Kinetic Energy Of Vehicle Research Articles

Optimal Complete Vehicle Control for Fuel Efficiency

CONVENIENT is a project where prediction and integrated control are applied on several subsystems with electrified actuators. The technologies developed in this project are applied to a long-haul tractor and semi-trailer combination. A Volvo truck meeting the Eu6 emission standard is rebuilt with a number of controllable electrified actuators. An e-Horizon system collects information about future road topography and speed limits. Controllable aerodynamic wind deflectors reduce the wind drag. The tractor is also equipped with a full digital cluster for human machine interface development.A primary project goal is to develop a model-based optimal controller that uses predictive information from the e-Horizon system in order to minimize fuel consumption. Several energy buffers are controlled in an integrated and optimal way using model predictive control. Several buffers are considered, such as the cooling system, the battery, and the vehicle kinetic energy. This paper presents details on the model predictive controller of the battery system and of the cooling system. Another project goal is to reduce fuel consumption by using adaptive aerodynamics. Controllers are developed that automatically sets an optimal roof deflector angle and the optimal side deflector angle. The results presented in this paper are encouraging. A third focus is the human machine interface and especially the communication between the driver and the control system during driving. This project develops a driver interface that encourages the driver to use the adaptive cruise controller when appropriate.The CONVENIENT project will be finalized this year. This paper presents the main project findings.

Investigation of CO2 Emissions in Production and Usage Phases for a Hybrid Vehicle System Component

The transport sector in Japan emits a large amount of CO2. Passenger vehicles’ and trucks’ emissions are the largest part of the emission in the transport sector. Electrified vehicles are expected to be key technologies for reducing CO2 emissions. Using electric propulsion systems, such as hybrid system, the efficiency of vehicles for the propulsion can be improved. The kinetic energy of vehicles can be recycled by regeneration and the energy can be used for the following accelerations. As the consequent, the CO2 emissions will be reduced in comparison with conventional vehicles. This study focuses on the improvement of drive energy and investigates the impact of electric components in hybrid systems on CO2 emission reductions. Electric components in a hybrid vehicle system enable electric propulsion and contribute to reducing fuel consumptions. At the same time, such electric components contain materials of which the production consumes a large amount of energy. To estimate the CO2 reduction effect of hybrid electric vehicles, life cycle assessments are important. In this paper, the CO2 emissions in the production phase of an electric component are estimated and compared with the emissions of a hybrid electric vehicle in usage phase.

Driving risk assessment using near-crash database through data mining of tree-based model

This paper considers a comprehensive naturalistic driving experiment to collect driving data under potential threats on actual Chinese roads. Using acquired real-world naturalistic driving data, a near-crash database is built, which contains vehicle status, potential crash objects, driving environment and road types, weather condition, and driver information and actions. The aims of this study are summarized into two aspects: (1) to cluster different driving-risk levels involved in near-crashes, and (2) to unveil the factors that greatly influence the driving-risk level. A novel method to quantify the driving-risk level of a near-crash scenario is proposed by clustering the braking process characteristics, namely maximum deceleration, average deceleration, and percentage reduction in vehicle kinetic energy. A classification and regression tree (CART) is employed to unveil the relationship among driving risk, driver/vehicle characteristics, and road environment. The results indicate that the velocity when braking, triggering factors, potential object type, and potential crash type exerted the greatest influence on the driving-risk levels in near-crashes.

Optimal Gear Ratio Planning for Flywheel-Based Kinetic Energy Recovery Systems in Motor Vehicles

An efficient computational methodology is proposed for optimal gear ratio planning in motor vehicle kinetic energy recovery systems (KERS) using a flywheel and continuously variable transmission (CVT). Initial modeling of a clutch-less KERS, comprising an input wheel, CVT, flywheel, and bearings, shows that the “least effort” or “minimum energy loss” optimal control problem can be formulated in two ways: one being a conventional two-state formulation involving input wheel angular velocity and CVT gear ratio, for which least effort control can be solved in simple cases with Pontryagin's maximum principle. The second formulation involves a single-state CVT gear ratio equation for which the input wheel angular velocity and acceleration appear as unknown time-dependent parameters. A novel multiparameter optimization methodology is proposed using the single-state formulation to find optimal CVT gear ratios by adopting two discrete time scales: one being a small time scale for numerical integration of the model, and the second involving discrete transitions, hundreds of times larger. Using Chebyshev polynomial expansions (CPEs) to initially generate sets of zero-energy-loss least effort kinematics for use as the time-dependent parameters in the CVT gear ratio equation, two solution approaches are developed. The first involves a single large discrete time transition, which only requires discretization of the input wheel angular acceleration at the start and end-of-transition. The second approach involves multiple large-scale discrete time transitions as a generalization of the first, but additionally needing discretization of the input wheel angular velocity, and the CVT gear ratio, plus dynamic programming to find the optimum. Both approaches are tested using the clutchless KERS model by assuming a “super CVT” gear ratio range (but with no restrictions for use with slipping clutches). Comparison with least effort control via Pontryagin's maximum principle shows that the single transition approach is in practice far superior. The single transition approach is then used to compare a minimum energy loss clutchless KERS gear ratio plan, with one obtained using constant input wheel angular acceleration as a benchmark. This comparison, involving power losses throughout the KERS, shows the very clear benefits of adopting an optimal gear ratio plan.

Application of an adaptive fuzzy sliding mode controller in velocity control of a secondary controlled hydrostatic transmission system

A secondary controlled hydrostatic transmission system (SC-HST), which considered being an energy-saving system, can recuperate most of the lost vehicle kinetic energy in decelerating and braking time and it shows advantage in fuel economy improvement of vehicle. Because of nonlinear characteristics of almost secondary control units (SCU) in a SC-HST, such as dead-zone input, it is difficult to obtain precise position or velocity control by conventional linear controllers. This problem limits the application of SC-HST in industry and mobile vehicle. To solve the problem, this paper gives a description of SC-HST and proposes an adaptive fuzzy sliding mode controller (AFSMC) for velocity control of SCU. Experiments were carried out in the condition of disturbance load by using both the proposed controller and PID controller for comparison and evaluation the effectiveness of the proposed controller. The experimental results indicated that the proposed controller was excellent from the standpoints of performance and stability for velocity control of SC-HST.

Kinetic Energy Regenerative Braking System

Kinetic Energy Recovery System (KERS) is a system for recovering the moving vehicle's kinetic energy under braking and also to convert the usual loss in kinetic energy into gain in kinetic energy. When riding a bicycle, a great amount of kinetic energy is lost while braking, making start up fairly strenuous. Here we used mechanical regenerative braking system by means of a flywheel to store the energy which is normally lost during braking, and reuse it to help propel the rider when starting. The rider can charge the flywheel when slowing or descending a hill and boost the bike when accelerating or climbing a hill. The flywheel increases maximum acceleration and nets 10% pedal energy savings during a ride where speeds are between 12.5 and 15 km/hr.

Characterization of Brake Pads by Variation in Composition of Friction Materials

Brake pads are the most important component of an automobile braking system. It help in smooth retardation of a vehicle and finally bringing it to halt. Brake pads convert the vehicle's kinetic energy into thermal energy by friction. The effectiveness of the brakes depends completely on frictional material used, which in turn affect the performance of the brake pads. In the present investigation the brake pads were produced by varying constituents (wt%) of the existing composition and new formulations were made with other friction materials. The brake pads were manufactured using powder metallurgy technique. The manufactured brake pads were tested for coefficient of friction, wear, shear strength, hardness and micro structural analysis. The various test results were compared with the existing brake pad composition. Hard friction materials were found in brake pads wear at a lower rate but results in higher brake noise. Brake pads S2 and S4 showed results which are equivalent to the existing brake pad.

Energy Based Set Point Modulation for Obstacle Avoidance In Haptic Teleoperation of Aerial Robots

Abstract This paper presents a novel obstacle avoidance approach that is capable of dealing with both static and dynamic obstacles in the environment with guaranteed collision-free navigation for haptic teleoperation of VTOL aerial robots. The proposed approach modulates the set point for the vehicle's controller based on the user input energy, estimated potential energy and vehicle's kinetic energy. By shuffling the potential and kinetic energy, vehicle's velocity is regulated according to the permissible kinetic energy and thus obstacle avoidance is achieved. With careful design of the potential field, this approach offers a guaranteed collision-free navigation with the presence of both stationary and moving obstacles. Incorporating the novel approach with the Dynamic Kinesthetic Boundary, the human operator can better perceive the environment where the robot is deployed through the rich spatial haptic cues rather than an onset gradual single force vector. Analysis is provided and proves that in the case of perfect velocity tracking of the slave system, the proposed algorithm can guarantee a collision-free navigation through the environment. Simulations and experiments were conducted, and the results provide verification of the effectiveness of the proposed approach in obstacle and collision avoidance for haptic teleoperation of aerial robots.

Research on Vehicle ABS Detection Technology Based on Flywheel Inertia Simulation

Anti-lock Braking System (ABS) has widespread used depending on its mature technology and superior performance. We design a test rig which can simulate the running condition of wheels for ABS to detect the braking performance. The kinetic energy of vehicle is replaced by the kinetic energy of rotating flywheel, and the tire-road friction coefficient is replaced by magnetic powder clutch. The amplitude of exciting current to the clutch has linear relationship with the friction coefficient, so as to provide a datum for detecting the working status of ABS under various road conditions. The system can realize simulating test of single road surface, bisectional road surface and joint road surface. The validity of the road simulation method can be verified by the real-time data from the user interface.

Influence of vehicle secondary impact following an emergency braking on an unbelted occupant's neck, head and thorax injuries

Passive safety has for many years reduced the number of fatalities on the roads. However, its effect on occupants’ safety has now stabilised, meaning that new active safety features are needed to reduce further the number of casualties. These active safety features, like autonomous emergency braking (AEB), aim to prevent vehicle collisions and reduce the vehicle kinetic energy on impact. A previous study has shown that unbelted occupants kinematics are affected by the pre-braking phase, suggesting that the occupant's hand positions on the steering wheel, combined with a bracing behaviour, could cause the occupant to miss the deploying airbag in the case of a secondary rigid wall impact. This paper will investigate the variations of the secondary vehicle impact crash patterns by calculating crash pulses based on typical vehicle frontal accident scenarios and conclude on these effects on the human occupant's neck, head and thorax injuries.

Velocity control of a secondary controlled closed-loop hydrostatic transmission system using an adaptive fuzzy sliding mode controller

A secondary-controlled hydrostatic transmission system (SC-HST), which considered being an energy-saving system, can recuperate most of the lost vehicle kinetic energy in decelerating and braking time and it shows advantage in fuel economy improvement of vehicle. Almost secondary control units (SCU) in SC-HST inherently contain nonlinear characteristics such as dead-zone input. Therefore, it is difficult to obtain precise position or velocity control by conventional linear controllers. This problem limits the application of SC-HST in industry and mobile vehicle. This paper gives a description of SC-HST and proposes an adaptive fuzzy sliding mode controller (AFSMC) for velocity control of SCU. Experiments were carried out in the condition of disturbance load by using both the proposed controller and PID controller for the comparison and evaluation of the effectiveness of the proposed controller. The experimental results showed that the proposed controller was excellent from the standpoints of performance and stability for the velocity control of SC-HST.

Dynamics Models of Interacting Torques of Hydrodynamic Retarder Braking Process

Hydrodynamic retarder is a kind of assist braking device, which can transfer the vehicle kinetic energy into the heat energy of working medium. There are complicated three-dimensional viscous incompressible turbulent flows in hydrodynamic retarder, so that it is difficult to represent the parameters changing phenomenon and investigate the interactional law. In order to develop a kind of reliable theoretical model for internal flow field, in this study, the dynamics models of interacting torques between impellers and working fluid were constructed based on braking energy transfer principle by using Euler theory to describe the flow state in view of time scale. The model can truly represent the dynamic braking process.

Study on the Casting Defects of Vermicular Cast Iron Brake Disc and the Countermeasures

Brake disc is the most important component in disc braking device. It transforms the kinetic energy of vehicles into frictional heat energy through the friction with brake lining and dissipates the heat into the surrounding environment. This paper focuses on the analysis of the shrinkage cavity and porosity as a major casting defect in vermicular cast iron brake disc and the explanation of its causes including the hazardous elements of pig iron, vermicular technique, and the quantity of curing agent to be added. Countermeasures to solve these problems are also proposed to effectively increase the qualification rate of flaw detection of brake disc.

Experimental Research of a Flywheel Hybrid Vehicle

A flow-coupled flywheel hybrid vehicle was proposed which has simpler configuration, fewer components and easier control method. And it was confirmed that this system had enough capability to recover vehicle kinetic energy that might otherwise be lost as heat during braking. Then, more attentions were paid to initial speed of recovery flywheel and displacement ratio of variable displacement pump/motor that influenced recovery efficiency of the proposed hybrid vehicle. It is also significant to point out that in order to improve recovery efficiency, the displacement size of variable displacement pump/motor is required so as to make it operates as maximum displacement, and the initial speed of the recovery flywheel is limited at a suitable scope (about 1000rpm~3000rpm) with regard to the windage and axial loss and the amount of energy storage. Hence, it is indicated that this type of hybrid vehicle can be as an optional configuration to widely use in hybrid vehicle.

스크롤 기기 이용 공압식 회생제동시스템의 연비향상 효과에 관한 연구

하이브리드 자동차는 전기방식 회생제동을 이용하여 연비가 우수하다. 본 논문에서는 새로운 공압식 회생제동 장치를 소개하였다. 공압식 회생제동장치는 압축과 팽창기능을 동시에 가지는 스크롤 기구를 이용한다. 차량 감속시에는 스크롤 기기는 압축기로 작동되면서 대기중의 공기를 압축하여 압축탱크에 저장한 후 차량 가속시에는 스크롤기구가 팽창기로 작동되면서 탱크에 저장된 압축공기가 차량 운동에너지로 활용된다. 회생제동장치를 사용함으로써 개선되는 연비를 분석하기 위해, CVS-75 모드 주행조건에서 시뮬레이션을 수행하였다. The hybrid vehicle has a good fuel economy with a electric type braking energy regeneration system. This paper introduced a novel pneumatic type braking energy regeneration system. The novel system use a scroll mechanism which have both compression function and expansion function. While vehicle is decelerating, the scroll machinery, being operated as a scroll compressor, compress a atmospheric air to save the vehicle's kinetic energy and reuse a compressed air which is reserved in a air tank while vehicle is accelerating. In order to analyze fuel improvements by applying braking energy regeneration system to a vehicle, we simulated the rate of braking energy regeneration through CVS-75 mode driving patterns.

Modelling and control of handling dynamics for a hydrostatically driven vehicle

This paper presents a model for analysing the handling dynamics and lateral stability control of a vehicle featuring a hydrostatic independent wheel drive system for integrating energy efficiency with safety. The stability control system determines the necessary corrective yaw moment and achieves correction of oversteer or understeer via a controlled differential actuation of the wheel-end hydraulic pump/motors. During aggressive handling manoeuvres, the motors can be operated as pumps for re-generating the vehicle's kinetic energy into on-board hydraulic accumulators. This system has the distinct benefit of avoiding excessive activation of the friction brakes as is common in current stability control technology.

A Low Cost Air Hybrid Concept

The air hybrid engine absorbs the vehicle kinetic energy during braking, stores it in an air tank in the form of compressed air, and reuses it to propel a vehicle during cruising and acceleration. Capturing, storing and reusing this braking energy to give additional power can therefore improve fuel economy, particularly in cities and urban areas where the traffic conditions involve many stops and starts. In order to reuse the residual kinetic energy, the vehicle operation consists of 3 basic modes, i.e. Compression Mode (CM), Expander Mode (EM) and normal firing mode. Unlike previous works, a low cost air hybrid engine has been proposed and studied. The hybrid engine operation can be realized by means of production technologies, such as VVT and valve deactivation. In this work, systematic investigation has been carried out on the performance of the hybrid engine concept through detailed gas dynamic modelling using Ricardo WAVE software. Valve timing optimization has been done for the more efficient operation of air hybrid operation and obtaining higher braking and motoring mean effective pressure for CM and EM respectively.

Simulation of Battery SOC State of a Hybrid Electric Vehicle (Applying a Proposed Method of Road Inclination Convert to a Data Received by GPS)

This report evaluates a position of SOC (State of Charge) along with a down hill drive on a real world to its simulation on an emission chassis dynamometer with a gradient road load. On a down hill drive, a vehicle kinetic energy regenerates the battery continuously and an amount of charge volume which shifts the battery SOC up. Excessive charge is a negative factor for the battery life which is designed both a long term of life and a long distance of drive. This regenerating driving mode could not be evaluated on a flat road. A gradient drive way or a gradient simulation system forced energy into a vehicle could evaluate the mode. To evaluate, on the one hand some necessary investigation is carried out to a realization of a down hill drive simulation on an emission chassis dynamometer and problems hitting upon the investigation has been clarified. On the other hand the real world data driving down hill is measured by HEV (Hybrid Electric Vehicle). The real world data collected by GPS (Global Positioning System) has fluctuated widely. This report proposes a method of spline interpolation to the data for a chassis simulation test and reviews the results of the test to the real world mode and evaluates the studies. And here the author also reports an applied chassis simulation for the study of this method.

Large-scale, hypervelocity, high-fidelity interceptor lethality development in AEDC's range G

The hypervelocity ballistic range G at the Arnold Engineering Development Center (AEDC) is extensively used to conduct kinetic energy lethality tests for the Missile Defense Agency (MDA). Over the years, AEDC has continuously responded to the lethality test and evaluation requirements of Ballistic Missile Defense Systems (BMDS) at hypervelocity intercept conditions. Projectiles launched from two-stage light-gas guns experience acceleration loads that are typically orders of magnitude greater than those of the actual missile defense system. These acceleration loads drive design compromises in the projectiles' geometry and mass–density distribution necessary to survive the launch environment. A “high-fidelity” projectile with the proper geometry and mass–density distribution would provide a more representative simulation of the flight vehicle kinetic energy release at impact. Prior to the current upgrades, the range G facility provided the capability to launch large projectiles [8-in. (203-mm) diameter] with weights up to 12 kg at launch velocities up to 4 km/s but at acceleration loads near 40 K g's. Current upgrades provide for the capability to launch large-scale “higher fidelity” projectiles at the same high velocities but at half the g loads. In addition, AEDC is developing a new technique for controlling the projectile pitch at the point of impact with a simulated target. These unique capabilities will make it possible to obtain more flight-representative lethality data in a ballistic range. This paper describes the upgraded capabilities now in place and continuing plans for further upgrades.

Comparison of the energy absorption capability of crash boxes assembled by spot-weld and continuous joining techniques

The design of vehicle front structures for crashworthiness is nowadays commonly based on a series of rigid subsystems that constitute a nearly undeformable survival cell for the passengers, and deformable subsystems able to efficiently dissipate the vehicle kinetic energy. During frontal crash, which is by far the most dangerous impact situation, the front rails represent the main deformable components aimed to dissipate the kinetic energy of the vehicle, therefore their behaviour is crucial to obtain good vehicle performance, with stable and controlled energy dissipation. The design of the front rail, usually consisting of a thin-walled prismatic column, requires definition of the geometry, that is, of the shape and dimensions of the cross section, of the thickness of the material, and of the material itself. The results of an experimental programme aimed to study the progressive collapse behaviour of some thin-walled closed-section structural sections made from deep-drawing steels and joined with different joining systems are reported. Solutions characterized by different continuous joining technologies, non-conventional for automotive constructions, are examined and compared to the usual spot-welding solution. Different types of adhesives (acrylic and epoxy) and laser-welding are considered. Furthermore, since the collapse is influenced by the loading rate and the materials used in this application are known to be strain-rate sensitive, static and impact loading conditions were examined. The obtained results demonstrate that continuously joined structures are at least equivalent to and generally better than spot-welded structures, and have further advantages typical of these joining solutions (higher stiffness and fatigue strength, improved vibration response, especially in the case of adhesive joints).