Papers by Jonathan LeSage
This paper presents an approach for using two-port circuit synthesis methods as a basis for desig... more This paper presents an approach for using two-port circuit synthesis methods as a basis for designing actuator subsystems. The development of this methodology is generally motivated by problems in retrofit design, where technology reinsertion is required to replace legacy systems, or for early stage design in new mechatronic systems. The particular problem of electric ship control surface actuation is used as an example application. A procedure that integrates two-port network synthesis methods with a model-basis conveyed using bond graphs is presented and applied to the problem of synthesizing a candidate actuation system for a submarine control surface. Studying the control surface actuator problem shows that a synthesis method is capable of providing insight into balancing passive compensation with actuation (active elements). The ability to partition active and passive system elements suggests promise in developing a means for integrating passive energy storage with actuation subsystems.
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This paper examines methods that can be adopted in early stage or retrot design of actuator subs... more This paper examines methods that can be adopted in early stage or retrot design of actuator subsystems, and is motivated by the modern trend toward retrotting legacy hydraulic actuation of submarine control surfaces with electromechanical systems. This problem highlights the familiar need designers have to relate system response requirements to selected subsystems to enable focused development of the latter. This paper shows the utility of adopting a model basis, and specically uses a bond graph approach in combination with two-port immittance relations. Bond graphs benet study of multidisciplinary systems and provide insight into system interconnection and causality. In combination with bond graphs, immittance functions enable key relations to be established based on the overall system description, and provide a way to specify response requirements. Immittance functions also enable adopting network synthesis methods, which are used in this paper to show how passive and active compensation can be integrated to benefit proposed actuation schemes. It is shown how this combination of methods provides designers with a systematic way of relating system response requirements to targeted subsystems. The methods described are demonstrated using a simplied control surface actuation problem, and simulation results of key static and dynamic requirements are presented. The derived passive and active compensation are used to augment conventional feedback controlled actuator models, and simulations demonstrate how compensation can reduce energy consumed by actuation subsystems.
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Electric Ship Technologies …
Initial design considerations of shipboard power distribution grids require a priori load dynamic... more Initial design considerations of shipboard power distribution grids require a priori load dynamics assumptions for size assessment, power/energy requirements, and system stability considerations. For the analysis of dc micro-grids, power processing units and dynamic loads are often assumed destabilizing constant power loads for simplified stability studies. The constant power load is shown to be valid under certain load conditions, and other potential destabilizing load forms are introduced and discussed. As an example, a hydrodynamic load on a typical shipboard motor is shown to influence the stability characteristics of the power grid. Additionally, a model reduction analysis is proposed for early stage power system stability analysis.
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Papers by Jonathan LeSage