JPH0991020A - Method for controlling teaching robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the interpolation of a track and to eliminate the necessity of a high performance computing element by independently interpolating the xy coordinates of plural specific points as functions of time by a quadratic curve, finding out the xy coordinates of the plural points and converting the xy coordinates into three-dimensional coordinates to obtain track interpolation points. SOLUTION: It is supposed that teaching points are set up as P1 to P3 and a robot is moved at a fixed speed without stopping at the intermediate teaching point (intermediate point) P. In this case, new neighbor points separated from the intermediate point P2 respectively by a distance 1a in respective directions from the point P2 to the start point P1 and the end point P3 are set up as Pa and Pb together with the point P2. A plane including the new points Pa, P2, Pb is set up as an xy coordinate plane, and in the case of interpolaring a distance between the points Pa, Pb by a quadratic curve y=ax<2> +bx+c, respective coordinates x, y are individaully interpolated as the functions of time (t) and then the interpolated coordinates x, y are synthesized to obtain an interpolated track. Thus track interpolation can be executed by the simple equation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of a teaching playback robot (teaching robot),
The present invention relates to a route control method for a robot.

[0002]

2. Description of the Related Art In controlling a teaching robot, linear interpolation or circular interpolation is performed between teaching points, interpolation coordinates are obtained, and a joint angle of the robot corresponding to the interpolation coordinates is obtained.
The robot controls the path of the robot's hand by performing control every moment to achieve this joint angle. In this case, when operating at a constant speed without stopping at the teaching point,
In the vicinity of the desired teaching point, circular interpolation or curved interpolation is performed so as to smoothly move between linear paths, and as a result, overshoot and vibration are prevented.

As shown in FIG. 1 referred to in the embodiment of the present invention, P ₁ , P ₂ and P _{3 in} FIG. 1 are teaching points and P
_{When the} robot is moved in order of P ₁ , P ₂ and P ₃ without stopping at ₂ , in the vicinity of the teaching point P ₂ ,
For example, by interpolating the points P _a and P _b with a curve, smooth operation without overshoot or vibration is performed.

[0004]

[Problems to be Solved by the Invention] The above teaching point P
_As an interpolation method in the vicinity of _two , for example, a method using a circular arc is conceivable. In this case, in calculating the interpolation trajectory, an arc equation inscribed between the straight lines P ₁ P ₂ and P ₂ P ₃ is calculated each time. Therefore, it is necessary to interpolate, the amount of calculation increases, and when the interpolation cycle is highly accurate, a high-performance computing unit is required.

In view of the above problems, it is an object of the present invention to provide a teaching robot control method in which trajectory interpolation is simplified and a high-performance computing unit is unnecessary.

[0006]

Means for Solving the Problems The present invention which achieves the above-mentioned object is as follows. (1) Based on three teaching points, two new points near the intermediate point including the intermediate point are specified, and these two new points are specified. In the xy plane in which is present, the xy coordinates of these two new points are made independent as a function of time and interpolated by quadratic curves, and the xy coordinates of the new two points are obtained and further converted into three-dimensional coordinates. It is characterized in that the trajectory interpolation points are obtained, and (2) among the three teaching points, the speed and distance from the start point to the intermediate point and from the intermediate point to the end point are made equal.

As a function of time, x-coordinates and y-coordinates can be interpolated along a quadratic curve, sequential interpolation trajectories can be calculated, and the x-coordinates need only be monotonically increasing. Will be easy.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described with reference to FIGS. In FIG. 1, consider a case where the teaching points are P ₁ , P ₂ , and P ₃ and the teaching points are moved at a constant speed without stopping at an intermediate teaching point (intermediate point) P ₂ . That is, among the teaching points, there are a starting point P ₁ , an intermediate point P ₂ , and an ending point P ₃ , and the teaching point moves linearly from the starting point P ₁ to the intermediate point P ₂ without stopping at the intermediate point P _{2 and also} at the intermediate point P ₂ . Consider the case of a straight line movement from ₂ to the end point P ₃ . In this case, in the vicinity of the intermediate point P _2, the point of distance l _a from the midpoint P ₂ to the start P ₁ direction P _b,
A new point is set together with the intermediate point P ₂ .

Here, the planes on which the new points P _a , P ₂ and P _b exist are set as x and y coordinate planes and the new points P _a and P _{b are set.}
In interpolating the interval with the quadratic curve y = ax ² + bx + c, each of x and y is individually interpolated as a function of time t, and then x and y are combined to obtain an interpolation trajectory. Since the time t is used as a function, the speed from the starting point P ₁ to the new point P _a changes the speed from the point P _a to the intermediate point P a.
Assuming that the move to _2, and the travel time t _1, also the time to move from the intermediate point P ₂ to the end point P ₃ direction until the point P _b and t _2, and t ₁ = t _2. Thus, at times t ₁ and t ₂ , the straight lines in the x and y planes shown in FIG. 2 are made independent as a function of time as shown in FIGS. 3 and 4. Here, t ₁ = t ₂ , and the distances l _a from the intermediate points P ₂ to the points P _a and P _b are equal, and x monotonically increases with respect to t as shown in FIG. Therefore, the calculation amount of x is reduced.

On the other hand, for y, the time t is as shown in FIG. 4, and y (t) = at ² + bt + c is 2
Interpolate with the next curve. In this case, the coefficients a, b, c are obtained on the condition that the quadratic curve at the starting point P ₁ and the ending point P ₃ and the straight line consisting of the line segments P ₁ , P ₂ and P ₂ , P ₃ are in contact with each other. In this case, the transition from the straight track to the curved interpolation track is smoothly performed. That is, since the slope of the tangent line at time o matches the slopes of the straight lines P ₁ and P ₂ , the formula y (t) =
For at ² + bt + c, points P ₁ , P ₂ , on the xy plane,
The coordinates of P ₃ are P ₁ (x ₁ y ₁ ), P ₂ (x ₂ y ₂ ), P
_{When 3} (x ₃ y ₃ ), the result is as follows.

[Equation 1]

Thus, x, y consisting of a function of time t is
can be obtained from t, and therefore the next interpolation cycle t
x and y coordinates can be calculated and obtained individually, and t
₁+ T ₂It is possible to calculate the interpolation trajectory up to.

[0012]

As described above, according to the present invention, trajectory interpolation can be performed by a simple calculation formula, and a conventional high-performance computing unit is not required. In addition, the acceleration on the orbit is constant and smooth movement is possible. Furthermore, since the x and y coordinates are obtained as a function of time, it is possible to obtain interpolated coordinates at fixed time intervals.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of teaching point interpolation.

FIG. 2 is an explanatory diagram of an xy coordinate plane that includes points P _a and P _b near an intermediate point P ₂ .

FIG. 3 is a diagram showing a change in coordinate x with respect to time t.

FIG. 4 is a diagram showing a change in coordinate y with respect to time t.

[Explanation of symbols]

P _1, P _2, P ₃ start of the teaching point, intermediate point, end point P _a, P _b new point

Claims (2)

[Claims] 1. Specifying two new points in the vicinity of an intermediate point including an intermediate point based on three teaching points, and determining the xy coordinates of these two new points on an xy plane where these two new points exist. A teaching robot control method, which is independent as a function of time and is interpolated by a quadratic curve, and the xy coordinates of the new two points are obtained and further converted into three-dimensional coordinates to obtain trajectory interpolation points. 2. The teaching robot control method according to claim 1, wherein the speed and distance from the start point to the intermediate point and from the intermediate point to the end point are made equal among the three teaching points.