JP2002321178A - Determination method of acceleration and deceleration time for robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a determination method of acceleration and deceleration time that can shorten the motion time in low torque and improve the life in high torque for robot drive axes. SOLUTION: The mass and gravity center position of each axis of a robot are stored beforehand as parameters. The method includes the following steps: a step for calculating the first acceleration time and the first deceleration time corresponding to the load of each axis at the initial point and at the terminal point by providing the location, movement direction, movement speed of each drive axis at each point; a step for calculating an acceleration end position and a deceleration start position from the first acceleration time and the first deceleration time; a step for calculating each axis load at the acceleration end position and at the deceleration start position, and then calculating the second acceleration time and the second deceleration time corresponding to the load of each axis; a step for comparing the first acceleration time and the second acceleration time then choosing the bigger one as the decided acceleration time, and comparing the first deceleration time and the second deceleration time then choosing the bigger one as the decided deceleration time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive which is affected by the moment of inertia, the moment of inertia, the interference torque due to the operation of another axis, etc., depending on the position and posture of the teaching point of the robot, the operating direction and operating speed of each axis. The present invention relates to a method for determining an acceleration / deceleration time of a robot having an axis.

[0002]

2. Description of the Related Art Generally, in a robot performing a path work, when operating at a high speed, acceleration / deceleration control is performed to obtain a smooth movement.

As a method of determining the acceleration / deceleration time when performing such acceleration / deceleration control, a method of calculating a load inertia (inertia) from the posture of the robot and determining an acceleration / deceleration time constant based on the load inertia ( JP-A-5-462
No. 34) and interference torque and centrifugal force.
There is known a method of determining the acceleration / deceleration time so that the torque generated on each axis does not exceed the allowable maximum torque (see Japanese Patent Application Laid-Open No. Hei 7-261822).

In these acceleration / deceleration time determination methods,
The load on each axis is estimated and processed based on the posture of the robot at the start point and the end point.

[0005]

However, in practice, since the posture of the robot is changed by the movement, the influence of the moment of inertia, the interference torque, and the centrifugal force is also changed. Therefore, the maximum load is not limited to the start point and the end point.

For example, when the teaching as shown in FIG. 3 is made, the inertia moment and the weight moment of the first axis in the postures of the start point and the end point are relatively small. Therefore, the acceleration / deceleration time in consideration of the load at the start point and the end point is shortened.

However, when the posture of the robot changes during operation and reaches the commanded speed, the posture of the robot is extended, and the moment of inertia and weight moment on the first axis increases, and the start point and the end point are increased. In the acceleration / deceleration time obtained in consideration of the posture, there is a problem that the load may be too large and the torque may be saturated.

Accordingly, the present invention provides a method for determining the acceleration / deceleration time of a robot which can shorten the operation time of the drive shaft of the robot at low torque and improve the life at high torque.

[0009]

In order to solve the above-mentioned problems, in the method for determining the acceleration / deceleration time of a robot according to the present invention, a heavy force is determined by the position and orientation of the teaching point of the robot, the operating direction and operating speed of each axis. In a method for determining the acceleration / deceleration time of a robot having a drive axis that is affected by moment, acceleration inertia, interference torque due to movement of another axis, etc., the mass and the center of gravity of each axis of the robot are stored in advance as parameters, and the starting point And the position of each drive shaft at the end point,
Determining a load on each axis at a start point and an end point by giving an operation direction and an operation speed, and obtaining a first acceleration time and a first deceleration time according to each axis load; the first acceleration time and the first deceleration; From the time, a step of obtaining an acceleration reaching position at which acceleration is completed and a deceleration start position at which deceleration is started, obtaining a load on each axis at the acceleration reaching position and deceleration start position, and a second acceleration time and A step of obtaining a second deceleration time and comparing the first acceleration time with the second acceleration time, and determining a larger one as a determined acceleration time; comparing the first deceleration time with the second deceleration time; A step of obtaining the determined deceleration time.

[0010] By using the above means, the acceleration / deceleration time which becomes the maximum allowable torque of the drive shaft is obtained in consideration of the load torque generated near the acceleration reaching position and the deceleration start position during the operation of the robot. Therefore, the obtained acceleration / deceleration time is the shortest acceleration / deceleration time within a range where the load torque does not exceed the allowable maximum torque in the operation section.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of a system for implementing the method. In FIG.
11 is a teaching section, 12 is a teaching data storage area, 13 is a parameter storage area, 14 is an acceleration / deceleration time calculation section, 15 is an interpolation calculation section, and 16 is a drive section.

FIG. 2 shows an acceleration / deceleration time calculation unit 14 shown in FIG.
1 shows an example of a flowchart relating to the processing of the acceleration / deceleration time determination method of the present invention in FIG.

Step Sl The dynamics of the starting point are obtained from the posture of the robot at the starting point, and the dynamics of the ending point are obtained from the posture at the ending point.

The robot mass and moment required for obtaining the dynamics are stored in a parameter storage area 1 in advance.
3 is stored.

Here, the dynamics will be described.

The dynamics are elements necessary for estimating the torque applied to each axis from the posture and speed of the robot.

In the case of an n-axis articulated robot, the torque acting on each axis is represented by the following equation.

[0019]

(Equation 1) The inertia matrix J (θ), the centrifugal / Coriolis force C (θ, θ ′), and the gravitational moment g (θ) defined from the posture and speed of the robot will be referred to as dynamics.

As for the centrifugal / Coriolis force, since the Coriolis force has little effect on the torque for the amount of calculation, the calculation of the Coriolis force may be omitted to shorten the calculation time.

Step S2 Based on the starting point dynamics obtained in step S1, the starting point at the starting point is considered so that each axis does not exceed the allowable maximum torque.
1 Find the acceleration time tal. Similarly, the first deceleration time tdl at the end point is obtained from the end point dynamics. As a method for obtaining the first allowable acceleration time and the first allowable deceleration time from the dynamics, as disclosed in Japanese Patent Application Laid-Open No. Hei 7-261822, the value of the load torque component affected by the acceleration / deceleration is determined by the value of the drive shaft. There is a method of obtaining an acceleration / deceleration time which is a value obtained by subtracting a value of a load torque component which is not affected by acceleration / deceleration from an allowable maximum torque value. Specifically, the acceleration / deceleration time is obtained by the following method.

The torque acting on each axis is represented by the equation shown in Equation 1.

The acceleration is a speed / acceleration time. In the case of a robot, the acceleration is usually controlled by making the acceleration time of all axes the same. Therefore, θ ″ = θ ′ / t, where t: acceleration time. Accordingly, the torque applied to the i-th axis is obtained as follows.

Τi = Ji (θ) θ ′ / t + Ci (θ, θ ′) + gi where Ji (θ) = [Ji1, Ji2,... Jin] Ci (θ, θ ′) = [Ci1 , Ci2,... Cin] When this is solved for t, t = Ji (θ) θ ′ / ｛τi− (Ci (θ, θ ′) + g
i) Substituting the maximum allowable torque of the i-th axis into the torque τi and substituting the instruction speed of the teaching data into the speed θ ′ to solve the limit so that the torque generated on the i-th axis becomes the maximum allowable torque. Acceleration time can be determined.

If the maximum acceleration time is selected from the acceleration times of the respective shafts thus obtained, it becomes the allowable acceleration time in which the generated torque of all the axes does not exceed the allowable maximum torque.

The allowable deceleration time can be obtained in the same manner.

In step S3, ta1 and td1 obtained in step S2 are compared with the command speed.
To obtain the acceleration reaching position: Pa and the deceleration starting position: Pd when accelerating and decelerating. If the moving amount is not sufficient for the obtained acceleration / deceleration time and the speed steady part does not exist, the maximum speed reaching point in the section is separately obtained, and the positions are set as the acceleration reaching position and the deceleration starting position. I do.

Step S4 As in step Sl, the dynamics in the posture at the acceleration reaching position and the dynamics in the posture at the deceleration start position are obtained.

Step S5 In the same way as in step S2, the acceleration reaching position dynamics and the deceleration start position dynamics obtained in step S4 are used.
The second acceleration time ta2 at the acceleration reaching position and the second deceleration time td2 at the deceleration start position are determined so that each axis does not exceed the allowable maximum torque.

Step S6 The acceleration times ta1 and ta2 obtained as described above are compared, and the larger one is determined as the determined acceleration time tacc. The calculated deceleration times td1 and td2 are compared, and the larger one is determined as the determined deceleration time. td
ec.

In the above embodiments, the present invention has been described with reference to the most preferred embodiments. However, variations in the details of the configuration and various modifications may be made without departing from the spirit of the present invention described in the claims. Obviously, it can be changed to any combination or a combination thereof.

[0032]

As described above, according to the present invention, it is possible to obtain the shortest acceleration / deceleration time within a range in which the load torque generated on each axis of the robot does not exceed the allowable maximum torque of each axis. Therefore, there is an effect that the operation time can be shortened at a low torque and the life can be improved at a high torque.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart showing one embodiment of the present invention.

FIG. 3 shows a relationship between a teaching position of a robot and a load state in a conventional example.

[Explanation of symbols]

 11 teaching unit 12 teaching data storage area 13 parameter storage area 14 acceleration / deceleration time calculation unit 15 interpolation calculation unit 16 drive unit

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shinichi Hito 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu-shi, Fukuoka F-term (reference) 3C007 AS00 AS14 CY40 KS22 KS23 KS28 KS35 KS38 LU03 LU06 LV12 LV18 MT02 5H269 AB33 CC09 EE01 EE11

Claims (1)

[Claims] The present invention relates to a robot having a drive shaft which is affected by a gravity moment, inertia due to acceleration, interference torque due to the movement of another axis, etc., depending on the position and posture of a teaching point of the robot, the movement direction and movement speed of each axis. In the acceleration / deceleration time determination method, the mass and the center of gravity of each axis of the robot are stored in advance as parameters, and the position, operation direction, and operation speed of each drive axis at the start point and end point are given, so that Obtaining a load on the shaft and obtaining a first acceleration time and a first deceleration time corresponding to each of the shaft loads; starting from the first acceleration time and the first deceleration time, an acceleration reaching position and deceleration at which acceleration is completed; Obtaining a deceleration start position, obtaining a load on each axis at the acceleration reaching position and the deceleration start position, and calculating a second acceleration time and a second
Determining the deceleration time, the first acceleration time and the second
The acceleration time is compared, and the larger one is set as the determined acceleration time, and the first deceleration time and the second deceleration time are compared,
A method for determining an acceleration / deceleration time of a robot, comprising a step of determining a larger one as a determined deceleration time.