scholarly journals MODELING AND INVESTIGATION OF THE REGULATOR WORKING IN THE POINTWISE SLIDING MODE

2021 ◽  
Vol 7 (5(41)) ◽  
pp. 3-5
Author(s):  
Asif Yusif-oqlu Gasimov ◽  
Afaq Tofiq Mammedova
Keyword(s):  
Equilibrium Point ◽  
High Frequency ◽  
Sliding Mode ◽  
Small Neighborhood ◽  
Control Signal ◽  
Main Disadvantage ◽  
Isolated Points ◽  
Frequency Variations

The main disadvantage of the classic sliding mode is that the control signal is made of high frequency variations. In the recommended pointwisesliding mode the frequency of the variations decreases, since the control signal makes jumps at the isolated points. At the same time, the trajectory remains in a small neighborhood of the plane of switching. In the finish mode, the trajectories that start over the sliding plane reach simultaneously the equilibrium point. It is possible to assume that these regulators will expand the implementation scope of the sliding (quazisliding) modes.

scholarly journals Delay compensation based controller for rotary electrohydraulic servo system

2021 ◽  
Author(s):  
Zakarya Omar ◽  
Xingsong Wang ◽  
Khalid Hussain ◽  
Mingxing Yang
Keyword(s):  
High Frequency ◽  
Dead Time ◽  
Sliding Mode ◽  
Servo System ◽  
Smith Predictor ◽  
Delay Compensation ◽  
Mechanical Parts ◽  
System Output ◽  
Electrohydraulic Servo System ◽  
The Stability

AbstractThe typical power-assisted hip exoskeleton utilizes rotary electrohydraulic actuator to carry out strength augmentation required by many tasks such as running, lifting loads and climbing up. Nevertheless, it is difficult to precisely control it due to the inherent nonlinearity and the large dead time occurring in the output. The presence of large dead time fires undesired fluctuation in the system output. Furthermore, the risk of damaging the mechanical parts of the actuator increases as these high-frequency underdamped oscillations surpass the natural frequency of the system. In addition, system closed-loop performance is degraded and the stability of the system is unenviably affected. In this work, a Sliding Mode Controller enhanced by a Smith predictor (SMC-SP) scheme that counts for the output delay and the inherent parameter nonlinearities is presented. SMC is utilized for its robustness against the uncertainty and nonlinearity of the servo system parameters whereas the Smith predictor alleviates the dead time of the system’s states. Experimental results show smoother response of the proposed scheme regardless of the amount of the existing dead time. The response trajectories of the proposed SMC-SP versus other control methods were compared for a different predefined dead time.

Dynamic Stability of a Water Brake Dynamometer

1998 ◽  
Vol 120 (1) ◽  
pp. 89-96 ◽  
Author(s):  
R. A. Van den Braembussche ◽  
H. Malys
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Lumped Parameter Model ◽  
Stable Operation ◽  
Pressure Oscillations ◽  
Lumped Parameter ◽  
Flow Oscillations ◽  
Brake Dynamometer ◽  
Low Torque ◽  
Frequency Variations

A lumped parameter model to predict the high frequency pressure oscillations observed in a water brake dynamometer is presented. It explains how the measured low frequency variations of the torque are a consequence of the variation in amplitude of the high frequency flow oscillations. Based on this model, geometrical modifications were defined, aiming to suppress the oscillations while maintaining mechanical integrity of the device. An experimental verification demonstrated the validity of the model and showed a very stable operation of the modified dynamometer even at very low torque.

scholarly journals Experimentally Validated Sliding Mode Control of Multi-rotor UAV with Control Signal Constraints

2020 ◽  
Vol 53 (2) ◽  
pp. 8860-8865
Author(s):  
Yuankang Zhu ◽  
Liuping Wang ◽  
Jyoti Mishra
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Control Signal ◽  
Mode Control

scholarly journals High frequency variations of the Earth's orbital parameters and climate change

2002 ◽  
Vol 29 (18) ◽  
pp. 40-1-40-4 ◽  
Author(s):  
C. Bertrand ◽  
M. F. Loutre ◽  
A. Berger
Keyword(s):  
Climate Change ◽  
High Frequency ◽  
Orbital Parameters ◽  
Frequency Variations

scholarly journals Frequency variations of gravity waves interacting with a time-varying tide

2013 ◽  
Vol 31 (10) ◽  
pp. 1731-1743 ◽  
Author(s):  
C. M. Huang ◽  
S. D. Zhang ◽  
F. Yi ◽  
K. M. Huang ◽  
Y. H. Zhang ◽  
...  
Keyword(s):  
Gravity Waves ◽  
High Frequency ◽  
Lower Atmosphere ◽  
Horizontal Wind ◽  
Frequency Variation ◽  
Time Varying ◽  
Transient Nature ◽  
Critical Layers ◽  
Favorable Conditions ◽  
Frequency Variations

Abstract. Using a nonlinear, 2-D time-dependent numerical model, we simulate the propagation of gravity waves (GWs) in a time-varying tide. Our simulations show that when a GW packet propagates in a time-varying tidal-wind environment, not only its intrinsic frequency but also its ground-based frequency would change significantly. The tidal horizontal-wind acceleration dominates the GW frequency variation. Positive (negative) accelerations induce frequency increases (decreases) with time. More interestingly, tidal-wind acceleration near the critical layers always causes the GW frequency to increase, which may partially explain the observations that high-frequency GW components are more dominant in the middle and upper atmosphere than in the lower atmosphere. The combination of the increased ground-based frequency of propagating GWs in a time-varying tidal-wind field and the transient nature of the critical layer induced by a time-varying tidal zonal wind creates favorable conditions for GWs to penetrate their originally expected critical layers. Consequently, GWs have an impact on the background atmosphere at much higher altitudes than expected, which indicates that the dynamical effects of tidal–GW interactions are more complicated than usually taken into account by GW parameterizations in global models.

scholarly journals High Frequency Variations of Earth Rotation Parameters from GPS and GLONASS Observations

Sensors ◽  
2015 ◽  
Vol 15 (2) ◽  
pp. 2944-2963 ◽  
Author(s):  
Erhu Wei ◽  
Shuanggen Jin ◽  
Lihua Wan ◽  
Wenjie Liu ◽  
Yali Yang ◽  
...  
Keyword(s):  
Earth Rotation ◽  
High Frequency ◽  
Earth Rotation Parameters ◽  
Rotation Parameters ◽  
Frequency Variations

Discrete-Time H-Infinity Synthesis of Frequency-Shaped Sliding Mode Control for Suppression of Vibration With Multiple Peak Frequencies

2016 ◽  
Author(s):  
Minghui Zheng ◽  
Masayoshi Tomizuka
Keyword(s):  
High Frequency ◽  
Sliding Mode ◽  
Disk Drive ◽  
Sliding Surface ◽  
Surface Dynamics ◽  
H Infinity ◽  
High Frequencies ◽  
Multiple Peak ◽  
Significant Performance ◽  
The Stability

Vibration with multiple large peaks at high frequencies may cause significant performance degradation and have become a major concern in modern high precision control systems. To deal with such high-frequency peaks, it is proposed to design a frequency-shaped sliding mode controller based on H∞ synthesis. It obtains an ‘optimal’ filter to shape the sliding surface, and thus provides frequency-dependent control allocation. The proposed frequency-shaping method assures the stability in the presence of multiple-peak vibration sources, and minimizes the weighted H∞ norm of the sliding surface dynamics. The evaluation is performed on a simulated hard disk drive with actual vibration sources from experiments, and the effectiveness of large vibration peak suppression is demonstrated.

scholarly journals Dynamic Modeling and Adaptive Robust Synchronous Control of Parallel Robotic Manipulator for Industrial Application

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-23
Author(s):  
Haiqiang Zhang ◽  
Hairong Fang ◽  
Qi Zou ◽  
Dan Zhang
Keyword(s):  
Trajectory Tracking ◽  
High Frequency ◽  
Parallel Manipulator ◽  
Sliding Mode ◽  
Virtual Work ◽  
Parallel Manipulators ◽  
Adaptive Robust Control ◽  
Lyapunov Theory ◽  
Synchronous Control ◽  
Effective Manner

Control of parallel manipulators is very hard due to their complex dynamic formulations. If part of the complexity is resulting from uncertainties, an effective manner for coping with these problems is adaptive robust control. In this paper, we proposed three types of adaptive robust synchronous controllers to solve the trajectory tracking problem for a redundantly actuated parallel manipulator. The inverse kinematic of the parallel manipulator was firstly developed, and the dynamic formulation was further derived by mean of the principle of virtual work. Furthermore, linear parameterization regression matrix was determined by virtue of command function “equationsToMatrix” in MATLAB. Secondly, the three adaptive robust synchronous controllers (i.e., sliding mode control, high gain control, and high frequency control) are developed, by incorporating the camera sensor technique into adaptive robust synchronous control architecture. The stability of the proposed controllers was proved by utilizing Lyapunov theory. A sequence of simulation tests were implemented to prove the performance of the controllers presented in this paper. The three proposed controllers can theoretically guarantee the errors including trajectory tracking errors, synchronization errors, and cross-coupling errors asymptotically converge to zero for a given trajectory, and the estimated unknown parameters can also approximately converge to their actual values in the presence of unmodeled dynamics and external uncertainties. Moreover, all the simulation comparative results were presented to illustrate that the adaptive robust synchronous high-frequency controller possess a much superior comprehensive performance than two other controllers.

scholarly journals Vibration Reduction of the Nonlinearly Tufted Carpet Yarn by a Modified Sliding Mode Control Method

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Shuang Huang ◽  
Xin Wu ◽  
Peixing Li
Keyword(s):  
Sliding Mode Control ◽  
High Frequency ◽  
Control Algorithm ◽  
Control Method ◽  
Sliding Mode ◽  
Control Law ◽  
Control Force ◽  
Fuzzy Sliding Mode Control ◽  
Mode Control ◽  
Fuzzy Sliding Mode

The yarn vibration causes the yarn tension value to fluctuate, causing a change in the amount of yarn feed, thus causing a deviation of the carpet pile height from the predetermined value. To solve this problem, the sliding mode control algorithm is used to design the sliding mode function and the sliding mode control law. And four variables in the yarn vibration system are controlled by the MATLAB software. For solving the chattering problem of the control law, the sliding mode control law is improved. The fuzzy sliding mode control algorithm based on the quasisliding mode is adopted. The results show that the sliding mode control algorithm is effective, but the sliding mode control force needs to be switched at high frequency and there is severe chattering. The fuzzy sliding mode control algorithm based on quasisliding mode is adopted to achieve better control effect with a smaller force. In addition, the control force does not have high-frequency switching, and the change is relatively stable, which reduces the chattering phenomenon of sliding mode control.

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