A model for a flywheel automatic assistedmanual transmission

This paper is focused on the model and dynamical analysis of a flywheel assisted transmis- sion aiming at reducing the torque gap during gear shift manoeuvres. A completely passive device, consisting of a planetary gear set mounting a flywheel on the sun gear shaft, allows to continuously connect the engine to the load shaft. Depending on the operating condi- tions, it can either absorb energy from the engine or deliver the previously stored kinetic energy to the wheels when the clutch is disengaged, thus allowing better vehicle performances and/or ride comfort through a suitable coordinated control of engine and clutc

Experimental device to identify friction levels for airport applications

This paper presents an experimental device aimed at identifying different road friction levels; it has been designed at the Politecnico di Torino as part of the research program AWIS (Airport Weather Information System: study and realisation of a system for the prediction, monitoring and management of meteorological winter emergencies in airports) funded by Regione Piemonte

On the Power-Weighted Efficiency of Multimode Powertrains: A Case Study on a Two-Mode Hybrid System

Multimode powertrains represent one of the most versatile solutions for hybrid electric vehicles where multiple power sources are integrated with aim of improving fuel economy and reducing pollutants emission in every operating condition. Some hybrid powertrain designs feature multiple planetary gear sets whose components can be directly driven by the powertrain actuators (electric motor or thermal engine) or can be connected through clutches and brakes. The advantages due to the availability of multiple modes are mitigated by the increase of production costs and complexity because of the higher number of components required if compared with the single mode solutions. A numerical methodology is adapted from the literature to analyze, categorize, and compare each distinct working configuration. The energy consumption of each powertrain configuration is then evaluated through the power-weighted efficiency concept whose formulation normalize the contribution from each power source. This paper aims at extending the methodology to investigate the operating range for each powertrain configuration to always achieve the maximum efficiency. The methodology is then applied to the realistic case study of the EVT 2-Mode Hybrid System

Steering Behavior of an Articulated Amphibious All-Terrain Tracked Vehicle

This paper presents a study related to an Articulated Amphibious All-Terrain Tracked Vehicle (ATV) characterized by a modular architecture. The ATV is composed by two modules: The first one hosts mainly the vehicle engine and powertrain components, meanwhile the second one can be used for goods transportation, personnel carrier, crane and so on. The engine torque is transmitted to the front axle sprocket wheel of each module and finally distributed on the ground through a track mechanism. The two modules are connected through a multiaxial joint designed to guarantee four relative degrees of freedom. To steer the ATV, an Electro Hydraulic Power System (EHPS) is adopted, thus letting the vehicle steerable on any kind of terrain without a differential tracks speed. The paper aims to analyze the steady-state lateral behavior of the ATV on a flat road, through a non-linear mathematical vehicle model built in Matlab/Simulink environment. The model describes the vehicle main planar motion and the interaction between the two modules through the application of a hydraulic steering torque. The model simulates steady-state handling maneuvers in Matlab/Simulink. Two scenarios are considered: One with the application of an open-loop hydraulic steering torque without any vehicle feedback; the second one with a closed-loop steering torque actuation based on the relative angle between the two modules (hitch angle). Finally, the influence of the ATV longitudinal speed on vehicle lateral characteristics is also presented

A Methodology for Parameter Estimation of Nonlinear Single Track Models from Multibody Full Vehicle Simulation

In vehicle dynamics, simple and fast vehicle models are required, especially in the framework of real-time simulations and autonomous driving software. Therefore, a trade-off between accuracy and simulation speed must be pursued by selecting the appropriate level of detail and the corresponding simplifying assumptions based on the specific purpose of the simulation. The aim of this study is to develop a methodology for map and parameter estimation from multibody simulation results, to be used for simplified vehicle modelling focused on handling performance. In this paper, maneuvers, algorithms and results of the parameter estimation are reported, together with their integration in single track models with increasing complexity and fidelity. The agreement between the multibody model, used as reference, and four single track models is analyzed and discussed through the evaluation of the correlation index. The good match between the models validates the adopted simulation methodology both during steady-state and during transient maneuvers. In a similar way, this method could be applied to experimental data gathered from a real instrumented car rather than from a multibody model

Energy Management Strategy for Hybrid Multimode Powertrains: Influence of Inertial Properties and Road Inclination

Multimode hybrid powertrains have captured the attention of automotive OEMs for their flexible nature and ability to provide better and optimized efficiency levels. However, the presence of multiple actuators, with different efficiency and dynamic characteristics, increases the problem complexity for minimizing the overall power losses in each powertrain operating condition. The paper aims at providing a methodology to select the powertrain mode and set the reference torques and angular speeds for each actuator, based on the power-weighted efficiency concept. The power-weighted efficiency is formulated to normalize the efficiency contribution from each power source and to include the inertial properties of the powertrain components as well as the vehicle motion resistance forces. The approach, valid for a wide category of multimode powertrain architectures, is then applied to the specific case of a two-mode hybrid system where the engagement of one of the two clutches enables an Input Split or Compound Split operative mode. The simulation results obtained with the procedure prove to be promising in avoiding excessive accelerations, drift of powertrain components, and in managing the power flow for uphill and downhill vehicle conditions

Torsional Dynamic Performance of a Transmission Test Bench: An Investigation on the Effect of Motors Controllers Parameters

Besides in-vehicle testing, automotive powertrains and their subsystems are extensively studied and verified, in the different development phases, through dedicated test benches having various mechanical layouts according to the specific target. The torsional load is typically applied to the transmission by electric motors connected at both ends of the driveline. The electric motors drives allow speed and torque closed-loop control so that the desired combination of speed and torque can be imposed over time during the experiment. The parameters of such controllers therefore play a crucial role in the torsional dynamic behavior of the bench and therefore must be carefully selected and tuned to achieve optimal reference tracking and disturbance rejection performance. This paper aims at proposing a model-based sensitivity analysis of the PID controllers parameters starting from an experimentally validated torsional model of a Dual Clutch Transmission test rig. The methodology here proposed also contributes to achieving the Sustainable Development Goal 11 promoted by ONU

Articulated Steering Control for an All-Terrain Tracked Vehicle

The objective of this study is to analyse and control the cornering behaviour of an Articulated All-Terrain Tracked Vehicle (ATV). The ATV is characterized by two units connected through a mechanical multiaxial joint designed to overcome extreme longitudinal and side slopes. The hydraulic actuation of the joint enables an articulated steering feature thus avoiding any thrusts adjustment as it happens for skid-steering vehicles. A direct curvature controller is presented for analysing the steady-state ATV behaviours through a nonlinear model. Furthermore, a hitch angle controller is introduced to overcome the necessity of a curvature feedback measurement. The methodology is verified by simulating typical manoeuvres adopted for evaluating vehicle handling performance

Light Commercial Vehicle ADAS-Oriented Modelling: An Optimization-Based Conversion Tool from Multibody to Real-Time Vehicle Dynamics Model

In the last few years, the number of Advanced Driver Assistance Systems (ADAS) on road vehicles has been increased with the aim of dramatically reducing road accidents. Therefore, the OEMs need to integrate and test these systems, to comply with the safety regulations. To lower the development cost, instead of experimental testing, many virtual simulation scenarios need to be tested for ADAS validation. The classic multibody vehicle approach, normally used to design and optimize vehicle dynamics performance, is not always suitable to cope with these new tasks; therefore, real-time lumped-parameter vehicle models implementation becomes more and more necessary. This paper aims at providing a methodology to convert experimentally validated light commercial vehicles (LCV) multibody models (MBM) into real-time lumped-parameter models (RTM). The proposed methodology involves the definition of the vehicle subsystems and the level of complexity required to achieve a good match between the simulation results obtained from the two models. Thus, an automatic vehicle model converter will be presented together with the assessment of its accuracy. An optimization phase is included into the conversion tool, to fine-tune uncertain vehicle parameters and to compensate for inherent modelling differences. The objective function of the optimization is based on typical performance indices used for vehicle longitudinal and lateral dynamics assessment. Finally, the simulation results from the original and converted models are compared during steady-state and transient tests, to prove the conversion fidelity

On the Experimental Analysis of Integral Sliding Modes for Yaw Rate and Sideslip Control of an Electric Vehicle with Multiple Motors

With the advent of electric vehicles with multiple motors, the steady-state and transient cornering responses can be designed and implemented through the continuous torque control of the individual wheels, i.e., torque-vectoring or direct yaw moment control. The literature includes several papers on sliding mode control theory for torque-vectoring, but the experimental investigation is so far limited. More importantly, to the knowledge of the authors, the experimental comparison of direct yaw moment control based on sliding modes and typical controllers used for stability control in production vehicles is missing. This paper aims to reduce this gap by presenting and analyzing an integral sliding mode controller for concurrent yaw rate and sideslip control. A new driving mode, the Enhanced Sport mode, is proposed, inducing sustained high values of sideslip angle, which can be limited to a specified threshold. The system is experimentally assessed on a four-wheel-drive electric vehicle. The performance of the integral sliding mode controller is compared with that of a linear quadratic regulator during step steer tests. The results show that the integral sliding mode controller significantly enhances the tracking performance and yaw damping compared to the more conventional linear quadratic regulator based on an augmented singletrack vehicle model formulation. © 2018, The Korean Society of Automotive Engineers and Springer-Verlag GmbH Germany, part of Springer Natur