1,720,960 research outputs found
Nonlinear setpoint regulation of dynamically redundant actuators
No full textIn this paper we propose a control scheme to induce optimal input allocation of dynamically redundant nonlinear actuators whose dynamics satisfies some suitable regularity and stability assumption. The allocation scheme is parametrized by a cost function associated with the most desirable actuator configuration and guarantees convergence to the desired set point as well as to the minimum of the cost function. The overall scheme is also shown to reduce, in some special cases, to a nonlinear version of a PI type of control action. The proposed technique is illustrated on a simulation example inspired by an industrial application. © 2012 AACC American Automatic Control Council)
Optimal control with input constraints applied to internal combustion engine test benches
No full textOptimal control of nonlinear systems provides a major challenge in control engineering. Constraints on the input signals are common to many real-world applications and render the problem to be tackled even more complicated. This paper proposes a method to map the input constraints by nonlinear functions to the state equations of the system, afterwards an approximation of the solution of the resulting optimization problem is calculated by means of a dynamic extension to the state of the system. The approach is applied in the control of test benches for internal combustion engines, where speed and torque references need to be tracked at the crankshaft of the engine. Simulation results using a high-quality simulator, also regarding effects that have not been included in the model for controller design, show the performance of the proposed approach. © IFAC
Optimal control of internal combustion engine test benches equipped with hydrodynamic dynamometers
No full textThis paper considers the problem of tracking dynamic reference profiles for rotational speed and torque at the crankshaft of an internal combustion engine at a test bench. The test bench is equipped with a hydrodynamic dynamometer that can only load the internal combustion engine. A proper formulation of this tracking problem with input constraints by nonlinear functions to the state equations of the system and an extension of the state to approximately solve the resulting optimization problem is used to design a control law achieving at the same time a criterion of optimality. Simulation results using a high-quality simulator of the test bench show the performance of the proposed approach
Identification and inverse torque control of hydrodynamic dynamometers
No full textHydrodynamic dynamometers are employed in internal combustion engine (ICE) test benches for the entire range of ICEs, from cart engines to large ship engines. They are inexpensive and characterized by a relatively small moment of inertia. Although nonlinearities and the absence of accurate models make controlling these dynamometers a difficult task, they are currently used almost exclusively for stationary measurements. To overcome this limitation, this paper proposes an inverse torque control based on a Wiener approximation whose parameterization is strongly simplified by choosing a suitable set of basis functions for the nonlinear map. As inverting this nonlinear map would be computationally demanding, it is replaced with a dynamic inversion which-together with the actuator redundancy-allows additional optimality criteria to be incorporated. The performance of the proposed control law is validated by measurements on a test bench and shows significant improvement compared with classical implementations. © 2013 IEEE
Approximate optimal control of internal combustion engine test benches
No full textThis paper proposes the design of an optimal simultaneous control of speed and torque for dynamic internal combustion engine test bench by means of a dynamic extension to the state of the system which allows to avoid the explicit solution of the Hamilton-Jacobi-Bellman partial differential equation. To this end, a dynamic control law is firstly designed based on a simplified and approximate model of the test bench and then modified in order to cope with non-modeled dynamics and nonlinearities. The control is designed on this basis and its performance of the control law is tested and validated on an accurate simulator of the internal combustion engine test bench
Approximate optimal control of the air path of a diesel engine
No full textThe problem of regulating the fresh mass air flow MAF and the absolute pressure in the intake manifold MAP in the air path of a Diesel engine to set-point reference values is considered here. To begin with, a NARX model of the air path of a Diesel engine is obtained in terms of two (coupled) difference equations from input/output measurements of the actual system. A continuous-time state-space representation of this model is then determined and used to design a control law that solves the regulation problem, achieving at the same time a criterion of optimality. To conclude the paper, the performances of the proposed control law are tested in simulation. © 2012 AACC American Automatic Control Council)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Inverse torque control of hydrodynamic dynamometers for combustion engine test benches
No full textHydrodynamic dynamometers can be used for the entire range of combustion engines from cart engines up to large ship engines, are inexpensive and have a small moment of inertia. Due to their strong nonlinearities and the absence of precise models, they are still rarely used for dynamic testing. Against this background, this paper proposes an inverse control of an approximate form determined experimentally. As the paper shows using measurements on a dynamic truck engine test bench, the proposed approach is able to offer a significantly better performance with respect to the classical implementation thus opening a new path for the intended use for dynamic testing. © 2011 AACC American Automatic Control Council
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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