A Method of Optimal Control for Class 8 Vehicle Platoons Over Hilly Terrain

This work develops and implements an NMPC control system to facilitate fuel-optimal platooning of Class 8 vehicles over challenging terrain. Prior research has shown that Cooperative Adaptive Cruise Control (CACC), which allows multiple Class 8 vehicles to follow in close succession, can save between 3 and 8% in overall fuel consumption on flat terrain. However, on more challenging terrain, e.g. rolling hills, platooning vehicles can experience diminished fuel savings, and, in some cases, an increase in fuel consumption relative to individual vehicle operation. This research explores the use of Nonlinear Model Predictive Control (NMPC) with predefined route grade profiles to allow platooning vehicles to generate an optimal velocity trajectory with respect to fuel consumption. In order to successfully implement the NMPC system, a model relating vehicle velocity to fuel consumption was generated and validated using experimental data. Additionally, the predefined route grade profiles were created by using the vehicle's GPS velocity over the desired terrain. The real-time NMPC system was then implemented on a two-truck platoon operating over challenging terrain, with a reference vehicle running individually. The results from NMPC platooning are compared against fuel results from a classical proportional-integral-derivative (PID) headway control method. This comparison yields the comparative fuel savings and energy efficiency benefit of NMPC system. In the final analysis, significant fuel savings of greater than 14 and 20% were seen for the lead and following vehicles relative to their respective traditional cruise control and platooning architectures.

Potential impact of additive manufacturing and topology optimization inspired lightweight design on vehicle track performance

This paper describes an interactive approach for analyzing the impact of the enhanced design freedom in additive manufacturing (AM) combined with topology optimization. The main goal is to identify weight saving potentials on a holistic vehicle level and evaluate the influence on vehicle performance by means of lap time savings. Therefore lightweight use cases enabled by AM are gathered in a database. Projecting the weight reduction rates of this database to a sports car as reference vehicle by means of a weight list, CAD data and a part relation analysis leads to an overall weight saving potential. This analysis shows significant weight saving potentials for each technical section of an already lightweight design focused sports car, namely the Bugatti Chiron. The improvement in track performance considering the weight savings is put into perspective by means of lap time simulation on the Nürburgring Nordschleife and corroborate the identified weight saving potentials.

Measurements of the Emissions of a “Golden” Vehicle at Seven Laboratories with Portable Emission Measurement Systems (PEMS)

In the last years, the in-use emissions of vehicles are measured on the road with portable emissions measurement systems (PEMS). PEMS cannot measure as accurately as the laboratory grade equipment, and studies on their measurement uncertainty have continued since their appearance in the market. In this study we compared PEMS to laboratory grade equipment in Italian laboratories testing a diesel “Golden” (i.e., reference) vehicle for two consecutive years. The results showed equal means of PEMS and laboratory grade equipment for carbon dioxide (CO2), nitrogen oxides (NOx), and particle number (PN), with a variability of ±5 g/km for CO2, ±10 mg/km for NOx, and ±1 × 1011 p/km for PN, which further decreased in the second year. For carbon monoxide (CO), the PEMS were on average 5–20 mg/km higher than the bags (variability ±40 mg/km). The main conclusion of this study is that PEMS are accurate under controlled laboratory ambient conditions, without any indications of significant bias.

Determination of passenger car noise equivalent for mid-sized cities in India

The heterogeneity in traffic flow composition increases the complexity of road traffic noise analysis for mid-sized in India. This study aims to determine a passenger car noise equivalent (PCNE) with respect to the average traffic stream speed that represents the number of a particular vehicle category with reference to an identified vehicle based on their noise emission characteristics. In the present study, vehicles are classified as bus, truck, light commercial vehicles (minibus, minitruck), three-wheelers (vikram-rickshaw), two-wheelers (bike/scooter), car, e-rickshaw and auto-rickshaw, and tractor-trailer. Car is taken as a reference vehicle for estimation of PCNE in our study due to its high percentage in traffic stream. Data has been collected on both bituminous and concrete pavement in Kanpur city, India, to analyze the differential effect of pavement on the noise level. As per this study, tractors-trailers, trucks, three-wheelers, and buses had a higher PCNE value, while two-wheelers and cars had almost similar PCNE value. A comparative analysis of PCNE value at concrete pavement is also conducted by considering car running on the bituminous pavement as reference vehicle. The study suggests to employ PCNE value in traffic noise analysis as it converts the divergent traffic volume in terms of the car.

Wing Structure of the Next-Generation Civil Tiltrotor: From Concept to Preliminary Design

The main objective of this paper is to describe a methodology to be applied in the preliminary design of a tiltrotor wing based on previously developed conceptual design methods. The reference vehicle is the Next-Generation Civil Tiltrotor Technology Demonstrator (NGCTR-TD) developed by Leonardo Helicopters within the Clean Sky research program framework. In a previous work by the authors, based on the specific requirements (i.e., dynamics, strength, buckling, functional), the first iteration of design was aimed at finding a wing structure with a minimized structural weight but at the same time strong and stiff enough to comply with sizing loads and aeroelastic stability in the flight envelope. Now, the outcome from the first design loop is used to build a global Finite Element Model (FEM), to be used for a multi-objective optimization performed by using a commercial software environment. In other words, the design strategy, aimed at finding a first optimal solution in terms of the thickness of composite components, is based on a two-level optimization. The first-level optimization is performed with engineering models (non-FEA-based), and the second-level optimization, discussed in this paper, within an FEA environment. The latter is shown to provide satisfactory results in terms of overall wing weight, and a zonal optimization of the composite parts, which is the starting point of an engineered model and a detailed FEM (beyond the scope of the present work), which will also take into account manufacturing, assembly, installation, accessibility and maintenance constraints.

Advanced rule-based energy management for better fuel economy of hybrid electric tracked vehicle

All recent technological developments in the field of power distribution in hybrid electric tracked vehicles are often hard to apply and carry high computational burden which makes them impractical for real-time applications. In this paper, a novel control strategy is proposed for parallel hybrid electric tracked vehicle based on robust and easy to implement thermostat strategy with added merits of power follower control strategy (PFCS). The goal of the control strategy is enhanced fuel economy. Serbian infantry fighting vehicle BVP M80-A is chosen as the reference vehicle. For the purpose of validation, a backward-looking, high fidelity model is created in Simulink environment. Investigation of the results indicates that the proposed control strategy offers 12.8% better fuel economy while effectively maintaining battery state of charge (SOC). Even better results (23.2%) were achieved applying the proposed strategy to a model with an additional generator. It is concluded that further improvements can be made with combined sizing and control optimization.

Natural Gas as a New Prospect in Everyday Use of Electric Vehicles

We study here the urban use of electric vehicles (EVs), focusing on the electricity production for charging purposes. This work proposes an innovative charging scheme for EVs, by introducing a home-applied power station, consisting of a fuel cell combined with an internal reforming unit, which is fed by natural gas and can thus be directly connected to the already-established natural gas grid. We therefore overcome the barriers posed by hydrogen use (establishment of storage equipment, energy consumption for keeping high pressure, development of supply grid, etc.) while we eliminate the environmental impact, since no fossil fuels are required for electricity production. Furthermore, comparisons against EVs charged by grid and vehicles fueled by petrol, both subjected to urban everyday use, have been carried out here. Precisely, we financially compare the use of an EV charged directly through the national electric grid against our innovative power station. Both options are also compared with the same vehicle, powered by an internal combustion engine fueled by petrol. This study also implements a detailed thermodynamic analysis for this state-of-the-art power station and an additional financial analysis for the everyday use of these vehicles under the three different scenarios. For the sake of equivalence, the new Peugeot 208 was selected as the reference-vehicle, as it is equipped either with a petrol engine or an electric motor, under a roughly identical performance profile. This work also introduces the use of the existing grid of natural gas to produce the necessary electricity for charging EVs, rather than using other renewables (solar, wind, etc.), and could further strengthen the worldwide acceptance of the EVs as a viable and a financially feasible solution for everyday urban transportation.

On the Impact of Maximum Speed on the Power Density of Electromechanical Powertrains

In order to achieve the European Commission’s ambitious climate targets by 2030, BEVs (Battery Electric Vehicles) manufacturers are faced with the challenge of producing more efficient and ecological products. The electromechanical powertrain plays a key role in the efficiency of BEVs, which is why the design parameters in the development phase of electromechanical powertrains must be chosen carefully. One of the central design parameters is the maximum speed of the electric machines and the gear ratio of the connected transmissions. Due to the relationship between speed and torque, it is possible to design more compact and lighter electric machines by increasing the speed at constant power. However, with higher speed of the electric machines, a higher gear ratio is required, which results in a larger and heavier transmission. This study therefore examines the influence of maximum speed on the power density of electromechanical powertrains. Electric machines and transmissions with different maximum speeds are designed with the state-of-the-art for a selected reference vehicle. The designs are then examined with regard to the power density of the overall powertrain system. Compared to the reference vehicle, the results of the study show a considerable potential for increasing the power density of electromechanical powertrains by increasing the maximum speed of the electric machines.

Innovative Multiple Matching Charts approach to support the conceptual design of hypersonic vehicles

Several well-established best practices and reliable tools have been developed along the years to support aircraft conceptual and preliminary design. In this context, one of the most widely used tool is the Matching Chart (MC), a graphical representation of the different performance requirements (curves representing the thrust-to-weight ratio (T/W) requirement as function of the wing loading (W/S)) for each mission phase. The exploitation of this tool allows the identification of a feasible design space as well as the definition of a reference vehicle configuration in terms of maximum thrust, maximum take-off weight, and wing surface since the very beginning of the design process. Although the tool was originally developed for conventional aircraft, several extensions and updates of the mathematical models have been proposed over the years to widen its application to innovative configurations. Following this trend, this paper presents a further evolution of the MC model to support the conceptual design of high-speed transportation systems, encompassing supersonic and hypersonic flight vehicles. At this purpose, this paper reports and discusses the updates of the methodology laying behind the generation of the MC for high-speed transportation. Eventually, the results of the validation of the updated methodology and tool are reported, using as case study, the STRATOFLY MR3 vehicle configuration, a Mach 8 antipodal civil transportation system, currently under development within the H2020 STRATOFLY project.

Around View Monitoring-Based Vacant Parking Space Detection and Analysis

Accelerated urbanization and the ensuing rapid increase in urban populations led to the need for a tremendous number of parking spaces. Automated parking systems coupled with new parking lot layouts can effectively address the need. However, most automated parking systems available on the market today use ultrasonic sensors to detect vacant parking spaces. One limitation of this method is that a reference vehicle must be parked in an adjacent space, and the accuracy of distance information is highly dependent on the positioning of the reference vehicle. To overcome this limitation, an around view monitoring-based method for detecting parking spaces and algorithms analyzing the vacancy of the space are proposed in this study. The framework of the algorithm comprises two main stages: parking space detection and space occupancy classification. In addition, a highly robust analysis method is proposed to classify parking space occupancy. Two angles of view were used to detect features, classified as road or obstacle features, within the parking space. Road features were used to provide information regarding the possible vacancy of a parking space, and obstacle features were used to provide information regarding the possible occupancy of a parking space. Finally, these two types of information were integrated to determine whether a specific parking space is occupied. The experimental settings in this study consisted of three common settings: an indoor parking lot, an outdoor parking lot, and roadside parking spaces. The final tests showed that the method’s detection rate was lower in indoor settings than outdoor settings because lighting problems are severer in indoor settings than outdoor settings in around view monitoring (AVM) systems. However, the method achieved favorable detection performance overall. Furthermore, we tested and compared performance based on road features, obstacle features, and a combination of both. The results showed that integrating both types of features produced the lowest rate of classification error.