On the Benefits of Surrogate Lagrangians in Optimal Control and Planning Algorithms

This paper explores the relationship between numerical integrators and optimal control algorithms. Specifically, the performance of the differential dynamical programming (DDP) algorithm is examined when a variational integrator and a newly proposed surrogate variational integrator are used to propagate and linearize system dynamics. Surrogate variational integrators, derived from backward error analysis, achieve higher levels of accuracy while maintaining the same integration complexity as nominal variational integrators. The increase in the integration accuracy is shown to have a large effect on the performance of the DDP algorithm. In particular, significantly more optimized inputs are computed when the surrogate variational integrator is utilized

Improving Transient Performance of Adaptive Control Architectures using Frequency-Limited System Error Dynamics

We develop an adaptive control architecture to achieve stabilization and command following of uncertain dynamical systems with improved transient performance. Our framework consists of a new reference system and an adaptive controller. The proposed reference system captures a desired closed-loop dynamical system behavior modified by a mismatch term representing the high-frequency content between the uncertain dynamical system and this reference system, i.e., the system error. In particular, this mismatch term allows to limit the frequency content of the system error dynamics, which is used to drive the adaptive controller. It is shown that this key feature of our framework yields fast adaptation with- out incurring high-frequency oscillations in the transient performance. We further show the effects of design parameters on the system performance, analyze closeness of the uncertain dynamical system to the unmodified (ideal) reference system, discuss robustness of the proposed approach with respect to time-varying uncertainties and disturbances, and make connections to gradient minimization and classical control theory.Comment: 27 pages, 7 figure

Model-Based Control Using Koopman Operators

This paper explores the application of Koopman operator theory to the control of robotic systems. The operator is introduced as a method to generate data-driven models that have utility for model-based control methods. We then motivate the use of the Koopman operator towards augmenting model-based control. Specifically, we illustrate how the operator can be used to obtain a linearizable data-driven model for an unknown dynamical process that is useful for model-based control synthesis. Simulated results show that with increasing complexity in the choice of the basis functions, a closed-loop controller is able to invert and stabilize a cart- and VTOL-pendulum systems. Furthermore, the specification of the basis function are shown to be of importance when generating a Koopman operator for specific robotic systems. Experimental results with the Sphero SPRK robot explore the utility of the Koopman operator in a reduced state representation setting where increased complexity in the basis function improve open- and closed-loop controller performance in various terrains, including sand.Comment: 8 page

Autonomous suspended load operations via trajectory optimization and variational integrators

Advances in machine autonomy hold great promise in advancing technology, economic markets, and general societal well-being. For example, the progression of unmanned air systems (UAS) research has demonstrated the effectiveness and reliability of these autonomous systems in performing complex tasks. UAS have shown to not only outperformed human pilots in some tasks, but have also made novel applications not possible for human pilots practical. Nevertheless, human pilots are still favored when performing specific challenging tasks. For example, transportation of suspended (sometimes called slung or sling) loads requires highly skilled pilots and has only been performed by UAS in highly controlled environments. The presented work begins to bridge this autonomy gap by proposing a trajectory optimization framework for operations involving autonomous rotorcraft with suspended loads. The framework generates optimized vehicle trajectories that are used by existing guidance, navigation, and control systems and estimates the state of the non-instrumented load using a downward facing camera. Data collected from several simulation studies and a flight test demonstrates the proposed framework is able to produce effective guidance during autonomous suspended load operations. In addition, variational integrators are extensively studied in this dissertation. The derivation of a stochastic variational integrator is presented. It is shown that the presented stochastic variational integrator significantly improves the performance of the stochastic differential dynamical programming and the extended Kalman filter algorithms. A variational integrator for the propagation of polynomial chaos expansion coefficients is also presented. As a result, the expectation and variance of the trajectory of an uncertain system can be accurately predicted.Ph.D

Government Policy and Technical Change: an Endogenous Technology Study of U.S. Agriculture

Agricultural Economic

Responsabilidad Social de la Empresa Del Dicho al Hecho: Anales

Los Anales de la II Conferencia Interamericana sobre RSE celebrada en México.Responsabilidad social empresarial

Laboratorio de la forma urbana: adaptación de un espacio para la interdisciplina

El contexto urbano mundial se caracteriza por dos condiciones en tensión. Por un lado, está el avance en la interconexión, es decir, el flujo de información y conocimiento, y el movimiento de las variables científicas y sus aplicaciones tecnológicas. Esta condición se refiere al proceso de globalización y afecta de manera diferenciada a regiones, ciudades y naciones. Por el otro, está la acumulación de crisis en diversas dimensiones (ambiental, económica, social, cultural) que se evidenciaron con la pandemia de COVID-19. Es este contexto el que nos motiva a revisar las formas y los procesos de los espacios de la producción y gestión del conocimiento sobre la ciudad, con el fin de establecer ajustes en su ruta y agenda de trabajo. Este texto tiene el objetivo de mostrar algunos elementos con los cuales se plantea la reconfiguración del Laboratorio de la Forma Urbana (UAM-Azcapotzalco), para posicionarse como una fuente complementaria del desarrollo del pensamiento crítico, el avance académico y la gestión del conocimiento sobre la comprensión de los procesos morfológicos de las ciudades en el siglo XXI. Dos ejes estructuran este proceso: el fortalecimiento de la docencia y el trabajo interdisciplinario. Todo lo planteado forma parte de una reflexión colectiva que se realizó en el Área de Estudios Urbanos y el Posgrado en Diseño y Estudios Urbanos.The global urban context can be characterized by the tension between two conditions. On one hand, there is the advance of interconnection or the information and knowledge flow, and the movement of scientific variables and their technological applications. This condition refers to the globalization process and affects in different ways to regions, nations, and cities. On the other hand, the accumulation of multidimensional crisis (environmental, economic, social, cultural) that has become more evident because of the COVID-19 pandemic. This is the context that impels to review the forms and the processes of the spaces for the production and management of urban knowledge, with the purpose of establish adjustments in its agenda. The goal of this paper is to expose the elements in the Urban Form Laboratory (UAM Azcapotzalco) reconfiguration to become a complementary source for the critical thinking, academic development, and knowledge management, to the understanding of the morphological processes of XXI century cities. This process has two axes: the strengthening of teaching and the interdisciplinary work. Everything is part of a collective reflection that takes place in the Area of Urban Studies and the Postgraduate Program in Design and Urban Studies