Real-time model-based video stabilization for microaerial vehicles

The emerging branch of micro aerial vehicles (MAVs) has attracted a great interest for their indoor navigation capabilities, but they require a high quality video for tele-operated or autonomous tasks. A common problem of on-board video quality is the effect of undesired movements, so different approaches solve it with both mechanical stabilizers or video stabilizer software. Very few video stabilizer algorithms in the literature can be applied in real-time but they do not discriminate at all between intentional movements of the tele-operator and undesired ones. In this paper, a novel technique is introduced for real-time video stabilization with low computational cost, without generating false movements or decreasing the performance of the stabilized video sequence. Our proposal uses a combination of geometric transformations and outliers rejection to obtain a robust inter-frame motion estimation, and a Kalman filter based on an ANN learned model of the MAV that includes the control action for motion intention estimation.Peer ReviewedPostprint (author's final draft

Identifikacija bespilotnih ronilica korištenjem postupka vlastitih oscilacija

Control of underwater vehicles is a challenging task since these systems demonstrate highly coupled and nonlinear behavior in uncertain and often unknown environment. In order to successfully design higher levels of control hierarchy, sufficiently accurate parameters of a mathematical model describing the vessel is required. These parameters vary significantly depending on the payload; hence conventional, time-consuming identification methods are tedious. This paper introduces a self-oscillation based method for determining inertia and drag parameters for underwater vehicles. The procedure is easily implementable in field conditions and gives satisfactory results. Both linear and nonlinear models of yaw, heave and surge degree of freedom can be identified. Experimental results obtained from yaw identification experiments on a real underwater vehicle will be presented. In addition to this, the same methodology will be used to determine which model describes the vehicle dynamics more suitably. Modifications of the proposed algorithm for systems with delays and discrete-time systems will be described, together with an estimate of parameter error bounds due to quantization levels.Upravljanje bespilotnim ronilicama predstavlja zahtjevan zadatak budući da ronilice pokazuju snažno spregnuto i nelinearno ponašanje u nepredvidljivim i često nepoznatim okruženjima. U svrhu uspješnog projektiranja viših razina u njihovoj upravljačkoj hijerarhiji, potrebno je dovoljno dobro poznavati parametre matematičkog modela plovila. Ovi se parametri mogu znatno mijenjati ovisno o opremi i drugim uvjetima tijekom misije, stoga su uobičajeni, vremenski zahtjevni identifikacijski postupci neprikladni. Članak opisuje postupak koji koristi vlastite oscilacije za određivanje inercije i otpornosti bespilotnih ronilica. Postupak je lako primjenjiv u terenskim uvjetima i daje zadovoljavajuće rezultate. Linearan i nelinearan model zaošijanja, zaranjanja i napredovanja mogu´ce je identificirati. U radu su prikazani eksperimentalni rezultati dobiveni na identifikacijskim ekperimentima zaošijanja na stvarnoj ronilici. Uz navedeno, ista metodologija je iskorištena za odlučivanje o modelu koji prikladno opisuje stvarnu ronilicu. U radu su opisane i preinake predloženog algoritma za sustave s transportnim kašnjenjem i diskretne sustave, kao i procjene pogrešaka u određivanju parametara koje su posljedica kvantizacije

Assessment of quality indicators of the automatic control system influence of accident interference

This work concentrates the analysis of the system of automatic control of the directive diagram of the moving active electronically scanned array with a limited number of transceiver modules. The analysis revealed a number of shortcomings that lead to a significant increase in standard deviations, quadratic integral estimates, and an increase in transient time. The identified disadvantages lead to a decrease in the efficiency of the antenna system, an increase in the error rate at the reception, the inability of the system to react to disturbances applied to any point of the system in the event of a mismatch of a given signal/noise level. In accordance with the analysis, the mathematical model of the automatic control system of the directional diagram of the moving active electronically scanned array was considered, considering this a new method of estimating the quality indicators of the automatic control diagram of the directional diagram of the active electronically scanned array in a random setting and disturbing action was developed. The difference between the proposed method and the existing method is in the construction of an automatic control system with differential coupling equivalent to the combination due to the introduction of derivatives of the random setting action of the open compensation connection

Model based tuning of a variable-speed governor for a distributor fuel-injection pump

Iako prevaziđeni, mehanički regulatori su još uvek u velikoj meri zastupljeni kao deo postojećih, pa čak i novih sistema za ubrizgavanje goriva kod dizel-motora. Mehanički regulatori se nameni prilagođavaju pomoću podesivih elemenata kojima se diskretno menja karakteristika regulatora. Radi što jednostavnijeg podešavanja i sveobuhvatnog sagledavanja uticaja pojedinih parametara na regulatorsku karakteristiku, formiran je i predstavljen matematički model regulatora. Rad se bavi analizom uticaja podesivih parametara na statičke i dinamičke karakteristike sverežimskog regulatora distributor pumpe tipa DPA. Analiza dinamičkog ponašanja regulatora spregnutog sa motorom, u zatvorenoj petlji, vršena je u okviru sveobuhvatne jednodimenzionalne višedomenske simulacije.Rather obsolete, mechanical governors are still used in an enormous number of existing and even some new diesel engine injection systems. Change of a governor characteristic and adapting to a specific engine application is possible through adjustments of governor's elements. In order to achieve fast and accurate evaluation of adjustable parameters, mathematical model of a governor is introduced. This paper deals with the impact of adjustable parameters on static and dynamic characteristics of the mechanical variable-speed governor in DPA distributor type fuel injection pump. Dynamic testing of a closed loop Diesel engine - governor - injection system is conducted within comprehensive 1D multidomain simulation environment

Model based tuning of a variable-speed governor for a distributor fuel-injection pump

Iako prevaziđeni, mehanički regulatori su još uvek u velikoj meri zastupljeni kao deo postojećih, pa čak i novih sistema za ubrizgavanje goriva kod dizel-motora. Mehanički regulatori se nameni prilagođavaju pomoću podesivih elemenata kojima se diskretno menja karakteristika regulatora. Radi što jednostavnijeg podešavanja i sveobuhvatnog sagledavanja uticaja pojedinih parametara na regulatorsku karakteristiku, formiran je i predstavljen matematički model regulatora. Rad se bavi analizom uticaja podesivih parametara na statičke i dinamičke karakteristike sverežimskog regulatora distributor pumpe tipa DPA. Analiza dinamičkog ponašanja regulatora spregnutog sa motorom, u zatvorenoj petlji, vršena je u okviru sveobuhvatne jednodimenzionalne višedomenske simulacije.Rather obsolete, mechanical governors are still used in an enormous number of existing and even some new diesel engine injection systems. Change of a governor characteristic and adapting to a specific engine application is possible through adjustments of governor's elements. In order to achieve fast and accurate evaluation of adjustable parameters, mathematical model of a governor is introduced. This paper deals with the impact of adjustable parameters on static and dynamic characteristics of the mechanical variable-speed governor in DPA distributor type fuel injection pump. Dynamic testing of a closed loop Diesel engine - governor - injection system is conducted within comprehensive 1D multidomain simulation environment

Synthesis of low-order regulators by specified placement of closed system poles

Algorithm of regulator synthesis supporting arrangement of closed system dominant poles in specified points and arrangement of non-dominant poles in specified area has been suggested. Two-phase algorithm is based on the method of D-partitioning modified with conditions for system poles arrangement and the method of searching the best solution in parameter region which guarantees the desired pole arrangement. The example is give

Control Space Reduction and Real-Time Accurate Modeling of Continuum Manipulators Using Ritz and Ritz-Galerkin Methods

To address the challenges with real-time accurate modeling of multisegment continuum manipulators in the presence of significant external and body loads, we introduce a novel series solution for variable-curvature Cosserat rod static and Lagrangian dynamic methods. By combining a modified Lagrange polynomial series solution, based on experimental observations, with Ritz and Ritz-Galerkin methods, the infinite modeling state space of a continuum manipulator is minimized to geometrical position of a handful of physical points (in our case two). As a result, a unified easy to implement vector formalism is proposed for the nonlinear impedance and configuration control. We showed that by considering the mechanical effects of highly elastic axial deformation, the model accuracy is increased up to 6%. The proposed model predicts experimental results with 6%-8% (4-6 mm) mean error for the Ritz-Galerkin method in static cases and 16%-20% (12-14 mm) mean error for the Ritz method in dynamic cases, in planar and general three-dimensional motions. Comparing to five different models in the literature, our approximate solution is shown to be more accurate with the smallest possible number of modeling states and suitable for real-time modeling, observation, and control applications

Safety-Conscious Pushing on Diverse Oriented Surfaces with Underactuated Aerial Vehicles

Pushing tasks performed by aerial manipulators can be used for contact-based industrial inspections. Underactuated aerial vehicles are widely employed in aerial manipulation due to their widespread availability and relatively low cost. Industrial infrastructures often consist of diverse oriented work surfaces. When interacting with such surfaces, the coupled gravity compensation and interaction force generation of underactuated aerial vehicles can present the potential challenge of near-saturation operations. The blind utilization of these platforms for such tasks can lead to instability and accidents, creating unsafe operating conditions and potentially damaging the platform. In order to ensure safe pushing on these surfaces while managing platform saturation, this work establishes a safety assessment process. This process involves the prediction of the saturation level of each actuator during pushing across variable surface orientations. Furthermore, the assessment results are used to plan and execute physical experiments, ensuring safe operations and preventing platform damage.Comment: Accepted to the 2024 IEEE International Conference on Robotics and Automation (ICRA2024

Control Space Reduction and Real-Time Accurate Modeling of Continuum Manipulators Using Ritz and Ritz-Galerkin Methods

To address the challenges with real-time accurate modeling of multi-segment continuum manipulators in the presence of significant external and body loads, we introduce a novel series solution for variable-curvature Cosserat rod static and Lagrangian dynamic method. By combining a modified Lagrange polynomial series solution, based on experimental observations, with Ritz and Ritz-Galerkin methods, the infinite modeling state space of a continuum manipulator is minimized to geometrical position of a handful of physical points (in our case two). As a result, a unified easy to implement vector formalism is proposed for the nonlinear impedance and configuration control. We showed that by considering the mechanical effects of highly elastic axial deformation, the model accuracy is increased up to 6%. The proposed model predicts experimental results with 6-8% (4-6 [mm]) mean error for the Ritz-Galerkin method in static cases and 16-20% (12-14 [mm]) mean error for the Ritz method in dynamic cases, in planar and general 3D motions. Comparing to five different models in the literature, our approximate solution is shown to be more accurate with the smallest possible number of modeling states and suitable for real-time modeling, observation and control applications