scholarly journals Perturbation Stability of Frictional Sliding With Varying Normal Force

1996 ◽  
Vol 118 (3) ◽  
pp. 491-497 ◽  
Author(s):  
P. E. Dupont ◽  
D. Bapna
Keyword(s):  
Machine Tools ◽  
Constant Velocity ◽  
Normal Force ◽  
Steady Motion ◽  
Domain Of Attraction ◽  
Critical Value ◽  
Tangential Displacement ◽  
Control Input ◽  
State Variables ◽  
Friction Dampers

In many systems, the normal force at friction contacts is not constant, but is instead a function of the system’s state variables. Examples include machine tools, friction dampers, brake systems and robotic contact with the environment. Friction at these contacts has been shown to possess dynamics associated with changes in normal force. In an earlier paper, the authors derived a critical value of system stiffness for stability based on a linearized analysis of constant velocity sliding (Dupont and Bapna, 1994). In this paper, the domain of attraction for the steady sliding equilibrium point is characterized for a system in which normal force is coupled to tangential displacement. Perturbations consisting of sudden changes in the displacement and velocity of the loading point are considered. These perturbations can be viewed as either actuator disturbances or changes in control input. The effect and interaction of the frictional and geometric parameters are elucidated. The results are applicable to the design and analysis of systems in which steady motion without friction-induced limit cycles is desired.

scholarly journals Application of Nadal Limit for the Prediction of Wheel Climb Derailment

2011 ◽  
Author(s):  
Brian Marquis ◽  
Robert Greif
Keyword(s):  
Alternative Explanation ◽  
Normal Force ◽  
Contact Point ◽  
Angle Of Attack ◽  
Steady Motion ◽  
Critical Value ◽  
Contact Forces ◽  
Creep Force ◽  
Rigid Body Mechanics ◽  
Tangential Friction

Application of the Nadal Limit to the prediction of wheel climb derailment is presented along with the effect of pertinent geometric and material parameters. Conditions which contribute to this climb include wheelset angle of attack, contact angle, friction and saturation surface properties, and lateral and vertical wheel loads. The Nadal limit is accurate for high angle of attack conditions, as the wheelset rolls forward in quasi-static steady motion leading to a flange climbing scenario. A detailed study is made of the effect of flange contact forces Ftan and N, the tangential friction force due to creep and the normal force, respectively. Both of these forces vary as a function of lateral load L. It is shown that until a critical value of L/V is reached, climb does not occur with increasing L since Ftan is saturated and the flange contact point slides down the rail. However, for a certain critical value of L/V (i.e. the Nadal limit) Ftan is about to drop below its saturated value and flange climb (rolling without sliding) up the rail occurs. Additionally, an alternative explanation of climb is given based on a comparison of force resultants in track and contact coordinates. The effects of longitudinal creep force Flong and angle of attack are also investigated. Using a saturated creep resultant based on both (Ftan, Flong) produces a climb prediction L/V larger (less conservative) than the Nadal limit. Additionally, for smaller angle of attack the standard Nadal assumption of Ftan = μN may lead to an overly conservative prediction for the onset of wheel climb. Finally, a useful analogy for investigating conditions for sliding and/or rolling of a wheelset is given from a study of a disk in rigid body mechanics.

DESIGN AND ANALYSIS OF SUPER TWISTING SLIDING MODE CONTROL FOR MACHINE TOOLS

2016 ◽  
Vol 78 (10-3) ◽  
Author(s):  
Chiew Tsung Heng ◽  
Zamberi Jamaludin ◽  
Ahmad Yusairi Bani Hashim ◽  
Nur Aidawaty Rafan ◽  
Lokman Abdullah ◽  
...  
Keyword(s):  
Machine Tools ◽  
Sliding Mode ◽  
Tracking Error ◽  
Control Algorithms ◽  
Sliding Mode Controller ◽  
Control Input ◽  
Positioning System ◽  
Direct Drive ◽  
Chattering Effect

High demands of precision on machine tools are hardly cope by using existing classic control algorithms. This paper focuses on the design, analysis and validation of a super twisting sliding mode controller on a single axis direct drive positioning system for improved tracking performances. The second order positioning system parameters were determined using input and output of measured data. Effects of two gain parameters in control algorithm on the quality of the control input and tracking error were analysed experimentally. The gain parameters were selected based on magnitude reduction in chattering during practical application. The performance of tuned super twisting sliding mode controller was compared with a traditional sliding mode controller using sigmoid-like function. Results showed that super twisting sliding mode controller reduced the chattering effect and improved the performance of system in terms of tracking error by 16.5%.  

Structural balance for discrete-time complex dynamical network associated with the controlled nodes

2020 ◽  
Vol 34 (10) ◽  
pp. 2050098
Author(s):  
Lizhi Liu ◽  
Yinhe Wang ◽  
Xiaoxiao Li ◽  
Zilin Gao
Keyword(s):  
Numerical Simulation ◽  
Discrete Time ◽  
Generation Mechanism ◽  
Control Input ◽  
State Variables ◽  
Complex Dynamical Network ◽  
Dynamic Coupling ◽  
Coupling Term ◽  
Structural Balance ◽  
Auxiliary Role

In this paper, the discrete-time complex dynamical networks with dynamic weighted value of connection relationships are regarded to be composed of the node and link subsystems, and the state variables of the two subsystems are mutually coupled. Different from most of the existing researches on synchronization or stabilization of nodes, the emphasis of this paper is on the links instead of nodes. This paper mainly focuses on the generation mechanism of structural balance in the link subsystem, the nodes only play an auxiliary role. Associated with the dynamic coupling term in the link subsystem, the suitable controller is proposed for node subsystem such that the structural balance of link subsystem without control input be achieved indirectly. Finally, a numerical simulation is given to show the effectiveness of the method in this paper.

IMM-UKF-TFS Model-based Approach for Intelligent Navigation

2013 ◽  
Vol 66 (6) ◽  
pp. 859-877 ◽  
Author(s):  
M. Malleswaran ◽  
V. Vaidehi ◽  
S. Irwin ◽  
B. Robin
Keyword(s):  
Kalman Filter ◽  
Constant Velocity ◽  
Unscented Kalman Filter ◽  
Interacting Multiple Model ◽  
Multiple Model ◽  
State Variables ◽  
Constant Acceleration ◽  
Positional Accuracy ◽  
Model Based ◽  
Novel Approach

This paper aims to introduce a novel approach named IMM-UKF-TFS (Interacting Multiple Model-Unscented Kalman Filter-Two Filter Smoother) to attain positional accuracy in the intelligent navigation of a manoeuvring vehicle. Here, the navigation filter is designed with an Unscented Kalman Filter (UKF), together with an Interacting Multiple Model algorithm (IMM), which estimates the state variables and handles the noise uncertainty of the manoeuvring vehicle. A model-based estimator named Two Filter Smoothing (TFS) is implemented along with the UKF-based IMM to improve positional accuracy. The performance of the proposed IMM-UKF-TFS method is verified by modelling the vehicle motion into Constant Velocity-Coordinated Turn (CV-CT), Constant Velocity – Constant Acceleration (CV-CA) and Constant Acceleration-Coordinated Turn (CA-CT) models. The simulation results proved that the proposed IMM-UKF-TFS gives better positional accuracy than the existing conventional estimators such as UKF and IMM-UKF.

Reduction of Quantization Error in Multirate Output Feedback Control

2016 ◽  
Vol 28 (5) ◽  
pp. 640-645
Author(s):  
Takao Sato ◽  
◽  
Hironobu Sakaguchi ◽  
Nozomu Araki ◽  
Yasuo Konishi
Keyword(s):  
Control System ◽  
Feedback Control ◽  
Output Feedback ◽  
Design Method ◽  
Output Feedback Control ◽  
Quantization Error ◽  
Design Parameters ◽  
Control Input ◽  
State Variables ◽  
Feedback Control System

[abstFig src='/00280005/04.jpg' width='250' text='Multirate output feedback control' ] In the new design method we propose for a multirate output feedback control system, the hold interval of control input is longer than the sampling interval of plant output. In this system, unknown state variables are calculated using control input and plant output without observers. The multirate output feedback control system has been extended by introducing new design parameters that are designed independent of the calculation of the state variable. To our knowledge, however, no systematic design scheme has ever been proposed for design parameters in this case. In this study, quantization error is dealt with statistically and design parameters are decided to minimize quantization error.

Robust Control of Automotive Active Seat-Suspension System Subject to Actuator Saturation

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Zhou Gu ◽  
Shumin Fei ◽  
Yaqin Zhao ◽  
Engang Tian
Keyword(s):  
Controller Design ◽  
Actuator Saturation ◽  
Input Saturation ◽  
Output Feedback Control ◽  
Suspension System ◽  
Linear Matrix ◽  
Control Input ◽  
State Variables ◽  
Sampled Data ◽  
Seat Suspension

This paper deals with the problem of robust sampled-data control for an automotive seat-suspension system subject to control input saturation. By using the nature of the sector nonlinearity, a sampled-data based control input saturation in the control design is studied. A passenger dynamic behavior is considered in the modeling of seat-suspension system, which makes the model more precisely and brings about uncertainties as well in the developed model. Robust output feedback control strategy is adopted since some state variables, such as, body acceleration and body deflection, are unavailable. The desired controller can be achieved by solving the corresponding linear matrix inequalities (LMIs). Finally, a design example has been given to demonstrate the effectiveness and advantages of the proposed controller design approach.

scholarly journals Sliding mode control of biogas production by anaerobic digestion with addition of acetate

2019 ◽  
Vol 93 ◽  
pp. 03002
Author(s):  
Plamena Zlateva
Keyword(s):  
Anaerobic Digestion ◽  
Sliding Mode Control ◽  
Expert Knowledge ◽  
Sliding Mode ◽  
Biogas Production ◽  
External Disturbance ◽  
Control Input ◽  
State Variables ◽  
Mode Control ◽  
And Control

Biogas production by anaerobic digestion with addition of acetate is considered. Sliding mode control for regulation of the biogas flow rate using the addition of acetate as a control action is proposed. The control design is carried out with direct use of nonlinear model and expert knowledge. Chattering phenomena are avoided by realizing the sliding mode with respect to the control input derivative. The state variables, external disturbance, process output and control input are varied in the known intervals. The performance of the designed sliding mode control is investigated by varying the process set point and the uncertain process parameter, which reflecting the influence of the external disturbance. The excellent performance of presented control is proved through simulation investigations in MATLAB using Simulink.

scholarly journals Tracking Control Strategy Using Filter-Based Approximation for the Unknown Control Direction Problem of Uncertain Pure-Feedback Nonlinear Systems

Mathematics ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 1341
Author(s):  
Yun Ho Choi ◽  
Sung Jin Yoo
Keyword(s):  
Controller Design ◽  
Tracking Error ◽  
Design Procedure ◽  
Control Input ◽  
State Variables ◽  
Feedback Systems ◽  
Unknown Control Directions ◽  
Unknown Control ◽  
Unknown Control Direction ◽  
Control Direction

A filter-based recursive tracker design approach is presented for the problem of unknown control directions of pure-feedback systems with completely unknown non-affine nonlinearities. In the controller design procedure, the first-order filters for error surfaces, a control input, and state variables are employed to design nonadaptive virtual and actual control laws independent of adaptive function approximators. In addition, for the unknown control direction problem, the filtering signals are incorporated with Nussbaum functions. Different from existing adaptive approximation-based control schemes in the presence of unknown control directions, the proposed approach does not require any adaptive technique regardless of completely unknown nonlinear functions. Therefore, a simplified tracking structure can be constructed. Using the Lyapunov stability analysis, it is shown that the tracking error is reduced within an adjustable neighborhood of the origin while ensuring all the closed-loop signals are bounded.

scholarly journals Adaptive Neural Control of Hypersonic Vehicles with Actuator Constraints

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Changxin Luo ◽  
Humin Lei ◽  
Dongyang Zhang ◽  
Xiaojun Zou
Keyword(s):  
Control Problem ◽  
Neural Control ◽  
Control Method ◽  
Input Saturation ◽  
Control Input ◽  
Input Constraints ◽  
State Variables ◽  
Control Effect ◽  
Adaptive Neural Control ◽  
Loop Control

An adaptive neural control method is proposed in this paper for the flexible air-breathing hypersonic vehicle (AHV) with constraints on actuators. This scheme firstly converts the original control problem with input constraints into a new control problem without input constraints based on the control input saturation function. Secondly, on the basis of the implicit function theorem, the radial basis function neural network (RBFNN) is introduced to approximate the uncertain items of the model. And the minimal-learning-parameter (MLP) technique is adopted to design the adaptive law for the norm of network weight vector, which significantly reduces calculations. Meanwhile, the finite-time convergence differentiator (FD) is introduced, through which the model state variables and their derivatives are accurately estimated to ensure the control effect. Finally, it is theoretically proved that the closed-loop control system is stable. And the effectiveness of the designed controller is verified by simulation.

Stability of a stratified fluid with a vertically moving sidewall

2008 ◽  
Vol 609 ◽  
pp. 305-317 ◽  
Author(s):  
FRANÇOIS BLANCHETTE ◽  
THOMAS PEACOCK ◽  
RÉMI COUSIN
Keyword(s):  
Boundary Layer ◽  
Experimental Study ◽  
Stability Analysis ◽  
Constant Velocity ◽  
Critical Value ◽  
Quantitative Agreement ◽  
Stratified Fluid ◽  
Boundary Effects ◽  
Layer Flow ◽  
The Stability

We present the results of a combined theoretical and experimental study of the stability of a uniformly stratified fluid bounded by a sidewall moving vertically with constant velocity. This arrangement is perhaps the simplest in which boundary effects can drive instability and, potentially, layering in a stratified fluid. Our investigations reveal that for a given stratification and diffusivity of the stratifying agent, the sidewall boundary-layer flow becomes linearly unstable when the wall velocity exceeds a critical value. The onset of instability is clearly observed in the experiments, and there is good quantitative agreement with some predictions of the linear stability analysis.

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