Stephan Rottmann

Toward automated driving in cities using close-to-market sensors: An overview of the V-Charge Project

Future requirements for drastic reduction of CO2 production and energy consumption will lead to significant changes in the way we see mobility in the years to come. However, the automotive industry has identified significant barriers to the adoption of electric vehicles, including reduced driving range and greatly increased refueling times. Automated cars have the potential to reduce the environmental impact of driving, and increase the safety of motor vehicle travel. The current state-of-the-art in vehicle automation requires a suite of expensive sensors. While the cost of these sensors is decreasing, integrating them into electric cars will increase the price and represent another barrier to adoption. The V-Charge Project, funded by the European Commission, seeks to address these problems simultaneously by developing an electric automated car, outfitted with close-to-market sensors, which is able to automate valet parking and recharging for integration into a future transportation system. The final goal is the demonstration of a fully operational system including automated navigation and parking. This paper presents an overview of the V-Charge system, from the platform setup to the mapping, perception, and planning sub-systems.

Undervolting in Real World WSN Applications: A Long-Term Study

The fault-tolerant character of WSN protocols and applications that do not assume completely reliable systems legitimize undervolting - a highly efficient energy management technique where the supply voltage is set below the minimum specifications. As has been shown in earlier work, by using thereliable IdealVolting undervolting scheme the lifetime of WSN applications can be increased significantly while keeping the node in a safe state even under rough environmental conditions. To show the usability of undervolting in a real world WSN deployment, we performed a long-term study of IdealVolting in a Smart Farming application. All measurements were performed on a generic outdoor testbed for WSNs (PotatoNet) which is also presented within this paper. We collected a long-term dataset of a WSN running for one farming season on a potato fieldto compare the reliability and performance characteristics of IdealVolting against a regular powered WSN.

Demo: PotatoNet -- Robust Outdoor Testbed for WSNs: Experiment like on your desk. Outside.

We present PotatoNet, an outdoor testbed for Wireless Sensor Networks (WSNs). Its primary focus is robustness, reliability and flexibility. PotatoNet is designed to operate without on-site maintenance for extended periods of time. It can withstand heat, dust and rain and has already been tested running outside for several months.

Amphisbaena: A Two-Platform DTN Node

In most Wireless Sensor Network deployments, the energy supply is a major challenge. Especially for nodes with high computational power or high bandwidth communication interfaces, the required size of batteries might increase to infeasible levels, even if the option of energy harvesting exists. For many use cases, some nodes are idling most of the time and transmitting only a few bytes from time to time. In this paper, we present a two-platform node consisting of a high-power and a low-power platform. Both platforms are using the same Delay-Tolerant Networking (DTN) architecture and the same protocols. A novel concept offers the opportunity for both platforms to appear as a single node to communication partners. The high-power part is running a full-featured Linux operating system, the low power platform is built around an energy-efficient 32-bit microcontroller and is able to fulfill tasks, which would have required to wake up the high power node in a conventional setup. Our system can increase the energy efficiency in WSN scenarios where the demand of bandwidth and computational performance is strongly fluctuating.

Mitigating Blackhole attacks in a hybrid VDTN

In the past we presented a delay tolerant network that used public buses and trams in the city of Braunschweig to monitor air pollution. Today, as smartphones are becoming computationally more powerful and offer a variety of communication interfaces, it becomes attractive to investigate whether smartphones and vehicular nodes can cooperate with each other, forming a network that can provide better quality of service to applications. In this paper, we evaluate the feasibility of creating an integrated Delay- and Disruption-Tolerant Network (DTN) consisting of smartphones and the public transportation system. Most importantly we propose a Misbehavior Detection System (MDS) to protect the security of the hybrid network. The evaluation results show that our MDS is able to efficiently detect attackers and defend the hybrid network against the interference of malicious nodes.

Design and implementation of a low-power energy management module with emergency reserve for solar powered DTN-nodes

DTN nodes often idly wait for contacts and unnecessarily consume energy during these periods. For solar-powered nodes this means that solar panels and batteries could be much smaller with an efficient energy management, reducing the physical size of these nodes. We present our design of a solar-powered DTN node including a module that handles solar charge management, energy management and a discovery mechanism to wake sleeping nodes. Moreover, the system senses the remaining battery capacity, and keeps a reserve for emergency communications. Our evaluation shows that the power management modules design is energy-efficient and performs as intended. Furthermore, we evaluate the discovery mechanism. The results show that the capabilities of the module offer a promising new approach to the implementation of energy efficient routing in DTNs.

On the Experiences with Testbeds and Applications in Precision Farming

While success stories are likely to be reported, failures are rarely published -- even if a lot can be learned from them. In this paper we present experiences and findings from our testbed and WSN deployments. Our PotatoNet has been deployed on an agricultural area in 2015 to perform several WSN outdoor experiments while measuring the stress of potato crops. It was extended a year later by the PotatoMesh, a solar panel-based mesh network of nodes. Throughout both of these deployments we experienced problems and failures at different stages of the projects. We derive key problems and some important concepts when it comes to outdoor WSN deployments.

Automated valet parking and charging for e-mobility

Automated valet parking services provide great potential to increase the attractiveness of electric vehicles by mitigating their two main current deficiencies: reduced driving ranges and prolonged refueling times. The European research project V-Charge aims at providing this service on designated parking lots using close-to-market sensors only. For this purpose the project developed a prototype capable of performing fully automated navigation in mixed traffic on designated parking lots and GPS-denied parking garages with cameras and ultrasonic sensors only. This paper summarizes the work of the project, comprising advances in network communication and parking space scheduling, multi-camera calibration, semantic mapping concepts, visual localization and motion planning. The project pushed visual localization, environment perception and automated parking to centimetre precision. The developed infrastructure-based camera calibration and semi-supervised semantic mapping concepts greatly reduce maintenance efforts. Results are presented from extensive month-long field tests.

No-cost distance estimation using standard WSN radios

Being able to determine the location of a node is of great advantage in many IoT and WSN applications. For example, in health care scenarios or for autonomous configuration of IoT setups this information can be useful. One of the key challenges in localization is to estimate the distance between nodes. Most present indoor localization systems require additional hardware for this estimation which is costly in terms of money and energy consumption. To overcome this disadvantage, we developed a system which is able to perform distance measurements without adding any extra hardware and costs. It is based on phase measurements performed by the IEEE 802.15.4 transceiver chip that is normally solely used to realize communication. In the evaluation we investigate the performance of our system in different real world environments that are typical for IoT and WSN setups.

Paint it Black: Increase WSN Energy Efficiency with the Right Housing

It is a well-known fact that Wireless Sensor Networks (WSNs) that are exposed to real environmental conditions suffer from harsh temperatures. Yet, the temperature does not only have negative impact as the energy efficiency of processing units benefits from higher temperatures. The minimal voltage for correct operation of CMOS circuits is bounded by the temperature. Thus, temperature-dependent undervolting schemes for WSN nodes have been proposed in the past to extend the network lifetime. However, not much thought has been given into directly influencing the most relevant factor: Temperature. In this work we look at the influence of various WSN housings onto the temperature profile of WSN nodes and quantify the energy saving potential of choosing the right housing.