A state-of-the-art survey on vehicular mechatronics focusing on by-wire systems. Daniel Frede, Mohammad Khodabakhshian, Daniel Malmquist October 2010 TRITA MMK 2010:10 iii Abstract This report is the result of a survey of the current state of the art/ practice in vehicular mechatronics. It summarizes a large quantity of scientific papers and theses, as well as white papers and field trips to manufacturers. Mechatronics is a multi-domain discipline which is the result of the evolution of the single-domain engineering disciplines mechanics, electronics, information processing and control. Mechatronics is central for most new innovations in automotive products; “according to manufacturers statements, about 90% of all innovations for automobiles are due to electronics and mechatronics” [41]. The consequence of this is that vehicular mechatronics has become an important field of research. Since this is an incredibly broad field of research, the focus of this report has mainly been on brake and steering systems but the report also covers a wider more general scope of systems. The report covers a wide range of subjects within vehicular mechatronics, e.g. everything from legislative requirements to actual prototypes. One of the conclusion drawn in this report is that there is a lack of research with a more holistic approach to the systems. Most research only treat individ- ual systems and omit the level of integration and interplay between subsystems and engineering domains which is typical for modern vehicles. There is also a lack of result validation in real conditions; most research are only evaluated through software simulations or in best case with hardware-in-the-loop simu- lations. Another problem is that most research focus on single aspects like e.g. fuel consumption when there is a lot more properties which need to be taken into account. iv Contents Contentsv Abbreviations ix 1 Introduction1 1.1 General Overview............................. 1 1.2 Vehicular Mechatronics ......................... 2 1.3 Scope Definition ............................. 3 1.4 Requirements............................... 3 2 Products/Prototypes5 2.1 Vehicles.................................. 5 2.2 Braking .................................. 6 2.2.1 General Overview of Electromechanical Brake Systems.... 6 2.2.2 Regenerative brake systems................... 6 2.2.3 Design aspects .......................... 8 2.2.4 Control strategies......................... 9 2.2.5 Brake systems in product state................. 11 2.3 Steering.................................. 14 2.3.1 Overview of steering systems .................. 14 2.3.2 New steering systems ...................... 16 2.3.3 Steering system products .................... 20 2.4 Other by-Wire systems.......................... 21 3 System Architecture 23 3.1 System Design .............................. 23 3.2 Fault-tolerance and Safety........................ 26 4 Legislation & Standards 31 4.1 ECE 13 & 79............................... 31 4.2 AUTOSAR ................................ 32 4.3 ISO 26262................................. 33 v vi CONTENTS 5 Methodology 37 5.1 Development methodology and multi-domain optimization . 37 5.2 Tools.................................... 40 6 Conclusions 43 Bibliography 45 CONTENTS vii Abbreviations Abbreviation Explanation ABS Anti-lock Brake System ACC Adaptive Cruise Control AFS Active Front Steering ASIL Automotive Safety Integrity Levels ATC Automatic Traction Control AUTOSAR AUTomotive Open System Architecture CAN Controller Area Network CBIICS City-Bus Information Integrated Control System CMM Capability Capture Model CMMi Capability Capture Model Integration CPU Central processing unit DAS Distributed Application Subsystem DC Direct Current DD Deep Discharge DECOS Dependable Embedded Components and Systems E/E Electrical/Electronical ECU Electronic Control Unit EHPS Electrohydraulical Power Steering EMB Electromechanical Brake EMS Electromechanical Power Steering EPA Environmental Protection Agency EPG Exhaust Pressure Governor EPS Electrically Assisted Power steering ESP Electronic Stability Program ETA Event Tree Analysis EV Electric Vehicle FAA Front Axle Actuator FCV Fuel Cell Vehicle FEM Finite element method FIR Finite Impulse Response FMEA Failure Mode and Effects Analysis FO Fail-Operational ix x ABBREVIATIONS FS Fail-Safe FSLI Fail-Silent FTA Fault Tree Analysis FTP Federal Test Procedure FTT-CAN Flexible Time-Triggered communication on CAN FUDC Federal Urban Driving Schedule GM General Motors HA Hazard Analysis HEV Hybrid Electric Vehicle HIL Hardware-In-the-Loop HPS hydraulic power steering HRB Hydrostatic Regenerative Brake System HWA Hand Wheel Actuator IDIOM Integrated Design and Optimization of Mechatronic Products ISO International Organization for Standardization KTH Kungliga Tekniska Högskolan MD Micro Discharge MEMS Microelectromechanical systems MR Magnetic Responsive MTTF Mean Time To Failure NEDC New European Driving Cycle NVH Noise, vibration, and harshness OASIS Optimization of Auxiliary Systems In hybrid heavy vehicleS OEM Original Equipment Manufacturer PLA Product Line Approach RAMS Reliability, Availability, Maintainability, Safety RBS Regenerative Brake System SAE Society of Automotive Engineers SEI Software Engineering Institute SIL Safety Integrity Level SBA Simulator Brake Actuation SOC State Of Charge TCS Traction Control System TFD Tactile Feedback Device TMC Tandem Master Cylinder TMR Triple Modular Redundancy TTCAN Time-triggered CAN VEB Volvo Engine Brake VCB Volvo Compression brake VDI Verein Deutscher Ingenieure xi Chapter 1 Introduction 1.1 General Overview The consequent evolution of the single-domain engineering disciplines mechanics, electronics, information processing and control is merged into the multi-domain discipline called “mechatronics1”. However, mechatronics is not just the design of systems incorporating these disciplines, it’s rather their intelligent mutual interac- tion and integration. According to [95], the development of mechatronic systems involves finding an optimal balance between the basic mechanical structure, the im- plementation of sensors and actuator, the automatic digital information processing and overall control, whose synergy results in innovative solutions. Applying control strategies is a core feature of mechatronic products. Also, as described in chapter 3, a new level of safety diagnosis and fault tolerance needs to be considered. Due to the wide scope of mechatronics as a holistic engineering discipline, its field of application and a corresponding list of examples is broad. However, some examples of mechatronic products are for instance computer hard drives, service robots and digital cameras. Furthermore, mechatronics also spans the component level; besides integrated hydraulic or pneumatic servo drives, one can also refer to automatic gearboxes, magnetic gearings and MEMS as mechatronic products. According to Dieterle [13], the main drivers for the next generation of mechatronic products are the so-called “market pull” (i.e. market requirements) and “tech- nology push” (technological trends). He points out some trends up to the year 2020: New products shall be cheaper, smaller and provide advanced functionality with software dominating function and quality of these systems. Furthermore, as 1The term mechatronics was first used by the Japan based Yaskawa Electric Corporation in 1969, [28]. 1 2 CHAPTER 1. INTRODUCTION electrical/electronical (E/E) systems will successively replace mechanical/hydraulic systems, Moore’s law (performance of electronic circuits doubles every 18 months) will stay valid. Besides, Dieterle states that the wish for physical mobility will remain dominant (despite Internet, Virtual Reality, etc.) and that the customers require more individualized products according to their specific wishes and needs. This report is developed within the KTH (“Kungliga Tekniska Högskolan”, Royal Institute of Technology) projects OASIS (Optimization of Auxiliary Systems In hybrid heavy vehicleS) and IDIOM (Integrated Design and Optimization of Mecha- tronic Products). It seeks to give an overview of current technologies in the vast field of automotive mechatronics. Therefore, not only the state of art is covered but also the current state of practice. 1.2 Vehicular Mechatronics The last section gave a quick overview on mechatronic systems. However, it did not yet discuss the field of vehicular mechatronics in detail, although this area is probably one of the more extensive ones. Isermann writes in [41] that “according to manufacturers statements, about 90% of all innovations for automobiles are due to electronics and mechatronics”. Automotive mechatronics is a driving factor for the development of new vehicle features as well as it pushes the general development of mechatronic systems. Lit- eratures e.g. [40], refer to the anti-lock brake system (ABS) as the first mechatronic product in vehicles, introduced by the Robert Bosch GmbH in 1978. Another well known early example is the automatic traction control (ATC) also termed as trac- tion control system (TCS)2. Yet another well established mechatronic product in vehicles is the mechatronic suspension, which was introduced in 1999 by Mercedes. One other example would be the common rail injection for Diesel engines, which uses piezoelectric injectors for precise high pressure diesel injection into the engine (1997). Among more recent developments are for instance the second generation of auto- matic motor stop systems (2006, series use