The aim of this study is to develop an exhaustive optimal energy management system in order to address the cruising range challenge of the BEV that supports ecological driving. From the control engineering perspective,RSNMPC is the promising approach to realize the semi-autonomous ecological driving in the BEVs. Similar to the conven- tionalACCsystems, the driver pre-sets the desired velocity with preferred safe distance from the preceding vehicle in this system. The semi-autonomous Ecological Adaptive Cruise Control (Eco-ACC) system predictively regulates the velocity with respect to the
longitudinal motion of the BEV dynamics, its energy consumption characteristic map, road geometric navigation and traffic sign information, as well as the plausible motion of the preceding vehicle. While the driver handles the steering control of the vehicle, this system should plan a proper safe and energy-efficient cruising velocity profile au- tonomously for the entire trip without requiring the driver’s interventions. In addition, the proposedEco-ACC system should be able to operate at full-range speed assistance and handles the cut-in/out scenarios.
In order to reach the objectives of this study, the following research questions will be addressed:
1. What are the most effective factors that influence on theBEV’s cruising range? 2. Which ADASconcepts can be utilised to improve the safety and energy efficiency
of the BEVs?
3. How to enhance the performance of the ACC systems for theBEVs?
4. How to formulate the controller of the proposed Eco-ACC system in theOCP? 5. How should the control system be modelled?
6. How to deal with uncertainties of the Eco-ACC system in theOCP?
7. How to enhance the tradeoff challenge between the performance and the robustness of the controller?
8. Which approaches have prospects to solve the obtained OCPin a real-time man- ner?
9. What are the performance indexes to evaluate theEco-ACCsystem and its impact on the BEV’s cruising range?
10. How does the proposedEco-ACCsystem perform on theBEVunder various driv- ing and traffic situations?
11. What are the impacts of theEco-ACC system on safety and cruising range of the
BEV?
A three-step is taken to answer the research questions. The first step is to review the works of the literature to identify the state-of-the-art and knowledge gap on theADAS
concepts as well as principle system design and their impact on the safety and energy efficiency of the BEV. This step answers research questions 1-3. In the second step, the overall control system is derived in the domains of SNMPCs and fast optimisation
approaches. A real-time stochastic optimal control framework based on the SMPC
theory for the proposedEco-ACCis developed. This system is based on theACCsystem with extended functionalities to deal with the hilly and curvy roads with traffic signs information. The main source of the system uncertainty in this study is the unknown behaviour of the preceding vehicle in traffic network. Different approaches to handle the system uncertainties are reviewed and a real-timeRSNMPCwith generic numerical solution algorithm is proposed.
The overall route is provided by the navigation system including 3D terrain information. The optimisation algorithm will compute the safe and ecological velocity profile in a way that the overall energy consumption of theBEV is minimised along the route. For that purpose, dynamics of the BEV, as well as its energy consumption model, will be identified. In addition, the road profile is modelled regarding the upcoming route slopes, curves, and traffic sign information. This information will also be used to introduce a physical-statistical model of the preceding vehicle motion. From a control algorithm point of view, it is important to develop an efficient algorithm that delivers robust optimisation results in real-time including a nonlinear dynamics and chance-constraints without demanding too high computational power. This step answers research questions 4-8. In the third step, the proposed Eco-ACC system with RSNMPC is applied and tested on theBEV. The performance and impacts of theEco-ACCon safety and cruising range of theBEVare evaluated under different scenarios using the numerical simulation tests and field practical experiments. This step answers research questions 9-11.
The target of this study is theADASapplications for theBEVon motorway traffic due to fewer interruptions caused by e.g., traffic lights. The assumed traffic conditions are mo- torway with moderate traffic where stop&go phases are also considered. The proposed semi-autonomous ADAS application with limited capability to sense the surrounding environment has low efficiency in urban traffic situations and driver intervention might be required. Moreover, the main focus of the ADAS applications is based on theACC
system with extended functionalities. The automatic steering control manoeuvres such as lane changes as well as overtaking are not considered and the driver has the respon- sibility for these steering manoeuvres. Moreover, the proposed system depends on the road map information that requires driver’s intervention if it is not provided. From a methodological perspective, this study focuses on the real-time RSNMPC for safe and ecological driving in theBEVusing theEco-ACCsystem to improve the cruising range. In this study, all the driving situations are not covered by the proposedEco-ACCsystem and an emergency braking system is developed to overcome its limitations and ensure the safety in critical situations. Furthermore, other aspects of the ITS and the ADAS
applications applied to the BEVs are not considered and the SNMPC algorithms that are computationally expensive are not in the main spotlight of this study.