Abstract

At least two different actuators work in cooperation in regenerative braking for electric and hybrid vehicles. Torque blending is an important area, which is responsible for better manoeuvrability, reduced braking distance, improved riding comfort, etc. In this paper, a control method for electric vehicle blended antilock braking system based on fuzzy logic is promoted. The principle prioritizes usage of electric motor actuators to maximize recuperation energy during deceleration process. Moreover, for supreme efficiency it considers the battery’s state of charge for switching between electric motor and conventional electrohydraulic brakes. To demonstrate the functionality of the controller under changing dynamic conditions, a hardware-in-the-loop simulation with real electrohydraulic brakes test bed is utilized. In particular, the experiment is designed to exceed the state-of-charge threshold during braking operation, what leads to immediate switch between regenerative and friction brake modes. Document type: Part of book or chapter of book

Abstract

In most large cities in developing countries, buses continue to be the public transport option of choice, carrying a large share of urban travelers. However, transit bus companies in these countries are often cash-strapped. In many cases, the operating cost per bus kilometer exceeds revenues and bus fares are often kept low irrespective of the cost of providing service. Many cities are dominated by old and fuel-intensive buses with high operating costs. Transit systems are also often plagued by overcrowded and undependable service, congested roadways and chaotic operating environments. Across the board, city officials in developing countries are under strong pressure to improve the efficiency and enhance the attractiveness of bus transportation. Fuel makes up a relatively large fraction of total bus operating costs, especially when labor costs are low, as in many developing countries. Fuel costs can be reduced by improving the driving style of bus drivers and through sound maintenance practices. A safe and economical driving style can reduce variable costs, decrease down time due to repair work and maintenance, mitigate negative environmental impacts and improve road safety. This guidance note1 provides detailed and practical recommendations on how city bus operations managers and their technical staff can plan and implement such enhancements to their fleets through Operations and Maintenance (O and M) practices without significant capital investments. By implementing such recommendations, municipal officials and bus operators can increase the efficiency and fuel economy of their bus systems and reduce their cities' energy consumption, congestion and pollution. This guidance note provides detailed and practical recommendations on how city bus operations managers and their technical staff can plan and implement such enhancements to their fleets through O and M practices without significant capital investments.

Abstract

Ths skid resistance of the road surface is one of the parameters that influence the active vehicle safety and consequently the traffic safety. Up till now, in the Netherlands skid resistance has been evaluated by means of of a statistical relation between the skid resistance value and accident risk. In order to be able to fulfil the demands of a more detailed evaluation an approach is suggested with the focus on the physical description of mechanisms in traffic safety. This approach is innovative and quite different from standard solutions in traffic safety research. One of the major challenges in this approach is to integrate a wide range of disciplines, i.e. road technology, tyre-road interaction, vehicle dynamics and human factors for the prediction of the braking performance of vehicle from specified road characteristics. In this way, the braking performance model supports a better mutual understanding between the governments, road constructors and vehicle manufacturers. One of the crucial elements in the model is the accurate description of the tyre-road interaction. The Magic Formula tyre model is a general accepted model to describe interaction forces within the automotive industry. This paper focuses on the extension of the Magic Formula tyre model with speed dependent friction for especially the wet conditions and also the scaling of the Magic Formula parameters based on standard road-skid resistance and road macro texture measurements. This extended model is valid for dry and wet surfaces. It enables the scientist to enlarge the accuracy and validity range of the tyre-road interaction model towards a wide range of surfaces and thus increasing the accuracy of the prediction of the vehicle braking performance