Anibal T. de Almeida

Olfaction-based mobile robot navigation

It is well known that insects and other animals use olfactory senses in a wide variety of behavioural processes, namely to recognize and locate food sources, detect predators, and find mates. This article discusses the gathering of olfactive information and its utilization by a mobile robot to find a specific odour source in a room with turbulent phenomenas and multiple sources of odour. Three navigation algorithms are compared with a simple gas sensor and with an electronic nose. Their performance in finding an ethanol source in a room with obstacles is evaluated. The first navigation strategy is based on bacteria chemotaxis. The second strategy is based on the male silkworm moth algorithm that is used to search and track a female moth pheromone plume. The last strategy is based on the estimation of odour geometry and gradient tracking. The electronic nose utilized is composed by an array of different and weakly selective metal oxide gas sensors. The odours are identified and quantified by a pattern recognition algorithm based on an artificial neural network. The test bed for the navigation algorithms was a Nomad Super Scout II mobile robot.

Particle swarm-based olfactory guided search

This article presents a new algorithm for searching odour sources across large search spaces with groups of mobile robots. The proposed algorithm is inspired in the particle swarm optimization (PSO) method. In this method, the search space is sampled by dynamic particles that use their knowledge about the previous sampled space and share this knowledge with other neighbour searching particles allowing the emergence of efficient local searching behaviours. In this case, chemical searching cues about the potential existence of upwind odour sources are exchanged. By default, the agents tend to avoid each other, leading to the emergence of exploration behaviours when no chemical cue exists in the neighbourhood. This behaviour improves the global searching performance.The article explains the relevance of searching odour sources with autonomous agents and identifies the main difficulties for solving this problem. A major difficulty is related with the chaotic nature of the odour transport in the atmosphere due to turbulent phenomena. The characteristics of this problem are described in detail and a simulation framework for testing and analysing different odour searching algorithms was constructed. The proposed PSO-based searching algorithm and modified versions of gradient-based searching and biased random walk-based searching strategies were tested in different environmental conditions and the results, showing the effectiveness of the proposed strategy, were analysed and discussed.

Sensor-based demand controlled ventilation: a review

With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation is modulated over time based on the signals from indoor air pollutant or occupancy sensors. SBDCV offers two potential advantages: better control of indoor pollutant concentrations, and lower energy use and peak energy demand. Based on theoretical considerations and on a review of literature, SBDCV has the highest potential to be cost-effective in applications with the following characteristics: (a) a single or small number of pollutants dominate so that ventilation sufficient to control the concentration of the dominant pollutants provides effective control of all other pollutants; (b) large buildings or rooms with unpredictable temporally variable occupancy or pollutant emission; and (c) climates with high heating or cooling loads or locations with expensive energy. At present, most SBDCV systems are based on monitoring and control of carbon dioxide (CO2) concentrations. There is a limited number of well-documented case studies that quantify the energy savings and the cost-effectiveness of SBDCV. The case studies reviewed suggest that in appropriate applications, SBDCV produces significant energy savings with a payback period typically of a few years.

Standards for Efficiency of Electric Motors

In this article, feasible minimum limits for IE4 class are analyzed, taking into account the estimated efficiency limits and rated efficiency for emergent or commercially best available line-start PMSM technologies. The presented results can be useful to set up future international standard super-premium or IE4-class levels/limits. The practicability and technical limits associated with the IE4-class efficiency levels are addressed, taking into account technical and economical limitations. It is expected that advanced technologies will enable manufacturers to design motors for the IE4-class efficiency levels, with mechanical dimensions compatible with the existing IMs of lower efficiency classes (e.g., flanges, shaft heights, or frame sizes as defined in standards EN 50347 and NEMA MG1). NEMA frames sizes are larger than the IEC frame sizes, allowing the use of more active materials. In addition, 60-Hz operation enables higher power density and higher efficiency levels with the same frame sizes.

Energy-efficient motor systems in the industrial and in the services sectors in the European Union: characterisation, potentials, barriers and policies

This paper shows how electricity is used by electric motors in both the industrial and the services’ sectors in the European Union, as well as the potential electricity savings by the year 2015 with the application of Energy-Efficient Motors and Variable Speed Drives. Additionally, the main barriers identified in the field characterization study and the measures to overcome those barriers are presented.

Beyond induction motors — Technology trends to move up efficiency

Premium/IE3 efficiency class motors are now mandatory in North America. Super-Premium/IE4 and Ultra-Premium/IE5 efficiency classes are to be defined in the 2nd Edition of the IEC 60034-30 standard. For line-start fixed-speed applications, Super-Premium/IE4-class line-start permanentmagnet (PM) motors and squirrel-cage induction motors are recent entrances in the industrial motor market. For variable-speed applications, IE4-class synchronous reluctance motors are also a recent entrance in the market. For the low-power range, moving from the IE4 to the IE5 class may require moving away from radial-flux induction motor technology and into PM and reluctance technology, either using rare-earth or ferrite magnets. In this paper, efficiency analysis on the best available emerging electric motor technologies, such as axial-flux PM synchronous motors, is presented. The potential efficiency gain associated with several design options as well as some considerations on the theoretical maximum efficiency achievable taking into account those existing design options.

Simulating pursuit with machines. Experiments with robots and artificial vision

This article describes one solution for the problem of pursuit of objects moving on a plane by using a mobile robot and an active vision system. The solution deals with the interaction of different control systems using visual feedback and it is accomplished by the implementation of a visual gaze holding process interacting cooperatively with the control of the trajectory of a mobile robot. These two systems are integrated to follow a moving object at constant distance and orientation with respect to the mobile robot. The orientation and the position of the active vision system running a gaze holding process give the feedback signals to the control used to pursuit the target in real-time. The paper addresses the problems of visual fixation, visual smooth pursuit, navigation using visual feedback and compensation for systems movements. The algorithms for visual processing and control are described in the article. The mechanisms of cooperation between the different control and visual algorithms are also described. The final solution is a system able to operate at approximately human walking rates as the experimental results show in the paper.

Multi-robot exploration and fire searching

Exploration of an unknown environment is a fundamental concern in mobile robotics. This paper presents an approach for cooperative multi-robot exploration, fire searching and mapping in an unknown environment. The proposed approach aims to minimize the overall exploration time, making it possible to localize fire sources in an efficient way. In order to achieve this goal, the robots should cooperate in an effective way, so they can individually and simultaneously explore different areas of the environment while they identify fire sources. The proposed approach employs a decentralized frontier based exploration method which evaluates the cost-gain ratio to navigate to target way-points. The target way-points are obtained by an A* search variant algorithm. The potential field method is used to control the robots motion while avoiding obstacles. When a robot detects a fire, it estimates the flames position by triangulation. The communication between the robots is done in a decentralized control way where they share the necessary data to generate the map of the environment and to perform cooperative actions in a behavioral decision making way. This paper presents simulation and experimental results of the proposed exploration and fire search method and concludes with a discussion of the obtained results and future improvements.

Market transformation of energy-efficient motor technologies in the EU

Based on a recent study carried out for the European Union (EU), this paper briefly characterizes the motor electricity end-use consumption in the industrial and in the services sectors, in the EU countries, and estimates the identified electricity savings potential with the application of energy-efficient motor technologies, namely energy-efficient motors, variable speed drives and efficient end-use devices (pumps, fans and compressors). Additionally, there is a detailed presentation of the barriers for the penetration of energy-efficient motor systems, which have been identified in the field, as well as an extensive description of the measures to overcome those barriers and promote energy-efficient motor systems.

OmniClimbers: Omni-directional magnetic wheeled climbing robots for inspection of ferromagnetic structures

This paper introduces Omniclimber, a new climbing robot with high maneuverability for inspection of ferromagnetic flat and convex human made structures. In addition to maneuverability, adaptability to various structures with different curvatures and materials are addressed. The conceptual and detailed design of OmniClimbers are presented and two prototypes of the robot are introduced. Several laboratory and field tests are reported, and the results are discussed.