JPS58211881A - Industrial robot - 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 The present invention relates to an articulated childbirth robot whose arm can move smoothly.

Normally, the arm of a robot is driven by reducing the rotation of the drive motor with a reduction gear, but in order to maintain the robot's trajectory or position repeatability, the reduction mechanism used must be designed to minimize backlash. is required. In response to this demand, a speed reduction mechanism called a harmonic gear is currently being widely used, but this type of speed reduction gear still has other features based on rigidity. In other words, because the rigidity of the reducer, which is the motor torque transmission mechanism, is low, the motor
In the drive system area consisting of the reducer and the robot arm, the current situation is that the mouth and robot arm move while vibrating greatly, causing a resonance state.

This abnormal phenomenon significantly reduces the robot's position reproducibility accuracy, posing a major problem in the practical use and design of robots.

The present invention aims to provide a new industrial robot that solves these conventional problems. Essentially, avoiding resonance in a mechanical system is a difficult design issue, and general countermeasures can be broadly divided into two: removing the resonance frequency from the practical range and absorbing vibration. by the way,,
For practical robots, it is currently difficult to adopt conventional general measures due to factors such as the fact that the resonant frequency changes depending on the state of the robot's arm, the load on the tip of the arm, etc., and the manufacturing cost increases significantly.

In contrast, the present invention is essentially different from conventional vibration prevention measures, and has a new resonance vibration prevention function that employs an electrical feedback control method.Prior to the configuration of the present invention,
First, the configuration of conventional robot arm drive control will be described with reference to FIG. 1.

In the figure, a speed command signal & is passed to a comparator 2 from a speed command signal generator 1 which receives rotational speed and direction commands from a computer or the like. A rotational speed feedback signal from the drive motor 3 is returned to the comparator 2 via a feedback signal converter 4. Therefore, the speed deviation signal in (a-b) is passed to the speed command signal/1' torque converter 6, a changing torque is given to the motor 3, and the motor 3 rotates at the specified speed regardless of load fluctuations. . Now, the present invention has a function of detecting abnormal vibrations occurring in the robot arm. For example, an acceleration detector using a strain gauge or piezoelectric element detects changes in velocity at the tip of a robot arm. Next, the present invention can be realized by adding this detection signal to the conventional control system.

Fig. 2 shows the principle of the present invention in a block diagram similar to Fig. 1, and includes the same block elements as Fig. 1.
1 to 61, it has a speed change detection section 6 for detecting acceleration or vibration. The detection feedback signal C from the detection section 6 is given to the conventional comparison section 2, which compares the three signals a, b, and c, and determines the speed command that eliminates the resonance vibration. That is, a speed change command that is the same as the vibration period is given to the speed command signal/torque converter 6.

As for the phenomenon, the present invention can be thought of as providing a feedback speed loop that changes the motor speed command signal to cancel the generated vibration, and the responsiveness of this feedback loop depends on the actual vibration period of the robot arm. It can be made sufficiently short and can be realized without any problems in terms of circuit configuration. In addition,
The dotted line in FIG. 2 indicates that vibrations are transmitted.

Describing the experimental results of the present invention, it was confirmed that no resonance state occurred in the robot of the present invention.

That is, according to the results of measurement using a vibration meter installed at the tip of the robot yl-, the present invention exhibited a remarkable effect of reducing the vibration speed to below that of the conventional technology.

In addition, the present invention performs a control function to suppress acceleration when starting and stopping the robot 7), making acceleration and deceleration smooth, and has the great feature of reducing vibrations that occur during starting and stopping to below Y. have.

As described above, the present invention reduces the vibration of a mechanical system by performing simple electrical control, and has a significant effect on the industry in that it can be realized at a significantly lower cost than conventional mechanical reduction measures. be.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a speed control section of a conventional robot, and FIG. 2 is a block diagram of a speed control section of a robot according to the present invention. 1... Speed command signal generation section 1, 2... Comparison section, 3... Drive motor, 4... Feedback signal conversion section, 5... ...Speed command signal/torque conversion section, 6...Speed change detection section. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] An industry characterized in that the arm is provided with an acceleration detector, and the required arm has an arm drive feedback control function in which the acceleration detected by 'A' or the speed converted from the acceleration is used as a feedback control factor. robot 1-
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