Piotr Kaniewski

Airborne radar terrain imaging system

Synthetic aperture radar (SAR) imaging systems are becoming increasingly useful in military and civilian surveillance applications. Installation of a SAR system on a miniature unmanned aerial vehicle (mini UAV) enables high resolution terrain imaging in adverse observational conditions, e.g. at night, in fog or in smoke, where classical or infrared cameras would be useless. Use of a small and relatively low-cost radar platform allows for reduction of the mission costs and reduces the risk of detection and destruction of the carrier by the enemys air defence. The paper presents a concept, a structure, and the most important elements of the UAV-based SAR terrain imaging system, currently developed in a project WATSAR, jointly realized by the Institute of Radioelectronics of the Faculty of Electronics, Military University of Technology, Warsaw, Poland and a Polish private company WB Electronics S.A., under a grant financed by the National Centre for Research and Development. It is assumed that the system will provide high resolution radar images, comparable with aerial photographs, which will be used for tactical scale military reconnaissance. The SAR images from the developed system can also augment multisensory data processed in Battlefield Management Systems (BMS), supporting decision processes on contemporary battlefield and increasing situational awareness of individual soldiers.

Motion compensation for unmanned aerial vehicle's synthetic aperture radar

The paper presents a method of calculation of motion correction parameters for a Synthetic Aperture Radar (SAR) installed on an Unmanned Aerial Vehicle (UAV). The UAV on-board system consists of a Radar Sensor, an Antenna System, a SAR Processor and a Navigation System. The main task of the navigation part is to determine the vector of difference between a theoretical and a real trajectory of the UAVs center of gravity. The paper includes chosen results of experiments obtained during ground tests.

Chosen results of flight tests of WATSAR system

The paper describes a Synthetic Aperture Radar system currently developed by the Military University of Technology and a Polish private company WB Electronics S.A. in a frame of a project under acronym WATSAR. The project is aimed at designing, development and testing of a terrain imaging radar system operating from a miniature UAV. The paper presents structure and way of operation of the system and its current state of development. The main focus of the paper is directed onto presentation of radar images obtained during two flight campaigns realized in May and July 2015. The paper addresses also the algorithms used for SAR processing and the adopted methodology of in-flight experiments.

Inertial navigation system for radar terrain imaging

The article presents a navigation system used to improve the quality of terrain images obtained from a Synthetic Aperture Radar (SAR) installed on a miniature unmanned aerial vehicle. An inertial navigation system is used to determine the flight path deviations from an assumed straight line. Calculated position corrections are used to correct the phase of the received echo signal in order to get a focused SAR image. The paper describes chosen results of in-flight experiments, presenting the influence of navigation correction on SAR images.

Comparison of estimation accuracy of EKF, UKF and PF filters

Abstract Several types of nonlinear filters (EKF – extended Kalman filter, UKF – unscented Kalman filter, PF – particle filter) are widely used for location estimation and their algorithms are described in this paper. In the article filtering accuracy for non-linear form of measurement equation is presented. The results of complex simulations that compare the quality of estimation of analyzed non-linear filters for complex non-linearities of state vector are presented. The moves of maneuvering object are described in two-dimensional Cartesian coordinates and the measurements are described in the polar coordinate system. The object dynamics is characterized by acceleration described by the univariate non-stationary growth model (UNGM) function. The filtering accuracy was evaluated not only by the root-mean-square errors (RMSE) but also by statistical testing of innovations through the expected value test, the whiteness test and the WSSR (weighted sum squared residual) test as well. The comparison of filtering quality was done in the MATLAB environment. The presented results provide a basis for designing more accurate algorithms for object location estimation.

A method of swath calculation for side-looking airborne radar

The article describes a method of determining the boundaries of an area (called swath) scanned by a side-looking airborne radar. The method assumes that the boundaries of the area are associated with the effective (measured at a level of −3 dB) antenna beam width in the range direction. It takes into account the aircraft altitude above the ground level and its roll and yaw angles. The presented method was tested using measurements obtained from a synthetic aperture radar system.

Estimation of object position using non-linear filters

The paper presents chosen results of testing of non-linear filtering algorithms (an Extended Kalman Filter, two versions of Unscented Kalman Filters and a Particle Filter) in tracking applications. The accuracy of filters have been assessed and compared. The movement of tracked objects has been modeled in a Cartesian frame of reference, whereas the measurements are assumed to be realized in a polar frame of reference. The simulations have been realized under the assumption that the acceleration is described with the Univariate Non-Stationary Growth Model. All the tests have been performed in Matlab®.

Estimation of ballistic object trajectory using non-linear Kalman filtering

The paper addresses a problem of ballistic object trajectory estimation on the basis of measurements from a cinetheodolite electro-optical tracking system. The object flight dynamics is modeled using a three degrees of freedom equations of motion. The estimation of object trajectory is performed with the use of an Extended Kalman Filter.

Visual-based navigation system for unmanned aerial vehicles

The paper presents the way of operation of a Vision-Based Navigation (VBN) system based on the Scene Matching Area Correlation (SMAC) algorithm and demonstrates its applicability for highly autonomous navigation of Unmanned Aerial Vehicles (UAVs). Chosen simulation results included in the paper show that the algorithm proposed by the authors works properly in ideal conditions and demonstrate its acceptable performance in case of typical problems met in VBN systems, i.e. differences of scales of compared images due to altitude errors and their rotation with respect to each other due to yaw errors.

Chosen results of field tests of synthetic aperture radar system installed on board UAV

The paper presents a synthetic information on a UAV-based radar terrain imaging system, its purpose, structure and working principle as well as terrain images obtained from flight experiments. A SAR technology demonstrator has been built as a result of a research project conducted by the Military University of Technology and WB Electronics S.A. under the name WATSAR. The developed system allows to obtain high resolution radar images, both in on-line and off-line modes, independently of the light conditions over the observed area. The software developed for the system allows to determine geographic coordinates of the imaged objects with high accuracy. Four LFM-CW radar sensors were built during the project: two for S band and two for Ku band, working with different signal bandwidths. Acquired signals were processed with the TDC algorithm, which allowed for a number of analyses in order to evaluate the performance of the system. The impact of the navigational corrections on a SAR image quality was assessed as well. The research methodology of the in-flight experiments of the system is presented in the paper. The projects results show that the developed system may be implemented as an aid to tactical C4ISR systems.