scholarly journals Analysis of the Compliance Properties of an Industrial Robot with the Mozzi Axis Approach

Robotics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 80 ◽  
Author(s):  
Doria ◽  
Cocuzza ◽  
Comand ◽  
Bottin ◽  
Rossi
Keyword(s):  
Industrial Robot ◽  
Industrial Robots ◽  
Robotic Assembly ◽  
Robot Arm ◽  
Machined Surface ◽  
End Effector ◽  
Chatter Vibrations ◽  
Modes Of Vibration ◽  
Machining Robot ◽  
Robot Performance

In robotic processes, the compliance of the robot arm plays a very important role. In some conditions, for example, in robotic assembly, robot arm compliance can compensate for small position and orientation errors of the end-effector. In other processes, like machining, robot compliance may generate chatter vibrations with an impairment in the quality of the machined surface. In industrial robots, the compliance of the end-effector is chiefly due to joint compliances. In this paper, joint compliances of a serial six-joint industrial robot are identified with a novel modal method making use of specific modes of vibration dominated by the compliance of only one joint. Then, in order to represent the effect of the identified compliances on robot performance in an intuitive and geometric way, a novel kinematic method based on the concept of “Mozzi axis” of the end-effector is presented and discussed.

scholarly journals Modeling and Identification of an Industrial Robot with a Selective Modal Approach

2020 ◽  
Vol 10 (13) ◽  
pp. 4619 ◽  
Author(s):  
Matteo Bottin ◽  
Silvio Cocuzza ◽  
Nicola Comand ◽  
Alberto Doria
Keyword(s):  
Dynamic Model ◽  
Material Removal ◽  
Industrial Robot ◽  
Joint Stiffness ◽  
Industrial Applications ◽  
Industrial Robots ◽  
Robotic Assembly ◽  
Machined Surface ◽  
Modal Approach ◽  
Removal Processes

The stiffness properties of industrial robots are very important for many industrial applications, such as automatic robotic assembly and material removal processes (e.g., machining and deburring). On the one hand, in robotic assembly, joint compliance can be useful for compensating dimensional errors in the parts to be assembled; on the other hand, in material removal processes, a high Cartesian stiffness of the end-effector is required. Moreover, low frequency chatter vibrations can be induced when low-stiffness robots are used, with an impairment in the quality of the machined surface. In this paper, a compliant joint dynamic model of an industrial robot has been developed, in which joint stiffness has been experimentally identified using a modal approach. First, a novel method to select the test configurations has been developed, so that in each configuration the mode of vibration that chiefly involves only one joint is excited. Then, experimental tests are carried out in the selected configurations in order to identify joint stiffness. Finally, the developed dynamic model of the robot is used to predict the variation of the natural frequencies in the workspace.

Adaptive control of an industrial robot

Robotica ◽  
1986 ◽  
Vol 4 (4) ◽  
pp. 243-246 ◽  
Author(s):  
Ajit M. Karnik ◽  
Naresh K. Sinha
Keyword(s):  
Control Systems ◽  
Industrial Robot ◽  
Industrial Robots ◽  
Superior Performance ◽  
Robot Arm ◽  
Adaptive Controllers ◽  
Self Tuning ◽  
On Line ◽  
Robot Performance ◽  
And Performance

SUMMARYFor the past several years, industrial robots are being used extensively. These robots are generally equipped with relatively simple control systems. Such control systems have proved adequate, but with increased demand on robot performance, there is need for advanced and sophisticated controllers. One of the probelms in the control of robots is that system dynamics change due to several factors such as the orientation of arms and their effective inertia.Adaptive controllers have the advantage that the system is continuously modelled and controller parameters are evaluated on-line, thus resulting in superior performance. Adaptive controllers can be realized in several ways.This paper describes the design and performance of an explicit self tuning regulator for a robot arm.

scholarly journals Experimental studies of robotic assembly of precision parts

2021 ◽  
Vol 49 (1) ◽  
pp. 44-55
Author(s):  
Mikhail Polishchuk ◽  
M. Tkach
Keyword(s):  
High Speed ◽  
Industrial Robot ◽  
Economic Effect ◽  
Experimental Studies ◽  
Industrial Robots ◽  
Robotic Assembly ◽  
Robot Arm ◽  
Positioning Accuracy ◽  
Position Correction ◽  
The Cost

At present, robotization of assembly processes is achieved through the use of industrial robots with high positioning accuracy in conjunction with tactile means of adaptation to the conditions of assembly of precision parts. The cost of such robots is many times higher than the cost of simple robots with low positioning accuracy of the robot arm. The research in this article is aimed at reducing the cost of assembly processes for precision parts by applying the position correction of the connected parts not by the robot hand, but by an additional technological module that is installed on the manipulator of a simple robot and performs high-speed stochastic mismatch scan of assembly objects. The article presents the results of a full factorial experiment of the process of joining precision cylindrical parts with a gap of no more than 3...5 microns. A regression model of this process is proposed, a formula for calculating the quasi-optimal modes of precision assembly and graphanalytical dependences of the assembly time on the scanning modes of the misalignment of assembly objects are given. The proposed high-speed method for compensating for the positioning error of an industrial robot makes it possible to assemble precision parts in a very short time within 1...3(s). The main economic effect of the research results is that the device for scanning the misalignment of assembly objects, which is installed on the arm of an inexpensive robot with a low positioning accuracy, can significantly increase the assembly speed and reduce capital investments in robotic assembly of high-precision parts.

Finding Features of Positioning Error for Large Industrial Robots Based on Convolutional Neural Network

2021 ◽  
Author(s):  
Daiki Kato ◽  
Kenya Yoshitugu ◽  
Naoki Maeda ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
...  
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Production Systems ◽  
Industrial Robot ◽  
Three Dimensional ◽  
Industrial Robots ◽  
Numerical Control ◽  
Robot Motion ◽  
Positioning Error ◽  
End Effector

Abstract Most industrial robots are taught using the teaching playback method; therefore, they are unsuitable for use in variable production systems. Although offline teaching methods have been developed, they have not been practiced because of the low accuracy of the position and posture of the end-effector. Therefore, many studies have attempted to calibrate the position and posture but have not reached a practical level, as such methods consider the joint angle when the robot is stationary rather than the features during robot motion. Currently, it is easy to obtain servo information under numerical control operations owing to the Internet of Things technologies. In this study, we propose a method for obtaining servo information during robot motion and converting it into images to find features using a convolutional neural network (CNN). Herein, a large industrial robot was used. The three-dimensional coordinates of the end-effector were obtained using a laser tracker. The positioning error of the robot was accurately learned by the CNN. We extracted the features of the points where the positioning error was extremely large. By extracting the features of the X-axis positioning error using the CNN, the joint 1 current is a feature. This indicates that the vibration current in joint 1 is a factor in the X-axis positioning error.

Study on Improving Accuracy in Robotic Milling of Aluminum Alloy

2018 ◽  
Author(s):  
Shaochun Sui ◽  
Kai Guo ◽  
Jie Sun ◽  
Yiran Zang
Keyword(s):  
Aluminum Alloy ◽  
Industrial Robot ◽  
Vibration Signal ◽  
Industrial Robots ◽  
Machining Process ◽  
Cnc Machine ◽  
Machined Surface ◽  
Improving Accuracy ◽  
High Level ◽  
Monolithic Components

Nowadays, the application of using industrial robots in manufacture is a diminutive due to its own low rigidity and low stiffness. This leads to high level of vibrations that limits the quality and the precision of the workpiece. So they are usually used for welding, grinding and paint shop. However, the potential of industrial robot applications in machining has be realized. The volume of monolithic components is large and there are many issues in machining process such as geometric tolerance and quality of machined surface. In such cases the traditional CNC machine is replaced by industrial robots, which will reduce the production cost, reduce labor and increase the efficiency. In this paper, the milling experiment of 7050-T7451 aeronautical aluminum alloy was carried out by using industrial robot KR210 R2700. In addition, the experiment was employed to study the influence of milling speed, feed-rate, cutting depth and cutting width on vibrations, surface roughness was also measured to evaluate the machining quality. Besides, the axis of angle was changed which led to the different industrial robot’s postures. The vibration signal of different postures was acquired, which was used to analysis the optimal workspace of industrial robot. The best process parameters were obtained, which will play a guiding significance on the actual production.

scholarly journals Detachable Robotic Grippers for Human-Robot Collaboration

2021 ◽  
Vol 8 ◽  
Author(s):  
Zubair Iqbal ◽  
Maria Pozzi ◽  
Domenico Prattichizzo ◽  
Gionata Salvietti
Keyword(s):  
Degrees Of Freedom ◽  
Tactile Feedback ◽  
Industrial Robots ◽  
Physical Interaction ◽  
Robot Arm ◽  
Robotic Hands ◽  
End Effector ◽  
External Power ◽  
Self Powered ◽  
Automatic Tool

Collaborative robots promise to add flexibility to production cells thanks to the fact that they can work not only close to humans but also with humans. The possibility of a direct physical interaction between humans and robots allows to perform operations that were inconceivable with industrial robots. Collaborative soft grippers have been recently introduced to extend this possibility beyond the robot end-effector, making humans able to directly act on robotic hands. In this work, we propose to exploit collaborative grippers in a novel paradigm in which these devices can be easily attached and detached from the robot arm and used also independently from it. This is possible only with self-powered hands, that are still quite uncommon in the market. In the presented paradigm not only hands can be attached/detached to/from the robot end-effector as if they were simple tools, but they can also remain active and fully functional after detachment. This ensures all the advantages brought in by tool changers, that allow for quick and possibly automatic tool exchange at the robot end-effector, but also gives the possibility of using the hand capabilities and degrees of freedom without the need of an arm or of external power supplies. In this paper, the concept of detachable robotic grippers is introduced and demonstrated through two illustrative tasks conducted with a new tool changer designed for collaborative grippers. The novel tool changer embeds electromagnets that are used to add safety during attach/detach operations. The activation of the electromagnets is controlled through a wearable interface capable of providing tactile feedback. The usability of the system is confirmed by the evaluations of 12 users.

scholarly journals Modular fastening system and tool–holder working unit for incremental forming

2019 ◽  
Vol 299 ◽  
pp. 05005
Author(s):  
Melania Tera ◽  
Claudia–Emilia Gîrjob ◽  
Cristina–Maria Biriș ◽  
Mihai Crenganiș
Keyword(s):  
Machine Tools ◽  
Incremental Forming ◽  
Industrial Robot ◽  
Industrial Robots ◽  
Cnc Milling ◽  
End Effector ◽  
Tool Holder ◽  
Cnc Milling Machine ◽  
Milling Machines ◽  
Sheet Metal Workpiece

Incremental forming can be usually unfolded either on CNC milling machine–tools or serial industrial robots. The approach proposed in this paper tackles the problem of designing a modular fastening system, which can be adapted for both above mentioned technological equipment. The fastening system of the sheet–metal workpiece is composed of a fixing plate and a retaining plate. The fixing and retaining plates will be made up of different individual elements, which can be easily repositioned to obtain different sizes of the part. Moreover, the fastening system has to be able to be positioned either horizontally (to be fitted on CNC milling machines) or vertically (to be fitted on industrial robots. The paper also presents the design of a tool–holder working unit which will be fitted on KUKA KR 210 industrial robot. The working unit will be mounted as end–effector of the robot and will bear the punch, driving it on the processing toolpaths.

scholarly journals Online pose correction of an industrial robot using an optical coordinate measure machine system

2018 ◽  
Vol 15 (4) ◽  
pp. 172988141878791 ◽  
Author(s):  
Sepehr Gharaaty ◽  
Tingting Shu ◽  
Ahmed Joubair ◽  
Wen Fang Xie ◽  
Ilian A Bonev
Keyword(s):  
Root Mean Square ◽  
Spot Welding ◽  
Industrial Robot ◽  
Industrial Robots ◽  
Mean Square ◽  
End Effector ◽  
Proportional Integral ◽  
Accuracy Requirement ◽  
Robot Controller ◽  
Correction Scheme

In this article, a dynamic pose correction scheme is proposed to enhance the pose accuracy of industrial robots. The dynamic pose correction scheme uses the dynamic pose measurements as feedback to accurately guide the robot end-effector to the desired pose. The pose is measured online with an optical coordinate measure machine, that is, C-Track 780 from Creaform. A root mean square method is proposed to filter the noise from the pose measurements. The dynamic pose correction scheme adopts proportional-integral-derivaitve controller and generates commands to the FANUC robot controller. The developed dynamic pose correction scheme has been tested on two industrial robots, FANUC LR Mate 200iC and FANUC M20iA. The experimental results on both robots demonstrate that the robots can reach the desired pose with an accuracy of ±0.050 mm for position and ±0.050° for orientation. As a result, the developed pose correction can make the industrial robots meet higher accuracy requirement in the applications such as riveting, drilling, and spot welding.

Auto-Calibration for Vision-Based 6-D Sensing System to Support Monitoring and Health Management for Industrial Robots

2021 ◽  
Author(s):  
Guixiu Qiao ◽  
Guangkun Li
Keyword(s):  
High Precision ◽  
Health Management ◽  
Calibration Method ◽  
Industrial Robots ◽  
Smart Manufacturing ◽  
Robot Arm ◽  
Sensing System ◽  
Robot Accuracy ◽  
Robot Machining ◽  
Machining Robot

Abstract Industrial robots play important roles in manufacturing automation for smart manufacturing. Some high-precision applications, for example, robot drilling, robot machining, robot high-precision assembly, and robot inspection, require higher robot accuracy compared with traditional part handling operations. The monitoring and assessment of robot accuracy degradation become critical for these applications. A novel vision-based sensing system for 6-D measurement (six-dimensional x, y, z, yaw, pitch, and roll) is developed at the National Institute of Standards and Technology (NIST) to measure the dynamic high accuracy movement of a robot arm. The measured 6-D information is used for robot accuracy degradation assessment and improvement. This paper presents an automatic calibration method for a vision-based 6-D sensing system. The stereo calibration is separated from the distortion calibration to speed up the on-site adjustment. Optimization algorithms are developed to achieve high calibration accuracy. The vision-based 6-D sensing system is used on a Universal Robots (UR5) to demonstrate the feasibility of using the system to assess the robot’s accuracy degradation.

scholarly journals Evaluating the use of human aware navigation in industrial robot arms

2021 ◽  
Vol 12 (1) ◽  
pp. 379-391
Author(s):  
Matthew Story ◽  
Cyril Jaksic ◽  
Sarah R. Fletcher ◽  
Philip Webb ◽  
Gilbert Tang ◽  
...  
Keyword(s):  
Science Fiction ◽  
Mobile Robotics ◽  
Industrial Robot ◽  
Lessons Learned ◽  
Human Robot Interaction ◽  
Industrial Robots ◽  
Robot Arm ◽  
Robot Arms ◽  
Safety Guidelines ◽  
Current Standards

Abstract Although the principles followed by modern standards for interaction between humans and robots follow the First Law of Robotics popularized in science fiction in the 1960s, the current standards regulating the interaction between humans and robots emphasize the importance of physical safety. However, they are less developed in another key dimension: psychological safety. As sales of industrial robots have been increasing over recent years, so has the frequency of human–robot interaction (HRI). The present article looks at the current safety guidelines for HRI in an industrial setting and assesses their suitability. This article then presents a means to improve current standards utilizing lessons learned from studies into human aware navigation (HAN), which has seen increasing use in mobile robotics. This article highlights limitations in current research, where the relationships established in mobile robotics have not been carried over to industrial robot arms. To understand this, it is necessary to focus less on how a robot arm avoids humans and more on how humans react when a robot is within the same space. Currently, the safety guidelines are behind the technological advance, however, with further studies aimed at understanding HRI and applying it to newly developed path finding and obstacle avoidance methods, science fiction can become science fact.

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