Sliding motion on the intersection of two manifolds: Spirally attractive case

The combination of sliding/rolling motion can influence the degree of precision degradation of ball screw. Precision degradation modeling and factors analysis can reveal the evolution law of ball screw precision. This paper presents a precision degradation model for factors analysis influencing precision due to mixed sliding-rolling motion. The precision loss model was verified through the comparison of theoretical models and experimental tests. The precision degradation due to rolling motion between the ball and raceway accounted for 29.09% of the screw precision loss due to sliding motion. Additionally, the total precision degradation due to rolling motion accounted for 21.03% of the total sliding precision loss of the screw and nut, and 17.38% of the overall ball screw precision loss under mixed sliding-rolling motion. In addition, the effects of operating conditions and structural parameters on precision loss were analyzed. The sensitivity coefficients of factors influencing were used to quantitatively describe impact degree on precision degradation.

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Zero-Width Quasi-Sliding Mode Band in the Presence of Non-Matched Uncertainties

Energies ◽

10.3390/en14113011 ◽

2021 ◽

Vol 14 (11) ◽

pp. 3011

Author(s):

Paweł Latosiński ◽

Andrzej Bartoszewicz

Keyword(s):

Sliding Mode Control ◽

Discrete Time ◽

Sliding Mode ◽

Control Strategies ◽

Relative Degree ◽

Band Width ◽

Representative Point ◽

Mode Control ◽

Sliding Motion ◽

Selection Of

Sliding mode control strategies are well known for ensuring robustness of the system with respect to disturbance and model uncertainties. For continuous-time plants, they achieve this property by confining the system state to a particular hyperplane in the state space. Contrary to this, discrete-time sliding mode control (DSMC) strategies only drive the system representative point to a certain vicinity of that hyperplane. In established literature on DSMC, the width of this vicinity has always been strictly greater than zero in the presence of uncertainties. Thus, ideal sliding motion was considered impossible for discrete-time systems. In this paper, a new approach to DSMC design is presented with the aim of driving the system representative point exactly onto the sliding hyperplane even in the presence of uncertainties. As a result, the quasi-sliding mode band width is effectively reduced to zero and ideal discrete-time sliding motion is ensured. This is achieved with the proper selection of the sliding hyperplane, using the unique properties of relative degree two sliding variables. It is further demonstrated that, even in cases where selection of a relative degree two sliding variable is impossible, one can use the proposed technique to significantly reduce the quasi-sliding mode band width.

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Friction and Wear Behaviors of Steel Ball Against Polyimide-PTFE Composite Under Rolling-Sliding Motion

Tribology Letters ◽

10.1007/s11249-021-01476-0 ◽

2021 ◽

Vol 69 (3) ◽

Author(s):

Yuanyuan Jiang ◽

Lei Chen ◽

Chen Xiao ◽

Ningning Zhou ◽

Tao Qing ◽

...

Keyword(s):

Friction And Wear ◽

Steel Ball ◽

Ptfe Composite ◽

Sliding Motion

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Detecting the Absence of Lung Sliding in Lung Ultrasounds Using Deep Learning

Applied Sciences ◽

10.3390/app11156976 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6976

Author(s):

Miroslav Jaščur ◽

Marek Bundzel ◽

Marek Malík ◽

Anton Dzian ◽

Norbert Ferenčík ◽

...

Keyword(s):

Neural Network ◽

Deep Learning ◽

Lung Ultrasound ◽

Video Recording ◽

X Rays ◽

Surgery Complications ◽

Temporal Dimension ◽

Sliding Motion ◽

Post Surgery ◽

Lung Sliding

Certain post-thoracic surgery complications are monitored in a standard manner using methods that employ ionising radiation. A need to automatise the diagnostic procedure has now arisen following the clinical trial of a novel lung ultrasound examination procedure that can replace X-rays. Deep learning was used as a powerful tool for lung ultrasound analysis. We present a novel deep-learning method, automated M-mode classification, to detect the absence of lung sliding motion in lung ultrasound. Automated M-mode classification leverages semantic segmentation to select 2D slices across the temporal dimension of the video recording. These 2D slices are the input for a convolutional neural network, and the output of the neural network indicates the presence or absence of lung sliding in the given time slot. We aggregate the partial predictions over the entire video recording to determine whether the subject has developed post-surgery complications. With a 64-frame version of this architecture, we detected lung sliding on average with a balanced accuracy of 89%, sensitivity of 82%, and specificity of 92%. Automated M-mode classification is suitable for lung sliding detection from clinical lung ultrasound videos. Furthermore, in lung ultrasound videos, we recommend using time windows between 0.53 and 2.13 s for the classification of lung sliding motion followed by aggregation.

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Reaching Law Based Sliding Mode Control of Sampled Time Systems

Energies ◽

10.3390/en14071882 ◽

2021 ◽

Vol 14 (7) ◽

pp. 1882

Author(s):

Piotr Leśniewski ◽

Andrzej Bartoszewicz

Keyword(s):

Sliding Mode Control ◽

Discrete Time ◽

Sliding Mode ◽

Rate Of Change ◽

Reaching Law ◽

Mode Control ◽

Sliding Motion ◽

Control Precision ◽

Continuous Time Systems ◽

Time Systems

In this paper, discrete time reaching law-based sliding mode control of continuous time systems is considered. In sliding mode control methods, usually the assumption of bounded absolute values of disturbances is used. However in many cases, the rate of change of the disturbance is also bounded. In the presented approach, this knowledge is used to improve the control precision and reduce the undesirable chattering. Another advantage of the proposed method is that the disturbance does not have to satisfy the matching conditions. In the paper two new reaching laws are analyzed, one of them ensures the switching quasi-sliding motion and the other the non-switching motion. For both of them, the robustness is assessed by calculating the quasi-sliding mode band width, as well as the greatest possible state error values. Specifically, the state errors are not considered only at the sampling instants, as is usual for discrete time systems, but the bounds on the continuous values “between” the sampling instants are also derived. Then, the proposed approaches are compared and analyzed with respect to energy expenditure of the control signal.

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Stabilization of networked switched affine systems with event-triggered strategy

Transactions of the Institute of Measurement and Control ◽

10.1177/01423312211021304 ◽

2021 ◽

pp. 014233122110213

Author(s):

Dandan Li ◽

Zhiqiang Zuo ◽

Yijing Wang

Keyword(s):

Affine Systems ◽

Switching Law ◽

Event Time ◽

Sliding Motion ◽

State Dependent ◽

Event Triggering ◽

Stability Issue ◽

The Stability ◽

Event Based ◽

Selection Of

Using an event-based switching law, we address the stability issue for continuous-time switched affine systems in the network environment. The state-dependent switching law in terms of the region function is firstly developed. We combine the region function with the event-triggering mechanism to construct the switching law. This can provide more candidates for the selection of the next activated subsystem at each switching instant. As a result, it is possible for us to activate the appropriate subsystem to avoid the sliding motion. The Zeno behavior for the switched affine system can be naturally ruled out by guaranteeing a positive minimum inter-event time between two consecutive executions of the event-triggering threshold. Finally, two numerical examples are given to demonstrate the effectiveness of the proposed method.

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Sliding Motion of Magnetizable Beads Coated with Chara Motor Protein in a Magnetic Field

Journal of the Physical Society of Japan ◽

10.1143/jpsj.67.345 ◽

1998 ◽

Vol 67 (1) ◽

pp. 345-350 ◽

Cited By ~ 7

Author(s):

Go Uchida ◽

Yuuki Mizukami ◽

Tomomi Nemoto ◽

Yoshimi Tsuchiya

Keyword(s):

Magnetic Field ◽

Motor Protein ◽

Sliding Motion

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Control of Fractional-Order Systems Using Chatter-Free Sliding Mode Approach

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4025771 ◽

2014 ◽

Vol 9 (3) ◽

Cited By ~ 20

Author(s):

Mohammad Pourmahmood Aghababa

Keyword(s):

Fractional Derivative ◽

Sliding Mode ◽

Variable Structure ◽

Stability And Convergence ◽

Control Input ◽

Fractional Systems ◽

Sliding Motion ◽

Efficient Performance ◽

Sliding Manifold ◽

Chattering Free

The problem of stabilization of nonlinear fractional systems in spite of system uncertainties is investigated in this paper. First, a proper fractional derivative type sliding manifold with desired stability and convergence properties is designed. Then, the fractional stability theory is adopted to derive a robust sliding control law to force the system trajectories to attain the proposed sliding manifold and remain on it evermore. The existence of the sliding motion is mathematically proven. Furthermore, the sign function in the control input, which is responsible to the being of harmful chattering, is transferred into the fractional derivative of the control input. Therefore, the resulted control input becomes smooth and free of the chattering. Some numerical simulations are presented to illustrate the efficient performance of the proposed chattering-free fractional variable structure controller.

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