Bálint Vanek

Longitudinal motion control of a high-speed supercavitation vehicle

This article focuses on theoretical developments in modeling and control of High-Speed Supercavitating Vehicles (HSSV). A simplified model of longitudinal dynamics is developed for control, and a dynamic inversion based inner-loop control technique is proposed to handle the switched, time-delay dependent behavior of the vehicle. Two outer-loop control schemes are compared for guidance level tracking. Various aspects of disturbance characteristics and actuator dynamics are investigated and analyzed.

Collision avoidance for UAV using visual detection

Unmanned Arial Vehicles (UAVs) require the development of some on-board safety equipments before inheriting the sky. An on-board collision avoidance system is being built by our team. Due to the strict size, weight, power, and costs constraints, visual intruder airplane detection is the only option. This paper introduces our visual airplane detector algorithm, which is designed to be operational in clear and in cloudy situations under regular daylight visual conditions. To be able to implement the algorithm on-board, we have carefully selected topographic operators, which can be efficiently solved on cellular processor arrays.

Practical approach to real-time trajectory tracking of UAV formations

An unmanned aerial vehicle (UAV) formation in a leader-follower structure, where the UAVs are flying a common trajectory determined by a route planner hosted on the leader is considered. The path description is compressed by polynomial functions with respect to the flight envelope constraints and transmitted to the followers, where a model predictive control (MPC) outer loop controller specifies the command signals for the 7-h locally controlled dynamics with respect to the nonlinear constraints of the aircraft dynamics. Real time feasibility issues associated with the design are discussed.

Theoretical aspects of high-speed supercavitation vehicle control

A control system based on feedback linearization is developed for a high-speed supercavitating underwater vehicle. The supercavitation bubble surrounding the body leads to reduced drag but is also responsible for the undesired switched, nonlinear and delay dependent behavior caused by the phenomena known as planing. The theoretical contributions of the switched control design are discussed in connection with the mathematical description of the system. Special attention is made to understand and handle the complex and novel dynamics of the vehicle

Performance Characteristics of a Complete Vision Only Sense and Avoid System

The present paper investigates the real world feasibility of a purely vision based sense and avoid system, required for small unmanned aerial vehicles (UAV) to routinely access the national airspace. The two distinct functions, sensing and avoidance are integrated into a common framework. No information is exchanged between aircraft, only passive 2-D vision information is available to estimate the encountering traffic. Based on the predicted intruder motion the time of the encounter and the minimum distance are predicted. In case an intruder violates the minimum separation the onboard autopilot initiates an avoidance maneuver. The viability of the system is demonstrated on several estimation approaches, using Extended Kalman filter (EKF) and Unscented Kalman filter (UKF) implementations. Since it is shown that for certain type of observer movements the estimation process remains unobservable in bearings-only problems, the sensitivity of the estimation performance and the resulting avoidance response with respect to different intruder motion is investigated in a Monte-Carlo simulation. The system is tested on a high fidelity Hardwarein-the-Loop (HIL) simulation platform, where flight control algorithms, scene rendering, image processing and estimation algorithms are implemented individually over a network of computers with special emphasis on parallel implementation of computationally intensive tasks. Representative encounter scenarios are presented to provide performance measures, including detection time and achieved miss distance of distinctive approaches to assess the applicability of the results.

Performance analysis of a vision only sense and avoid system for small UAVs

This paper investigates the real world feasibility of a purely vision based sense and avoid system, required for small unmanned aerial vehicles (UAV) to routinely access the national airspace. No information is exchanged between aircraft, only passive 2-D vision information is available to estimate the encountering tra c. The viability of the system is demonstrated on several estimation approaches, using Extended Kalman lter (EKF) and Unscented Kalman lter (UKF) implementations. Since it is shown that for certain type of observer movements the estimation process remains unobservable in bearings-only problems, the sensitivity of the estimation performance with respect to the self motion of the own craft is investigated. The system is tested on a high delity Hardware-in-the-Loop (HIL) simulation platform, where ight control algorithms, scene rendering, image processing and estimation algorithms are implemented individually over a network of computers with special emphasis on parallel implementation of computationally intensive tasks. Representative encounter scenarios are presented to provide performance measures, including detection time and miss distance of distinctive approaches to assess the applicability of the results.

Hybrid decentralized receding horizon control of vehicle formations

A hybrid rule-based extension of a recently proposed decentralized receding horizon control (RHC) scheme is presented for vehicle formation control. The scheme makes use of logic rules which improve stability and feasibility of the decentralized method by enforcing coordination. The decentralized control laws which respect the rules are computed using hybrid control design techniques. The basic ideas are illustrated on a two-vehicle formation flight example. A more complex simulation involving six vehicles is shown as well to demonstrate the potential benefits of using rules for coordination within the RHC scheme

Control of high-speed underwater vehicles

I (GB) was fortunate that early in my career I had the opportunity to work with Keith Glover. Keith had just begun his obsession with golf. A simple game where a ball stands still and the player advances it from different parts of the landscape into a hole. During a golf outing, Keith vigorously struck a ball off the fairway. It drove through a water hazard and miraculously ended up a few feet off the green. I was amazed by the image I saw as the ball moved through the water. Due to its velocity, a cavitation bubble was generated behind it. I had no inkling that my golf outing with Keith would lead many years later to an interest in the control of supercavitating vehicles.

A five-camera vision system for UAV visual attitude calculation and collision warning

A five-camera vision system was developed for UAV visual attitude calculation and collision warning. The vision system acquires images by using five miniature cameras, stores, and evaluates the visual data real-time with a multi-core processor system implemented in FPGA. The system was designed to be able to operate on a medium sized UAV platform, which raised numerous strict physical constraints.

Visual Detection and Implementation Aspects of a UAV See and Avoid System

One of the missing critical on-board safety equipment of the Unmanned Arial Vehicles (UAVs) is the collision avoidance system. In 2010 we launched a project to research and develop an SAA system for UAS. As the system will be on-board in a small aircraft we have to minimize the weight, the volume, and the power consumption. The acceptable power consumption is 1–2W and the mass of the control system is maximum 300–500g. Here we present the concept of a visual input based See and Avoid (SAA) system. This paper introduces the long range visual detection algorithm and the implementation aspect of the many core processor device.