Evaluation of machine vision techniques for use within flight control systems

In this thesis, two of the main technical limitations for a massive deployment of Unmanned Aerial Vehicle (UAV) have been considered.;The Aerial Refueling problem is analyzed in the first section. A solution based on the integration of \u27conventional\u27 GPS/INS and Machine Vision sensor is proposed with the purpose of measuring the relative distance between a refueling tanker and UAV. In this effort, comparisons between Point Matching (PM) algorithms and Pose Estimation (PE) algorithms have been developed in order to improve the performance of the Machine Vision sensor. A method of integration based on Extended Kalman Filter (EKF) between GPS/INS and Machine Vision system is also developed with the goal of reducing the tracking error in the \u27pre-contact\u27 to contact and refueling phases.;In the second section of the thesis the issue of Collision Identification (CI) is addressed. A proposed solution consists on the use of Optical Flow (OF) algorithms for the detection of possible collisions in the range of vision of a single camera. The effort includes a study of the performance of different Optical Flow algorithms in different scenarios as well as a method to compute the ideal optical flow with the aim of evaluating the algorithms. An analysis on the suitability for a future real time implementation is also performed for all the analyzed algorithms.;Results of the tests show that the Machine Vision technology can be used to improve the performance in the Aerial Refueling problem. In the Collision Identification problem, the Machine Vision has to be integrated with standard sensors in order to be used inside the Flight Control System

• Addressing pose estimation issues for application of machine vision to UAV Autonomous Aerial Refueling

ABSTRACT The purpose of this thesis is to describe the results of an effort on the analysis of the performance of specific algorithms for the ‘pose estimation’ problem within the context of applying Machine Vision-based control laws for the problem of Autonomous Aerial Refueling (AAR) for UAVs. It is assumed that the MV-based AAR approach features several optical markers installed on specific points of the refueling tanker. However, the approach can be applied without any loss of generality to the more general case of the use feature extraction methods to detect specific points and corners of the tanker in lieu of the optical markers. The document proposes a robust ‘detection and labeling algorithm’ for the correct identification of the optical markers, which is then provided to the ‘pose estimation’ algorithm. Furthermore, a detailed study of the performance of two specific ‘pose estimation’ algorithms (the GLSDC and the LHM algorithms) is performed with special emphasis on required computational effort, robustness, error propagation. Extensive simulation studies demonstrate the potential of the LHM algorithm and also highlight the importance of the robustness of the ‘detection and labeling’ algorithm. The simulation effort is performed with a detailed modeling of the AAR maneuver using the USAF refueling method. SOMMARIO Lo scopo di questa tesi è descrivere i risultati di uno studio riguardante l’analisi delle prestazioni di specifici algoritmi per il problema della stima della posizione in un contesto applicato ad una legge di controllo basata su Machine Vision (MV) per il problema del rifornimento aereo in modo autonomo (AAR) per veicoli aerei non pilotati (UAVs). Si assume che l’avvicinamento durante il rifornimento avvenga grazie a diversi markers ottici installati in punti specifici dell’aeromobile che fornisce il carburante (Tanker). Il metodo può comunque essere usato senza perdita di generalità in un caso dove si usa il metodo della feature extraction per trovare dei punti specifici sul contorno del Tanker al posto dei markers ottici. Il documento propone un algoritmo robusto per la corretta identificazione dei markers ottici, i quali vengono poi forniti agli algoritmi di stima della posizione. Inoltre si propone uno studio dettagliato di due specifici algoritmi per la stima della posizione (il GLSDC e LHM) dove si da particolare importanza al peso computazione, la robustezza e la propagazione dell’errore. Numerose simulazioni dimostrano il potenziale dell’algoritmo LHM evidenziando l’importanza della robustezza e dell’algoritmo di identificazione dei markers ottici. Le simulazioni sono state eseguite con un modello dettagliato della manovra di AAR usando il metodo proposto da USAF

Registered Replication Report on Fischer, Castel, Dodd, and Pratt (2003)

The attentional spatial-numerical association of response codes (Att-SNARC) effect (Fischer, Castel, Dodd, & Pratt, 2003)—the finding that participants are quicker to detect left-side targets when the targets are preceded by small numbers and quicker to detect right-side targets when they are preceded by large numbers—has been used as evidence for embodied number representations and to support strong claims about the link between number and space (e.g., a mental number line). We attempted to replicate Experiment 2 of Fischer et al. by collecting data from 1,105 participants at 17 labs. Across all 1,105 participants and four interstimulus-interval conditions, the proportion of times the effect we observed was positive (i.e., directionally consistent with the original effect) was 50. Further, the effects we observed both within and across labs were minuscule and incompatible with those observed by Fischer et al. Given this, we conclude that we failed to replicate the effect reported by Fischer et al. In addition, our analysis of several participant-level moderators (finger-counting habits, reading and writing direction, handedness, and mathematics fluency and mathematics anxiety) revealed no substantial moderating effects. Our results indicate that the Att-SNARC effect cannot be used as evidence to support strong claims about the link between number and space

Registered Replication Report on Fischer, Castel, Dodd, and Pratt (2003)

The attentional spatial-numerical association of response codes (Att-SNARC) effect (Fischer, Castel, Dodd, & Pratt, 2003)—the finding that participants are quicker to detect left-side targets when the targets are preceded by small numbers and quicker to detect right-side targets when they are preceded by large numbers—has been used as evidence for embodied number representations and to support strong claims about the link between number and space (e.g., a mental number line). We attempted to replicate Experiment 2 of Fischer et al. by collecting data from 1,105 participants at 17 labs. Across all 1,105 participants and four interstimulus-interval conditions, the proportion of times the effect we observed was positive (i.e., directionally consistent with the original effect) was .50. Further, the effects we observed both within and across labs were minuscule and incompatible with those observed by Fischer et al. Given this, we conclude that we failed to replicate the effect reported by Fischer et al. In addition, our analysis of several participant-level moderators (finger-counting habits, reading and writing direction, handedness, and mathematics fluency and mathematics anxiety) revealed no substantial moderating effects. Our results indicate that the Att-SNARC effect cannot be used as evidence to support strong claims about the link between number and space

Registered replication report on Fischer, Castel, Dodd, and Pratt (2003)

The attentional spatial-numerical association of response codes (Att-SNARC) effect (Fischer, Castel, Dodd, & Pratt, 2003)—the finding that participants are quicker to detect left-side targets when the targets are preceded by small numbers and quicker to detect right-side targets when they are preceded by large numbers—has been used as evidence for embodied number representations and to support strong claims about the link between number and space (e.g., a mental number line). We attempted to replicate Experiment 2 of Fischer et al. by collecting data from 1,105 participants at 17 labs. Across all 1,105 participants and four interstimulus-interval conditions, the proportion of times the effect we observed was positive (i.e., directionally consistent with the original effect) was .50. Further, the effects we observed both within and across labs were minuscule and incompatible with those observed by Fischer et al. Given this, we conclude that we failed to replicate the effect reported by Fischer et al. In addition, our analysis of several participant-level moderators (finger-counting habits, reading and writing direction, handedness, and mathematics fluency and mathematics anxiety) revealed no substantial moderating effects. Our results indicate that the Att-SNARC effect cannot be used as evidence to support strong claims about the link between number and space

Insight in cognitive impairment assessed with the Cognitive Assessment Interview in a large sample of patients with schizophrenia

The Cognitive Assessment Interview (CAI) is an interview-based scale measuring cognitive impairment and its impact on functioning in subjects with schizophrenia (SCZ). The present study aimed at assessing, in a large sample of SCZ (n = 601), the agreement between patients and their informants on CAI ratings, to explore patients' insight in their cognitive deficits and its relationships with clinical and functional indices. Agreement between patient- and informant-based ratings was assessed by the Gwet's agreement coefficient. Predictors of insight in cognitive deficits were explored by stepwise multiple regression analyses. Patients reported lower severity of cognitive impairment vs. informants. A substantial to almost perfect agreement was observed between patients' and informants' ratings. Lower insight in cognitive deficits was associated to greater severity of neurocognitive impairment and positive symptoms, lower severity of depressive symptoms, and older age. Worse real-life functioning was associated to lower insight in cognitive deficit, worse neurocognitive performance, and worse functional capacity. Our findings indicate that the CAI is a valid co-primary measure with the interview to patients providing a reliable assessment of their cognitive deficits. In the absence of informants with good knowledge of the subject, the interview to the patient may represent a valid alternative

Adherence to antibiotic treatment guidelines and outcomes in the hospitalized elderly with different types of pneumonia

Background: Few studies evaluated the clinical outcomes of Community Acquired Pneumonia (CAP), Hospital-Acquired Pneumonia (HAP) and Health Care-Associated Pneumonia (HCAP) in relation to the adherence of antibiotic treatment to the guidelines of the Infectious Diseases Society of America (IDSA) and the American Thoracic Society (ATS) in hospitalized elderly people (65 years or older). Methods: Data were obtained from REPOSI, a prospective registry held in 87 Italian internal medicine and geriatric wards. Patients with a diagnosis of pneumonia (ICD-9 480-487) or prescribed with an antibiotic for pneumonia as indication were selected. The empirical antibiotic regimen was defined to be adherent to guidelines if concordant with the treatment regimens recommended by IDSA/ATS for CAP, HAP, and HCAP. Outcomes were assessed by logistic regression models. Results: A diagnosis of pneumonia was made in 317 patients. Only 38.8% of them received an empirical antibiotic regimen that was adherent to guidelines. However, no significant association was found between adherence to guidelines and outcomes. Having HAP, older age, and higher CIRS severity index were the main factors associated with in-hospital mortality. Conclusions: The adherence to antibiotic treatment guidelines was poor, particularly for HAP and HCAP, suggesting the need for more adherence to the optimal management of antibiotics in the elderly with pneumonia

METHODOLOGY FOR ASSEMBLY, INTEGRATION AND VERIFICATION OF THE AVIONIC SYSTEM OF A TECHNOLOGICAL EXPERIMENT ON-BOARD THE INTERNATIONAL SPACE STATION

This paper presents a methodology to carry out the Assembly, Integration and Verification of the avionic system of a technological experiment on-board the International Space Station. The avionic system consists of three main subsystems, i.e. the on-board data handling, the electric power and the health management subsystem, and supports a technological experiment which focuses on the investigation of passive thermal control subsystem. The Assembly, Integration and Verification (AIV) campaign is a fundamental step of the design process, as the final objective of the AIV is to demonstrate that the end product meets the specified requirements. The selection of simple technical solutions and the necessity to keep cost down have driven the definition of the AIV plan, which has been tailored for the avionic system under consideration. Main purpose of the methodology for the Assembly, Integration and Verification is to provide the designer with a step-by-step procedure to accomplish the verification and validation of the avionic system. The methodology shall pursue an incremental approach, which defines the test plan from components to parts, subsystems and system levels through subsequent integrations. Being the AIV a crucial process for the mission reliability of any system, the proposed methodology shall pursue the enhancement of the system reliability and safety by defining, for instance, the most appropriate verification methods to verify the compliance with requirements, the tests to perform and the most correct tests sequence. Models philosophies are discussed and the most suitable model philosophy for the avionic system is selected. The methodology has been developed for the avionic system of a technological experiment but is flexible enough to be applicable to multi-purpose avionic system, capable to support different types of experiments. This paper provides an introduction to the avionic system, then it proceeds with the description of the AIV methodology and the main results obtained by its application to the avionic system. Eventually main conclusions are drawn

METHODOLOGY FOR ASSEMBLY, INTEGRATION AND VERIFICATION OF THE AVIONIC SYSTEM OF A TECHNOLOGICAL EXPERIMENT ON-BOARD THE INTERNATIONAL SPACE STATION

This paper presents a methodology to carry out the Assembly, Integration and Verification of the avionic system of a technological experiment on-board the International Space Station. The avionic system consists of three main subsystems, i.e. the on-board data handling, the electric power and the health management subsystem, and supports a technological experiment which focuses on the investigation of passive thermal control subsystem. The Assembly, Integration and Verification (AIV) campaign is a fundamental step of the design process, as the final objective of the AIV is to demonstrate that the end product meets the specified requirements. The selection of simple technical solutions and the necessity to keep cost down have driven the definition of the AIV plan, which has been tailored for the avionic system under consideration. Main purpose of the methodology for the Assembly, Integration and Verification is to provide the designer with a step-by-step procedure to accomplish the verification and validation of the avionic system. The methodology shall pursue an incremental approach, which defines the test plan from components to parts, subsystems and system levels through subsequent integrations. Being the AIV a crucial process for the mission reliability of any system, the proposed methodology shall pursue the enhancement of the system reliability and safety by defining, for instance, the most appropriate verification methods to verify the compliance with requirements, the tests to perform and the most correct tests sequence. Models philosophies are discussed and the most suitable model philosophy for the avionic system is selected. The methodology has been developed for the avionic system of a technological experiment but is flexible enough to be applicable to multi-purpose avionic system, capable to support different types of experiments. This paper provides an introduction to the avionic system, then it proceeds with the description of the AIV methodology and the main results obtained by its application to the avionic system. Eventually main conclusions are drawn

GPS / MV based Aerial Refueling for UAVs

This paper describes the design of a simulation environment for a GPS / Machine Vision (MV)-based approach for the problem of Aerial Refueling (AR) for Unmanned Aerial Vehicles (UAVs) using the USAF refueling method. MV-based algorithms are implemented within this effort as smart sensor in order to detect the relative position and orientation between the UAV and the tanker. Within this effort, techniques and algorithms for the visualization the tanker aircraft in a Virtual Reality (VR) setting, for the acquisition of the tanker image, for the Feature Extraction (FE) from the acquired image, for the Point Matching (PM) of the features, for the tanker-UAV Pose Estimation (PE) have been developed and extensively tested in closed loop simulations. Detailed mathematical models of the tanker and UAV dynamics, refueling boom, turbulence, wind gusts, and tanker's wake effects, along with the UAV docking control laws and reference path generation have been implemented within the simulation environment. Mathematical model of the noise produced by GPS, MV, INS and pressure sensors are also derived. This paper also presents an Extended Kalman Filter (EKF) used for the sensors fusion between GPS and MV systems. Results on the accuracy reached for the estimation of the relative position are also provided