Evaluation and Modeling of the Friction in Robotic Joints Considering Thermal Effects

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Roberto Pagani ◽  
Giovanni Legnani ◽  
Giovanni Incerti ◽  
Matteo Gheza
Keyword(s):  
Degrees Of Freedom ◽  
Industrial Robot ◽  
Low Cost ◽  
Experimental Tests ◽  
Industrial Applications ◽  
Friction Model ◽  
Friction Torque ◽  
Working Cycle ◽  
Robotic Joints ◽  
Increasing Temperature

Abstract The paper presents a second-order friction model for the joints of industrial robot manipulators that takes into account temperature effects. A solution based on a polynomial description of the friction is proposed. The theoretical analysis and the experimental measurements have shown that friction decreases with increasing temperature, which in turn depends on the working cycle of the manipulator. The mathematical model here proposed allows to foresee the friction variation during extensive working cycles and it does not require the use of a transducer for the measurement of the joint internal temperature; therefore it is well suitable for low-cost industrial applications, to improve the control performance or to predict the energy consumption. Experimental tests performed on a commercial six degrees-of-freedom (6 DOF) manipulator show that the model is effective in estimating the joint temperature and the friction torque during the robot operations.

Modelling and Evaluation of the Friction in Robotic Joints Considering Thermal Effects

2019 ◽  
Author(s):  
Giovanni Legnani ◽  
Giovanni Incerti ◽  
Roberto Pagani ◽  
Matteo Gheza
Keyword(s):  
Industrial Robot ◽  
Low Cost ◽  
Experimental Tests ◽  
Industrial Applications ◽  
Friction Model ◽  
Friction Torque ◽  
Working Cycle ◽  
Robotic Joints ◽  
Increasing Temperature ◽  
The Mathematical Model

Abstract The paper presents a second order friction model for the joints of industrial robot manipulators that takes into account temperature effects. A solution based on a polynomial description of the friction is proposed. The theoretical analysis and the experimental measurements have shown that friction decreases with increasing temperature, which in turn depends on the working cycle of the manipulator. The mathematical model here proposed allows to foresee the friction variation during extensive working cycles and it does not require the use of a transducer for the measurement of the joint internal temperature; therefore it is well suitable for low-cost industrial applications, to improve the control performance or to predict the energy consumption. Experimental tests performed on a commercial 6 DOF manipulator show that the model is effective in estimating the joint temperature and the friction torque during the robot operations.

A New Friction Model for Mechanical Transmissions Considering Joint Temperature

2016 ◽  
Author(s):  
Giovanni Legnani ◽  
Luca Simoni ◽  
Manuel Beschi ◽  
Antonio Visioli
Keyword(s):  
Degrees Of Freedom ◽  
Industrial Applications ◽  
Friction Model ◽  
Control Performance ◽  
Industrial Manipulator ◽  
Working Cycle ◽  
Proposed Model ◽  
Increasing Temperature ◽  
6 Degrees Of Freedom ◽  
Mechanical Transmissions

This article illustrates a model that describes the behaviour of power loss (friction) in mechanical transmissions. The model is applied to joints of an industrial manipulator, it is justified on the bases of preliminary observations of some robot behaviour and it is validated with an extensive experimentation on a commercial 6 degrees of freedom anthropomorphic manipulator. The paper shows that friction decreases with increasing temperature which in turn depends on the working cycle of the manipulator. The proposed model permits a prediction of the variation of the friction contribution during extensive working operations and it is suitable for industrial applications to improve the control performance or to predict the energy consumption.

scholarly journals Computationally Efficient Magnetic Position System Calibration

2020 ◽  
Vol 2 (1) ◽  
pp. 72
Author(s):  
Stefano Lumetti ◽  
Perla Malagò ◽  
Dietmar Spitzer ◽  
Sigmund Zaruba ◽  
Michael Ortner
Keyword(s):  
Degrees Of Freedom ◽  
Low Cost ◽  
Industrial Applications ◽  
Position System ◽  
Computationally Efficient ◽  
System Calibration ◽  
Practical Challenge ◽  
3D Printed ◽  
Cost Efficient ◽  
Orientation Systems

Properties such as high resolution, contactless (and thus wear-free) measurement, low power consumption, robustness against temperature and contamination as well as low cost make magnetic position and orientation systems appealing for a large number of industrial applications. Nevertheless, one major practical challenge is their sensitivity to fabrication tolerances. In this work, we propose a novel method for magnetic position system calibration based on the analytical computation of the magnetic field and on the application of an evolutionary optimization algorithm. This scheme enables the calibration of more than 10 degrees of freedom within a few seconds on standard quad-core ×86 processors, and is demonstrated by calibrating a highly cost-efficient 3D-printed 3-axis magnetic joystick.

scholarly journals A Methodology for Industrial Robot Calibration Based on Measurement Sub-Regions

2021 ◽  
Author(s):  
Juan Sebastian Toquica ◽  
José Maurı́cio Motta
Keyword(s):  
Industrial Robot ◽  
Low Cost ◽  
Kinematic Model ◽  
Measurement Data ◽  
Industrial Applications ◽  
Industrial Robots ◽  
Robot Calibration ◽  
High Precision Measurement ◽  
Measurement Systems ◽  
Robot Accuracy

Abstract This paper proposes a methodology for calibration of industrial robots that uses a concept of measurement sub-regions, allowing low-cost solutions and easy implementation to meet the robot accuracy requirements in industrial applications. The solutions to increasing the accuracy of robots today have high-cost implementation, making calibration throughout the workplace in industry a difficult and unlikely task. Thus, reducing the time spent and the measured workspace volume of the robot end-effector are the main benefits of the implementation of the sub-region concept, ensuring sufficient flexibility in the measurement step of robot calibration procedures. The main contribution of this article is the proposal and discussion of a methodology to calibrate robots using several small measurement sub-regions and gathering the measurement data in a way equivalent to the measurements made in large volume regions, making feasible the use of high-precision measurement systems but limited to small volumes, such as vision-based measurement systems. The robot calibration procedures were simulated according to the literature, such that results from simulation are free from errors due to experimental setups as to isolate the benefits of the measurement proposal methodology. In addition, a method to validate the analytical off-line kinematic model of industrial robots is proposed using the nominal model of the robot supplier incorporated into its controller.

Robotized Montage Unit which Uses an Anthropomorphic Gripper with Five Fingers: CAD Modelling and Simulation

2014 ◽  
Vol 656 ◽  
pp. 146-153
Author(s):  
Sebastian Jitariu ◽  
Ionel Staretu ◽  
Catalin Moldovan
Keyword(s):  
Degrees Of Freedom ◽  
Simple Structure ◽  
Industrial Robot ◽  
Low Cost ◽  
Human Hand ◽  
Correct Operation ◽  
Virtual Interface ◽  
Functional Simulation ◽  
Cad Modelling ◽  
Real Robot

This paper presents an original integrated solution of montage robotization of assemblies of small and medium complexity. The robotic station (the robotized cell) proposed contains a joint industrial robot equipped with an anthropomorphic gripper with five fingers, two feeders, a montage table and a storage terminal. CAD modelling of the whole system and functional simulation are performed, which certifies the validity of its correct operation. The gripper used is anthropomorphic with five fingers and five degrees of freedom with a relatively simple structure but high functionality. The gripper, adapted by a popular variant is realized as prototype at low cost, through rapid prototyping, and tested. The gripper control is possible through the advanced method of human hand gestures capture with a Motion Leap device and their transmission through a virtual interface to the real gripper. In perspective, it is considered mounting the gripper in an improved variant, on a real robot and testing the operation of the proposed montage scenario.

scholarly journals Design and Performance of a XBee 900 MHz Acquisition System Aimed at Industrial Applications

2021 ◽  
Vol 11 (17) ◽  
pp. 8174
Author(s):  
Isidro Calvo ◽  
José Miguel Gil-García ◽  
Eneko Villar ◽  
Aitor Fernández ◽  
Javier Velasco ◽  
...  
Keyword(s):  
Low Cost ◽  
Experimental Tests ◽  
Industrial Applications ◽  
Cloud Services ◽  
Acquisition System ◽  
Media Access ◽  
Wireless Technologies ◽  
Industrial Environments ◽  
And Performance ◽  
Time Critical

Wireless technologies are being introduced in industrial applications since they provide certain benefits, such as the flexibility to modify the layout of the nodes, improving connectivity with monitoring and decision nodes, adapting to mobile devices and reducing or eliminating cabling. However, companies are still reluctant to use them in time-critical applications, and consequently, more research is needed in order to be massively deployed in industrial environments. This paper goes in this direction by presenting a novel wireless acquisition system aimed at industrial applications. This system embeds a low-cost technology, such as XBee, not frequently considered for deterministic applications, for deploying industrial applications that must fulfill certain QoS requirements. The use of XBee 900 MHz modules allows for the use of the 2.4 GHz band for other purposes, such as connecting to cloud services, without causing interferences with critical applications. The system implements a time-slotted media access (TDMA) approach with a timely transmission scheduling of the messages on top of the XBee 900 MHz technology. The paper discusses the details of the acquisition system, including the topology, the nodes involved, the so-called coordinator node and smart measuring nodes, and the design of the frames. Smart measuring nodes are implemented by an original PCB which were specifically designed and manufactured. This board eases the connection of the sensors to the acquisition system. Experimental tests were carried out to validate the presented wireless acquisition system. Its applicability is shown in an industrial scenario for monitoring the positioning of an aeronautical reconfigurable tooling prototype. Both wired and wireless technologies were used to compare the variables monitored. The results proved that the followed approach may be an alternative for monitoring big machinery in indoor industrial environments, becoming especially suitable for acquiring values from sensors located in mobile parts or difficult-to-reach places.

scholarly journals Friction Model of Industrial Robot Joint with Temperature Correction by Example of KUKA KR10

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Maksim N. Nevmerzhitskiy ◽  
Boris S. Notkin ◽  
Andrey V. Vara ◽  
Konstantin V. Zmeu
Keyword(s):  
Experimental Study ◽  
Axial Load ◽  
Industrial Robot ◽  
Friction Model ◽  
Temperature Correction ◽  
Friction Torque ◽  
Temperature Factor ◽  
Industrial Robots ◽  
Temperature Fields

The quality of industrial robots essentially depends on the properties of their kinematic couples. This research has involved conducting an experimental study of the friction torque in a joint of the KUKA KR10 industrial robot and building its model. It has been established that the largest impact on friction in the joint is caused by its axial load and velocity, as well as the temperature of the mechanism, which is generally not homogeneous. It is not possible to measure temperature fields in the joints of a serial industrial robot directly. This study has set forth a method to estimate friction torque taking into account the temperature factor indirectly. For this, we have used the motor temperature available for measuring in combination with special periodical motions, performed by the robot, during which we estimated the actual friction torque in the joint and calculated a temperature correction based on our findings.

Improved Model for Conical Dielectric Elastomer Actuators With Fewer Electrical Connections

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Hector Medina ◽  
Carson W. Farmer
Keyword(s):  
Degrees Of Freedom ◽  
Experimental Tests ◽  
Dielectric Elastomer ◽  
Artificial Muscles ◽  
Multiple Degrees Of Freedom ◽  
Dielectric Elastomer Actuators ◽  
Proposed Model ◽  
Robotic Joints ◽  
Improved Model ◽  
Electrical Connections

Abstract Dielectric elastomers (DEs) exhibit remarkable properties that make them stand out among other electroactive polymers. Various types of actuators based on DEs have been used in applications that include artificial muscles, Braille displays, and robotic joints. In particular, conical dielectric elastomer actuators (CDEAs) are very attractive due to their multiple degrees of freedom (DOF) and easiness of construction. In this study, an energy method is used to derive an improved mathematical model for a double-cone dielectric elastomer actuator (DCDEA) capable of predicting horizontal and rotational displacements. To create the model, a new variable is introduced into the equations, the azimuth angle. In addition, a new pattern of electrodes is proposed as a method for achieving five DOF using only half of the electrode connections of traditional DCDEAs. Experimental tests are carried out and used to validate the proposed model. Results show very close agreement. A limiting aspect of the proposed model is that it relies on two experimental correction coefficients. Nonetheless, the model derived provides a means to more accurately implement automatic control to robotic systems that use DCDEAs (work in progress).

Torque control based direct teaching for industrial robot considering temperature-load effects on joint friction

2019 ◽  
Vol 46 (5) ◽  
pp. 699-710 ◽  
Author(s):  
Liming Gao ◽  
Jianjun Yuan ◽  
Yingjie Qian
Keyword(s):  
Teaching Method ◽  
Industrial Robot ◽  
Viscous Friction ◽  
Joint Space ◽  
Friction Model ◽  
Friction Torque ◽  
Torque Control ◽  
Content Type ◽  
Friction Resistance ◽  
Direct Teaching

Purpose The purpose of this paper is to design a practical direct teaching method for the industrial robot with large friction resistance and gravity torque but without expensive force/torque sensor, where the gravity torque is just a function of joints position, whereas the friction is closely associated with joint velocity, temperature and load. Design/methodology/approach In the teaching method, the output torque of joint motor is controlled through current to compensate gravity torque completely and friction resistance incompletely. Three variables closely associated with friction are investigated separately by experiment and theoretical analysis, and then a comprehensive friction model which is used to calculate the required compensated friction torque is proposed. Finally, a SIASUN 7 degrees of freedom robot was used to verify the model and the method. Findings Experimental results demonstrated that the teaching method enables an operator to teach the robot in joint space by applying small force and torque on either end-effector or its body. The friction investigation suggests that the velocity and temperature have a strong nonlinear influence on viscous friction, whereas load torque significantly influences the Coulomb friction linearly and causes a slight Stribeck effect. Originality/value The main contribution includes the following: a practical joint space direct teaching method for a common industrial robot is developed, and a friction model capturing velocity, temperature and load for robot joints equipped with commercialized motors and harmonic drives is proposed.

scholarly journals Development of Fused Deposition Modeling Using Five-Axis Machine and Printing Methods

2021 ◽  
Author(s):  
Haiguang zhang ◽  
Kunlong zhao ◽  
Di Liu ◽  
Qingxi Hu ◽  
Herfried Lammer
Keyword(s):  
Degrees Of Freedom ◽  
Fused Deposition Modeling ◽  
Low Cost ◽  
Industrial Applications ◽  
3D Printer ◽  
Lightweight Structures ◽  
Fused Deposition ◽  
3D Geometry ◽  
Deposition Modeling ◽  
Five Axis

Abstract Fused deposition modeling (FDM) is one of most widely used 3D printing technologies due to inexpensive equipment and materials, and easy to operate. FDM forms a 3D geometry by slicing a model along the XY-plane and assembling the resulting individual layers along the Z-axis, with extruded thermoplastic filaments. FDM printed parts usually need supporting structures, have stair step effect, and unfavorable mechanical properties. In order to address these deficiencies, a five-axis 3D printer and corresponding printing methods are proposed and developed in this paper. The 3D printer was designed five degrees of freedom through adding a platform that can rotate and swing. Based on the obtained results from different case studies, the discussed machine and methods could become more significant in industrial applications such as low cost, fabricating parts with better surface quality and lightweight structures.

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