Solid State Phenomena Vol. 198

Abstract: The analysis of the available fuel cells technologies indicates that Polymer Electrolyte Membrane Fuel Cells (PEMFCs) currently offer the highest attainable efficiency. This technology has been especially useful for underwater applications, since the moment it reached the greatest mass and volumetric power density among all available types of fuel cells (i.e. respectively more than 700 W/kg and 1100 W/dm3) [1,. The article presents the results of the preliminary research steps, aimed at establishing the genuine power supplying system of an underwater platform, to verify the applicability of this technology to specific underwater conditions.

Abstract: In the first part of the paper, specific aspects concerning the omnidirecional Mecanum wheels are presented, while the second part is dedicated to the presentation of two prototypes of omnidirectional robots, equipped with omnidirectional Swedish wheels.

Abstract: River Formation Dynamics is a heuristic optimization algorithm based on the manner, in which drops of water form the river bed. The idea is to imitate the movement of drops on the edges between given nodes thus performing a search based on their height, which is modified through the mechanism of soil erosion and sediment deposition. In this way decreasing gradients are constructed, and these are followed by subsequent drops to compose new gradients and reinforce the best ones. This paper presents implementation of the method in wheeled mobile robot path searching task in an environment with obstacles. At first, a concise introduction to the RFD algorithm is presented, along with the problems requirements. In the main part a simulation test has been performed using the algorithm to find the shortest route from the starting point to the goal. The tests were made with different landscape layouts, measuring the computation time. The last section presents a real life implementation of the algorithm using a Pioneer P3-DX mobile robot. The validity of this solution is discussed, as well as any modifications, along with a brief comparison with a similar, popular search path algorithm.

Abstract: Water and underwater vehicles are driven by propellers. Various models use propellers with 2 to 7 blades with either fixed or controllable pitch. Another known solution are water-jet propellers. Water is sucked from the front of the vehicle and ejected through a nozzle at the rear. A propeller is usually the water pumping component. This paper presents the design of a novel type of water-jet propeller, inspired by the way animals move in the aquatic environment. It discusses the mechanisms of propeller operation and its structural solutions. It also presents theoretical simulation studies and actual studies on a real object, which enabled assessment of the propellers parameters.

Abstract: This paper presents a practical implementation of a complementary filter for 3D attitude estimation in an indoor setting. The structure of the filter is chosen basing on design principles described in [. It demonstrates the basic foundations of a complementary filter and proposes a simple and concise implementation for sensor fusion of data collected using an IMU and a Hokuyo URG 04LX laser scanner. Experimental results are shown for a handheld test bed satisfactory quality of estimation.

Abstract: The necessary hardware and stereovision obstacle avoidance algorithm used by UAV (unmanned aerial vehicles) are described in this paper. The algorithm bases on method of matching the areas of image by using the standard SAD (sum of absolute differences) as a measure of fit. The rapid machining of the image is done by compare the windows areas. Method didn't check individual pixels what is important feature. The application target is operating in unknown environment with the changing light conditions which may disturb the proper operation of the obstacle avoidance algorithm. To reduce the reflection effect the averaging filter for each frame image is applied. This is realized by compare of the average brightness values in successive video frames. It allows to control the factor of the achromatic color in the image. To increase the performance, in the anti-collision system the algorithm controls only the area being the center of the picture connected with the direction of the UAV flight. When the obstacle is detected the image is tested globally to find the direction of the avoidance maneuver. Onboard computer for anti-collision system uses a serial communication with the autopilot ArdupilotMega. A quadrocopter (multicopter that is propelled by four rotors) was chosen as a control object.

Abstract: The article presents a measurement system for a micro UAV designed at the Department of Avionics and Control Systems of Rzeszów University of Technology. Since the project is based on earlier projects, e.g.[[[[1[[[1, the introduction begins with their short presentation [they are mentioned in the introduction firs. Then, the current project is discussed. The major objective of the project is to create a miniature autopilot cooperating with navigation units, data transmission units and measurement units. The system is based on Polish technological solutions. The autopilot is designed as a single unit, however the system is open and it allows you to use different elements. The system development is also possible. In-flight testing will be realized with the use of two unmanned flying platforms equipped with an electrical engine and a piston engine. The total mass of the platforms is 5 kg and 25 kg respectively. The article presents the structure of the control and navigation system and then, the structure of the measurement system. The measurement units consist of a GPS receiver, an attitude and heading reference system (AHRS) and an air data computer (ADC). Similar configuration is used in other micro UAV solutions, such as Micropilot or Kestrel. Then, algorithms of the measurement system are described. Navigation is based on GPS data with a DGPS (Differential GPS) advanced module. If the measurement information is complete, GPS data are used to correct measurements from other units. The system estimates wind disturbances and calculates accelerometers errors. In the case of missing GPS signals implementation of low-cost sensors may lead to significant measurement errors, and hence navigation only by means of the INS is impossible. In such a case, navigation is realized with the use of an inertial navigation system (INS), the magnetic heading measurement and ADC. AHRS unit algorithms use quaternion algebra for attitude calculation. For correction, complementary filtering is implemented [, [. The correction signal for the attitude (pitch and roll angles) is calculated with the use of acceleration measurements. Measurements of accelerations and yaw rates are used for the correction switching mechanism, since in dynamic states signals calculated from accelerations cannot be used for correction. Heading is corrected by means of magnetic heading measurement. ADC algorithms are based on typical aerodynamic dependences.

Abstract: Controlling the flight of Micro Aerial Vehicles (MAV) is a highly challenging task, mostly due to nonlinearity of their models and highly varying longitudinal and lateral derivatives coefficients [. As such, it requires a proper form of robust control. The demand for such control is very high, as it is required in many applications. The following paper presents the application of Unfalsified Control Theory developed by Michael G. Safonov [1, 2, 6, . This interesting approach is based on the adaptive switching control, and does not require any previous knowledge of the controlled plant. The controlled dynamics is decoupled due to longitudinal and lateral motion of the Bell 540 single-delta wing micro aerial vehicle. The work involves design and simulation of the proper robust controller. The simulation is based on already obtained nominal model of the Bell 540 vehicle [. The developed controllers were proved to be efficient, based on performed calculations and simulation in Matlab.

Abstract: This article presents algorithm of autonomous microplane flight control in street canyons using image from a camera as a carrier of information about microplane surroundings. Algorithm structure and video information processing are formed in a way that enables their implementation with the use of available equipment such as microcameras, advanced autopilot and signal processor DSP. On the basis of the developed algorithm model simulation research was prepared and conducted. Obtained results confirm effectiveness of this algorithm in autonomous flight control of microplane in street canyons. However, conducted simulations did not use real video image, but only simplified model of street map perspective image.

Abstract: A configuration of universal base station designed to use mobile networks for long-range transmission of telemetry data is described in the paper. Types of cellular networks and modes of their operation are presented. Next, GPRS system is shown as a possible method of data transmission between UAV and Base Station. Communication modes of the station can be augmented by additional close-range communication system based on Xbee modules. The configuration and integration of test stand for telemetric signals monitoring are shown. Finally, the modes of possible operations based on the conditions of mobile networks are described.