Design of Reference Governor For A Class of Nonlinear Systems with Input Constraints

Hyun Min Do,Jin Young Choi,Jin Ho Kyung 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10

This paper presents a design method of the reference governor for a class of nonlinear systems with input constraints. When the input has a constraint, the input saturation might happen and thus, the controller cannot work correctly. Furthermore, the output might diverge in the case of an open loop unstable system. To overcome this problem, a novel approach to the design of a reference governor is proposed. A nonlinear system diffeomorphic to a normal form is considered and additionally, a bounded disturbance in the control input is considered. In the proposed method, the behaviors of the states and input are predicted and the reference is modified so that the predicted input never exceeds the saturation limits and the modified one is closest to the given command among the values which are achievable without the input saturation. The convergence of the newly generated reference trajectory is proved and some simulation results are included to verify the performance of the proposed method.

财政补贴、融资约束与高新技术企业创新投入

丁一丹,제혜금 인문사회 21 2023 인문사회 21 Vol.14 No.3

The purpose of this study is to study the relationship among financial subsidies, financing constraints and innovation input of high-tech enterprises.Based on the data of 356 Chinese A-share listed high-tech enterprises from 2016 to 2021, EXECL is used to calculate and collate some indicators, and Stata 16.0 is used to perform regression analysis on the data.This paper analyzes the influence of financial subsidies on innovation input of high-tech enterprises and the mediating role of financing constraints.There is a significant positive correlation between fiscal subsidies and enterprises’ innovation input. Fiscal subsidies can alleviate the financing constraints of high-tech enterprises, and financing constraints play a partial intermediary role in the influence of fiscal subsidies on enterprises’ innovation input. By grouping the samples according to ownership, it is concluded that the influence of government subsidies on innovation input of high-tech enterprises has ownership heterogeneity. The government should relax financing policies and increase government subsidies, so as to improve enterprise innovation input.

Finite-time sliding surface constrained control for a robot manipulator with an unknown deadzone and disturbance

Ik Han, Seong,Lee, Jangmyung Elsevier 2016 ISA transactions Vol.65 No.-

<P><B>Abstract</B></P> <P>This paper presents finite-time sliding mode control (FSMC) with predefined constraints for the tracking error and sliding surface in order to obtain robust positioning of a robot manipulator with input nonlinearity due to an unknown deadzone and external disturbance. An assumed model feedforward FSMC was designed to avoid tedious identification procedures for the manipulator parameters and to obtain a fast response time. Two constraint switching control functions based on the tracking error and finite-time sliding surface were added to the FSMC to guarantee the predefined tracking performance despite the presence of an unknown deadzone and disturbance. The tracking error due to the deadzone and disturbance can be suppressed within the predefined error boundary simply by tuning the gain value of the constraint switching function and without the addition of an extra compensator. Therefore, the designed constraint controller has a simpler structure than conventional transformed error constraint methods and the sliding surface constraint scheme can also indirectly guarantee the tracking error constraint while being more stable than the tracking error constraint control. A simulation and experiment were performed on an articulated robot manipulator to validate the proposed control schemes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Design an assumed model feedforward finite-time sliding mode controller for a robot manipulator system. </LI> <LI> Design a finite-time sliding mode controller with a tracking error constraint. </LI> <LI> Design a finite-time sliding mode controller with a sliding surface constraint. </LI> <LI> Design a finite-time sliding mode controller with tracking error and sliding surface constraint controls without requiring an extra deadzone compensator. </LI> </UL> </P>

Wireless Information and Power Transfer: Rate-Energy Tradeoff for Equi-Probable Arbitrary-Shaped Discrete Inputs

Il-Min Kim,Dong In Kim IEEE 2016 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.15 No.6

<P>In this paper, the fundamental rate-energy (R-E) tradeoffs are studied for simultaneous wireless information and power transfer (SWIPT). Unlike the existing results obtained using Gaussian input given an average power constraint, we focus on the equi-probable arbitrary shaped discrete inputs considering a peak power constraint as well as an average power constraint. For these power constraints, the transmit power strategies are presented and the R-E regions are derived. The optimality of different SWIPT schemes is first studied in terms of the R-E tradeoff for the case of negligible circuit power consumption in the information decoder. The results are extended to the case of non-negligible circuit power consumption in the information decoder. The asymptotic R-E regions are also derived, which give us useful insights into the fundamental R-E tradeoffs. Finally, the R-E regions of Gaussian input and discrete inputs are compared under an average power constraint.</P>

제약조건하의 승수효과분석은 왜 필요한가?

김호언(Gim, Ho Un) 한국지역개발학회 2014 韓國地域開發學會誌 Vol.26 No.2

Basically, the multiplier effects derived from the models of IO(input- output), OO(output-output), and FF(final demand-final output) between total output(x), final output (o), and final demand(f) are based on the unrestricted(or unconstrained) conditions in financing constraints. However, in the real economic activity, if a new injection program focused on sector j needs a reduction of expenditure in the remaining sectors, for i ≠ j , so as to maintain the total budget constraints of the government. On the basis of the latest research findings and results from the multiplier analysis under constraints in the recent economic literature, the specific objectives of this paper can be summed up as follows. (1) We testify the importance and necessity for the multiplier analysis under constraints through the limitations of the multiplier effects in the models of I(input), IO, OO, and FF. (2) We derive the model for the multiplier analysis under constraints and show the economic characteristics and usefulness of the model developed by the author. (3) We empirically calculated the multiplier effects under constraints by endogenous sectors through the output requirements for final demand(or Leontief inverse C<SUP>f</SUP>) from the raw data of the 2010 Input-Output Tables of Korea. Moreover, the Pearson correlation coefficients(PCC), γp, and the Spearman’s rank correlation coefficients(SRCC), γs, are calculated between the constrained multipliers and the decompositions of effects.

Adaptive Control of a Hose and Drogue System with Input Nonlinearities and Partial State Constraints

Liang Chang,Yingmin Jia 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.10

This paper proposes a novel multi-objective controller for the hose and drogue system, to address the input nonlinearities of dead-zone and constraint as well as partial state constraints. Based upon a smooth auxiliary function, a new dead-zone compensation method is developed to offset the unknown dead-zone nonlinearity, and the obtained controller can also deal with the input constraint by employing the Nussbaum-function-based method. Subsequently, based upon a new barrier Lyapunov function and the parameter projection method, the proposed controller can enforce the partial state constraints in the presence of the partial differential characteristics of the hose and drogue system. A simulation example is presented to illustrate the effectiveness of the proposed controller.

Nonlinear Optimal Control of an Input-Constrained and Enclosed Thermal Processing System

Kwan-Woong Gwak,Glenn Y. Masada 대한전기학회 2008 International Journal of Control, Automation, and Vol.6 No.2

Temperature control of an enclosed thermal system which has many applications including Rapid Thermal Processing (RTP) of semiconductor wafers showed an input-constraint violation for nonlinear controllers due to inherent strong coupling between the elements [1]. In this paper, a constrained nonlinear optimal control design is developed, which accommodates input constraints using the linear algebraic equivalence of the nonlinear controllers, for the temperature control of an enclosed thermal process. First, it will be shown that design of nonlinear controllers is equivalent to solving a set of linear algebraic equations-the linear algebraic equivalence of nonlinear controllers (LAENC). Then an input-constrained nonlinear optimal controller is designed based on that LAENC using the constrained linear least squares method. Through numerical simulations, it is demonstrated that the proposed controller achieves the equivalent performances to the classical nonlinear controllers with less total energy consumption. Moreover, it generates the practical control solution, in other words, control solutions do not violate the input-constraints.

Joint Decision and Control Strategy for a Class of Nonhomogeneous Markovian Jump Systems with Input Constraints

Zhendong Wang,Jin Zhu,Wanqing Xie,박준홍 제어·로봇·시스템학회 2014 International Journal of Control, Automation, and Vol.12 No.5

This paper is concerned with the joint decision and control strategy for a class of nonhomogeneous Markovian jump systems subject to input constraints. By assuming the mode transition rate matrix (MTRM) of Markovian jump systems is piecewise homogeneous instead of homogeneous, a higher-level Markov chain represented by the higher-level mode transition rate matrix (HMTRM) is introduced to describe the variation of MTRM. Based on this, taking into account the minimization of system cost, a novel joint decision and control strategy is proposed in the presence of input constraints. This strategy consists of two sections: decisions are applied to the HMTRM such that the occurrence probability of subsystems is adjusted ultimately; next on the basis of altered HMTRM, controller is designed in view of input constraints. In comparison with conventional control method, this strategy not only guarantees the stability of the considered system well, but also decreases the system cost effectively. Numeral examples along with comparisons are put forward to illustrate the effectiveness of the proposed strategy.

Integral Barrier Lyapunov Functions-based Neural Control for Strictfeedback Nonlinear Systems with Multi-constraint

Jun Zhang 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.4

A new robust tracking control approach is proposed for strict-feedback nonlinear systems with state and input constraints. The constraints are tackled by extending the control input as an extended state and introducing an integral barrier Lyapunov function (IBLF) to each step in a backstepping procedure. This extends current research on barrier Lyapunov functions(BLFs)-based control for nonlinear systems with state constraints to IBLF-based control for strict-feedback nonlinear systems with state and input constraints. Since the IBLF allows the original constraints to be mixed with the error terms, the use of IBLF decreases conservatism in barrier Lyapunov functionsbased control. In the backstepping procedure, neural networks (NNs) with projection modifications are applied to estimate system uncertainties, due to their ability in guaranteeing estimators in a given bounded area. To facilitate the use of the once-differentiable NNs estimators in the backstepping procedure, the virtual controllers are passed through command filters. Finally, simulation results are presented to illustrate the feasibility and effectiveness of the proposed control.

Leader-Following Consensus Control of Nonlinear Multi-Agent Systems with Input Constraint

Xiongfeng Deng,Xiuxia Sun,Shuguang Liu 한국항공우주학회 2019 International Journal of Aeronautical and Space Sc Vol.20 No.1

This paper investigates the consensus control problem of leader-following nonlinear multi-agent systems with input constraint and directed communication topology. First, a general control protocol is given to solve the consensus of the multi-agent systems without input constraint. Then, the case of input constraint is considered, a fuzzy system is applied in constrained control protocol design. Also, the assumption that the Lipschitz condition for nonlinear item should be satisfied in many papers is not considered in this work. The convergence of the proposed control protocols is analyzed using the sliding mode control approach, Lyapunov stability theory and graph theory. Finally, two examples are provided to illustrate the effectiveness of the theoretical analysis.