JPS63142405A - System for controlling locus of robot - Google Patents

Abstract

PURPOSE:To shorten the overall work time by providing a front end locus generating means which connects the start point, the end point, and each passing point with a polygonal line and interpolates crossing parts of straight lines with parabolas. CONSTITUTION:An operation controller 50 which controls the operation of a robot 4 consists of an input coordinate value part 1, a front end locus generating part 2, and an operation control part 3. The front end locus generating part 2 is provided with a timer, a timer table, a speed calculating part, a moving direction part, a vector synthesizing part, and an integration circuit, and start and end times of operation stop, acceleration, uniform speed, and deceleration in each section and the time elapsed after the start from the start point are inputted. The speed to time in each section is operated, and moving direction information is added to resultant information to synthesize speed vectors in respective sections, and the result is integrated and is converted to the position of the front end. Thus, the work time for work operation accompared with avoiding operation is shortened.

Description

[Detailed Description of the Invention] [Summary] A robot trajectory control method that is defined by the start point, end point, and one or more passing points of the robot tip motion, and the vicinity of the start point and end point is a straight line. In order to perform trajectory control that allows the robot to move smoothly and at high speed throughout its entire stroke, each point is connected with a broken line and the intersection of the straight lines is interpolated with a parabola. It becomes possible to shorten the total working time by making a combination of linear motion and curved motion such as avoidance motion into a series of motions.

[Industrial application field]

The present invention relates to a robot trajectory control method that realizes multi-point passage through continuous motion control of an articulated robot.

When applying Robo-Nodo to assembly work, the robot's movements may be affected due to problems such as when the object has a complex shape or when the installation environment has parts, sensors, etc. placed within the robot's work area. Often hindered by external factors.

In such cases, the robot performs actual tasks such as insertion,
In addition to pull-out and pick-and-press movements, avoidance movements from obstacles are required.

It is desired to shorten the total working time by performing actions other than the actual work such as avoidance actions at high speed, and by making them a series of actions with the actual work.

[Conventional technology]

FIG. 5 is a block diagram for explaining the conventional example, and FIG. 6 is a diagram for explaining the trajectory control situation in the conventional example.

FIG. 5 shows a motion control device 50 that controls the trajectory of the robot 4.
and a robot 4 having an articulated arm that moves according to a trajectory from a motion control device 50.

The motion control device 50 also includes an input coordinate value section 1 for setting a starting point coordinate value, a passing point coordinate value, an end point coordinate value, etc. when the robot 4 moves, and a predetermined sampling of the elapsed time after starting from the starting point. A timer 5 that generates data every time, a calculation unit 11 that calculates based on a spline function from the output of the timer 5 and sends out a predetermined trajectory, and a spline function unit 12 that generates data to interpolate the coordinates of each given point. Trajectory generation unit 2 comprising
0, and a motion control section 3 that controls the motion of the robot 4 according to the trajectory sent out from the trajectory generation section 20.

In this example, as shown in FIG. 6, there is an obstacle (al) in the movement range of the robot 4, and the movement trajectory control is performed when the robot 4 performs an avoidance movement.

Conventional control methods do not include a trajectory control method aimed at avoidance operations, and avoidance operations are achieved by combining various operations.

That is, the coordinate value of the starting point P1 when the robot 4 moves by a predetermined operation not shown in the input coordinate value section 1, 1ffi passing point P
Cent the coordinate values of 2 to P4 and the coordinate value of end point P5, respectively, and start.

At this time, each section (for example, the section from point P1 to P2) is divided into a plurality of predetermined sampling times, and speed control is performed for each sampling time. At this time, the timer 5 generates the elapsed time t from the starting point P1 at each sampling time.

The calculation section 1 performs calculations while interpolating using a six-dimensional spline function generated from the spline function section 12 according to the elapsed time t from the starting point P1, and calculates the target trajectory using the motion control section 3.
Send to.

Note that there are various types of spline functions; for example, a six-dimensional spline function is required in order for a robot with six degrees of freedom to operate. Also, the function used in this situation is called a cubic spline function.

The above operation locus becomes the locus (2) shown in FIG. 6, and it becomes possible to connect the locus from the starting point P1 to the ending point P5 with a smooth curve.

[Problem that the invention seeks to solve]

The method of generating the target trajectory while interpolating using the spline function described above allows the trajectory to pass accurately over each passing point P2 to P4 and connect the trajectory from the starting point PL to the ending point P5 with a smooth curve. I need to analyze a six-dimensional spline function.

This analysis is mainly performed using a program, and a complex program is required to perform this analysis. Therefore,
The processing time will increase significantly.

On the other hand, in the case of the trajectory {circle around (2)} shown in FIG. 6, separate operations are performed in each of a plurality of sections. That is, the movements of each section from the starting point P1 to the ending point P5 on the trajectory are controlled separately (point-to-point control), and by combining these multiple separated movements, the starting point Pl
A trajectory motion from to the end point P5 is realized.

In this case, there are problems such as stopping at passing points P2 to P4 that do not require positioning, and extra time is required for control operations up to end point P5.

[Means for solving problems]

FIG. 1 shows a detailed illustrative ivy diagram of the invention.

The principle block diagram of the present invention shown in FIG. 1 shows an outline of the configuration of a motion control device 50 that controls the motion of the robot 4, and the configuration is comprised of the human coordinate value section 1 described in FIG. The operation control unit 3 inputs the start and end times of operation stop, acceleration 2 constant velocity, and '$i speed' in each section, and the elapsed time after starting from the starting point, and calculates the speed with respect to time in each section. a tip trajectory generating means (tip trajectory generating section) 2 that calculates, adds moving direction information to the result information, synthesizes velocity vectors in each section, integrates the velocity vectors, and converts them to the tip position; It is configured with the following.

[Effect]

A tip locus generating means (tip locus generating unit) 2 is provided which connects the starting point, the ending point, and the elapsed point with a broken line and interpolates the intersection of the straight lines with a parabola. By configuring the motion control device 50 to control a series of motions, the total working time can be significantly shortened.

〔Example〕

The gist of the present invention will be specifically explained below with reference to embodiments shown in FIGS. 1 to 4.

FIG. 2 is a block diagram explaining the present invention in detail, FIG. 3 is a diagram explaining the timetable creation situation in the embodiment of the present invention, and FIG. 4 is a diagram explaining the avoidance operation in the embodiment of the present invention. are shown respectively.

Note that the same reference numerals indicate the same objects throughout the figures.

The tip trajectory generating section 2 of this embodiment shown in FIG. 2 includes the timer 5 explained in FIG. 5, the time table 6 created as shown in FIG. a speed calculation unit 7 that calculates the speed with respect to time t generated from the timer 5, and each section 1 to n-1.
A moving direction section 8 stores the moving direction (unit vector) at , a vector synthesizing section 9 synthesizes the velocity vectors in each section 1-n-1, and a vector synthesizing section 9 that synthesizes the velocity vectors in each section 1-n-1. It is configured to include an integrating circuit 10 that converts the position of the tip of the robot 4.

The control operation of this embodiment (also referred to as trajectory control using the broken line interpolation method) will be described below.

First, the input coordinate value section 1 contains a starting point coordinate P1, and coordinates P2 to Pn-1+end point coordinates P of a plurality of elapsed points. When given as
3 = P s is section 2, ..., pn-, -P is section n-1.

Next, a time table 6 is created as a pre-operation process.

As shown in Fig. 3, (1) the entire section 1 to n −1
Each section 1~ with common acceleration Acc and maximum speed νel
The start, end of acceleration, and deceleration of each section 1 to n-1 are performed based on two conditions: (1) controlling n-1 at a trapezoidal speed, and (2) matching the deceleration start time of the previous section with the operation start time of the next section. Time table 6 for each start and end time
Store inside.

Simultaneously with the start of the operation in the operation control device 50, the timer 5 is activated.

According to the time t for each sampling time dt output from the timer 5, each interval 1 is
~ Operating status at n-1 (stop, acceleration.

The operating states (such as constant speed, deceleration, etc.) are read, and the speed calculation unit 7 calculates the respective moving speeds V and %VFl-1 accordingly.

The directions in each section 1 to n-1 are sent out from the movement direction section 8 and added to the movement speeds 8 to v7-1 to form each unit speed vector.

This unit velocity vector is synthesized by a vector synthesis unit 9 to obtain a composite velocity vector called a vector.

Further, by integrating the composite velocity vector at the sampling time dt in the integrating circuit 10, a minute movement distance is obtained, and this is added to the current position to obtain a target tip position vector.

This target tip position vector is passed to the motion control section 3, and the robot 4 is controlled to move to that position.

The process after starting the above timer 5 is at the end point P. By repeating this until reaching , trajectory control is performed using the broken line interpolation method.

FIG. 4 shows an example in which the above-mentioned trajectory control is applied to actual work, and the working conditions are, for example, the pin withdrawal direction (indicated by an arrow) at the starting point P1, the pin insertion direction at the end point P4, and the obstruction shown by diagonal lines. Set up a work environment where (a) exists.

In this case, point P2. By providing the transition point P3, the bottle drawing operation is performed in a straight line, and the movement direction changes at the transition point P2. In the vicinity of P3, a smooth and high-speed direction change is performed by drawing a smooth curve (parabolic interpolation section shown in FIG. 4), and the final pin insertion is performed again in a linear motion.

Note that the thick line trajectory ■ is the trajectory of this embodiment, and this is the trajectory of each passing point P2. A shorter trajectory can be drawn than the solid line trajectory (■) passing through P3.

In addition, the dotted line trajectory ■ is a trajectory based on the spline interpolation method, and since the trajectory is based on the entire trajectory curve, linear movement is impossible, whereas in the trajectory of this embodiment, a curved trajectory and a straight trajectory are processed at the same time. This enables smoother and shorter trajectory control.

〔Effect of the invention〕

According to the present invention as described above, it is possible to significantly shorten the working time of a working movement involving an avoidance movement by an articulated robot.

[Brief explanation of the drawing]

FIG. 1 is a block diagram explaining the present invention in detail, FIG. 2 is a block diagram explaining the present invention in detail, FIG. 3 is a diagram explaining the creation situation of a timetable in an embodiment of the present invention, and FIG. 5 is a block diagram illustrating the conventional example, and FIG. 6 is a diagram illustrating the trajectory control situation in the conventional example. In the figure, 1 is an input coordinate value section, 2 is a tip trajectory generation section, 3 is an operation control section, 4 is a robot, 5 is a timer,
6 is a time table, 7 is a speed calculation section, 8 is a movement direction section, 9 is a vector synthesis section, 10 is an integration circuit, 2
0 indicates a trajectory generating unit, and 50 indicates an operation control device, respectively. $3 figure hand 4 figure

Claims (1)

[Claims] When the coordinates of points that define the robot's motion are input, the articulated robot (4) interpolates between the points to generate a continuous target trajectory, and controls the motion of the arm according to the trajectory. The motion control device (50) divides the trajectory into a plurality of sections, and controls the start/start of motion, acceleration, constant velocity, and deceleration in each section.
Input the end time and the elapsed time since starting from the starting point, calculate the speed versus time for each section, add moving direction information to the calculation result information, and synthesize the speed vector for each section. The tip trajectory generating means (2) is provided for creating a predetermined target trajectory, and when each coordinate value of a starting point, an ending point, and a passing point in space is given as a target value of the robot operation, the tip trajectory generating means (2) generates a predetermined target trajectory. 2) Connect the start point, end point, and passing point with a broken line, and then
A robot trajectory control method characterized in that a target trajectory is generated that connects intersection points of straight lines with a parabola, and the movement of the arm is controlled in accordance with the target trajectory.