Filtern
Erscheinungsjahr
- 2014 (10) (entfernen)
Dokumenttyp
Sprache
- Englisch (10) (entfernen)
Schlagworte
- Autonomous micro UAV (2)
- Data fusion (2)
- Gas source localization (2)
- Gas storage areas (2)
- Hazardous scenarios (2)
- Membrane-based gas sensing (2)
- Monitoring (2)
- Subsurface monitoring (2)
- Air-based (1)
- Biologically inspired robots (1)
In this paper, we show that a micro unmanned aerial vehicle (UAV) equipped with commercially available gas sensors can address environmental monitoring and gas source localization (GSL) tasks. To account for the challenges of gas sensing under real-world conditions, we present a probabilistic approach to GSL that is based on a particle filter (PF). Simulation and real-world experiments demonstrate the suitability of this algorithm for micro UAV platforms.
One of the main unsolved issues of under-ground storages for, e.g., CO2, H2, and natural gas is the comprehensive surveillance of these areas with reasonable effort and costs. Conventional sensors (e.g., soil air probes or borehole probes), however, can only be used for punctual or locally limited measurements; further their application can cause structural influences (invasive application).
In this paper, we describe in detail the setup of a CO2 injection soil test field. This test field will be used to enhance and validate an innovative ap-proach for distributed subsurface monitoring of gas storage areas. To the author’s knowledge, this is the first time that, for this purpose, a test field is built in an application relevant scale.
In this work an air-based sensor network for the localization of persons at extensive areas is presented. The developed network consists of a localization device which the person is wearing (BodyGuard-System), a mobile relay station in the air, and a base station. All three parts communicate with the same radio chip. The BodyGuard-System is an inertial navigation system which was developed for localization in difficult environments with high accuracy and low measurement uncertainty. To increase the range of the system, a multi-hop network was built up. The measured data of the BodyGuard-System and the mobile relay station is visualized on a PC in the base station. This multi-hop network is necessary for example for fire department missions.
Insect behavior is a common source of inspiration for roboticists and computer scientists when designing gas-sensitive mobile robots. More specifically, tracking airborne odor plumes and localization of distant gas sources are abilities that suit practical applications such as leak localization and emission monitoring. Gas sensing with mobile robots has been mostly addressed with ground-based platforms and under simplified conditions and thus, there exist a significant gap between the outstanding insect abilities and state of the art robotics systems. As a step towards practical applications, we evaluated the performance of three biologically inspired plume tracking algorithms. The evaluation is carried out not only with computer simulations, but also with real-world experiments in which, a quadrocopter-based micro Unmanned Aerial Vehicle autonomously follows a methane trail towards the emitting source. Compared to ground robots, micro UAVs bring several advantages such as their superior steering capabilities and fewer mobility restrictions in complex terrains. The experimental evaluation shows that, under certain environmental conditions, insect like behavior in gas-sensitive UAVs is feasible in real world environments.
Linear sensor for areal subsurface gas monitoring - calibration routine and validation experiments
(2014)
Membrane based linear gas sensors and fiber optical sensors feature similar geometries and complement each other in quantities to be measured. To the author's best knowledge, it is the first time that these sensors are combined to a multifunctional sensor for distributed measuring of gas concentrations, temperature, and strain. Objective is a comprehensive monitoring of underground gas storage areas. In the presented project a 400 m² test site and a corresponding laboratory system were just built up to characterize, validate, and optimize the combined sensor. Application of the sensor lines in a grid structure should enable spatial resolution of the measurement data and early detection of relevant events, as gas leakage, temperature change, or mechanical impact. A Calibration routine was developed which can be applied subsequent to underground installation. First measurement results indicate the potential of the method, with regard to highly topical energy transport and storage issues.
Multichannel measuring systems are used to measure strains and accelerations during drop tests of containments for dangerous goods. Conventional systems require cabling of each sensor and co-falling of the cable harness, causing problems in the test preparation and execution. Promising results of a single cable measuring system, consisting of measuring modules with data bus connection and local data acquisition were obtained in laboratory investigations and full-scale drop tests.
Comprehensive monitoring of pipelines over their full length is technically difficult and expensive. Considering a cost-benefit ratio it is reasonable to implement monitoring solutions in pipeline segments, which bear a high risk potential, like residential areas, construction sites, slopes, street or river crossings. Still such segments can measure up to several hundred meters in length, demanding for monitoring solutions that extend along such distances and enable fast response. Point wise sensing and periodical surveillance have clear drawbacks, particularly regarding early damage detection. Fibre optic sensors enable distributed sensing of temperature and strain, but they offer very limited possibilities for measuring gas concentrations. Linear membrane-based gas sensors enable the monitoring of gas concentrations alongside a pipeline. Such line-sensors are implemented in form of flexible tubes and can be arranged inside or outside the pipeline (also underwater or within the subsurface), corresponding to the technical requirements. The measuring method combines the gas specific diffusion rates through a membrane with Dalton’s law of partial pressures and enables the calculation of gas concentrations or the detection of a change of the gas composition. The objective is to detect gas leakages fast and with high reliability. Furthermore, the calibrated system enables to estimate the spatial extent of a leakage. So far the gas concentration measurement is tested for oxygen, carbon dioxide, methane; further gases should follow, e.g. hydrogen, carbon monoxide or mixtures like natural gas. The paper introduces in the different operating modes of line-sensors. A near real-time approach will be demonstrated to quantify the impact of a gas leak on the near environment. This approach is based on a critical length describing the expansion of the leaking gas.
The combination of radio-frequency identification (RFID) tags with different types of sensors offers excellent potential for applications with regard to identification, diagnosis, and monitoring. This should be demonstrated by means of two examples of actual developments carried out by the Federal Institute for Materials Research and Testing (BAM). The Identification and diagnosis of concrete components is a major task in the maintenance of critical infrastructure, for instance concrete bridges with heavy traffic volume. A feasibility study investigates the application of RFID sensor systems for this task. The second example reviews the transportation of dangerous goods. Using modern technologies enables promising possibilities to reduce accidents and to avoid non-conformity with transportation regulations. Project results demonstrate an innovative technical solution for monitoring of dangerous goods transports with RFID sensor systems.
The measurement characteristics of every conventional accelerometer are temperature dependent - often to an extent which is highly relevant for the addressed application. For instance, at BAM Container drop tests are performed to investigate and evaluate the structural integrity of Containers for transport and storage of dangerous goods. Often, the test program includes drop tests at specific temperatures, also as part of approval procedures. The applied sensors are exposed to these test conditions and get influenced by them. Acceleration sensors show a considerable temperature influence on their fünction and characteristics. Particularly the damping mechanism of the seismic mass is a critical part. In regard to such applications, capable equipment and methods are required to consider and investigate this aspect in an adequate way. A fortiori as Manufacturer’s infonnation often is deficient. This study presents the setup and results of a method for testing and calibration of acceleration sensors under high dynamic irnpact. It combines a Hopkinson Bar with a temperature chamber.
The combination of different types of sensors to multi-sensor devices offers excellent potential for monitoring applications. This should be demonstrated by means of four different examples of actual developments carried out by Federal Institute for Materials Research and Testing (BAM): monitoring and indoor localization of relief forces, a micro-drone for gas measurement in hazardous scenarios, sensor-enabled radio-frequency identification (RFID) tags for safeguard of dangerous goods, and a multifunctional sensor for spatially resolved under-surface monitoring of gas storage areas. Objective of the presented projects is to increase the personal and technical safety in hazardous scenarios. These examples should point to application specific challenges for the applied components and infrastructure, and it should emphasize the potential of multi-sensor systems and sensor data fusion.