A carregar...
2 resultados
Resultados da pesquisa
A mostrar 1 - 2 de 2
- Underwater Localization System Combining iUSBL with Dynamic SBL in ¡VAMOS! TrialsPublication . Almeida, José; Matias, Bruno; Ferreira, António João; Almeida, Carlos; Martins, Alfredo; Silva, EduardoEmerging opportunities in the exploration of inland water bodies, such as underwater mining of flooded open pit mines, require accurate real-time positioning of multiple underwater assets. In the mining operation scenarios, operational requirements deny the application of standard acoustic positioning techniques, posing additional challenges to the localization problem. This paper presents a novel underwater localization solution, implemented for the ¡VAMOS! project, based on the combination of raw measurements from a short baseline (SBL) array and an inverted ultrashort baseline (iUSBL). An extended Kalman filter (EKF), fusing IMU raw measurements, pressure observations, SBL ranges, and USBL directional angles, estimates the localization of an underwater mining vehicle in 6DOF. Sensor bias and the speed of sound in the water are estimated indirectly by the filter. Moreover, in order to discard acoustic outliers, due to multipath reflections in such a confined and cluttered space, a data association layer and a dynamic SBL master selection heuristic were implemented. To demonstrate the advantage of this new technique, results obtained in the field, during the ¡VAMOS! underwater mining field trials, are presented and discussed.
- Terrestrial intelligent general-purpose robotic explorerPublication . Amaral, Guilherme; Martins, Alfredo; Dias, André; Almeida, Carlos; Almeida, José; Silva, EduardoIn this work, the TIGRE - Terrestrial Intelligent General-purpose Robotic Explorer is presented. This ground robot was developed to support research activities in autonomous robotic applications in outdoor scenarios. It constitutes a testbed for validation and experimentation on robotic navigation and mapping for unstructured environments, long term autonomy, active perception algorithms, 3D environment modelling and multi robot coordination developments. The vehicle is based on a electric powered four wheel ATV (all terrain vehicle) equipped with navigation and application sensors, onboard computational power and wireless communications. A high precision GPS system and a set of laser scanner sensors equipped on the robot allows applications for precise 3D modelling of the environment. A modular approach was taken for both the hardware and software design ensuring a flexible and incremental development path. This coupled with the use of open source ROS middleware allows for a high degree of flexibility and rapid setup times for multiple robotics research experiments. The vehicle architecture, navigation, control and coordination systems are also described. The hybrid systems approach to the control architecture is discussed in the context of multiple robot coordination. A multi camera vision system, comprising visible spectrum and infra-red cameras is presented along with some vision based target detection results on an outdoor scenario.