Research on design method of time-varying uncertainty of bolted connections

Axial piston pumps (APPs) are the core energy conversion components in a hydraulic transmission system. Energy conversion efficiency is critically important for the performance and energy-saving of the pumps. In this paper, a time-varying reliability design method for the overall efficiency of APPs was established. The theoretical and practical instantaneous torque and flow rate of the whole APP were derived through comprehensive analysis of a single piston-slipper group. Moreover, as a case study, the developed model for the instantaneous overall efficiency was verified with a PPV103-10 pump from HYDAC. The time-variation of reliability for the pump was revealed by a fourth-order moment technique considering the randomness of working conditions and structure parameters, and the proposed reliability method was validated by Monte Carlo simulation. The effects of the mean values and variance sensitivity of random variables on the overall efficiency reliability were analyzed. Furthermore, the optimized time point and design variables were selected. The optimal structure parameters were obtained to meet the reliability requirement and the sensitivity of design variables was significantly reduced through the reliability-based robust design. The proposed method provides a theoretical basis for designers to improve the overall efficiency of APPs in the design stage.

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A Control-Theoretic Approach to Neural Pharmacology: Optimizing Drug Selection and Dosing

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4033102 ◽

2016 ◽

Vol 138 (8) ◽

Cited By ~ 1

Author(s):

Gautam Kumar ◽

Seul Ah Kim ◽

ShiNung Ching

Keyword(s):

Design Method ◽

Target Space ◽

Theoretic Approach ◽

Time Varying ◽

Drug Selection ◽

Modeling Paradigm ◽

Dosing Strategies ◽

Dose Dependent ◽

Optimal Construction ◽

Selection Of

The induction of particular brain dynamics via neural pharmacology involves the selection of particular agonists from among a class of candidate drugs and the dosing of the selected drugs according to a temporal schedule. Such a problem is made nontrivial due to the array of synergistic drugs available to practitioners whose use, in some cases, may risk the creation of dose-dependent effects that significantly deviate from the desired outcome. Here, we develop an expanded pharmacodynamic (PD) modeling paradigm and show how it can facilitate optimal construction of pharmacologic regimens, i.e., drug selection and dose schedules. The key feature of the design method is the explicit dynamical-system based modeling of how a drug binds to its molecular targets. In this framework, a particular combination of drugs creates a time-varying trajectory in a multidimensional molecular/receptor target space, subsets of which correspond to different behavioral phenotypes. By embedding this model in optimal control theory, we show how qualitatively different dosing strategies can be synthesized depending on the particular objective function considered.

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Fault-tolerant formation control of stochastic nonlinear multi-agent systems with time-varying weighted topology

Transactions of the Institute of Measurement and Control ◽

10.1177/0142331219891588 ◽

2020 ◽

Vol 42 (8) ◽

pp. 1461-1474 ◽

Cited By ~ 1

Author(s):

Mahdi Siavash ◽

Vahid Johari Majd ◽

Mahdie Tahmasebi

Keyword(s):

Formation Control ◽

Fault Tolerant ◽

Sliding Mode ◽

Design Method ◽

Time Varying ◽

Multi Agent Systems ◽

Agent Systems ◽

Rlc Circuit ◽

Adaptive Laws ◽

Multi Agent

In this paper, the fault-tolerant formation control of nonlinear stochastic multi-agent systems in the presence of actuator faults, disturbances, and time-varying weighted topology is considered. While most traditional fault-tolerant control methods in the literature use fixed weights on the topology edges, in this study these weights are considered time-varying using a pre-designed function, which allows formulating the system more realistically. Moreover, in contrast with previous works on fault-tolerant multi-agent systems, in this study, the model of the agents is considered to be stochastic in general. Furthermore, the actuators of the agents are considered to have a time-varying fault of additive and multiplicative types. A passive and an active fault-tolerant controllers are designed based on the back-stepping sliding-mode approach. In the passive method, a constant robust controller is proposed using an upper bound of the faults while, in the active controller, the additive and multiplicative faults are estimated using adaptive laws. The active and passive fault-tolerant controllers guarantee that the formation errors converge to a bounded region near the origin in a mean-square sense and all of the existing signals in the closed-loop system remain bounded in probability. The results of the formation control are extended to consensus control as well. Finally, a stochastic multi-aircraft model and an RLC circuit with stochastic part are used as two case studies to illustrate the effectiveness of the proposed design method.

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H∞Control for Flexible Spacecraft with Time-Varying Input Delay

Mathematical Problems in Engineering ◽

10.1155/2013/839108 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Ran Zhang ◽

Tao Li ◽

Lei Guo

Keyword(s):

Design Method ◽

Flexible Spacecraft ◽

Input Delay ◽

Control Input ◽

Time Varying ◽

Closed Loop System ◽

Slack Variables ◽

Attenuation Level ◽

Delay Dependent ◽

Dependent State

This paper is concerned withH∞control problem for flexible spacecraft with disturbance and time-varying control input delay. By constructing an augmented Lyapunov functional with slack variables, a new delay-dependent state feedback controller is obtained in terms of linear inequality matrix. These slack variables can make the design more flexible, and the resultant design also can guarantee the asymptotic stability andH∞attenuation level of closed-loop system. The effectiveness of the proposed design method is illustrated via a numerical example.

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State feedback observer-based control design for linear descriptor systems with multiple time-varying delays

IMA Journal of Mathematical Control and Information ◽

10.1093/imamci/dnaa010 ◽

2020 ◽

Vol 37 (4) ◽

pp. 1218-1236

Author(s):

V N Phat ◽

P Niamsup ◽

N H Muoi

Keyword(s):

State Feedback ◽

Design Method ◽

Sufficient Conditions ◽

Descriptor Systems ◽

Linear Matrix ◽

Multiple Time ◽

Time Varying ◽

Feedback Controllers ◽

Delay Function ◽

Delay Dependent

Abstract In this paper, we propose an linear matrix inequality (LMI)-based design method to observer-based control problem of linear descriptor systems with multiple time-varying delays. The delay function can be continuous and bounded but not necessarily differentiable. First, by introducing a new set of improved Lyapunov–Krasovskii functionals that avoid calculating the derivative of the delay function, we obtain new delay-dependent sufficient conditions for guaranteeing the system to be regular, impulse-free and asymptotically stable. Then, based on the derived stability conditions, we design state feedback controllers and observer gains via LMIs, which can be solved numerically in standard computational algorithms. A numerical example with simulation is given to demonstrate the efficiency and validity of the proposed deign.

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Delay-Dependent Robust Control for Discrete-Time Uncertain Stochastic Systems With Time-Varying Delays

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4036365 ◽

2017 ◽

Vol 139 (10) ◽

Cited By ~ 1

Author(s):

Cheung-Chieh Ku ◽

Guan-Wei Chen

Keyword(s):

Robust Control ◽

Discrete Time ◽

Stochastic Systems ◽

Design Method ◽

Sufficient Conditions ◽

Jensen Inequality ◽

Linear Matrix ◽

Time Varying ◽

Gain Scheduled Controller ◽

Delay Dependent

This paper investigates a delay-dependent robust control problem of discrete-time uncertain stochastic systems with delays. The uncertainty considered in this paper is time-varying but norm-bounded, and the delays are considered as interval time-varying case for both state and input. According to the considerations of uncertainty, stochastic behavior, and time delays, the problem considered in this paper is more general than the existing works for uncertain stochastic systems. Via the proposed Lyapunov–Krasovskii function, some sufficient conditions are derived into the extended linear matrix inequality form. Moreover, Jensen inequality and free matrix equation are employed to reduce conservatism of those conditions. Through using the proposed design method, a gain-scheduled controller is designed to guarantee asymptotical stability of uncertain stochastic systems in the sense of mean square. Finally, two numerical examples are provided to demonstrate applicability and effectiveness of the proposed design method.

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A Robust Disturbance Rejection Method for Uncertain Flexible Mechanical Vibrating Systems Under Persistent Excitation

Journal of Vibration and Control ◽

10.1177/1077536304034747 ◽

2004 ◽

Vol 10 (3) ◽

pp. 343-357 ◽

Cited By ~ 3

Author(s):

Liang-An Zheng

Keyword(s):

Stability Condition ◽

Disturbance Rejection ◽

Design Method ◽

Control Input ◽

Time Varying ◽

Persistent Excitation ◽

Rejection Method ◽

Time Varying Parameter ◽

Parameter Perturbations ◽

Vibrating Systems

This paper presents a robust disturbance rejection method for a class of flexible mechanical vibrating systems with time-varying parameter perturbations subject to persistent excitation. The control input is split into two parts as a common strategy: one is obtained from the regulator design that is responsible for primary stabilization; the other is assigned to cancel the effect of the persistent excitation. The states of controlled dynamics and excitation dynamics are estimated by a Kalman filter. Then, taking into account plant variations, a robust stability condition is proposed to ensure the stability of the resulting closed system. It is shown that, using the proposed stability condition, the designed controller can effectively suppress the persistent excitation and keep the flexible mechanical system from the possibility of instability caused by spillover and time-varying parameter perturbations. Finally, two examples are given to demonstrate the use of the design method.

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Delay Compensation for Teleoperation Systems Based on Communication Disturbance Observers

Journal of Advanced Computational Intelligence and Intelligent Informatics ◽

10.20965/jaciii.2016.p1044 ◽

2016 ◽

Vol 20 (7) ◽

pp. 1044-1050

Author(s):

Wen-An Zhang ◽

◽

Junkai Jin ◽

Xiang Qiu ◽

Li Yu

Keyword(s):

Control Problem ◽

Disturbance Rejection ◽

Disturbance Observer ◽

Controller Design ◽

Design Method ◽

Smith Predictor ◽

Time Varying ◽

Communication Delays ◽

Delay Compensation ◽

Teleoperation Systems

This paper investigates the control problem for a class of teleoperation systems with communication delays. The network-induced delays are usually inevitable in teleoperation systems, and may be time varying and unpredictable. Since the conventional Smith predictor is only useful for fixed delays, a novel delay compensation and controller design method is proposed in this paper. The proposed method combines a disturbance rejection controller and a communication disturbance observer (CDOB). Simulations are provided to show the effectiveness and superiority of the proposed delay compensation and controller design method.

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