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- Lau, G.K. (author), Chu, D.T. (author), Goosen, J.F.L. (author), Van Keulen, A. (author), Sarro, P.M. (author) patent 2008
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De Weerdt, E. (author), Chu, Q.P. (author), Mulder, J.A. (author)The problem of output optimization within a specified input space of neural networks (NNs) with fixed weights is discussed in this paper. The problem is (highly) nonlinear when nonlinear activation functions are used. This global optimization problem is encountered in the reinforcement learning (RL) community. Interval analysis is applied to...journal article 2009
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Maessen, D.C. (author), Guo, J. (author), Gill, E. (author), Gunter, B. (author), Chu, Q.P. (author), Bakker, G. (author), Laan, E. (author), Moon, S. (author), Kruijff, M. (author), Zheng, G.T. (author)The paper presents the latest results in the design of FAST-D, the Dutch micro-satellite for the Dutch–Chinese FAST (Formation for Atmospheric Science and Technology demonstration) formation flying mission. Over the course of the 2.5 year mission, the two satellites, FAST-D and FAST-T, will demonstrate various new technologies and perform...conference paper 2009
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Zaal, P.M.T. (author), Pool, D.M. (author), Chu, Q.P. (author), Van Paassen, M.M. (author), Mulder, M. (author), Mulder, J.A. (author)This paper presents a new method for estimating the parameters of multi-channel pilot models that is based on maximum likelihood estimation. To cope with the inherent nonlinearity of this optimization problem, the gradient-based Gauss-Newton algorithm commonly used to optimize the likelihood function in terms of output error is complemented with...journal article 2009
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De Weerdt, E. (author), Van Kampen, E.J. (author), Chu, Q.P. (author)The invention relates to a transmitter-receiver system comprising at least three transmitters and at least a first receiver and a second receiver, wherein the receivers are connected to a computing device that is arranged to analyse signals that said receivers receive from said transmitters and to calculate length and attitude information of an...patent 2009
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De Visser, C.C. (author), Chu, Q.P. (author), Mulder, J.A. (author)A new methodology for creating highly accurate, static nonlinear maps from scattered, multivariate data is presented. This new methodology uses the B-form polynomials of multivariate simplex splines in a new linear regression scheme. This allows the use of standard parameter estimation techniques for estimating the B-coefficients of the...journal article 2009
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Chu, A. (author), Wang, Z.B. (author), De Vriend, H.J. (author), Stive, M.J.F. (author)A process-based model for the Yangtze Estuary is constructed to study the sediment transport in the estuary. The proposed model covers the entire tidal region of the estuary, the Hangzhou Bay and a large part of the adjacent sea. The dominant processes, fluvial and tidal, are included in the model. The calibration of the model against extensive...conference paper 2010
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Lombaerts, T.J.J. (author), Looye, G.H.N. (author), Chu, Q.P. (author), Mulder, J.A. (author)This paper describes how the previously developed concept of Pseudo Control Hedging (PCH) can be integrated in a Fault Tolerant Flight Controller (FTFC) as a safe flight envelope protection system of the first degree. This PCH algorithm adapts the reference model for the system output in case of unachievable commands due to control input...conference paper 2010
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Van Kampen, E. (author), Chu, Q.P. (author), Mulder, J.A. (author)This paper applies interval optimization to the fixed-time multiple impulse rendezvous and docking problem. Current methods for solving this type of optimization problem include for example genetic algorithms and gradient based optimization. Unlike these methods, interval methods can guarantee that the globally best solution is found for a given...conference paper 2010
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Verveld, M.J. (author), Chu, Q.P. (author), De Wagter, C. (author), Mulder, J.A. (author)This work addresses the problem of indoor state estimation for autonomous flying vehicles with an optic flow approach. The paper discusses a sensor configuration using six optic flow sensors of the computer mouse type augmented by a three-axis accelerometer to estimate velocity, rotation, attitude and viewing distances. It is shown that the...conference paper 2010
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Lombaerts, T.J.J. (author), Smaili, M.H. (author), Stroosma, O. (author), Chu, Q.P. (author), Mulder, J.A. (author), Joosten, D.A. (author)A high fidelity aircraft simulation model, reconstructed using the Digital Flight Data Recorder (DFDR) of the 1992 Amsterdam Bijlmermeer aircraft accident (Flight 1862), has been used to evaluate a new Fault-Tolerant Flight Control Algorithm in an online piloted evaluation. This paper focuses on the piloted simulator evaluation results....conference paper 2010
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Sonneveldt, L. (author), Van Oort, E.R. (author), Chu, Q.P. (author), Mulder, J.A. (author)In this paper a theoretical framework for nonlinear adaptive flight control is developed and applied to a simplified, over-actuated nonlinear fighter aircraft model. The framework is based on a modular adaptive backstepping scheme with a new type of nonlinear estimator. The nonlinear estimator is constructed using an invariant manifold based...conference paper 2010
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Van Oort, E.R. (author), Sonneveldt, L. (author), Chu, Q.P. (author), Mulder, J.A. (author)A new adaptive nonlinear flight controller is designed for a high fidelity, six degrees of freedom F-16 model for the entire flight envelope. The design is based on a modular approach which separates the design of the control law and the online identifier. The control law design is based on backstepping with nonlinear damping terms to robustify...conference paper 2010
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Sieberling, S. (author), Chu, Q.P. (author), Mulder, J.A. (author)This paper presents a flight control strategy based on nonlinear dynamic inversion. The approach presented, called incremental nonlinear dynamic inversion, uses properties of general mechanical systems and nonlinear dynamic inversion by feeding back angular accelerations. Theoretically, feedback of angular accelerations eliminates sensitivity to...journal article 2010
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De Visser, C.C. (author), Chu, Q.P. (author), Mulder, J.A. (author)The ability to perform online model identification for nonlinear systems with unknown dynamics is essential to any adaptive model-based control system. In this paper, a new differential equality constrained recursive least squares estimator for multivariate simplex splines is presented that is able to perform online model identification and...journal article 2011
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Van Eykeren, L. (author), Chu, Q.P. (author)This paper presents a model-based fault detection algorithm for a specific fault scenario of the ADDSAFE project. The fault considered is the disconnection of a control surface from its hydraulic actuator. Detecting this type of fault as fast as possible helps to operate an aircraft more cost effective and can help to avoid an undetected...conference paper 2011
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De Weerdt, E. (author), Van Kampen, E. (author), Chu, Q.P. (author), Mulder, J.A. (author)Trajectory optimization has been a large field of research for many years. The drawback is that for non-convex, constrained problems practically all available solvers cannot guarantee that the globally optimal trajectory is found. Interval analysis based solvers however can provide this guarantee. Interval analysis has been applied to trajectory...conference paper 2011
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Falkena, W. (author), Van Oort, E.R. (author), Chu, Q.P. (author)This paper uses singular perturbation theory in order to design a backstepping control system. Earlier applications using singular perturbation theory for control of non-affine systems exist, but here the focus is shifted to uncertain systems. Dealing with uncertainties in this way could be a major benefit for certification of advanced control...conference paper 2011
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De Weerdt, E. (author), Van Oort, E.R. (author), Van Kampen, E. (author), Chu, Q.P. (author)Level set methods are used to determine the reachable set for a given time domain. In the aerospace industry level set methods are used to determine for example flight envelopes. A new level set method is presented which uses interval analysis to give guaranteed bounds on the solution. Unlike the current grid-based methods the new method does...conference paper 2011
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Van Oort, E.R. (author), Sonneveldt, L. (author), Chu, Q.P. (author), Mulder, J.A. (author)In this paper nonlinear adaptive flight control laws based on the backstepping approach are proposed which are applicable to over-actuated nonlinear systems. Instead of solving the control allocation exactly, update laws for the desired control effector signals are defined such that they converge to the optimal solution. Stability and...conference paper 2011