Demo: Gondola – a Parametric Robot Infrastructure for Repeatable Mobile Experiments

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When deploying a testbed infrastructure for Wireless Sensor Networks (WSNs), one of the most challenging features is to provide repeatable mobility. Wheeled robots, usually employed for such tasks, strive to adapt to the wide range of environments where WSNs are deployed, from chaotic office spaces to neatly raked potato fields. For this reason, wheeled robots often require an expensive customization step in order to adapt, for example, their localization and navigation systems to the specific environment. To avoid this issue, we present Gondola, a parametric robot infrastructure based on pulling wires, rather than wheels. Gondola avoids the most common problems of wheeled robots and easily adapts to many WSNs’ scenarios. Different from existing solutions, Gondola can easily move in 3-dimensional space, with no need of a complex localization system and with an accuracy that is comparable to o-the-shelf traditional robots.

Acm Digital Library | Paper  | Code and schematics on GitHub

Authors: Marco Cattani and Ioannis Protonotarios
Research groups:  Embedded Software group, Delft University of Technology
Conference: 14th ACM Conf. on Embedded Networked Sensor Systems (SenSys)
Year: 2016

Staffetta: Smart Duty-Cycling for Opportunistic Data Collection

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Recent opportunistic routing protocols address the problem of efficient data collection in dynamic wireless sensor networks, where the radio is duty cycled to save energy and
the topology changes due to link dynamics and node mobility.
Unlike traditional approaches that maintain a routing structure (e.g., a tree), opportunistic schemes forward packets to the first neighbor that wakes up, thereby reducing latency and energy consumption and increasing the robustness to network dynamics.
Notwithstanding the many advantages, this paper argues that existing opportunistic protocols do not fully exploit the synergy between duty cycling and routing in that all nodes wake up with the same fixed frequency. Instead, we present Staffetta, a duty-cycle scheduling mechanism that dynamically adjusts each node’s wake-up frequency in a distributed fashion, such that nodes closer to the sink are more active than nodes at the edge of the network. The resulting activity gradient effectively biases the forwarding choices of opportunistic mechanisms towards the sink, as the time to find an awake neighbor is shorter in the direction of the sink. We implement Staffetta in Contiki, and evaluate it in combination with three different opportunistic routing mechanisms
on two testbeds. Our results show that, across the board, Staffetta reduces packet latency by an order of magnitude while halving the energy consumption at minimal overhead.
In some cases the impact is even more profound. Compared to using ORW alone, adding Staffetta can lead to network lifetimes that are six times longer and end-to-end packet deliveries that are 450 times faster. In other words, by smart duty cycling, Staffetta improves opportunistic data collection basically for free.

Acm Digital Library | Paper | Code on GitHub | Presentation

Authors: Marco Cattani and Andreas Loukas and Marco Zimmerling and Marco A. Zuniga and Koen G. Langendoen
Research groups:  Embedded Software group, Delft University of Technology and  Networked Embedded Systems Group, TU Dresden
Conference: 14th ACM Conf. on Embedded Networked Sensor Systems (SenSys)
Year: 2016