Reinforcement Learning using Gaussian Processes for Discretely Controlled Continuous Processes

In many application domains such as autonomous avionics, power electronics and process systems engineering there exist discretely controlled continuous processes (DCCPs) which constitute a special subclass of hybrid dynamical systems. We introduce a novel simulation-based approach for DDCPs optimization under uncertainty using Rein-forcement Learning with Gaussian Process models to learn the transitions dynamics descriptive of mode execution and an optimal switching policy for mode selection. Each mode implements a parameterized feedback control law until a stopping condition trig-gers. To deal with the size/dimension of the state space and a continuum of control mode parameters, Bayesian active learning is proposed using a utility function that trades off information content with policy improvement. Throughput maximization in a buffer tank subject to an uncertain schedule of sev-eral inflow discharges is used as case study address-ing supply chain control in manufacturing systemsFil: de Paula, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológio - CONICET - Santa Fe. Instituto de Desarrollo y Diseño (i); ArgentinaFil: Martinez, Ernesto Carlos. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Santa Fe. Instituto de Desarrollo y Dise?o (i)

Fabrication of Micro-Batteries via Stop-Flow Lithography

Fabrication of micro-MEM devices and stretchable wearable electronics is important for future applications in materials, medicine and drug delivery. A key challenge in this area is the fabrication of rechargeable micro batteries with thicknesses \u3c 500 μm, area \u3c 0.1 mm2, energy densities of at least 1 to 10μWh cm-2 μμm-1. The overarching aim of this project is to develop a robust platform to fabricate micro batteries by combining double emulsion generation to fabricate porous microspheres that will serve as the anode and cathode materials and stop-flow lithography in microfludic devices to assemble the battery internals in a single step. In this presentation, I will discuss the tasks performed to assemble the stop flow lithography system, and the generation of active materials from double emulsions. The tasks include: (1) setting up the shutter and solenoid as well as syncing their operation, (2) fabricated masks for micro-particles by electric cutter and printing method, (3) performed trials to fabricate particles of different sizes and shapes, and (4) fabricated and operated double emulsion devices. The work accomplished during the summer serves as a strong foundation for the rest of the project

Biomimetic agonist-antagonist active knee prosthesis

Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 92-96).The loss of a limb is extremely debilitating. Unfortunately, today's assistive technologies are still far from providing fully functional artificial limb replacements. Although lower extremity prostheses are currently better able to give assistance than their upper-extremity counterparts, important locomotion problems still remain for leg amputees. Instability, gait asymmetry, decreased walking speeds and high metabolic energy costs are some of the main challenges requiring the development of a new kind of prosthetic device. These challenges point to the need for highly versatile, fully integrated lower-extremity powered prostheses that can replicate the biological behavior of the intact human leg. This thesis presents the design and evaluation of a novel biomimetic active knee prosthesis capable of emulating intact knee biomechanics during level-ground walking. The knee design is motivated by a mono-articular prosthetic knee model comprised of a variable damper and two series elastic clutch units spanning the knee joint. The powered knee system is comprised of two series-elastic actuators positioned in parallel in an agonist-antagonist configuration. This investigation hypothesizes that the biomimetic active-knee prosthesis, with a variable impedance control, can improve unilateral transfemoral amputee locomotion in level-ground walking, reducing the metabolic cost of walking at selfselected speeds. To evaluate this hypothesis, a preliminary study investigated the clinical impact of the active knee prosthesis on the metabolic cost of walking of four unilateral above-knee amputees. This preliminary study compared the antagonistic active knee prosthesis with subjects' prescribed knee prostheses. The subjects' prescribed prostheses encompass four of the leading prosthetic knee technologies commercially available, including passive and electronically controlled variable-damping prosthetic systems. Use of the novel biomimetic active knee prosthesis resulted in a metabolic cost reduction for all four subjects by an average of 5.8%. Kinematic and kinetic analyses indicate that the active knee can increase self-selected walking speed in addition to reducing upper body vertical displacement during walking by an average of 16%. The results of this investigation report for the first time a metabolic cost reduction when walking with a prosthetic system comprised of an electrically powered active knee and passive foot-ankle prostheses, as compared to walking with a conventional transfemoral prosthesis. With this work I aim to advance the field of biomechatronics, contributing to the development of integral assistive technologies that adapt to the needs of the physically challenged.by Ernesto Carlos Martinez-Villalpando.Ph.D

Estimation of ground reaction force and zero moment point on a powered ankle-foot prosthesis

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2006.Includes bibliographical references (leaves 89-97).Commercially available ankle-foot prostheses are passive when in contact with the ground surface, and thus, their mechanical properties remain fixed across different terrains and walking speeds. The passive nature of these prostheses causes many problems for lower extremity amputees, such as a lack of adequate balance control during standing and walking. The ground reaction force (GRF) and the zero moment point (ZMP) are known to be basic parameters in bipedal balance control. This thesis focuses on the estimation of these parameters using two prostheses, a powered ankle-foot prototype and an instrumented, mechanically-passive prosthesis worn by a transtibial amputee. The main goal of this research is to determine the feasibility of estimating the GRF and ZMP primarily using sensory information from a force/torque transducer positioned proximal to the ankle joint. The location of this sensor is ideal because it allows the use of a compliant artificial foot to be in contact with the ground, in contrast to rigid foot structures employed by walking robots. Both, the active and passive, instrumented prostheses were monitored with a wearable computing system designed to serve as a portable control unit for the active prototype and as an ambulatory gait analysis tool.(cont.) A set of experiments were conducted at MIT's gait laboratory whereby a below-knee amputee subject, using the prosthetic devices, was asked to perform single-leg standing tests and slow-walking trials. For each experiment, the GRF and ZMP were computed by combining the kinetic and kinematic information recorded from a force platform and a 3D motion capture system. These values were statistically compared to the GRF and ZMP estimated from the data collected by the embedded prosthetic sensory system and portable computing unit. The average RMS error and correlation factor were calculated for all experimental sessions. Using a static analysis procedure, the estimation of the vertical component of GRF had an averaged correlation coefficient higher than 0.96. The estimated ZMP location had a distance error of less than 1 cm, equal to 4% of the anterior-posterior foot length or 12% of the mediolateral foot width. These results suggest that it is possible to estimate the GRF between the ground and a compliant artificial prosthesis with a sensor positioned between the knee and the ankle joint.(cont.) Moreover, this sensory information is sufficient to closely estimate the ZMP location during the single support phase of slow walking and while standing on one leg. This research contributes to the development of fully integrated artificial extremities that mimic the behavior of the human ankle-foot complex, especially to help improve the postural stability of lower extremity amputees.by Ernesto Carlos Martinez Villalpando.S.M

On-line policy learning and adaptation for real-time personalization of an artificial pancreas

The dynamic complexity of the glucose-insulin metabolism in diabetic patients is the main obstacle towards widespread use of an artificial pancreas. The significant level of subject-specific glycemic variability requires continuously adapting the control policy to successfully face daily changes in patient´s metabolism and lifestyle. In this paper, an on-line selective reinforcement learning algorithm that enables real-time adaptation of a control policy based on ongoing interactions with the patient so as to tailor the artificial pancreas is proposed. Adaptation includes two online procedures: on-line sparsification and parameter updating of the Gaussian process used to approximate the control policy. With the proposed sparsification method, the support data dictionary for on-line learning is modified by checking if in the arriving data stream there exists novel information to be added to the dictionary in order to personalize the policy. Results obtained in silico experiments demonstrate that on-line policy learning is both safe and efficient for maintaining blood glucose variability within the normoglycemic range.Fil: de Paula, Mariano. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingeniería Olavarria. Departamento de Electromecánica. Grupo INTELYMEC; Argentina. Universidad Nacional del Centro de la Pcia.de Bs.as.. Centro de Investigaciones En Fisica E Ingenieria del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Tandil. Centro de Investigaciones En Fisica E Ingenieria del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernacion. Comision de Invest.cientificas. Centro de Investigaciones En Fisica E Ingenieria del Centro de la Provincia de Buenos Aires; ArgentinaFil: Acosta, Gerardo Gabriel. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ingenieria Olavarria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Martinez, Ernesto Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo y Diseño. Universidad Tecnológica Nacional. Facultad Regional Santa Fe. Instituto de Desarrollo y Diseño; Argentin

Evolución y uso del agua de riego en los sistemas campesinos de producción de leche del noroeste del Estado de México

Se analiza en retrospectiva, la evolución del sistema de riego y la actividad agropecuaria en la región noroeste del estado de México. Se emplearon diversas estrategias de análisis a partir de información proporcionada por dependencias gubernamentales, entrevistas a informantes clave, así como la aplicación de cuestionarios a productores que hicieron uso del recurso. Se logró identificar que la disponibilidad de agua ha contribuido al establecimiento de cultivos forrajeros orientados principalmente a la alimentación de vacas lecheras, dado que constituyen el eje pecuario de la región

Implementación de Servicios de media Streaming sobre IPV6 en Protocolos HTTP y RTP en una Red Académica de Tecnología Avanzada

Inside at the group in Electronics Research Laboratory and the Distrital University networks, we implement a prototype of Streaming Service on Operating Systems Fedora 13 with VLC on the Net Programme for Research and Technology from the Distrital University “RITA-UD” over IPv6. Tests were carried Streaming media service on the RTP and HTTP protocol

Construction of Social Sustainability in Milk Production Systems in Central Mexico

Objective: To build mathematical models to evaluate the social sustainability of small-scale milk production systems. Design/Methodology/Approach: Thirty small-scale cowsheds were analyzed. Two models were built using multivariate regression, estimated with ordinary least squares and considering the factors that producers perceive as important for social sustainability. Results: The first model (ER) included tangible variables and the second intangible variables (SR). Both models explained more than 80% of the variables associated with social sustainability. Study Limitations/Implications: The results represent an effort to link the statistical analysis with qualitative data that is difficult to quantify. Conclusions: The ER and SR models represent a proposal for counting immaterial indicators so they can be incorporated into the sustainability analysis. Both models could be a methodological proposal to connect statistical data with purely qualitative data such as perceptionThis study is part of the project with key 129449/2009 financed by CONACy