Faculty of Electrical Engineering

Czech Technical University in Prague

CTU in Prague

NavLIS - Navigation group of the Laboratory of Aircraft Instrumentation Systems

Department of Measurement
Technická 2, 166 27 Praha 6
Phone: 00420 2 2435 2191, Fax: 00420 2 3333 9929


Who we are

Ing. Jan Roháč, Ph.D.
A coordinator of activities carried on within the NavLIS group aimed at research and development of navigation systems and their measuring units. The activities include both HW and SW design plus system modeling and integration, algorithms for data processing and fusion, and analog signal processing.

Ing. Martin Šipoš
A PhD. student whose research deals with the calibration of inertial sensors, magnetometers and tilt sensors, their signal and data processing, and GPS data handling and application, development of algorithms and data fusion using Kalman filtering approach.

Ing. Jakub Šimánek
A PhD. student whose research interests lie in state estimation techniques and development of navigation algorithms for unmanned vehicles. He works on the data fusion utilizing Kalman filtration and combining inertial sensors, GPS data, and odometry.

Ing. Mushfiqul Alam
A PhD. student currently focused on the application of adaptive data processing approaches in control systems. His interests extend to applied optimal control theory to complex aerospace systems such as flexible aircrafts and helicopters. Currently, he is working on a helicopter guidance system utilizing a Synthetic Aperture Radar (SAR).

Ing. Miroslav Strob
A PhD. student whose research deals with data processing of inertial sensors and aiding systems by using Kalman filtering. He works on implementation of navigation algorithms to FPGAs to provide a navigation solution with high update rate.

Bc. Marek Bílý
A master degree student working on the development of data acquisition units applied in navigation systems. He deals with the implementation of digital processing algorithms into microcontrollers.


NavLIS group activities

  • Calibration of inertial sensors and measuring units (multi-axial accelerometers and angular rate sensors), calibration of tilt sensors and magnetometers. Design and development of calibration devices.
  • Calibration of temperature dependencies of inertial sensors, tilt sensors, and magnetometer. Testing of vibration impacts on sensors' performance.
  • Estimation techniques of attitude and 3D position based on fusing data from measuring systems such as inertial sensors, magnetometers, tilt sensors, odometers, ultrasound distance sensors, and GNSS. The applicability is oriented at unmanned aerial and terrestrial vehicles, robots, hand-held devices, smart metal detectors etc.
  • Research and development of algorithms applied in navigation solutions enabling vibration impact reduction and correct dynamics recognition.
  • Research and development of data validation techniques.
  • Design and development of navigation systems with wide applicability in fields of unmanned aerial and terrestrial vehicles as well as on board the light aircrafts.
  • Development of algorithms for high update rate navigation solution for tracking of objects with high dynamics.
  • Development of algorithms for data validation and anomaly detection.
  • Development of multi-sensor navigation units with modified sensor configuration.

What it is good for

Research being done in the NavLIS group is primary oriented at increasing level of safety of light aircrafts, unmanned aerial and terrestrial vehicles, robots applications in the way to provide a correct navigation solution. Our main objective is increasing precision of navigation systems performance in estimation of both 3D position and attitude of a navigated object. Since theoretical knowledge about navigation equations and principles are well known, practice is often different which could be caused by varying application dynamics, environmental impacts on measuring systems and their imperfections. In the NavLIS group we aim at research, design, and development of navigation algorithms covering previously mentioned characteristics and thus we reduce their effect on a final navigation system precision. Applicability of our navigation solutions and designed navigation systems is wide in many fields, for instance they can be used in aerial and terrestrial vehicles providing terrain and urban area monitoring and positioning, in tracking systems used for security issues optically measuring a position of the object being monitored, in navigation solutions used in an autonomous flight control, etc.

Projects and research activities

Modular system for attitude and position estimation

The project carried on from 2010 to 2012 and financed by Czech Technical University in Prague. The aim of the project was to design new approaches to complex data acquisition and an innovative structure of heterogeneous multi-sensor system (see Fig. 1) to satisfy criterions of precise positioning with low-cost and readily available sensors and measuring subsystems. For the purpose of the complex system experimental evaluation there was a need to develop an integrated system with a modular structure of used sensors and subsystems. The complex and integrated system in its final form included IMU (Inertial Measurement Unit) as a primary subsystem aided by GPS, ADC (Air Data Computer), magnetometer, electrolytic tilt sensors, optical and ultrasound distance sensors. The whole modular system in full configuration was experimentally verified when placed on board the UAV Bellanca Super Dectahlon XXL manufactured by Hacker Model Production Ltd., see Fig. 1.

Fig. 1 - UAV Bellanca Super Dectahlon XXL (left), a modular navigation system for attitude and position estimation (center), sensor placement on UAV (right)

Research and development of technologies for radiolocation mapping and navigation systems

The project is financed by Technology Agency of the Czech Republic under No. TA02011092. The project deals with the R&D of a radiolocation mapping and navigation system and with the extension of knowing-how in this field in the Czech Republic. The system consists of a radiolocation unit based on SAR (Synthetic Aperture Radar) technology, an inertial navigation unit, and of a control module. The integration of mentioned units brings a unique system fulfilling functions of a continual navigation and the evaluation of landscape image even under adverse weather conditions. In this project our group is responsible for a navigation unit research, design, and development, as well as the whole system integration and user interface. The system should be capable of real time navigation providing position, velocity, and orientation in space, and of monitoring terrestrial objects and terrain in a real time which covers image processing, evaluation of prominences, comparison of the image with its model. First version of the navigation unit is shown in Fig. 2, the second multi-sensor version is shown in Fig. 3 and the general SAR performance is denoted in Fig. 4.

Fig. 2 - Navigation system allowing connection of external magnetometer and GPS receiver with a wi-fi module (left), the artificial horizon displayed in a tablet with Android operating system (right)

Fig. 3 - Multi-sensor inertial measurement unit with modified accelerometer configuration

Fig. 4 - Real scenery (left) and SAR scenery image (right)

The survey points range-finding system utilization for perimeter security (screen)

Is solved as a part of project VG20122015076 financed by Ministry of the Interior of the Czech Republic. The project deals with two survey points range-finding system (TRS) with horizontal or vertical base for protection of strategic infrastructure. A demonstration model of TRS will be designed and verified and it will enable an implementation of the TRS principle on the condition that the target will be observable by at least two cameras at the same time. It will enable measurement of the target axis, its velocity vector and trajectory extrapolation of the target incl. the data transfer to users. The concept of all system is shown in Fig. 5.

Fig. 5 - Principle scheme of the structure of the range-finding system used for perimeter security

Modern methods in development of inertial navigation systems

A project financed by Czech Technical University in Prague under grant No. SGS13/144/OHK3/2T/13. The project has two main objectives. First one is to develop a precise INS using only accurate inertial sensors, such as fiber optic gyroscopes DSP-3100 (KVH manufacturer) and quartz accelerometers INN-204 (Innalabs manufacturer), see Fig. 6. The challenge lies not only in the system development and realization including design and implementation of algorithms needed for attitude and position determination that is not relying on other sensor aiding, but also in the system testing, calibration, and experimental verification. Since high accuracy is required and precise inertial sensors are planned to use, it is necessary to implement a complex navigation equation calculation without any simplifications, which allows getting close to the accuracy of precise and expensive industrial navigation solutions. The second objective of the proposal lies in a miniature and very low-cost INS design, which could be further used for various purposes. Advantages of such a system will originate from unique integration of up-to-date sensors combined with algorithms improving the precision of the position and attitude estimates. The applicability of both units will be very broad, starting with small and medium sized aircrafts, intelligent mine detector, unmanned aerial vehicles or mobile robots, hand-held devices for pedestrian navigation.

Fig. 6 - Realization of "Tactical grade" inertial navigation system (from left): concept scheme, quartz accelerometer INN-204, mounting frame for accelerometers, mounting frame for fiber optic gyroscopes DSP-3100, realization "Tactical grade" inertial system.

Techniques and devices to calibrate and test measuring systems used for navigation purposes

Research, design, and development of All-In-One calibration platform, shown in Fig. 7, supplemented by research and calibration algorithms and techniques to provide time and cost-effective approach. The platform can be used for multi-axial accelerometers, angular rate sensors, magnetometers, and tilt sensors calibration. The platform does not affect a magnetic field because it is made from non-magnetic materials. It utilizes reference measuring system formed by a fiber optic gyro DSP-3100 (see Fig. 6) and a precise inclinometer HCA528T, see Fig. 8. We also study the behavior of mentioned measurement systems under different environmental conditions, such as temperature and vibration, and consequently we include these behaviors into our navigation algorithms for their compensation.

Fig. 7 - Platform for the calibration of low-cost tilt measurement systems (left), a principle image of the All-In-One calibration platform (right).

Fig. 8 - System for precise tilt measurements - an inclinometer HCA528T (left), a PCB for its signal processing (right).

Financial support

  • SGS10/288/OHK3/3T/13 - Modular system for attitude and position estimation, internal CTU grant (2010-2012)
  • TA02011092 - Research and development of technologies for radiolocation mapping and navigation systems, the grant of the Technology Agency of the Czech Republic (2012-2014)
  • VG20122015076 - The survey points range-finding system utilization for perimeter security (screen), the grant of the Ministry of the Interior of the Czech Republic (2012-2015)
  • SGS13/144/OHK3/2T/13 - Modern methods in development of inertial navigation systems, internal CTU grant (2013-2014)

Industry collaboration in research

  • OPROX a.s. - development of position and localization systems for security applications,
  • Hacker Model Production s.r.o. - UAV manufacturer, 3D printing,
  • DevCom Praha s.r.o. - development and manufacture of aircraft onboard instruments,
  • PEGASUS Network - cooperation based on joint research projects, internships, and on high level education in aerospace field and increasing its quality,
  • Skylife Engineering - development of calibration platform for navigation systems.

Selected publications

  • Šimánek, J. - Reinštein, M. - Kubelka, V.: Evaluation of the EKF-based Estimation Architectures for Data Fusion in Mobile Robots. IEEE-ASME TRANSACTIONS ON MECHATRONICS. 2014, vol. 20, no. 2, p. 985-990. ISSN 1083-4435.
  • Nováček, P. - Roháč, J. - Šimánek, J. - Ripka, P.: Metal Detector Signal Imprints of Detected Objects. IEEE Transactions on Magnetics. 2013, vol. 49, no. 1, p. 69-72. ISSN 0018-9464.
  • Ďaďo, S. - Roubíček, T. - Roháč, J.: Methods of Evaluation of Output Signals from Resonance Accelerometers. Sensors and Transducers [online]. 2014, vol. 177, no. 8, p. 286-293. ISSN 1726-5479.
  • Šipoš, M. - Pačes, P. - Roháč, J. - Nováček, P.: Analyses of Triaxial Accelerometer Calibration Algorithms In: IEEE Sensors Journal. 2012, vol. 12, no. 5, p. 1157-1165. ISSN 1530-437X.
  • Roháč, J. - Ďaďo, S.: Impact of Environmental Vibration on Inertial Sensors' Output. Sensors and Transducers [online]. 2013, vol. 24, p. 19-27. ISSN 1726-5479.
  • Šipoš, M. - Roháč, J. - Nováček, P.: Analyses of Electronic Inclinometer Data for Tri-axial Accelerometer's Initial Alignment In: Przeglad Elektrotechniczny. 2012, vol. 88, no. 01a, p. 286-290. ISSN 0033-2097.
  • Šipoš, M. - Roháč, J. - Nováček, P.: Improvement of Electronic Compass Accuracy Based on Magnetometer and Accelerometer Calibration In: Acta Physica Polonica A. 2012, vol. 121, no. 4, p. 945-949. ISSN 0587-4246.
  • Nováček, P. - Roháč, J. - Ripka, P.: Complex Markers for a Mine Detector. IEEE Transactions on Magnetics. 2012, vol. 48, no. 4, p. 1489-1492. ISSN 0018-9464.
  • Roháč, J. - Šipoš, M. - Šimánek, J. - Tereň, O.: Inertial Reference Unit in a Directional Gyro Mode of Operation In: IEEE SENSORS 2012 - Proceedings. Piscataway: IEEE Service Center, 2012, p. 1356-1359. ISBN 978-1-4577-1765-9.
  • Roháč, J. - Reinštein, M. - Draxler, K.: Data Processing of Inertial Sensors in Strong-Vibration Environment In: Intelligent Data Acquisition and Advanced Computing Systems (IDAACS). Piscataway: IEEE, 2011, vol. 1, p. 71-75. ISBN 978-1-4577-1426-9.
  • Reinštein, M. - Roháč, J. - Šipoš, M.: Algorithms for Heading Determination using Inertial Sensors In: Przeglad Elektrotechniczny. 2010, vol. 86, no. 9, p. 243-246. ISSN 0033-2097.
  • Ripka, P. - Nováček, P. - Reinštein, M. - Roháč, J.: Position Sensing System for Eddy-current Mine Imager In: EUROSENSORS XXIV - Proceedings [CD-ROM]. Linz: Elsevier BV, 2010, p. 276-279. ISSN 1877-7058.
  • Reinštein, M. - Šipoš, M. - Roháč, J.: Error Analyses of Attitude and Heading Reference Systems In: Przeglad Elektrotechniczny. 2009, vol. 85, no. 8, p. 114-118. ISSN 0033-2097.
  • Alam, M. - Narenathreyas, K.: Oblique Wing: Future Generation Transonic Aircraft. World Academy of Science, Engineering and Technology. 2014, vol. 8, no. 5, p. 75-78. ISSN 1307-6892.

Responsible person: doc. Ing. Milan Polívka, Ph.D.