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.

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.

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 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.

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.

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.

The Influence of Heat Exchanges on Friction in Robotic Joints: Theoretical Modelling, Identification and Experiments

2020 ◽  
Author(s):  
Roberto Pagani ◽  
Giovanni Legnani ◽  
Giovanni Incerti ◽  
Manuel Beschi ◽  
Monica Tiboni
Keyword(s):  
Thermal Effects ◽  
Rotation Speed ◽  
Industrial Robot ◽  
Experimental Tests ◽  
Theoretical Modelling ◽  
Degree Polynomial ◽  
Identification Procedure ◽  
Good Reliability ◽  
Robotic Joints ◽  
Heat Exchanges

Abstract This paper presents a model that describes the effect of heat exchange on dynamic friction in the joints of an industrial robot. As concern the modeling of friction as a function of the rotation speed of the joint, a third degree polynomial is used. The coefficients of the polynomial, which depends on the temperature, are estimated by means of a suitable identification procedure. The proposed technique is simple to implement and economically convenient. Experimental tests have shown that the method here proposed, despite its simplicity, can estimate with good reliability the variations of friction that occur during the operation of an industrial robot due to thermal effects. Possible fields of application are the improvement of the friction compensation algorithms used for robot control systems and the prediction of energy consumption.

scholarly journals Passive Measurement of Three Optical Beacon Coordinates Using a Simultaneous Method

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5235
Author(s):  
Jiri Nemecek ◽  
Martin Polasek
Keyword(s):  
Mathematical Model ◽  
Relative Position ◽  
Experimental Tests ◽  
Image Sensor ◽  
Geometric Parameters ◽  
Light Sources ◽  
Feature Points ◽  
Passive Measurement ◽  
The Mathematical Model ◽  
Physical Principles

Among other things, passive methods based on the processing of images of feature points or beacons captured by an image sensor are used to measure the relative position of objects. At least two cameras usually have to be used to obtain the required information, or the cameras are combined with other sensors working on different physical principles. This paper describes the principle of passively measuring three position coordinates of an optical beacon using a simultaneous method and presents the results of corresponding experimental tests. The beacon is represented by an artificial geometric structure, consisting of several semiconductor light sources. The sources are suitably arranged to allow, all from one camera, passive measurement of the distance, two position angles, the azimuth, and the beacon elevation. The mathematical model of this method consists of working equations containing measured coordinates, geometric parameters of the beacon, and geometric parameters of the beacon image captured by the camera. All the results of these experimental tests are presented.

scholarly journals Remote Reflectivity Sensor for Industrial Applications

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1301
Author(s):  
Federico Cavedo ◽  
Parisa Esmaili ◽  
Michele Norgia
Keyword(s):  
Low Cost ◽  
Cost Effective ◽  
Industrial Applications ◽  
Interference Immunity ◽  
Surface Reflection ◽  
Measurement Systems ◽  
Digital Detector ◽  
Reflected Light ◽  
Surface Optical ◽  
Diffused Light

A low-cost optical reflectivity sensor is proposed in this paper, able to detect the presence of objects or surface optical properties variations, at a distance of up to 20 m. A collimated laser beam is pulsed at 10 kHz, and a synchronous digital detector coherently measures the back-diffused light collected through a 1-inch biconvex lens. The sensor is a cost-effective solution for punctual measurement of the surface reflection at different distances. To enhance the interference immunity, an algorithm based on a double-side digital baseline restorer is proposed and implemented to accurately detect the amplitude of the reflected light. As results show, the sensor is robust against ambient light and shows a strong sensitivity on a wide reflection range. The capability of the proposed sensor was evaluated experimentally for object detection and recognition, in addition to dedicated measurement systems, like remote encoders or keyphasors, realized far from the object to be measured.

scholarly journals Deconstruction of Lignin: From Enzymes to Microorganisms

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2299
Author(s):  
Jéssica P. Silva ◽  
Alonso R. P. Ticona ◽  
Pedro R. V. Hamann ◽  
Betania F. Quirino ◽  
Eliane F. Noronha
Keyword(s):  
Microbial Communities ◽  
Metabolic Pathways ◽  
Low Cost ◽  
Direct Analysis ◽  
Industrial Applications ◽  
Natural Environments ◽  
Lignocellulosic Residues ◽  
Complementary Techniques ◽  
Plant Polymer ◽  
Powerful Strategy

Lignocellulosic residues are low-cost abundant feedstocks that can be used for industrial applications. However, their recalcitrance currently makes lignocellulose use limited. In natural environments, microbial communities can completely deconstruct lignocellulose by synergistic action of a set of enzymes and proteins. Microbial degradation of lignin by fungi, important lignin degraders in nature, has been intensively studied. More recently, bacteria have also been described as able to break down lignin, and to have a central role in recycling this plant polymer. Nevertheless, bacterial deconstruction of lignin has not been fully elucidated yet. Direct analysis of environmental samples using metagenomics, metatranscriptomics, and metaproteomics approaches is a powerful strategy to describe/discover enzymes, metabolic pathways, and microorganisms involved in lignin breakdown. Indeed, the use of these complementary techniques leads to a better understanding of the composition, function, and dynamics of microbial communities involved in lignin deconstruction. We focus on omics approaches and their contribution to the discovery of new enzymes and reactions that impact the development of lignin-based bioprocesses.

Sign in / Sign up

Export Citation Format

Share Document