scholarly journals PID electro-hydraulic cylinder force tracking system with friction compensation

2018 ◽  
Vol 192 ◽  
pp. 02019 ◽  
Author(s):  
Weerapong Chanbua ◽  
Unnat Pinsopon
Keyword(s):  
Tracking System ◽  
Tracking Error ◽  
Estimation Procedure ◽  
Hydraulic Cylinder ◽  
Friction Model ◽  
Average Error ◽  
Friction Compensation ◽  
Velocity Signal ◽  
Lugre Friction Model ◽  
Force Tracking

Friction can be found in all mechanical systems, and is the cause of control tracking error. In this article, LuGre friction model for symmetric hydraulic cylinder was studied and obtained experimentally. The estimated friction force was applied for reference force compensation. Force tracking performances of PID force control systems with and without friction compensation were tested and compared. Control system with friction compensation outperformed one without in all cases of tracking tests. The best result was found in the square force tracking tests, with an average error at maximum compression force of 86.105 N in the case of with friction compensation compared with error of 511.996 N in the case without. However, the estimated friction achieved in the study was noisy. This is due to the use of noisy numerically differentiated velocity signal in the friction estimation procedure.

scholarly journals Research on Adaptive Friction Compensation of Digital Hydraulic Cylinder Based on LuGre Friction Model

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Shouling Jiang ◽  
Kun Zhang ◽  
Hui Wang ◽  
Donghu Zhong ◽  
Jinpeng Su ◽  
...  
Keyword(s):  
Control Method ◽  
Dead Zone ◽  
Hydraulic Cylinder ◽  
Friction Model ◽  
Friction Compensation ◽  
State Variables ◽  
Lugre Friction Model ◽  
Overall Performance ◽  
Lugre Friction ◽  
Adaptive Ability

This paper aims to eliminate nonlinear friction from the performance of the digital hydraulic cylinder to enable it to have good adaptive ability. First, a mathematical model of a digital hydraulic cylinder based on the LuGre friction model was established, and then a dual-observer structure was designed to estimate the unobservable state variables in the friction model. The Lyapunov method is used to prove the global asymptotic stability of the closed-loop system using the adaptive friction compensation method. Finally, Simulink is used to simulate the system performance. The simulation results indicate that the addition of adaptive friction compensation control can effectively reduce system static error, suppress system limit loop oscillation, “position decapitation,” “speed dead zone,” and low-speed creep phenomena, and improve the overall performance of the digital hydraulic cylinder. The control method has practical application value for improving the performance index of the digital hydraulic cylinder.

scholarly journals Friction compensation using Coulomb friction model with zero velocity crossing estimator for a force controlled model in the loop suspension test rig

2015 ◽  
Vol 230 (12) ◽  
pp. 2028-2045 ◽  
Author(s):  
Pooh Eamcharoenying ◽  
Andy Hillis ◽  
Jos Darling
Keyword(s):  
Coulomb Friction ◽  
Tracking Error ◽  
Force Sensor ◽  
Friction Model ◽  
Friction Compensation ◽  
Test Rig ◽  
Zero Crossing ◽  
Force Tracking ◽  
Coulomb Friction Model ◽  
Suspension Test

This paper presents a method of friction compensation for a linear electric motor in a model in the loop suspension test rig. The suspension consists of a numerically modeled spring and damper, with inputs of suspension motion. The linear motor is force controlled using a force sensor to track the output of the numerical model. The method uses a Coulomb friction model and applies a feedforward step signal when velocity zero crossing occurs. Velocity zero crossing estimation is achieved using an algorithm based on measured feedback velocity and force. Experimental results indicate reduction of force tracking error caused by Coulomb friction leading to improved test rig accuracy.

High Performance Adaptive Control of Mechanical Servo System With LuGre Friction Model: Identification and Compensation

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Xingjian Wang ◽  
Shaoping Wang
Keyword(s):  
Adaptive Control ◽  
Parameter Identification ◽  
Control Algorithm ◽  
Servo System ◽  
Friction Model ◽  
Friction Compensation ◽  
Lugre Friction Model ◽  
Identification Technique ◽  
Lugre Friction ◽  
Adaptive Control Algorithm

LuGre dynamic friction model has been widely used in servo system for friction compensation, but it increases the difficulty of controller design because its parameters are difficult to be identified and its internal state is immeasurable. This paper presents a parameter identification technique based on novel evolutionary algorithm (NEA) for LuGre friction model. In order to settle the practical digital implementation problem of LuGre model, this paper also proposes a modified dual-observer with discontinuous mapping and smooth transfer function. On the basis of the parameter identification results and the modified dual-observer, this paper designs an adaptive control algorithm with dynamic friction compensation for hydraulic servo system. The comparative experiments indicate that the proposed parameter identification technique and the adaptive control algorithm with modified dual-observer are effective with high tracking performance.

Adaptive Trajectory Control and Dynamic Friction Compensation for a Flexible-Link Robot

2010 ◽  
Vol 26 (2) ◽  
pp. 205-217 ◽  
Author(s):  
Vahid Erfanian ◽  
Mansour Kabganian
Keyword(s):  
Internal State ◽  
Friction Model ◽  
Distributed Parameter ◽  
Friction Compensation ◽  
Flexible Link ◽  
Lugre Friction Model ◽  
Control Schemes ◽  
Vibration Attenuation ◽  
Different Types ◽  
Lugre Friction

AbstractFriction compensation techniques are studied for control of a flexible-link robot based on the LuGre friction model. To overcome the problem of uncertain parameters in the friction model, adaptive control schemes are used for two different types of parametric uncertainties. A novel dual-observer technique is proposed to estimate the internal state inside the friction model. A distributed-parameter dynamic model is used for the flexible arm to design the controllers. The Lyapunov stability theorem is used to guarantee the global asymptotic stability of the controllers. The performance of position tracking and link vibration attenuation is verified through experimental results. The results also confirm the effectiveness of the proposed friction compensation schemes.

scholarly journals Quantitative Assessment Method of Force Tracking Capabilities for Detection of Motor Intentional Disorders

2021 ◽  
Vol 11 (7) ◽  
pp. 3244
Author(s):  
Kihyo Jung ◽  
Byung Hwa Lee ◽  
Sang Won Seo ◽  
Doo Sang Yoon ◽  
Baekhee Lee ◽  
...  
Keyword(s):  
Force Control ◽  
Tracking System ◽  
Tracking Error ◽  
Assessment Method ◽  
Control Measures ◽  
Control Group ◽  
Force Tracking ◽  
Patient Groups ◽  
Action Intention ◽  
The Brain

Early detection of motor intentional disorders associated with dysfunction in the action–intention system of the brain is clinically important to provide timely intervention. This study developed a force tracking system that can record forces exerted by the index finger while tracking 5 N, 10 N, 15 N, and 20 N of target forces varying over time. The force tracking system quantified force control measures (initiation time IT; development time, DT, maintenance error, ME; termination time, TT; tracking error, TE) for the individual and overall force control phases. This study evaluated the effectiveness of the force tracking system for a normal control group (n = 12) and two patient groups diagnosed with subcortical vascular mild cognitive impairment (svMCI, n = 11) and subcortical vascular dementia (SVaD, n = 13). Patients with SVaD showed significantly worse force control capabilities in IT (0.84 s) and ME (1.71 N) than those with svMCI (0.64 s in IT, and 1.38 N in ME). Patients with svMCI had significantly worse capabilities in IT, ME, and TE (3.80 N) than the control group (0.49 s in IT, 0.78 N in ME, and 3.07 N in TE). The prevalence rates of force control capabilities lower than the 99% confidence interval of the control group ranged from 17% to 62% for the two patient groups. The force tracking system can sensitively quantify the severity of the force control deficiencies caused by dysfunction in the action–intention system of the brain.

Studying noise immunity of radio information transmission systems with noise-like phase-shift keyed signals and synchronization delay errors

2019 ◽  
pp. 105-113
Author(s):  
G. N. Maltsev ◽  
A. V. Evteev
Keyword(s):  
Phase Shift ◽  
Information Transmission ◽  
Noise Immunity ◽  
Tracking System ◽  
Tracking Error ◽  
Information Symbol ◽  
Transmission Systems ◽  
Synchronization System ◽  
Correlation Receiver ◽  
Selection Of

Introduction: Radio information transmission systems with noise-like phase-shift keyed signals based on pseudo-random sequences have potential noise immunity provided by accurately tracking the delay of the received signal in the correlation receiver. When working with moving objects, the delay of the received signal varies continuously, and the reception quality for noise-like phase-shifted signals highly depends on the synchronization system operation and on the accuracy of estimating the received signal delay by the tracking system. To ensure the required signal reception quality, it is necessary to provide an informed choice of tracking system parameters, taking into account their effects, which are the random and systematic components of the delay tracking error, on the selected noise immunity indicator.Purpose: Analyzing how the errors in tracking the delay of a received phase-shift keyed signal based on a pseudorandom sequence by the synchronization system of a radio information transmission system can affect the probability of erroneous reception of an information symbol.Results: The calculation method was used to obtain families of dependencies of the probability of erroneous reception of an information symbol on the signal-noise ratio (SNR), and the values of the random and systematic components of the delay tracking error which are normalized to the capture band of the correlation receiver. It has been shown that at a fixed SNR, the values of the random and systematic components of the delay tracking error are critical for the erroneous reception probability. In all the cases discussed, all the dependencies are characterized by a slow change of the erroneous reception probability while the synchronization errors within the area of small SNR have fixed values. As the SNR value grows, the erroneous reception probability rapidly drops. To ensure the specified signal reception quality and the reliability of the selection of information symbols and messages in a radio information transmission system with noise-like phase-manipulated signals, its synchronization system requires a joint selection of the tracking system parameters, taking into account the limitations imposed by the operating conditions and technical implementation features.Practical relevance: The obtained results can be used in noise immunity analysis of radio information transmission systems with noise-like phase-shift keyed signals in a wide range of communication conditions, and in providing technical solutions for synchronization systems ensuring the required quality of signal reception.

scholarly journals Robot-assisted Ultrasound-guided Tracking of Anatomical Structures for the Application of Focused Ultrasound

2020 ◽  
Vol 6 (3) ◽  
pp. 123-126
Author(s):  
Michael Unger ◽  
Johann Berger ◽  
Bjoern Gerold ◽  
Andreas Melzer
Keyword(s):  
Focused Ultrasound ◽  
Varicose Veins ◽  
Tracking System ◽  
Tracking Error ◽  
Uterine Fibroids ◽  
High Intensity Focused Ultrasound ◽  
Robot Assisted ◽  
Anatomical Structures ◽  
Surgical Tool ◽  
Custom Made

AbstractHigh intensity focused ultrasound is used as a surgical tool to treat completely non-invasively several diseases. Examples of clinical applications are uterine fibroids, prostate cancer, thyroid nodules, and varicose veins. Precise targeting is key for improving the treatment outcome. A method for an automated, robot-assisted tracking system was developed and evaluated. A wireless ultrasound scanner was used to acquire images of the target, in this case, a blood vessel. The active contour approach by Chan and Vese was used to segment and track while moving the scanner along the target structure with a collaborative robotic arm. The performance was assessed using a custom made Agar phantom. The mean tracking error, which is defined as the remaining distance of the lesion to the images’ centre line, was 0.27 mm ± 0.18 mm.

scholarly journals Asymmetric and chaotic responses of dry friction oscillators with different static and kinetic coefficients of friction

Meccanica ◽  
2021 ◽  
Author(s):  
Gábor Csernák ◽  
Gábor Licskó
Keyword(s):  
Dry Friction ◽  
Continuation Method ◽  
Friction Model ◽  
Lugre Friction Model ◽  
Kinetic Coefficients ◽  
Friction Oscillator ◽  
Lugre Friction ◽  
Friction Parameters ◽  
Two Parameter ◽  
Parameter Bifurcation

AbstractThe responses of a simple harmonically excited dry friction oscillator are analysed in the case when the coefficients of static and kinetic coefficients of friction are different. One- and two-parameter bifurcation curves are determined at suitable parameters by continuation method and the largest Lyapunov exponents of the obtained solutions are estimated. It is shown that chaotic solutions can occur in broad parameter domains—even at realistic friction parameters—that are tightly enclosed by well-defined two-parameter bifurcation curves. The performed analysis also reveals that chaotic trajectories are bifurcating from special asymmetric solutions. To check the robustness of the qualitative results, characteristic bifurcation branches of two slightly modified oscillators are also determined: one with a higher harmonic in the excitation, and another one where Coulomb friction is exchanged by a corresponding LuGre friction model. The qualitative agreement of the diagrams supports the validity of the results.

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