Component based design of a drug delivery capsule robot

Since the introduction of Wireless Capsule Endoscopy (WCE) researchers have started exploring the design space of Medical Capsule Robots (MCRs): embedded micro-systems that can operate autonomously within the human body and can diagnose, prevent, monitor, and cure diseases. Although the research in the area of MCRs is an active topic and has grown exponentially, current devices provide only limited functionalities because their design process is expensive and time consuming. To open this research field to a wider community and, at the same time, create better designs through advanced tool support, in our previous works we presented a design environment for the rapid development of MCRs. In this paper, this environment was adopted to design a Drug Delivery Capsule (DDC) based on a coil-magnet-piston mechanism. The force of the coil acting on the magnetic piston and the drug release profile were modeled and assessed on bench-top with a maximum relative error below 5%. Then, in vivo trials were performed to validate the DDC functionality with a scheduled drug release profile for a 5 h and 24 min procedure. The resulting design environment template is available open source for further development of drug delivery applications as well as to serve as guideline in prototyping novel MCRs addressing other clinical needs

On the Scalability of Routing Integrated Time Synchronization

Abstract. Reactive time synchronization is becoming increasingly popular in the realm of wireless sensor networks. Unlike proactive protocols, traditionally implemented as a standalone middleware service that provides a virtual global time to the application layer, reactive techniques establish a common reference time base post facto, i.e. after an event of interest has occurred. In this paper, we present the formal error analysis of a representative reactive technique, the Routing Integrated Time Synchronization protocol (RITS). We show that in the general case, the presence of clock skews cause RITS to scale poorly with the size of the network. Then we identify a special class of sensor network applications that are resilient to this scalability limit. For applications outside this class, we propose an in-network skew compensation strategy that makes RITS scale well with both network size and node density. We provide experimental results using a 45-node network of Berkeley MICA2 motes.

inTrack: High precision tracking of mobile sensor nodes

Abstract. Radio-interferometric ranging is a novel technique that allows for fine-grained node localization in networks of inexpensive COTS nodes. In this paper, we show that the approach can also be applied to precision tracking of mobile sensor nodes. We introduce inTrack, a cooperative tracking system based on radio-interferometry that features high accuracy, long range and low-power operation. The system utilizes a set of nodes placed at known locations to track a mobile sensor. We analyze how target speed and measurement errors affect the accuracy of the computed locations. To demonstrate the feasibility of our approach, we describe our prototype implementation using Berkeley motes. We evaluate the system using data from both simulations and field tests.

Time of arrival data fusion for source localization

The paper presents two sensor fusion algorithms that were utilized in a wireless sensor network-based acoustic countersniper system. The technique for fusing muzzle blast Time Of Arrival (TOA) data is able to eliminate multipath effects prevalent in urban environments and to resolve multiple simultaneous acoustic sources. The approach for fusing shockwave TOA data that are generated by supersonic projectiles is able to reconstruct the trajectory with an accuracy of 1 degree in both azimuth and elevation for long range shots. If a few muzzle blast detections are also available then accurate range estimation is also performed. The system performance was demonstrated multiple times at different MOUT (Military Operations in Urban Terrain) facilities of the U

Marmote SDR: Experimental Platform for Low-Power Wireless Protocol Stack Research

Abstract: Over the past decade, wireless sensor network research primarily relied on highly-integrated commercial off-the-shelf radio chips. The rigid silicon implementation of the radio stack restricted access to the lower layers; thus, research focused mainly on the medium access control (MAC) layer and above. SRAM field-programmable gate array (FPGA)-based software-defined radios (SDR), on the other hand, provide a flexible architecture to experiment with any and all layers of the radio stack, but usually require desktop computers and draw high currents that prohibit mobile or longer-term outdoor deployments. To address these issues, we have developed a modular flash FPGA-based wireless research platform, called Marmote SDR, that has computational resources comparable to those of SRAM FPGA-based radio platforms, but at a reduced power consumption, with duty cycling support. We discuss the design decisions underlying Marmote SDR and evaluate its power consumption. Furthermore, we present and evaluate an asynchronous and multiple access communication protocol specifically designed for data-gathering wireless sensor networks

The flooding time synchronization protocol

Wireless sensor network applications, similarly to other distributed systems, often require a scalable time synchronization service enabling data consistency and coordination. This paper describes the Flooding Time Synchronization Protocol (FTSP), especially tailored for applications requiring stringent precision on resource limited wireless platforms. The proposed time synchronization protocol uses low communication bandwidth and it is robust against node and link failures. The FTSP achieves its robustness by utilizing periodic flooding of synchronization messages, and implicit dynamic topology update. The unique high precision performance is reached by utilizing MAC-layer timestamping and comprehensive error compensation including clock skew estimation. The sources of delays and uncertainties in message transmission are analyzed in detail and techniques are presented to mitigate their effects. The FTSP was implemented on the Berkeley Mica2 platform and evaluated in a 60-node, multihop setup. The average per-hop synchronization error was in the one microsecond range, which is markedly better than that of the existing RBS and TPSN algorithms