A review on AI Safety in highly automated driving

Remarkable progress in the fields of machine learning (ML) and artificial intelligence (AI) has led to an increased number of applications of (data-driven) AI systems for the partial or complete control of safety-critical systems. Recently, ML solutions have been particularly popular. Such approaches are often met with concerns regarding their correct and safe execution, which is often caused by missing knowledge or intransparency of their exact functionality. The investigation and derivation of methods for the safety assessment of AI systems are thus of great importance. Among others, these issues are addressed in the field of AI Safety. The aim of this work is to provide an overview of this field by means of a systematic literature review with special focus on the area of highly automated driving, as well as to present a selection of approaches and methods for the safety assessment of AI systems. Particularly, validation, verification, and testing are considered in light of this context. In the review process, two distinguished classes of approaches have been identified: On the one hand established methods, either referring to already published standards or well-established concepts from multiple research areas outside ML and AI. On the other hand newly developed approaches, including methods tailored to the scope of ML and AI which gained importance only in recent years

Automated grading of cerebral vasospasm to standardize computed tomography angiography examinations after subarachnoid hemorrhage

Background: Computed tomography angiography (CTA) is frequently used with computed tomography perfusion imaging (CTP) to evaluate whether endovascular vasospasm treatment is indicated for subarachnoid hemorrhage patients with delayed cerebral ischemia. However, objective parameters for CTA evaluation are lacking. In this study, we used an automated, investigator-independent, digital method to detect vasospasm, and we evaluated whether the method could predict the need for subsequent endovascular vasospasm treatment.Methods: We retrospectively reviewed the charts and analyzed imaging data for 40 consecutive patients with subarachnoid hemorrhages. The cerebrovascular trees were digitally reconstructed from CTA data, and vessel volume and the length of the arteries of the circle of Willis and their peripheral branches were determined. Receiver operating characteristic curve analysis based on a comparison with digital subtraction angiographies was used to determine volumetric thresholds that indicated severe vasospasm for each vessel segment. Results: The automated threshold-based volumetric evaluation of CTA data was able to detect severe vasospasm with high sensitivity and negative predictive value for predicting cerebral hypoperfusion on CTP, although the specificity and positive predictive value were low. Combining the automated detection of vasospasm on CTA and cerebral hypoperfusion on CTP was superior to CTP or CTA alone in predicting endovascular vasospasm treatment within 24 h after the examination. Conclusions: This digital volumetric analysis of the cerebrovascular tree allowed the objective, investigator-independent detection and quantification of vasospasms. This method could be used to standardize diagnostics and the selection of subarachnoid hemorrhage patients with delayed cerebral ischemia for endovascular diagnostics and possible interventions

SMASS – A Lightweight Satellite Simulation Framework for Concurrent Engineering in Education

The “Satellite Mission Analysis and Simulation System” (SMASS) for small satellites developed at the Technical University Berlin (TU Berlin) is mainly used in the education of aerospace students at universities with the focus on understanding the relations between system parameters [1]. The design of a satellite with SMASS is based on the dynamic simulation of entire mission scenarios, which goes beyond the classical approach of designing and simulating uncoupled subsystems with static dependencies. However, after a detailed analysis of SMASS, it turned out that it is highly recommended to re-engineer SMASS to make it flexible for future extensions. The goal was to develop a new highly modular structure. After an introduction, this paper presents the basic layer structure of the new modular SMASS framework. In the next sections, the different layers are explained. This includes their functions and the connections between them. In the end, an example explains the new feature of comparing different satellite configurations using only one simulation run

A Generic Simulink Model Template for Simulation of Small Satellites

This paper presents a template architecture for a straightforward specification of small satellite missions by means of a domain specific language. Furthermore, the process to transform this model to a platform-dependent, executable simulation is depicted. As a first prototype environment, Simulink has been selected. The design adaptation during the developing process is illustrated using the power system of the OOV-TET satellite

Trade-off analysis for different architectures of safety-critical systems

Trade-off analysis offers the possibility to make design decisions transparent. Systems were designed according to previously defined requirements. If the systems can meet the requirements, possible solutions are identified. With the use of trade-off analysis, the solutions can be evaluated with regard to the degree of fulfillment of the requirements. Considering various requirements regarding functionality, safety, costs and risks, it is easy to understand that these are difficult to compare with one another. However, the trade-off analysis has to face this challenge and find a method by which a system design can be selected as a solution. The paper will show the scalability of the method so that it can be applied to evaluate system solutions by considering also safety requirements. By using a practical example, it will be shown how the classical trade-off approach can be extended

Concurrent Systems Engineering in Aerospace: From Excel-based to Model Driven Design

Concurrent engineering is a modern and very effective discipline of systems engineering. In the European space domain, the European Space Agency is the pioneer in this area and has performed early design studies for 10 years now. The Integrated Design Model (IDM) is still the state of the art in concurrent engineering software environments. It is based on Microsoft Excel, which induces several benefits and drawbacks related to concurrent engineering. The German Aerospace Center has used the IDM for several design studies and has identified two promising approaches to further increase the effectiveness of the concurrent engineering software environment by using modern model driven software technologies. Both concepts were implemented, and in this paper they are compared to each other and opposed to the IDM

Simulation-based System Engineering in the Virtual Satellite Project

The development of complex space systems requires the collaboration of specialists in a variety of disciplines. The main challenge of the "concurrent engineering" approach is to keep a consistent view of the system and to organize the data exchange between the specialists appropriately. One way to achieve system model consistency is to use a shared SysML model. Each specialist accesses the model via a discipline-specific view. Unfortunately, SysML tools neither support the reuse of available system components or component assemblies, nor do they provide sufficient support for the data exchange among the different disciplines. To close this gap, the German Aerospace Center (DLR) in 2007 initiated the "Virtual Satellite" project. At the heart of the project a system component repository keeps SysML models of system components, together with related metainformation. This includes ports of the components and information from past space projects, such as parameterizations and configurations. In addition, complex models of entire spacecraft configurations can be stored in the repository. As a first step in the development of a new spacecraft model, the system engineer browses the repository in search of an existing SysML model that fits the intended configuration as closely as possible. Components can be deleted and others can be added as required. Each component model provides views for all engineering disciplines, with ports describing the discipline-specific input/output data. In a second step, for each engineering discipline the corresponding specialist uses a SysML tool to connect the open ports between components and thus completes the logical view of the system. Together with the SysML models and metadata, the repository contains static and dynamic simulation models for each component. Based on the SysML model of a complete space system, and using the simulation models of its components, an automatic transformation tool generates an executable simulation code which can be used to analyze the space system in mission scenarios. The dynamic simulation provided by the Virtual Satellite will be used to optimize the system design for new space missions at the DLR Concurrent Engineering Facility (CEF). The CEF closely follows the concept of ESA's Concurrent Design Facility (CDF). In a CEF session the team of specialists determines optimal system parameters for all disciplines. The set of all those parameters is represented by the Integrated Design Model (IDM) which is generated automatically from the Virtual Satellite system model. The Virtual Satellite approach will improve the system development process in two ways: By collecting system models and metadata of earlier design studies, the repository makes the knowledge collected in those studies available for all future missions. By applying dynamic simulation early in the development process to validate the given constraints, system discrepancies will be detected early, thus saving costs and time

Modell-basierter Systementwurf mit dem PrEMISE-Modell

Ein neues Modell für den modellbasierten Systementwurf technischer Systeme, kurz PrEMISE genannt, wird vorgestellt und dessen Anwendung anhand anschaulicher Beispiele demonstriert. Dazu werden die Probleme derzeitiger Implementierungen modellbasierter Ansätze diskutiert und das neue Modell wird mit verbreiteten Normen in Zusammen-hang gebracht. Beispiele aus unterschiedlichen Anwendungs-gebieten zeigen inwieweit sich PrEMISE fachübergreifend einsetzen lässt und dabei den effizienten Systementwurf fördert