JPH05505893A - How to control the robot cell path - 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] How to control the robot cell path The present invention provides a robot with at least 5 degrees of freedom and a workpiece with at least 2 degrees of freedom. the robot and workpiece manipulators synchronously. A method for controlling the path of a robot cell including a control unit that controls the Manual control at key points on the road allows the robot and manipulator to the position of the robot and manipulator relative to each other at said points; The present invention relates to a control method in which direction-related data are stored in a control unit.

Synchronize motion between robot and workpiece manipulator, usually rotary table can be controlled over a controlled period relative to the workpiece placed on the rotary table. There are robotic systems in which path motion (eg linear motion) is achieved. This system synchronization allows for more complex paths than systems without synchronization. For example, welding In the middle, the axis of the rotary table is asynchronous because the path of the tool cannot be controlled in any other way. cannot be rotated within the system (e.g. linear motion is placed on a rotating table) (not straight against the curved workpiece). Prior art synchronized system In the case of systems, robots and rotary tables pass through the points they learned during the teaching phase. Proceed. Therefore, when an operator teaches a synchronized path, he first Rotate the work bead to a position that is advantageous to Seth, and then teach the point by the robot. must be shown. The axis of the rotary table when following the taught path turns in a straight line from its initial position to its final position, all the while the robot follows the desired path. Adopted to the table exercise to achieve. One problem is the orientation of the tool This means that it does not necessarily remain optimal for the machining process. and Even if the initial and final points of the welding path are taught in the so-called downward position, At some point along the path the welding burner is moved out of its downward position by a synchronized movement. There is a risk of being moved away.゛The purpose of the present invention is to perform synchronized movements, for example. A robot cell that does not have the above-mentioned problems associated with controlling the direction of tool placement in The purpose of this invention is to provide a route control method.

It is therefore an object of the invention to enable synchronized movements to be taught quickly and , considering the machining process so that the optimum orientation of the tool can be more easily achieved. The objective is to provide a robot cell with control unit based on the data about the steps of adding to the blocks and the orientation of each other. The method of the present invention is further characterized in that it further comprises the step of calculating an optimal route by will be accomplished.

In the case of the method of the invention, the robot and workpiece manipulator relative to the surroundings The location and orientation of the data should be such that it allows for the easiest possible teaching. You can choose. Robot tool gripper and workpiece during teaching phase Make sure that the orientation of the piece manipulators is in the correct position for working. is important. In addition to the points on the route, what is stored in the storage device is direction. The control unit then determines this orientation and, for example, the welding process. optimization criteria added to the control unit regarding the orientation of the welding burners during the process. As a basis, to calculate the final optimal route to be used during the actual performance of the task. Can be done. This makes the teaching phase even faster and easier, and it also makes the teaching process faster and easier. and the orientation of the workpieces relative to each other and their surroundings It is possible to obtain a route that is optimal for the execution of the task.

The orientation of the robot and workpiece manipulator relative to each other is preferably Let the position of the robot tool gripper coordinate system with respect to the robot base coordinate system be and also be stored as the angular position of the joint of the workpiece manipulator. is desirable. This method simply rotates the manipulator without changing its orientation. Control robots and workpiece manipulators by controlling the bot. It is simpler in that they can be brought to each other in a desired arrangement direction.

The method of the invention will be explained in more detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of the robot cell assembly of the present invention, and FIG. 2 is a schematic diagram of the robot cell assembly of the present invention. Indicate the positions of the cell quantities and their respective coordinate systems, Figure 3 shows the control system contained within the robot cell of Figure 1 in block diagram form. It is shown by the formula.

The method of the invention provides that the robot cell comprises a robot l with at least 5 degrees of freedom and a robot cell with at least 5 degrees of freedom. A rotary table 2 with at least two degrees of freedom, and a control unit that controls the robot and table. knit 3. The control unit 3 is a robot l Both the rotary table 2 and the rotary table 2 can be driven simultaneously. To rotary table 2 is the workpiece (not shown), and the necessary tools (not shown) are attached to the robot l. It is attached. Main robot joint Jl.

J2. J3 may be either a rotational joint or a linear joint.

Wrist joint J4. J5. J6 allows the control unit 3 to control the tool placement direction if necessary. It must be rotatable so that it can be changed. Joints JT and J8 are connected to the robot. in a rotary manner so that the control unit 3 can change the direction of placement of the workpieces relative to each other. Must be.

The orthogonal coordinate system T is at the intersection of the axes of the rotary table, and the orthogonal coordinate system T is at the intersection of the axes of the rotary table. A coordinate system W is located, and a Cartesian coordinate system P is located at the tip of the tool. The arrangement of the coordinate system T The positioning direction is determined by the joint angle of the axis of the rotary table.

When teaching various points of the route, each point P and the joint angle J7 of the rotating table are used. J8 The position of the coordinate system W or the coordinate system relative to T at stored in the client's storage device.

When performing synchronized movements, the path calculation is performed in phase with the coordinate system T instead of the coordinate system W. It is done vis-a-vis. The control unit 3 controls the transfer from the coordinate system W to the coordinate system T and vice versa. Reverse, any necessary conversions are carried out. In order to optimize the route, the control unit 3 During operation, the two axes of the tool should have a predetermined, fixed orientation relative to the coordinate system W. drive the joints of the rotary table (for example, when welding, the Z-axis of the tool coordinate system or downward, the so-called downward position). During the calculation period, control The unit determines a new path point Pi relative to the coordinate system T and a new path point Pi located in the drifting system T. Joint angle J7 of rotary table 2 such that point Pi becomes the optimal position (point Pi 2) ．． The value for J8, Based on the position of point Pi 2 (point Pi 3) relative to the coordinate system W and the value of point Pi 3 From the joint angle Jl to J6 and the encoder El corresponding to the angle J1 to J8, The value of the position of E8 and A command to excite NS8 from each joint servo NSI to the calculated encoder value. calculated.

Optimization is performed during each calculation period, so when iterating a taught path, the entire path Is it possible to teach path points in non-optimal positions without holding the optimal position for a long time? It is Noh.

FIG. 1 shows a system that can implement the route optimization of the present invention. this The robot has a six-degree-of-freedom joint mechanism in which all joints are rotary joints. Ru.

The rotational axes of the joints are labeled Jl, J2 to J6. On rotary table 2 Two sets of revolute joints are included, and their axes are represented as J7 (rotation) and J8 (rotation). It is shown. The axes of the rotary table are perpendicular to each other and intersect at point A. . The axis J8 is parallel to the WOX axis of the coordinate system. Each joint has motors Ml to M8. Included, they can be driven from each joint servo NSI through NS8 Can be done. To read the position of the joint, the motor has absolute encoders El to E8. is included, and a signal is given from there to the corresponding joint servo NSI to NS8. It will be done. The workpiece is fixed to the rotary table 2, and the tool is attached to the tool flange of the robot. It is fixed to the table. For example, if a robot is equipped with welding equipment, the cell is used for welding arc pieces.

A simplified model of the system of FIG. 1 is shown in FIG. robot The direction of the coordinate system W is the Z-axis direction or the joint J1 direction, and the y-axis direction is the joint J1 direction. This is the direction of J2 when the angle Jl is zero, and the X axis is perpendicular to the above axes. Selected. The origin of the coordinate system W is the axis J1. It is located at the intersection B of J2. rotary table The Z-axis of the coordinate system T points in the direction J8 (=direction Jl), and the angle J7°J8 is zero. In this case, xlilt points in the direction of the WOX axis of the coordinate system. The origin of the coordinate system T is , J7. It is located at the intersection A of the axes of J8. Position of tool coordinate system P relative to coordinate system W and the placement direction depend on the joint angles J1 to J6 of the robot, and the origin of the tool coordinate system is placed at the tip of the tool.

FIG. 3 shows the cell control system. Joint servo NSI to NS8 are the corresponding motors Ml to M8 of robot l and rotary table 2, and Connected to encoders E1 to E8. Each joint servo is controlled by control unit 3. The joint can be controlled in response to commands received from the robot. The control unit , for example, commanding a joint servo to fire up to a desired encoder reading. Can also be done. When teaching a robot to go from one point to another, the teaching The determined points are stored in the storage device 7 of the control unit 3. relative to the coordinate system W The position of the coordinate system P and the joint angles J7°J8 of the rotary table are stored at each point. . Control unit 3 J: The functions of the included computing device 8 are controlled by the rotary table seat. Calculate interpolation points for various paths within the reference system and place them at the desired optimal position using a rotary table Change the direction, transform the optimized point to the coordinate system W, and correspond to the position of the point. Calculate J6 from joint angle Jl J7. J8 value is calculated during the optimization stage), the total The goal is to guide the joint servo to the calculated position. To achieve sufficient path accuracy , the interpolation calculation interval must be several ms.

During the teaching phase, the operator can keep the rotary table position unchanged . Point teaching allows the manual control 4 to move the robot 1 to the desired position relative to the workpiece. This occurs by advancing to a desired point in the positioning direction. The location and orientation of the points and the joint angles of the rotary table are stored in the storage device. Point location and placement The direction can be stored with respect to the coordinate system W1 or the coordinate system T, or as robot joint angles. I can do it. Joint angle of rotary table during teaching opportunity J7. J8 is a storage device stored within.

In this way all necessary points of the route are taught.

When repeating a taught path (for example, a straight path from point P1 to point P2), , the computing device 8 has to transform the points PI, P2 from the coordinate system W to the coordinate system T. . The points stored in storage are transformed into transformation matrices. (nx ox ax px) (nyoy　ay　I))’) Pw=(nz oz az pz) It can be expressed in the form of

Here vector (pX, p7. pz) = position vector of point origin (nx, ny , nz) = tool coordinate system at point Pw X axis Vector (ox, oy, oz) = tool coordinate system at point Pw y-axis Vector (ax, ay, az,) = tool coordinate system at point Pw Z axis The conversion of the point Pw from the coordinate system W to the coordinate system T is to convert the point Pw in the coordinate system W into the coordinate system By multiplying the inverse matrix T' of the transformation matrix T, which indicates the position and arrangement direction of T, The occurrence matrix T is the position of the origin of the coordinate system T in the coordinate system W and the axis of the rotary table. Line joint angle J7. It is easy to determine when J8 is known.

(C8-380’px) (C7”　S8　C7”　C8-37py)T=(S7°38　S7°C8C7 pz) (OOO1) Here C7=cos (J7) C8=cos (J8) S7=sin (J7) S 8 = s + n (J 8) Vector (px, py, pz) = coordinate system T in coordinate system W Origin position If the points PI, P2 of the route are known in the coordinate system T, the route is compensated for the coordinate system T. You can perform interval calculations.

In order to realize the optimal placement direction, a correction value is calculated for each interpolation point Pti of the path. Ru. The workpiece is brought to the optimal placement direction as follows.

A vector (T”　Ptiz　) is calculated.

(--------C8' ax -S8" ay -) T" Pti = (・ -...-C7" S8°ax 10C7°C8°ay-37°az...) (-...-S7" S8°ax + S7" C8°ay vector (T"Pt iz) is shown to be equal to the desired optimal placement direction V, and therefore the condition vx=　C8”ax　-S8°ay vy=C7” S8 ax + C7°C8°ay −S7” azv z = 37" S8°ax 10 S7" C8" ay + C7" az -... is obtained. Here, Unit vector (vx, vy, vz) = desired optimal placement direction.

J7. The optimal value of J8 is C7=cosJ7 and C3=cosJ8. If you remember it, you can understand it from this formation.

The interpolation point Pti is converted from the coordinate system T to the coordinate system W as follows.

Pwi=　To　　”　Pti Pwi = Optimized point To of route in coordinate system W = Optimized layout Transformation matrix of the coordinate system T in the direction Pt1 = path point regarding coordinate system T Based on Pwi, calculate 56 from the robot's joint angle Jl as the optimal point. Can be done. The control unit 3 converts the joint angle into the position data of E8 from the encoder El. Then, the joints are advanced to the relevant positions by joint servos NSI to NS8.

The method of the invention is described above by way of an exemplary embodiment relating to the application of the invention to welding. It was only explained. Either robot or workpiece manipulator for other robot cells with either optimization or ambient conditions. It should be understood that the method of the present invention may also be applied. The above surrounding conditions are direction of the cut or workpiece manipulator, along their path. This may be related to obstacles to be obtained, restrictions on the range of motion of some joints, etc. .

FI3.2 F old, 3

Claims (4)

[Claims] 1. A robot (1) with at least 5 degrees of freedom and a workpiece with at least 2 degrees of freedom a workpiece manipulator (2), the robot and the workpiece manipulator (2); a control unit (3) for synchronously controlling the robot cell; In the control method, the robot is controlled by manual control (4) at major points along the route. (1) and the manipulator (2) are brought to desired positions relative to each other; How the robot (1) and the manipulator (2) are arranged relative to each other at the various points a control method in which data regarding the direction are stored in the control unit (3); adding road optimization criteria to the control unit (3); the optimization criteria and the mutual arrangement directions of the robot and the manipulator; calculating an optimal route by said control unit (3) based on data regarding A control method comprising: 2. The method according to claim 1, wherein the robot (1) and the robot (1) The mutual arrangement direction of the nipulators (2) is the coordinate of the base (6) of the robot (1). The position of the coordinate system (P) of the tool gripper (5) of the robot (1) with respect to the system (W) and also as the angular positions of the manipulator joints (J7) and (J8). A method characterized by: 3. A method according to claim 1, in which the robot (1) with respect to its surroundings or that the arrangement direction of the manipulator (2) is included in the optimization criterion. How to characterize it. 4. The method according to claim 1, wherein the position of the manipulator is changed. By controlling the robot (1) without causing the robot (1) and characterized in that the manipulators (2) are brought to desired positions relative to each other; How to do it.