JP2680210B2 - Robot control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of attaching an arbitrary final actuator among a plurality of final actuators such as a hand, a tool, a detector, etc. The present invention relates to a robot control method in which a vessel draws a desired trajectory. 2. Description of the Related Art One of the reasons for existence of a robot is that its operation can be freely changed. But the robot
It is common to have operation functions unique to the system and change the entire operation by a combination of them. In this case, when the specific operation function is inconvenient for the robot user, it is necessary to modify the system for performing the specific operation, which is almost impossible in practice. This also applies to the case where the robot is allowed to perform another work or role, and the conventional robot is extremely inferior in operational applicability and expandability. [0003] Conventionally, IEEE TRANSACT has been proposed.
IONS ON SYSTEMS, MAN, AND
CYBERNETICS, VOL. SMC-11, N
o. 4, APRIL 1981 (Ai Transactions on Systems Man and Cybernetics Volume SMC 11 Number Yon April 1981) (pp.274-2
As described in 89), teaching and operation are separately programmed into the coordinate system of the robot's final actuator attachment site and the final actuator's coordinate system, and the points of the robot's operation path are defined between the coordinate systems. This is a control method of a robot that enables teaching and programming to be performed more easily by using the conversion. In the above prior art, the coordinate system of the final actuator and the coordinate system of the site where the final actuator is attached are used when the robot interpolates the path between points during playback and teaching. Is not performed, the trajectory during the path interpolation does not pass through the desired trajectory, causing a problem such as hitting an obstacle. The present invention has been made in view of the above circumstances, and the final actuator coordinate system is appropriately selected according to the type and function of the selected final actuator and the attachment portion to the robot, and the final action is performed. An object of the present invention is to provide a control method for a robot, which has applicability and expandability of motion functions such that the device draws a desired trajectory. In order to achieve the above-mentioned object, the present invention provides a robot to which any one of a plurality of types of final actuators can be attached, wherein the final actuator is attached to the robot. The final actuator attachment site of the robot is defined by a coordinate system that includes the position and orientation of the robot with respect to the attachment site, and is further determined according to the type and function of the final actuator selected. The final actuator coordinate system that differs in position and orientation from the coordinate system of the actuator attachment site is defined for each final actuator, and each defined final actuator coordinate system and the final actuator attachment site of the robot are defined. One final actuator coordinate selected by operating the final actuator attachment part of the robot, which comprises a coordinate system transformation matrix having position and orientation transformations that linearly relate to the coordinate system. When interpolating the position and orientation of the system, the position command value for operating the final actuator mounting portion of the robot is sequentially converted during the interpolation operation by the conversion matrix corresponding to the type and function of the selected final actuator. The position and orientation of the robot are changed temporarily by using the position and orientation of the final actuator, and the position and orientation of the final actuator portion of the robot are calculated based on the sequentially replaced position instruction values. By interpolating the transformation matrix to be selectively changed, the interpolated coordinate system is determined according to the type, function, and attachment site of the selected final actuator, and the final actuator is desired. A trajectory is drawn, and the position and orientation are converted into the coordinate system of the final actuator attachment site so that the robot operation function can be returned to the final actuator attachment site. And wherein the door. Hereinafter, the coordinate system transformation matrix will be described. Although the basic motion of the robot has a movement error for each actuator of each axis of the robot, its description is omitted here, and the interpolation of the linear movement and the posture movement of the hand, which is a feature of the high-performance robot, will be described. . That is,
High-performance robots include movement interpolation of these positions and interpolation of movement of attitude, and these movement functions are basically required, and conventionally realized by some method. Here, as shown in FIG. 1, a rectangular coordinate system in which the robot has six degrees of freedom and the Z axis is taken as the turning axis is a basic stationary coordinate system 1 on the robot system. X
The (i) axis, the Y (j) axis, and the Z (k) axis are the main directions here, and when expressed by the component of the unit vector, they are X axis (1φφ) Y axis (φ1φ) Z axis (φφ1). . Here, as shown in FIG.
Defines a similar orthogonal coordinate system, which is referred to as a hand coordinate system 2. This hand coordinate system 2 is the same as the stationary coordinate system 1 described above. ∵ (X _RX ) ² + (X _RY ) ² + (X _RZ ) ² = 1, And the component can be displayed. Whether the posture (position) of the robot is represented by an angle or a matrix containing the direction cosine of a unit vector as a component may be arbitrarily determined by the robot system, but is represented here by a matrix containing the direction cosine as a component. . [0010] Here, the matrix [L] is symbolized by matching the position and the direction to form a matrix [L]. , The position teaching of the robot is nothing less than finding this matrix [L]. That is, the operation of the robot is to interpolate the components of the matrix [L], which is this data, with the components of the other matrix [L], and move them continuously in time to move to the position of the other matrix [L]. The operation function of the robot is ultimately determined by the interpolation and which matrix [L] component is selectively changed. Does not change the data, Other components may be changed by. [0011] According to. This applies to changes in other components. In FIG. 1, reference numerals 4 to 9 represent robot joints, and θ _{1 to} θ ₆ represent rotation directions of the joints 4 to 9. Next, a specific example of the method of the present invention will be described with reference to FIG. FIG. 2 is a diagram showing the relationship between the hand coordinate system of the robot and the final actuator coordinate system. In FIG. 2, 3 is the final actuator coordinate system, and 11 is the final actuator such as the hand, tool, or detector. The rest is the same as that of FIG. 1, but the hand 10 is a mounting portion of the final actuator 11 here. This figure 2
In the same manner as the matrix [L] of the position component matrix [Q] of the final actuator 11. , The components of this matrix [Q] are Is represented by And λθ ₁ to λθ ₃ , λ in Eq. (4)
By appropriately setting the constants a _{1 to} λa ₃ , λb _{1 to} λb ₃ and λc _{1 to} λc ₃ , a desired final actuator coordinate system 3 different from the hand coordinate system 2 is defined. Also, formula (4) is rearranged and conversely [L] You can also ask for tricks [L]. In general, the operation function of the robot is fixed by a system unique to the hand coordinate system 2, and its change is not easy. However, the matrix [L] and the matrix [Q] have the same properties and functions, and even if the operation function for operating the matrix [L] possessed by the robot is directly applied to the matrix [Q], no inconvenience occurs. Absent. That is, in the flowchart for realizing the operation function of the robot shown in FIG.
By adding step 103 “execution of the inverse matrix of equation (4)”, the operation function of the robot can be arbitrarily and easily added to the final actuator 1.
It is possible to change from 1 to the coordinates of the mounting portion.
(4) disables the formula to return the operation function of the robot hand 10 side constants in equation _{(4), λθ 1 ~λθ 3 = φ λa} 1 ~λb 2 = λc 3 = 1 λa 2, λa _It may be determined that ₃ = λb ₁ , λb ₃ = λc ₁ , and λc ₂ = φ. Therefore, step 1 is performed by the robot controller.
By adding a block for executing 03, the operation function of the robot can be arbitrarily changed, and a robot having applicability and expandability can be achieved. Here, as one application example, a method of causing the robot's hand 10 to make a circular motion will be described with reference to FIG. That is, in order to make the hand 10 of the robot draw an arc around the point 12, the point 12 is simply matrixed by the constants in the equation (4). Well, it can be done easily without any special calculations. In FIG. 3, reference numerals 100 to 104 denote steps for executing the operations shown in the drawing. As described above, according to the present invention, the final actuator determined according to the type and function of the selected final actuator for the part of the robot to which the final actuator is attached. By defining a coordinate system and providing a coordinate system transformation matrix that correlates each defined final actuator coordinate system and the final actuator attachment site of the robot, by instructing the robot motion based on this matrix , It is possible to accurately and easily provide a suitable motion to the final actuator of the robot during playback and during motion teaching.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a relationship between a basic stationary coordinate system and a hand coordinate system of a robot, and FIG. 2 is a diagram for explaining a robot control method according to the present invention. FIG. 3 is a diagram showing the relationship between the hand coordinate system and the final actuator coordinate system. FIG. 3 is a flowchart showing the operation of the robot to which the robot control method according to the present invention is applied. [Explanation of Codes] 1 ... Basic stationary coordinate system, 2 ... Hand coordinate system, 3 ... Final actuator coordinate system, 4, 5, 6, 7, 8, 9 ... Joint, 10 ... Hand, 11 ... Final actuator.

   ────────────────────────────────────────────────── ─── Continuation of front page    (56) Reference JP-A-51-139544 (JP, A)                 JP-A-56-159709 (JP, A)                 JP-A-57-73410 (JP, A)                 "Automation Technology" Vol. 11, No. 8, P134               ~ 139

Claims (1)

(57) [Claims] In a robot to which an arbitrary final actuator of a plurality of final actuators can be attached, a coordinate including a position and a posture with respect to a robot attachment portion at a final actuator attachment portion of the robot to which the final actuator is attached A system is defined, and the final actuator coordinate system that is determined according to the type and function of the selected final actuator and has a different position and orientation from the coordinate system of the final actuator attachment part of the robot is used for each final actuator. An actuator, and a coordinate system transformation matrix having position and orientation transformations that linearly relate each defined final actuator coordinate system and the coordinate system of the final actuator attachment portion of the robot to each other, When operating the final actuator attachment part of the robot to interpolate the position and orientation of the selected final actuator coordinate system,
Positions and orientations for temporarily relating the position command position for operating the final actuator mounting portion of the robot during the interpolation operation by using the conversion matrix according to the type and function of the selected final actuator. After conversion, the position command value of the selected final actuator is replaced, and the maximum position of the robot is calculated based on the position command values that are sequentially replaced.
By interpolating the component <br/> transformation matrix representing the position and attitude of the end working unit selectively varying the type of final effect device which is selected, functions and in accordance with the mounting section to the robot is interpolated The coordinate system is determined so that the final actuator draws a desired trajectory, and further, the position and posture are converted into the coordinate system of the final actuator attachment site, and the robot operation function can be returned to the final actuator attachment site. A robot control method characterized by the above.