Papers by Author: Zdzisław Gosiewski

Abstract: To design vibration control system for flexible structures their mathematical model should be reduced. In the paper we consider the influence of the model reduction on the dynamics of the real closed-loop system. A simply cantilever beam is an object of consideration since we are able to formulate the exact analytical model of such structure. As a result of reduction the model with low frequency resonances is usually separated from the high frequency dynamics because high frequency part of the model is naturally strong damped. In order to estimate dynamical system for control purposes in the paper we applied a few orthogonal methods such as: modal, Rayleigh-Ritz and Schur decompositions. As it is shown all methods well calculate resonances frequencies but generate different anti-resonances frequencies. From control strategy in point of view of the flexible structures these anti-resonances have significantly influence on the stability and dynamics of the closed-loop systems.

Abstract: In this paper we describe a numerical model and a construction of an electromagnetic launcher (EML) consisting of ten copper coils located serially. The solenoids were mounted on the pipe-shaped slideway, inside which, the ferromagnetic core was moved driven by the coils magnetic force. The paper presents the model of an EML based on circuit approach involving lumped parameters which were obtained by means of a finite element methods (FEM). The numerical representation contained a mechanical part with introduced friction coefficients. In the article we proposed an algorithm which enabled us to fit the numerical model to the constructed device by selection of these friction parameters values. Thus, we were able to compare the signals from computer simulations and measurements which were taken during laboratory tests.

Abstract: The paper presents a model of the 10-coil launcher, which can be used as a catapult of micro aerial vehicles (MAVs). The main advantage of such a device is the possibility of controlling its acceleration. We have also shortly described main disadvantages of pneumatic and rubber launchers and compared them to our solution which involved magnetic phenomena. The history and the classification of magnetic launchers were also mentioned. The investigated magnetic system was described in details. The system voltage equations and energetic conversions which take place during the launch were presented. With the use of finite element method we calculated the lumped parameters of the system (self-and mutual inductances). Nonlinear model was implemented in the MATLAB packet. Launch operation was divided into an acceleration and a braking phase. Thus, nine coils operated as accelerators and the last one was employed as a magnetic brake. The system was controlled by means of PID regulators which were tuned manually. Current values in the modelled coils were also limited by bang-bang controllers. In the last part of the paper we presented results of simulations and discussion about possible improvements of the model in the future.

Abstract: The bearingless systems are a key technology in many power mechatronic applications. The topic of the paper reports the original, very relevant and very timely research. The methods of numerical and experimental testing of the bearingless induction motor, presented in the paper revised, are convergent with the directions of up-to-date research in this domain.

Abstract: In the paper we present development work on an electromagnetic launcher (EML) for micro aerial vehicles (MAVs). The requirements of controlled take-off were shortly described and main advantages and disadvantages of the commonly used rubber and pneumatic launchers were enumerated. Concept, design and construction of the magnetic coil launcher were presented. The driving coils geometry determination with using the method, which was based on finite element method (FEM) and mechanical power analyses, was proposed. Finally, construction and assembling process of the device were described. In addition, the results of preliminary laboratory tests, control issues and controller target platform were mentioned.

Abstract: The problem of autonomous formation flight control of UAVs (Unmanned Aerial Vehicles) is presented in the paper. A decentralized control method of the autonomous formation flight realization is described. A practical approach to the UAV formation flight control was shown. The applied method bases on the information exchange between flying objects. The shared data concern the position and velocity of the aircraft. Constructed UAV airframe was presented as well as used autopilot, developed formation flight control unit, wireless communication links and used data packet structure. The main aim of this work was the in-flight tests. The test of formation flight with Virtual Leader (VL) was examined. The autopilot reactions to the incoming data packets with desired altitude, airspeed and heading from formation flight controller were checked. During the flights the longitudinal and lateral positions of the UAV, orientation angles (pitch, roll, yaw), angular velocities (pitch rate, roll rate, yaw rate) and many other flight parameters were logged. The research and flight tests checked and verified the developed method of formation flight control.

Abstract: The paper presents integration process of commercial autopilot. The autopilot was integrated with a fixed wing airframe. The main aim of this work was an experimental study of the autopilot integrated with a micro aircraft. A few manual and autonomous mode flights were performed. During the field trials the autopilot PID parameters were tuned and, as a result, the process of PID gains selection was described. Selected PID gains were presented. Certain telemetry parameters such as longitudinal and lateral position of aircraft, orientation angles, and angular velocities were logged during flight and analyzed. Maximum and minimum airspeeds at a desired altitude were measured and presented. Moreover, Received Signal Strange Indicator between ground station and UAV equipped with special antenna was measured and logged for radio communication quality and range checking. Presented analysis of the autopilots work and obtained results were used to assess the applicability of this hardware to next formation flight operations.

Abstract: The paper describes matters of modeling and control of aerial vehicle in rotorcraft configuration. Equations of motion were derived and dynamic model of six-rotor was build. To find the best adjustment of model to real object the dynamics of the drives was joined to the control plant model. Trimming and linearization were performed. Open loop system and LQR controller were checked in simulation environment. Next the faults of the actuator/sensor elements were arranged and the minimal number of observed outputs and drives for LQR stabilization process were specified.

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.

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.