Safety Envelope for Orthogonal Collocation Methods in Embedded Optimal Control

Orthogonal collocation methods are direct simultaneous approaches for solving optimal control problems (OCP). A high solution accuracy is achieved with few optimization variables, making it more favorable for embedded and real-time NMPC applications. However, collocation approaches lack a guarantee about the safety of the resulting continuous trajectory as inequality constraints are only set on a finite number of collocation points. In this paper we propose a method to efficiently create a convex safety envelope containing the full trajectory such that the solution fully satisfies the OCP constraints. We make use of the Bernstein approximations of a polynomial's extrema and span the solution over an orthogonal basis using the Legendre polynomials. The tightness of the safety envelope estimation, high spectral accuracy of the method in solving the underlying differential equations, fast rate of convergence and little conservatism are properties of the presented approach making it a suitable method for safe real-time NMPC deployment. We show that our method has comparable computational performance to the pseudospectral approaches and can approximate the original OCP more accurately and up to 9 times more quickly than standard multiple-shooting methods in autonomous driving applications, without adding complexity to the formulation

In-flight structural identification:input/output versus output-only data processing

The problem of in-flight data analysis, for the purpose of structural model identification under both measured and uncontrolled non-stationary excitation, is addressed. Input/output and output-only eigenstructure identification methods are described and compared, within two classes of methods: subspace-based and prediction error. In particular, different types of relevant projections for handling the known (measured) and unknown (uncontrolled) inputs are discussed. The relevance of the methods is emphasized through numerical results obtained on flight test data sets

Robust design and optimization in vibro-acoustic engineering

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Discussions on Session 1B:Overview of quantum effects in chemistry and biology

Abstract

Improving active suspension performance by means of advanced vehicle state and parameter estimation

Active suspension systems aim to increase safety by improving vehicle ride and handling performance while ensuring superior passenger comfort. To achieve good control of this system, the control algorithm must be provided with reliable and accurate input signals. This paper presents the design and development of a state estimator that accurately provides the information required by a sky-hook controller, using a minimum of sensors. The vehicle inertial parameters are estimated by an algorithm based on Monte Carlo simulations and anthropometric data. All state updating is performed using Kalman filters. The resulting performance enhancement has been proven during test drives.status: publishe

Advanced State Estimator Design for an Active Suspension

Active suspension systems aim at increasing safety by improving vehicle ride and handling performance while ensuring superior passenger comfort. Good control of this active system can only be achieved by providing the control algorithm with reliable and accurate signals for the required quantities. This paper presents the design and development of a state estimator that accurately provides the information required by a sky-hook controller, using a minimum of sensors. The vehicle inertial parameters are estimated by an algorithm based on Monte Carlo simulations and anthropometric data. All state updating is performed using Kalman filters. The resulting performance enhancement has been proven during test drives.status: publishe

Advanced State and Parameter Estimation for an Active Suspension System

status: publishe

Investigation of the Influence of the Current-Hysteresis Bandwidth on Noise and Vibrations of Switched Reluctance Machines

The development of power converters has permitted the rise of switched reluctance machines(SRMs), due to their simple and cheap design and of their inherent fault tolerance. However,those machines suffer from torque ripple and noise and vibration issues, which constitute an obstacleto the extension of their application domain. This paper presents the influence of thebandwidth of a current-hysteresis controller on an 8/6 SRM in terms of noise, vibration andharshness. Simulations in AMESim environment and measurements on a 15 kW test bench areperformed in transient state, based on continuous variation of the hysteresis bandwidth. Phasecurrents, acoustic noise and radial vibrations are measured without and with load, allowing forcomparison of hysteresis-band-frequency plots. This transient state approach enables showingthe evolution of a part of the frequency components with hysteresis bandwidth and distinguishingthem from other components linked to speed or to structural behaviour of the motor. Resultsshow that the current chopping by means of a hysteresis controller generates broadband frequenciesin the phase currents that also appear in the vibration and sound pressure wave measurements.As the bandwidth increases, switching-related components are shifted towards lowerfrequencies, resulting in a higher excitation of the main resonance modes of the machine. Due tothe higher current ripple in the case of hard chopping mode, the influence of the bandwidth is ingeneral more important than in soft chopping mode. However, for the same bandwidth the rippleoccurs at much lower frequencies in the latter case and therefore more attention has to bepaid to possible interaction with the resonance frequencies.info:eu-repo/semantics/publishe