Fabrício José Pacheco Pujatti

Design and implementation of a low-cost robotic load carrier

Many professional or daily activities demand load displacement by human arms or by human powered vehicles. Those activities may cause muscle-skeleton diseases even in load carrying professionals as in people carrying their daily objects. In the field of robotics, the research developments to help people at those activities are made through human-robot cooperation systems actuated by servo drives. Due to the cost of those drives, many people are not able to acquire the robots and so they are prohibited from getting the associated health benefits. To promote robot-aided solutions, this paper presents the design and implementation of a load carrier human-robot cooperation system, which is built through an electrical load cart and driven by frequency inverter and induction motor. The robot controller is implemented by a force regulation structure which allows the conductor to set the mechanical trajectories through the multiplication of the force applied by his/her arms. Since the arms have a higher positioning bandwidth than the conductors legs, the controller dynamic response is tuned with human leg dynamics in mind, so as to increase the operational safety. The paper presents details of mounting, firmware design and measurements to show the robot performance.

The effect of energy efficiency increase on a PV plant with a non-conventional energy storage system income

This Photovoltaic (PV) plants are widely used to produce power in either large or small scales all around the world. In addition, compressed air energy storage (CAES) system has attracted considerable attention as one of the most efficient candidates for large scales energy storage applications in the recent years. In this work, detailed energy and exergy analysis of a 100 MWp grid connected PV plant equipped with a CAES system is carried out. The PV plant is assumed to be located in Brazil. The formulations related to the first and the second laws of thermodynamic for all components as well as detailed solar engineering formulations for both the PV farm and the solar heating unit are presented. The performance of the power plant is comprehensively investigated for one entire year in real circumstances. The results revealed that the annual average exergy and energy efficiencies of the power plant are 17.9% and 16.2%, respectively and for 1% energy efficiency enhancement the power plant, the annual income increases almost 4 million USD.

Ethanol Lean Combustion Characteristics of a GDI Engine

In the present study, ethanol combustion analysis was carried in a wall guided type GDI engine, to achieve combustion stability under lean burn operation and to expand the flammability limit for increasing engine efficiency. Tests were performed at constant engine speed, load and injection pressure (1000 rpm, NIMEP = 3 bar, 100 bar), for a wide range of injection, ignition and mixture formation parameters. NISFC, combustion stability, PMEP and burn duration were evaluated at each excess air ratio. An improvement on fuel economy and, consequently, increased engine efficiency was achieved for excess air ratios of λ = 1.1 and λ = 1.2.

Human-robot cooperation system with mechanical impedance emulation for friendly human perception

Many professional or daily activities require load displacement by human arms or human powered vehicles. Those activities may lead to muscle-skeleton diseases in load-carrying professionals as in people carrying their personal belongs. To help prevent those injuries, the scientific community has developed human-robot cooperation systems which are implemented through a robot that works as a force multiplier equipment and the human that works as the positioning or force setpoint generator. In order to provide the force multiplication feature and also to care about the human perception during the cooperative task, this paper presents the design and implementation of a robot that is dedicated to help in translational displacements while emulating an active mechanical impedance that provides a friendly perception to humans.

Methane combustion kinetic rate constants determination: an ill-posed inverse problem analysis

Methane combustion was studied by the Westbrook and Dryer model. This well-established simplified mechanism is very useful in combustion science, for computational effort can be notably reduced. In the inversion procedure to be studied, rate constants are obtained from [CO] concentration data. However, when inherent experimental errors in chemical concentrations are considered, an ill-conditioned inverse problem must be solved for which appropriate mathematical algorithms are needed. A recurrent neural network was chosen due to its numerical stability and robustness. The proposed methodology was compared against Simplex and Levenberg-Marquardt, the most used methods for optimization problems.