Investigation of novel teaching method for skillful operation of working plate with an industrial dual arm robot

T. Mase,R. Kitahata,T. Hirogaki,E. Aoyama 제어로봇시스템학회 2020 제어로봇시스템학회 국제학술대회 논문집 Vol.2020 No.10

With the advancement of the motion control of industrial robots in recent years, there is a demand for a method that can easily measure the accuracy of the synchronous control of a 2-axis dual-arm robot. Therefore, in this study, we propose a new measurement method that creates a ball rolling motion in a circular orbit on the work plate and uses the rolling motion error with respect to the reference circle. In this study, we conducted experiments on the teaching method when controlling the rolling motion of the ball at a position away from the center of the robot on the work plate. Results showed that an error occurred in the maximum inclination angle of the plate, which we kept the ball steady by correcting a teaching program. As the load is applied to the wrist joints by the plate, the effect of the correction of the teaching point angle cannot be obtained. However, the method of correcting the angular velocity between the teaching points was found to be effective.

Determining arrangement and cooperative operating control of two industrial robots based on torque margin method

K.Omoto,T.Hirogaki,E.Aoyama 제어로봇시스템학회 2020 제어로봇시스템학회 국제학술대회 논문집 Vol.2020 No.10

SKILLFUL OPERATION OF WORKING PLATE UNDER NON-UNIFORM LOADS WITH AN INDUSTRIAL DUAL-ARM ROBOT CONSIDERING POWER CONSUMPTION OF JOINTS MOTORS

R.Kitahata,T. Hirogaki,E. Aoyama 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10

With the advancement of the motion control of industrial robots in recent years, a method that can easily measure the accuracy of the synchronous control of a two-axis dual-arm robot is desired. Therefore, in this study, we propose a new measurement method that creates a ball rolling motion in a circular orbit on a work plate and uses the rolling motion error with respect to the reference circle. In addition, industrial robots in the field are always forced to operate continuously for a long period of time, and they work with all kinds of loads overlapping and applying non-uniform loads. In this study, we propose a new measurement method that creates a rolling motion of a ball on a circular track on a work plate and uses the error of the rolling motion relative to a reference circle. In particular, in order to elucidate the motion error during long-time continuous operation under high load, we approached the problem from the viewpoint of joint temperature and power consumption. As a result, we found that the ball trajectory error was caused by an increase in the temperature of the elbow and wrist motors, which increased the joint load and caused an angular error in the plate. Even when non-uniform loads were applied, the circular trajectory could be corrected by making corrections according to the temperature at each arm. The tendency of the angle error due to the temperature rise and the increase in joint load of each joint was found, and it was found that it was possible to correct the angle error by FF control.

Working plate operation for graspless handling technology with an industrial dual-arm SCARA robot

K. Shimizu,T. Hirogaki,E. Aoyama 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10

With the recent advances in industrial robot the motion control, there is a demand for a method that can easily measure the accuracy of the synchronous control of dual-arm selective compliance assembly robot arm (SCARA) robots. Therefore, in this study, a measurement method was developed in which a ball rolling motion is created in a circular orbit on the work plate and the rolling motion error with respect to the reference circle is utilized. An experiment was conducted on a teaching method for controlling the rolling motion of the ball at a position away from the center of the robot on the work plate. It was found that an error occurs in the peripheral speed in the rotation of the plate. When the work plate is grasped and the movement is taught, the program using the master–slave method was the primary influence on the motion error, confirming the possibility of correction.

Predicting Temperature Fluctuation of Five Axis Controlled Compact Machine Tool Equipped with a Wave Motion Gear Device Based on a Thermal Network Model

K. Ozawa,T. Hirogaki,E. Aoyama 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10

The manufacturing industry accounts for more than 40% of the total final energy consumption. Therefore, energy-saving measures are still required. Against this background, stable accuracy over a long period of time is necessary to realize automation and unmanned operation of machine tools. Therefore, thermal deformation, which is up to 75% of the overall geometric error of the workpiece, is the most important issue. In this study, we proposed a modeling method to predict the temperature rise during machine tool operation. To reduce the power consumption, a reduction gear attached to the rotation control shaft was employed in this study, and a wave gear device was used as the reduction gear. Such a wave gear device has the characteristic in that its efficiency changes significantly with temperature change. Therefore, while considering the characteristics of the wave gear device, the power consumption was recorded by the internal information monitor of the servo motor, and the rotating axis was operated under various drive conditions. The results indicate that the lubricating oil influenced the power value. In addition, we succeeded in analyzing a temperature rise prediction model from the power loss.

Machine-learning-based approach to improve the positioning accuracy of large industrial robots

K. Yoshitsugu,D. Kato,T. Hirogaki,E. Aoyama,K. Takahashi 제어로봇시스템학회 2020 제어로봇시스템학회 국제학술대회 논문집 Vol.2020 No.10

In this study, a system to reproduce the positional relationship of two flanges to be connected using an industrial robot and enable the manufacturing of the connecting pipes was developed. The objective was to ensure that the robot can exhibit a high absolute positioning accuracy even when trained offline so as to reproduce the space accurately. The error in various postures of the robot was measured using a laser tracker, and the servo information was simultaneously acquired by using the OpenNR-IF framework. The relationship between the positioning error and servo information was examined. It was noted that the relationship between multiple parameters such as the joint angle obtained as the servo information was highly complex. Therefore, the random forest approach was employed in machine learning to examine these relationships. Subsequently, the positioning error was predicted based on each parameter and corrected. Although the correction was inadequate, the mechanism to select the data to enhance the prediction accuracy was clarified, and several relevant key parameters were identified.

Position Calibration Method for Large size Industrial Robots Based on Random Forest

D. Kato,N. Maeda,T. Hirogaki,E. Aoyama,K. Takahashi 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10

Most industrial robots are unsuitable for variable production systems because they are taught using the teaching playback method. In contrast, the offline teaching method has been developed, but it has not progressed because of the low positioning accuracy. Therefore, several studies have proposed methods to calibrate for positioning errors using neural networks. However, it is difficult to identify the factors of positioning errors because the structure of neural networks is not clear. Herein, we applied the random forest method, which is a type of machine learning method, and constructed a prediction model for positioning errors. A large industrial robot was used, and three-dimensional coordinates of the end-effector were obtained using a laser tracker. The model to predict the positioning error from end-effector coordinates, joint angles, and joint torques was constructed using the random forest method, and the positioning error was predicted with high accuracy. The random forest analysis demonstrated that joint 2 was the primary factor of the X- and Z-axis errors. This suggested that the air cylinder used as an auxiliary to the servo motor of joint 2 was the error factor. The positioning error norm was reduced at all points using the proposed calibration.

Realization of Musical Saw Bowing by Industrial Humanoid Robot

H. Hanai,A. Mishima,A. Miura,T. Hirogaki,E. Aoyama 제어로봇시스템학회 2021 제어로봇시스템학회 국제학술대회 논문집 Vol.2021 No.10

In a previous study, we examined the performance of musical saw bows using a western saw, which is not only an unfamiliar tool but also difficult to handle owing to its excellent shape and flexibility among various musical instruments. In the previous study, we achieved performance control by blowing; however, we could not control the sound other than blowing. In this study, we focused on bowing, which is used in the evaluation of musical saw performance, in addition to striking. Moreover, self-excited vibrations must be generated by stick-slip based on the performance. Consequently, the pressure and velocity must be controlled to verify the generation of the self-excited vibration and the vibration itself. In addition to the generation of sound by a self-excited vibration, this study discusses the pure sound nature of the vibration. This approach differs from those implemented in previous studies to suppress the self-excited vibration. Furthermore, we present a method to realize the musical saw movement using an industrial humanoid robot.