Álvaro Marco

Robust estimator for non-line-of-sight error mitigation in indoor localization

Indoor localization systems are undoubtedly of interest in many application fields. Like outdoor systems, they suffer from non-line-of-sight (NLOS) errors which hinder their robustness and accuracy. Though many ad hoc techniques have been developed to deal with this problem, unfortunately most of them are not applicable indoors due to the high variability of the environment (movement of furniture and of people, etc.). In this paper, we describe the use of robust regression techniques to detect and reject NLOS measures in a location estimation using multilateration. We show how the least-median-of-squares technique can be used to overcome the effects of NLOS errors, even in environments with little infrastructure, and validate its suitability by comparing it to other methods described in the bibliography. We obtained remarkable results when using it in a real indoor positioning system that works with Bluetooth and ultrasound (BLUPS), even when nearly half the measures suffered from NLOS or other coarse errors.

Location-based services for elderly and disabled people

Many techniques have been developed to perform indoor location. Each strategy has its own advantages and drawbacks, with the application demanding location information the main determinant of the system to be used. In this paper, a system is presented that serves location to innovative services for elderly and disabled people, ranging from alarm and monitoring to support for navigation and leisure. The system uses ZigBee and ultrasound to fulfill the application requirements, differing in this respect from all other existing systems. ZUPS (ZigBee and ultrasound positioning system) provides wide multicell coverage, easy extension, robustness even in crowded scenarios, different levels of precision depending on the users profile and service requirements (from a few centimeters to meters), limited infrastructure requirements, simple calibration, and cost-effectiveness. The system has been evaluated from the technical, functional, and usability standpoints, with satisfactory results, and its suitability has also been demonstrated in a residence for people with disabilities located in Zaragoza, Spain.

A Smart Kitchen for Ambient Assisted Living

The kitchen environment is one of the scenarios in the home where users can benefit from Ambient Assisted Living (AAL) applications. Moreover, it is the place where old people suffer from most domestic injuries. This paper presents a novel design, implementation and assessment of a Smart Kitchen which provides Ambient Assisted Living services; a smart environment that increases elderly and disabled peoples autonomy in their kitchen-related activities through context and user awareness, appropriate user interaction and artificial intelligence. It is based on a modular architecture which integrates a wide variety of home technology (household appliances, sensors, user interfaces, etc.) and associated communication standards and media (power line, radio frequency, infrared and cabled). Its software architecture is based on the Open Services Gateway initiative (OSGi), which allows building a complex system composed of small modules, each one providing the specific functionalities required, and can be easily scaled to meet our needs. The system has been evaluated by a large number of real users (63) and carers (31) in two living labs in Spain and UK. Results show a large potential of system functionalities combined with good usability and physical, sensory and cognitive accessibility.

Hidden Issues in Deploying an Indoor Location System

Installing indoor location system prototypes yields practical lessons about how to design and deploy future ubiquitous technologies. The design of context-aware technologies has been on many research team agendas since Mark Weiser first described his ubiquitous computing vision. Determining the location of people and objects in indoor environments with a high degree of accuracy is a main technical obstacle to achieving this vision.

Study of the therapeutic effects of an advanced hippotherapy simulator in children with cerebral palsy: a randomised controlled trial

BackgroundAlthough hippotherapy treatment has been demonstrated to have therapeutic effects on children with cerebral palsy, the samples used in research studies have been very small. In the case of hippotherapy simulators, there are no studies that either recommend or advise against their use in the treatment of children with cerebral palsy. The aim of this randomised clinical study is to analyse the therapeutic effects or the contraindications of the use of a commercial hippotherapy simulator on several important factors relating to children with cerebral palsy such as their motor development, balance control in the sitting posture, hip abduction range of motion and electromyographic activity of adductor musculature.Methods/DesignThe study is a randomised controlled trial. It will be carried out with a sample of 37 children with cerebral palsy divided into two treatment groups. Eligible participants will be randomly allocated to receive either (a) Treatment Group with hippotherapy simulator, maintaining sitting posture, with legs in abduction and rhythmic movement of the simulator or (b) Treatment Group maintaining sitting posture, with legs in abduction and without rhythmic movement of the simulator. Data collection and analysis: all measurements will be carried out by a specially trained blind assessor. To ensure standardization quality of the assessors, an inter-examiner agreement will be worked out at the start of the study. The trial is funded by the Department of Research, Innovation and Development of the Regional Government of Aragon (Official Bulletin of Aragon 23 July 2007), project number PM059/2007.DiscussionInterest in this project is due to the following factors: Clinical originality (there are no previous studies analysing the effect of simulators on the population group of children with CP, nor any studies using as many variables as this project); Clinical impact (infantile cerebral palsy is a chronic multisystemic condition that affects not only the patient but also the patients family and their close circle of friends); Practical benefits (the development of an effective treatment is very important for introducing this element into the rehabilitation of these children).Trial registrationCurrent Controlled Trials ISRCTN03663478.

Synchronization of multihop wireless sensor networks at the application layer

Time synchronization is a key issue in wireless sensor networks; timestamping collected data, tasks scheduling, and efficient communications are just some applications. From all the existing techniques to achieve synchronization, those based on precisely time-stamping sync messages are the most accurate. However, working with standard protocols such as Bluetooth or ZigBee usually prevents the user from accessing lower layers and consequently reduces accuracy. A receiver-to-receiver schema improves timestamping performance because it eliminates the largest non-deterministic error at the senders side: the medium access time. Nevertheless, utilization of existing methods in multihop networks is not feasible since the amount of extra traffic required is excessive. In this article, we present a method that allows accurate synchronization of large multihop networks, working at the application layer while keeping the message exchange to a minimum. Through an extensive experimental study, we evaluate the protocol¿s performance and discuss the factors that influence synchronization accuracy the most.

Synchronization in wireless sensor networks using Bluetooth

Wireless sensor networks (WSNs) can take advantage of versatility, completeness, and low prices of standard wireless protocols; Bluetooth as we show later is a candidate suitable for WSNs. The fusion of data collected over a WSN is just an evident application of time synchronization. Bringing together these two issues, we find that synchronization using standard protocols poses an important drawback. In this paper, we present a simple method that allows clock synchronization in Bluetooth WSNs, down to few microseconds.

Design and Evaluation of a Sound Based Water Flow Measurement System

This paper presents a low-cost, easy to install sound-based system for water usage monitoring in a household environment. It extends the state of the art but not only detecting that water is flowing in a pipe, but also quantifying the flow thus allowing us to compute the amount of water used. We describe the system architecture including hardware, software and the signal processing and pattern recognition algorithms used. We present an extensive evaluation in a real life noisy kitchen environment. We show an accuracy of over 90 percent on classifying six different water flow levels. We also demonstrate good performance measuring water consumption when compared with the homes water meter.

Protocol and Architecture to Bring Things into Internet of Things

The Internet of Things (IoT) concept proposes that everyday objects are globally accessible from the Internet and integrate into new services having a remarkable impact on our society. Opposite to Internet world, things usually belong to resource-challenged environments where energy, data throughput, and computing resources are scarce. Building upon existing standards in the field such as IEEE1451 and ZigBee and rooted in context semantics, this paper proposes CTP (Communication Things Protocol) as a protocol specification to allow interoperability among things with different communication standards as well as simplicity and functionality to build IoT systems. Also, this paper proposes the use of the IoT gateway as a fundamental component in IoT architectures to provide seamless connectivity and interoperability among things and connect two different worlds to build the IoT: the Things world and the Internet world. Both CTP and IoT gateway constitute a middleware content-centric architecture presented as the mechanism to achieve a balance between the intrinsic limitations of things in the physical world and what is required from them in the virtual world. Said middleware content-centric architecture is implemented within the frame of two European projects targeting smart environments and proving said CTPs objectives in real scenarios.

Unmanned Aerial Vehicle Based Wireless Sensor Network for Marine-Coastal Environment Monitoring

Marine environments are delicate ecosystems which directly influence local climates, flora, fauna, and human activities. Their monitorization plays a key role in their preservation, which is most commonly done through the use of environmental sensing buoy networks. These devices transmit data by means of satellite communications or close-range base stations, which present several limitations and elevated infrastructure costs. Unmanned Aerial Vehicles (UAV) are another alternative for remote environmental monitoring which provide new types of data and ease of use. These aircraft are mainly used in video capture related applications, in its various light spectrums, and do not provide the same data as sensing buoys, nor can they be used for such extended periods of time. The aim of this research is to provide a flexible, easy to deploy and cost-effective Wireless Sensor Network (WSN) for monitoring marine environments. This proposal uses a UAV as a mobile data collector, low-power long-range communications and sensing buoys as part of a single WSN. A complete description of the design, development, and implementation of the various parts of this system is presented, as well as its validation in a real-world scenario.