Smart Traction Control Systems for Electric Vehicles Using Acoustic Road-type Estimation

The application of traction control systems (TCS) for electric vehicles (EV) has great potential due to easy implementation of torque control with direct-drive motors. However, the control system usually requires road-tire friction and slip-ratio values, which must be estimated. While it is not possible to obtain the first one directly, the estimation of latter value requires accurate measurements of chassis and wheel velocity. In addition, existing TCS structures are often designed without considering the robustness and energy efficiency of torque control. In this work, both problems are addressed with a smart TCS design having an integrated acoustic road-type estimation (ARTE) unit. This unit enables the road-type recognition and this information is used to retrieve the correct look-up table between friction coefficient and slip-ratio. The estimation of the friction coefficient helps the system to update the necessary input torque. The ARTE unit utilizes machine learning, mapping the acoustic feature inputs to road-type as output. In this study, three existing TCS for EVs are examined with and without the integrated ARTE unit. The results show significant performance improvement with ARTE, reducing the slip ratio by 75% while saving energy via reduction of applied torque and increasing the robustness of the TCS.Comment: Accepted to be published by IEEE Trans. on Intelligent Vehicles, 22 Jan 201

Innovative approaches fot tyre characterization aimed at road contact modelling for automotive applications

In Automotive the role of the tyre mechanics and physics is crucial for the optimization of vehicle stability, performance and safety. Most engineers usually face the analysis of tyres' mechanical and viscoelastic properties with the aim to comprehend the interaction phenomena between the tread and the road. In the last decades, compound-substrate modelling has been discussed a lot in the scientific literature. Many theories have been developed to determine the frictional behaviour of rubber sliding on a texture in a wide working range in terms of temperature, contact pressure, profile roughness, etc. The most common and recent theories, such as Klüppel's and Persson's [1, 2], are widely employed because they try to explain the contact modelling problem following different approaches and hypothesis. However, the analysis of the contact problem requires full knowledge of the roughness profile and the rubber viscoelastic properties. The identification of the macro-roughness scales and especially of the micro-scales is an enigma yet to be unequivocally solved for the optimization of the multiscale theories [3]. On the other side, the properties of the rubber compound are complex to determine, unless the tyre tread can be destroyed to obtain a specimen and then perform the Dynamic Mechanical Analysis (DMA), which usually requires expensive machines and a long time for a full time-temperature characterization of the material according to William-Landel-Ferry theory [4, 5]. Nonetheless, in most applications, as well as Motorsport ones, the tyres are linked to restrictions and they cannot be analysed by the standard and laboratory procedures. In this scenario, the main activities described in the present PhD thesis deal with the tyre tread compound characterization through innovative methodologies and devices in order to overcome the limits that Motorsport racing teams or tyre manufacturers are used to face with. The non-destructive viscoelastic analysis through the device developed thanks to the precious support of the skilled and motivating research team of the Industrial Engineering Department of the University of Naples Federico II, which is called VESevo (Viscoelasticity Evaluation System evolved), is an advantageous testing procedure proving indication of the tyre viscoelastic properties variations with respect to the temperature, wear phenomena, ageing, etc. Ergonomics, portability and smart analysis are key features of this device, allowing it to be widely used by engineers of racing teams on tracks during Motorsport races and events and further by operators in tyre 26 manufacturers facilities, that also need a fast and reliable analysis of the trustworthiness of their final product series. Once introduced the innovative approaches for tyres characterization, the contact mechanics models have been analysed in-depth highlighting their features and limits for automotive applications. Particularly, the GrETA (Grip Estimation for Tyre Analyses) tool, developed by the Applied Mechanics group of the Industrial Engineering Department of the University of Naples Federico II and improved during the PhD research period, is proposed as a multi-contact simplified physical model for the analysis of adhesive and hysteretic contributions to the overall friction between the rubber and the substrate macro and micro asperities. The main parameters of the GrETA have been identified thanks to specific experimental friction benches, which have involved the last part of the PhD program. The results achieved can be considered as a baseline for innovative approaches in terms of tyre characterization and contact modelling for friction prediction. Actually, some limits concerning the experimental friction analysis have been faced during the research program, which will be overcome thanks to the realization of the new proposed friction test bench allowing to strengthen the identification of the contact mechanics models and focus on new research scenarios, as well as the analysis of rubber wear phenomena

Phillips curve in a small open economy: A time series exploration of North Cyprus

The paper explores the existence and the stability of Phillips curve for North Cyprus, a small developing economy, using time series data. ADF unit root test is employed to check for stationarity. ARDL and DOLS approaches to cointegration have been used to explore the long run relation and ECM to understand short run dynamics. The predictive properties DOLS are better than those of the conventional methods. The estimates point to the existence of Phillips curve both in the long and the short run. CUSUM and CUSUMsq tests confirm a stable relation.Inflation, Unemployment, ADF, Cointegration, DOLS

Are workers close to cities paid higher non-agricultural wages in rural China?

In the present study, we investigate whether workers close to cities are paid higher non-agricultural wages than workers in outlying rural areas. We find that workers close to urban areas not only benefit from more opportunities to engage in non-agricultural activities, but also from better paid jobs. In addition, distance exhibits a strongly nonlinear impact. Distance always has a negative impact on wages but the effect is more detrimental, the closer the village is to the urban center. We also find evidence of urban hierarchy effects: workers living close to bigger cities are paid higher wages. Finally, we provide evidence on the transmission channels at work

Investigating the Apparent Seismic Diffusivity of Near-Receiver Geology at Mount St. Helens Volcano, USA

Acknowledgments: The SAGES VALIDATE forum provided travel money for the discussion of the methodology within De Siena and Benson.Peer reviewedPublisher PD

Performance of Anti-Lock Braking Systems Based on Adaptive and Intelligent Control Methodologies

Automobiles of today must constantly change their speeds in reaction to changing road and traffic circumstances as the pace and density of road traffic increases. In sophisticated automobiles, the Anti-lock Braking System (ABS) is a vehicle safety system that enhances the vehicle's stability and steering capabilities by varying the torque to maintain the slip ratio at a safe level. This paper analyzes the performance of classical control, model reference adaptive control (MRAC), and intelligent control for controlling the (ABS). The ABS controller's goal is to keep the wheel slip ratio, which includes nonlinearities, parametric uncertainties, and disturbances as close to an optimal slip value as possible. This will decrease the stopping distance and guarantee safe vehicle operation during braking. A Bang-bang controller, PID, PID based Model Reference Adaptive Control (PID-MRAD), Fuzzy Logic Control (FLC), and Adaptive Neuro-Fuzzy Inference System (ANFIS) controller are used to control the vehicle model. The car was tested on a dry asphalt and ice road with only straight-line braking. Based on slip ratio, vehicle speed, angular velocity, and stopping time, comparisons are performed between all control strategies. To analyze braking characteristics, the simulation changes the road surface condition, vehicle weight, and control methods. The simulation results revealed that our objectives were met. The simulation results clearly show that the ANFIS provides more flexibility and improves system-tracking precision in control action compared to the Bang-bang, PID, PID-MRAC, and FLC