Simone Battistini

Differential games missile guidance with bearings-only measurements

The implementation of missile guidance laws on collision course trajectories with bearings-only measurements may result in bad range observability. This in turn may result in poor engagement performance for those guidance algorithms that exploit range information in their steering law. Maneuvering away from the collision course trajectory improves range observability. To propose a sizing criterion for this maneuver, this work presents a new guidance strategy that exploits the information from the error covariance matrix of the homing loop integrated Kalman filter in the framework of a pursuit-evasion game. The new strategy has been tested in several scenarios against other guidance laws, such as the classical formulation of the pursuit-evasion game and proportional navigation. Numerical simulations on a set of Monte Carlo samples show that the proposed solution is able to improve engagement performance in terms of both miss distance and range observability.

Development of a meteorology and remote sensing experimental platform: The LAICAnSat-1

This work presents the first advanced level CanSat developed by the University of Brasilia, the LAICAnSat-1. The main objective is to design, build and launch an experimental high altitude balloon CanSat withmeteorology and remote sensing applications. Both the scientific need for a self retrievable radiosonde, with precise and high quality sensors, and a high altitude low-cost remote sensing experimental platform inspired the team on the concept of LAICAnSat-1. This platform has a broad sensor suite that provides information about temperature, pressure, humidity and UV light level. It also has a modular design, based on stacks, allowing other sensors to be easily embedded to the main module. The remote sensing sensor is a small high performance camera, constantly imaging the Earth surface. Those images can be used for several applications, including emergency and quick solutions for monitoring the Amazon forest, Pantanal, and other important biomes, supporting and complementing research projects on remote areas. The control system has four sensors to determine the payload attitude and position. Furthermore, this platform could potentially be exploited by the industry, representing a safe and inexpensive way to test components and circuits in high altitudes, as for instance to certify Commercial Off-The-Shelf electronic components with respect to their behavior under low temperature and pressure. The LAICAnSat-1 represents a preliminary step in the development of complex aerospace projects and is also an important first experience for engineering students.

System identification of a square parachute and payload for the LAICAnSat

This work is a part of the LAICAnSat project of the University of Brasilia aimed at developing near-space experimental BalloonSats for scientific missions and remote sensing applications. The project is divided in two main parts: Low Altitude Part (LAP) and High Altitude Part (HAP). For the HAP, two successful launches were made with a 1200 g latex balloon using helium and carrying a payload with embedded sensors in order to collect local information. Regarding the LAP, which is the focus of this work, the team is currently working on the identification of the aerodynamic model parameters of a square parachute to be used in future launches. The final goal is the implementation of a suitable control system to land the payload in a predefined area. The main motivation to develop such a system is to make the payload rescue easier, avoiding areas of difficult access such as dense forests. Therefore, it is important to develop a system that is capable navigating the payload, and the first step for that is the aerodynamic model identification. To reach this objective, the team is using a remote controlled parachute to collect data for the identification process and test the proposed model. Trajectory and speed are acquired by the BeeLine GPS 2-meter in a trimmed flight and used to identify steady-state coefficients (CL0 and CD0). The derivatives parameters, such as CLα, CDα, and others, will be estimated using biologically inspired computing and parachutes wind-tunnel data from the literature.

Trajectory control system for the LAICAnSat-3 mission

This work presents the trajectory control system for the LAICAnSat-3 mission. The LAICAnSat project was established at the University of Brasilia for creating a low cost educational platform for conducting experiments at high and low altitudes. LAICAnSat previous stages include two launches of balloon-sats (LAICAnSat-1 and LAICAnSat-2). These two launches allowed the test of a preliminary system, which included a broad sensor suite (a high performance camera, temperature, pressure, humidity, UV light level, altitude, position, speed, heading, and acceleration sensors) and a communication and tracking system. The trajectory control of the LAICAnSat-3 is active during its descent phase. The goal of the guidance is to autonomously land the vehicle in a prescribed area. The directional control of the vehicle is provided by a paraglider, which is steered laterally by a servo motor that pulls the lines of the canopies. The system does not have a glide slope control, therefore the only controllable trajectory is the one on the horizontal plane; the vertical motion is assumed constrained by gravity and by the lift to drag ratio of the vehicle. Trajectory planning is based on a kinematic model of the vehicle and foresees the implementation of a series of trajectory paths of maximum control deflection that guarantees to remain in a bounded area. The reference heading is tracked by a PID controller, implemented in the on-board computer of the LAICAnSat. Simulations have been performed to assess the robustness of the designed controller to disturbances like wind gusts. The on-board computer is a board designed ad-hoc for this mission. It includes a micro-controller, environmental and inertial sensors, data storage capability, a multi-GNSS module, and the interfaces with the other subsystems of the vehicle. The multi-GNSS module provides position and heading information, which are used both on ground to track the flight and on-board to provide the feedback to the PID.

Interacting multiple model unscented filter for tracking a ballistic missile during its boost phase

Boost-phase detection of a ballistic missile is an attractive option for defense systems because boosting rockets are easy to detect and, in this phase, countermeasures are less effective. Nevertheless, it raises technical criticalities due to the short burn-out times and to the unknown features and behavior of the missile. The boosting trajectory of a ballistic missile, in fact, can be divided in at least three phases, each one characterized by a different steering strategy: the vertical arc, the pitch maneuver, and the gravity turn. Furthermore, the overall trajectory is very sensitive to variations in the parameters of the model and in the kick angle chosen during the pitch maneuver. Therefore, the tracking of a boosting missile presents two major difficulties: the identification of the missile parameters (ballistic coefficient, mass rate, thrust over weight ratio, etc.), and the determination of the steering strategy. The multiple models filter approach has been adopted in this paper to cope with these issues. In particular, an improved version of the Interacting Multiple Model Unscented Filter (IM-MUF) for tracking a missile has been introduced. Essentially, a modified form of the filter Markov Transition Matrix (MTM), ad hoc designed for the problem of tracking a ballistic missile during its boost phase, is proposed. The probabilities of the state transitioning from one dynamic model to another are given by the MTM elements. In the traditional approach, these probabilities are supposed constant and known. In this work these conservative hypotheses have been relaxed and these probabilities have been considered to be functions of the estimated state vector, thanks to specific features of the missile trajectory. A numerical, three-dimensional Monte Carlo simulation has been implemented in order to reconstruct a state vector composed by the position, velocity and missile parameters vectors. The modified IMMUF runs several models, each one accounting for one of the phases of flight with a different value of thrust direction, and combines estimations in order to provide the final estimation. Noisy measurements are obtained from a radar. The results show that the proposed IMMUF with the variable MTM outperform the traditional form of the IMMUF, by giving more accurate estimation.