ (1) δ, ε: Weighting coefficient pi: Candidate point position vector V _(pi) : Candidate Translation velocity at point pi N _(pi) : Normal vector at candidate point pi u: External force direction vector b: Vector perpendicular to the force action line

[Route generation procedure] (Step 3 in FIG. 3) The result obtained by the contact point calculation procedure described in the absolute coordinate system is the point on the target route D'on the discrete work object C '. Becomes Next, the target path D ′ on the continuous work object C ′ is calculated by appropriately complementing this. For example, it is possible to complement the points on the target path D'on the discrete work object C'by a function of the third order path length as shown in the following expression (2).

[Equation 1]

The function of the above equation (2) complements a part of the points of the target path D'on the discrete work object C ', for example, by complementing the square error to minimize the continuous work object. A target path D'on object C'is calculated. Also,
The reference vector e of the contact attitude shown in FIG. 9 of the conventional example can be calculated by using the normal line of the plane to which the path belongs and the target path D ′ on the work object C ′. That is,
In this embodiment, since the target route D'on the work object C'is calculated by following the above procedure, CAD data for each work object C'as in the conventional example is necessary. do not do.

(Work specification storing procedure) (Step 4 in FIG. 3) Next, the target work specification is stored in the computer 14.
For example, referring to FIG. 9 of the conventional example, the target contact force F
_r , the scanning speed V _r , the contact position P _r , and the contact posture a _r are stored.

These are constants, functions of path lengths, time functions, or functions relating a plurality of information such as individual specifications and the number of revolutions of the end effector B '. It is also possible to Since the teaching of the contact position P _r and the contact attitude a _r is performed by following this procedure, the operation or guidance is performed so as to realize the target contact point position P _r and the contact attitude a _r at the time of teaching as in the conventional example. It does not require a complicated procedure.

[Target Value Generation Procedure] (Step 5 in FIG. 3) Next, the target value generation procedure will be described by taking the stiffness control in the working coordinate system as an example. First, the setting of the coordinate system is shown in FIGS. Coordinate system as shown in FIG. 5 (a) on the end effector B 'as a work coordinate system sigma _T, 5
As shown in (c), Σ _WK is set as the coordinate system of the work target C ′, and Σ _W as shown in FIG. 5B is set as an absolute coordinate system.

The control is performed by the end effector B'coordinate system Σ _T
Σ _Tr (target position and target attitude of the end effector B ′) is given as the target trajectory of Σ _T and Σ
_Tr shall not be affected by the rotation of the grinding wheel. Further, the coordinate system Σ _To representing the reference attitude is set as shown in the figure. Here, at time T, the end effector B '
Control target value Σ _Tr (O _{Tr (T Tr (T Tr )} when the work object C ′ coordinate system to be contacted by is calculated as Σ _{WK (T)} from the scanning speed and the target path D ′ on the work object C ′. ₎ , X _{Tr (T)} ,
y _{Tr (T)} , z _{Tr (T)} ) can be obtained by the following procedure.

First, the target posture x _{Tr (T)} , y _{Tr (T)} , z
_{Tr (T)} uses the standard posture Σ _To (x _To , y _To , z _To ) as the axis e.
Angle α with respect _{WKV (T) '= - D} (a r -γ) is derived as rotated. (X _{Tr (T),} y _{Tr (T),} z _{Tr (T)} ) = R [e _{wkv (T)} , α ′] (x _To , y _To , z _To ) (3) R [k, θ ]: Rotation coordinate conversion of angle θ with respect to axis k

Next, the end effector B'in Σ _To
The position vector p _{rc (T)} of the point to be touched by is _calculated by the following equation (4). _{p rc (T) = rR [} e, πD / 2] e wkv (T) -rtanγe ... (4) r: end-effector in _{p r} radius gamma: the end effector in _{p r} normal to x _{the To} -y _{the To} Angle formed by planes

At this time, the posture (x _{Tr (T)} y seen from Σ _W
If p _{rc (T} ) in _{Tr (T)} z _{Tr (T)} ) is p _{rc '(T)} , then p _{rc' (T)} = R [e _{wkv (T)} , α '] p _{rc (T)} ... (5) From this, when the stiffness in the p _{rc '(T)} direction is K, the target position is obtained by the following equation (6). O _{Tr (T)} = O _{wk (T)} -p _{rc '(T)} + (F _r / K) p _{rc' (T)} / ‖p _{rc '(T)} ‖… (6)

The above calculation example is an example of generating the target value in the stiffness control.
Given _{WK (T)} and work specifications, it is easy to generate target values for various control laws.

(Experimental Example) Next, an experimental example according to the present invention will be described. 6 and 7 show teaching results according to this experimental example. The experiment was performed on a work object C1: a work made of vinyl chloride as shown in FIG. Also, the end effector B '
For this, an actual grinder tool (radius: 3 mm) was used as it was.

FIG. 7A is a plot of the contact point locus α1 and the contact normal locus β1 calculated by the contact point calculation procedure in the absolute coordinate system. In FIG. 7B, the contact point is set to 2
A trajectory α2 and a trajectory normal trajectory β2 of the target route D ′ on the work target C1 complemented by using the following spline function.

The time required for teaching for the route of one work object C1 is only 10 seconds, and it can be confirmed that efficient teaching can be performed for a complicated route in a short time. Further, by giving a tool to be used and a work specification to the obtained target path D ′ on the work object C1, it is possible to generate control target values according to various work specifications without re-teaching.

[0032]

As described above, according to the method of the present invention, the contact point position intended at the time of teaching, which is a problem of the prior art,
CAD for the work object while omitting the complicated procedure of operating or guiding so as to realize the contact posture
No data needed.

Furthermore, in the robot in which the re-teaching may be necessary even in the case of changing only the tool posture and the contact position with respect to one work object in the prior art, It exhibits excellent usefulness such as realization of a work teaching calculation method.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a robot arm to which an embodiment of the present invention is applied.

FIG. 2 is a control system configuration diagram of the same.

FIG. 3 is a flowchart showing an implementation procedure of an embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of guiding the robot arm by an operator in the above.

5 (a), (b), (c), and (d) are diagrams showing respective setting examples of the coordinate system in the above.

FIG. 6 is a plan view showing the shape of a work object in the experimental example of the same.

FIG. 7 is a diagram showing a target route on a work object taught in the above.

FIG. 8 is a perspective view showing an example of a conventional copying operation.

FIG. 9 is a diagram showing work specifications of copying work and various parameters necessary for calculating a robot control target value.

[Explanation of symbols]

 A, A '... Robot arm B, B' ... End effector C, C '... Work object C1 ... Work object used in the experimental example D, D' ... Target path 1-6 ... Joint 7 ... Encoder 8 ... Up-down counter 9 ... 6-axis force detector 10 ... A / D converter 11 ... D / A converter 12 ... Servo amplifier 13 ... Actuator 14 ... Computer

Claims (1)

[Claims] 1. A robot having a function of detecting, calculating and measuring the three-dimensional position / orientation of a set end effector and a function of detecting, calculating and measuring an acting force applied to the end effector. Information for storing the three-dimensional position / posture and the acting force of the end effector when the operator guides the robot to the work object in order to calculate and teach the control target value motion information for the predetermined predetermined work. A storage procedure, a contact point calculation procedure for calculating a contact point position of the end effector on the work object from the three-dimensional position / posture and acting force of the end effector, and the work object from the contact point position. A route generation procedure for generating the above target route, a procedure for storing work specifications, and a control target value for the robot from the target route on the work target and the work specifications. Robot work calculated teaching method characterized by sequentially stepping the target value generation procedure.