Prospective and retrospective performance assessment of Advanced Driver Assistance Systems in imminent collision scenarios: the CMI-Vr approach

Structured abstract Introduction Prospective and retrospective performance assessment of Advanced Driver Assistance Systems (ADASs) is fundamental to pilot future enhancements for active safety devices. In critical road scenarios between two vehicles where ADAS activation enables collision mitigation only, currently available assessment methodologies rely on the reconstruction of the impact phase consequent to the specific intervention on braking and steering: the velocity change sustained by the vehicle in the collision ($$\Delta V$$ Δ V ) is retrieved, so that IR decrease for the vehicle occupants can be obtained by appropriate Injury Risk (IR) models. However, information regarding the ADAS performance is available only after the impact phase reconstruction and not just as when the criticality occurs in the pre-impact phase: the best braking and steering alternative cannot be immediately envisaged, since a direct correlation lacks between the braking/steering intervention and IR. Method This work highlights an ADAS performance assessment method based on the disaggregation of $$\Delta V$$ Δ V in the two pre-impact parameters closing velocity at collision ($$V_r$$ V r ) and impact eccentricity, represented by the Crash Momentum Index (CMI). Such a disaggregation leads to the determination of IR based solely on impact configuration between the vehicles, without directly considering the impact phase. The performance of diverse ADASs in terms of intervention logic are directly comparable based on the resulting impact configuration, associated with a single coordinate in the CMI-$$V_r$$ V r plane and a sole IR value as a consequence. Results The CMI-$$V_r$$ V r approach is employable for both purposes of prospective and retrospective performance assessment of ADAS devices. To illustrate the advantages of the methodology, a solution for prospective assessment based on the CMI-$$V_r$$ V r plane is initially proposed and applied to case studies: this provides direct suggestions regarding the most appropriate interventions on braking and steering for IR minimization, fundamental in the tuning or development phase of an ADAS. A method for retrospective assessment is ultimately contextualized in the EuroNCAP "Car-to-Car Rear moving" test for an Inter-Urban Autonomous Emergency Braking system, a device implemented on a significant portion of the circulating fleet. Conclusions Based on the evidenced highlights, it is demonstrated that the approach provides complementary information compared to well-established performance assessment methodologies in all stages of an ADAS life cycle, by suggesting a direct physical connection in the pre-impact phase between the possible ADAS interventions and the foreseeable injury outcomes

combined activation of braking and steering for automated driving systems adaptive intervention by injury risk based criteria

Abstract Increase in advanced driver assistance systems (ADAS) performances is a crucial step towards autonomous driving, allowing the design of increasingly reliable automated driving systems (ADS); ADAS devices play a key role in the enhancement of vehicle safety, which primarily results from the ability to avoid possible impacts. Nevertheless, inevitable collision states (ICS) can be triggered by obstacles as buildings and stationary vehicles interposing between the opponent and the working field of ADAS sensors, compromising their functions; therefore, the performance increase of ADAS devices on the market necessarily passes from the optimal handling of an ICS, which is not currently subject to evaluations. The work introduces ADAS intervention criteria which are based on the occupants' injury risk (IR): in a specific road scenario, the ADAS must primarily avoid the collision with maximum margin and minimize IR in the case of an ICS. Specifically, the ADAS must monitor the environment and intervene on braking and steering adapting to the scenario evolution, following an "adaptive" logic. The most critical aspect of the approach lies in reconstructing, for the specific intervention, the eventual impact: while being a time-consuming process, reconstruction of the impact phase is necessary to compute impact-related parameters (e.g., velocity change of the vehicle ∆V) which directly affect IR. To highlight the benefits offered by an adaptive ADAS compared to traditional ADASs, a special testing software has been developed: the best adaptive intervention to be applied at each instant is chosen in real-time through the criteria proposed, retrieving the required information from a pre-calculated database which collects the results of each braking and steering manoeuvre for a large variety of critical scenarios. Analyzing three ICS conditions, it is shown that the adaptive logic, differing from an autonomous emergency braking, aims at creating eccentrical impacts with minimum ∆V: the IR values associated with the ADAS adaptive intervention are consequently an order of magnitude lower than those obtained through traditional ADAS interventions

Optimal Rayleigh waves generation by continuous wave modulated laser

Laser-ultrasound technology is typically employed in case of non-destructive, non-contact inspection of mechanical components. In particular, low power laser sources (diodes) allow to contain implementation costs; on the other hand, identification of the ultrasonic peak is complex due to the low Signal-to-Noise Ratio (SNR), requiring the use of specific signal processing techniques. Features of the ultrasounds generated by the laser excitation, both in terms of frequencies and SNR, cannot be foreseen in advance, depending from the type of material and its thermo-elastic characteristics: it is thus fundamental to dispose of criteria to set in an optimal way the signal acquisition parameters to effectively apply a correct processing procedure and retrieve the useful information. In the work, surface R (Rayleigh) waves generated by a Continuous Wave (CW) low power laser are characterized, using a particular processing technique in the time domain. To identify the most influential input parameters on SNR, a Design Of Experiments (DOE) and a specific analysis are introduced: overall, the distance between source and receiver and the number of ensemble average applied before acquisition strongly affect SNR; the pulse duration results on the other hand influential at the same time on SNR and on the generated ultrasound frequency. Finally, analogies with longitudinal (L) waves generated by the same source are highlighted, allowing also for information on how to set up the investigation based on the type of wave and acquisition instruments employed

adas assisted driver behaviour in near missing car pedestrian accidents

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Principi e applicazioni

The work offers an overview of the models and empirical formulations generally utilised for the analysis and reconstruction of the various phases of road accidents. Based on a strict methodology, the phenomena involved in the accident are treated as a branch of physics and engineering, instead of being limited to a manual-type approach or a mere collection of typical accident case studies. The aim is to provide a theoretical basis that enables the models to be applied even in the non-canonical cases that are more frequently the rule in accident reconstruction. A work that is unique of its kind on the Italian publishing scene, it is addressed in particular to professionals working in the legal/insurance sector and road safety technicians