Showing papers by "Ivan Petrović published in 2013"

Active speaker localization with circular likelihoods and bootstrap filtering

Abstract: This paper deals with speaker localization in two dimensions from a mobile binaural head. A bootstrap particle filtering scheme is used to perform active localization, i.e. to infer source location by fusing the binaural perception with the sensor motor commands. It relies on an original pseudo-likelihood of the source azimuth which captures both the interaural level and phase differences. Since the pseudo-likelihood is discrete, it is fitted with a mixture of circular distributions in order to enhance its resolution. For the fitting task two mixtures are compared and evaluated, namely the mixture of von Mises and wrapped Cauchy distributions. Furthermore, a solution is presented for calculating the von Mises curvefitting with low uncertainty, since the direct implementation can quickly surpass double precision floating number representation. The performance of the filter is compared using both the raw and fitted pseudo-likelihoods on experiments recorded in an acoustically prepared room with ground-truth obtained from a motion capture system. The results show that the proposed algorithm successfully localizes the speaker with an advantage in the direction of the fitted von Mises mixture likelihood.

Global Localization Based on 3D Planar Surface Segments

Abstract: Global localization of a mobile robot using planar surface segments extracted from depth images is considered. The robot's environment is represented by a topological map consisting of local models, each representing a particular location modeled by a set of planar surface segments. The discussed localization approach segments a depth image acquired by a 3D camera into planar surface segments which are then matched to model surface segments. The robot pose is estimated by the Extended Kalman Filter using surface segment pairs as measurements. The reliability and accuracy of the considered approach are experimentally evaluated using a mobile robot equipped by a Microsoft Kinect sensor.

Efficient navigation for anyshape holonomic mobile robots in dynamic environments

Abstract: Platforms with holonomic drives are particularly interesting due to their maneuvering capabilities. Robots used for transportation tasks usually have a non-circular footprint. In this work, we present a navigation strategy for a holonomic mobile robot with anyshape footprint. Our technique introduces an efficient navigation method based on a strategy that makes use of discrete and continuous techniques. We introduce compact discrete intervals to represent the free space for computing fast-to-update plans. Based on these, we provide a continuous motion generation approach to generate smooth motions that are fast to compute. We evaluated our approach by running simulated experiments and by using a real holonomic L-shaped robot. Our experiments demonstrate that our technique can be carried out online and is able to smoothly drive the robot to its goal locations even in dynamic environments.

A leader-follower approach to formation control of multiple non-holonomic mobile robots

Abstract: Many cooperative tasks in real world environments need the robots to maintain some desired formations when moving. Formation control refers to the problem of controlling the relative position and orientation of robots in a group, while allowing the group to move as a whole. In this paper, a novel leader-follower formation control law for multiple non-holonomic mobile robots based on kinematic models and trajectory tracking techniques is proposed.

Global Localization Based on 3D Planar Surface Segments

Abstract: Global localization of a mobile robot using planar surface segments extracted from depth images is considered. The robot’s environment is represented by a topological map consisting of local models, each representing a particular location modeled by a set of planar surface segments. The discussed localization approach segments a depth image acquired by a 3D camera into planar surface segments which are then matched to model surface segments. The robot pose is estimated by the Extended Kalman Filter using surface segment pairs as measurements. The reliability and accuracy of the considered approach are experimentally evaluated using a mobile robot equipped by a Microsoft Kinect sensor.

Development and testing of small aerial vehicles with redundant number of rotors

Abstract: Multiple rotor Unmanned Aerial Vehicles (UAVs) are becoming ubiquitous due to simplicity of their construction, implementation and maintenance. Such UAVs are able to hover, take off and land vertically. In addition, it is relatively straightforward to design an on-board autopilot. In comparison with classical helicopters, multi-rotor aircrafts provide less dangerous testbed in urban and cluttered environments due to their small-size and light-weight blades. In this paper, we present two multi-rotor aircraft prototypes with payload up to one kilogram. In order to achieve greater payload capabilities and increase robustness due to motor failures, the presented prototypes have redundant number of rotors, one has six and other eight rotors. Furthermore, we propose algorithms for data fusion from gyroscopes, accelerometers, magnetometers and GPS for orientation and position estimation. Finally, control algorithms are designed in a multi-loop fashion and successfully tested on the prototypes. The developed UAVs are experimentally tested in real world outdoor environment conditions.

Concept of an intrabody networked brain-computer interface controlled assistive robotic system

Abstract: In this paper we present a concept of an assistive robotic system for the people with disabilities. Since the target users most likely have difficulties using standard user interfaces, e.g. keyboard and mouse as input devices for a graphical user interface, we propose braincomputer interface (BCI) to be used for controlling the system. Novelty of our approach lays in the integration of the entire system using an intrabody communication (IBC) network. Using the IBC network reduces the need of superfluous wiring and reduces the time needed to setup the system for use, i.e. it greatly simplifies the use of the system from the user perspective.