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Brake-by-Wire, Motivation and Engineering - GM Sequel
Abstract
Achieving optimum results and developing systems that are towards production intent is a challenge that the General Motors Sequel platform not only overcame, but also enhanced by providing an opportunity to achieve maximum integration of new technologies. Implementation of these new technologies during this project enabled us to understand the impact and rollout for future production programs to enhance performance and add features that will enable General Motors to make quantum leaps in the automotive industry. Presented are aspects, objectives and features of the Sequel's advanced Brake-By-Wire system as it migrates from concept towards production readiness. Also included in the paper are the objectives for system design; functional/performance requirements and the desired fault tolerance. The system design, component layout, control and electrical system architecture overviews are provided. Following this, an analysis and conclusion is presented on the adaptability of this technology for future implementation in regular production programs.
... Three-Motor Case: General Motor sequel deployed a single motor to drive the front axle and two in-wheel motors to independently drive the rear wheels [24], [25]. Other three-motor configurations were rarely reported. ...
... The cell current limits are converted to the following power constraints:P bat,total (k) ≥ V oc (k)I min n bat,base s bat (24) P bat,total (k) ≤ V oc (k)I max n bat,base s bat (25) where I min and I max are the allowable maximum charge current and discharge current, respectively. The battery pack mass m bat is scaled by m bat = m bat,base s bat (26) where m bat,base is the mass of the baseline battery pack. ...
This paper is concerned with combined power-source sizing and energy management optimization for multi-motor-driven electric powertrains. Existing studies focus mostly on adopting heuristically determined battery and motor sizes for such power-trains, without a sufficient exploration of the coupling between power-source dimension and energy management strategy. To address this research gap, this paper aims at presenting an alternative, convex programming-based method to optimize the multi-power-source integration problem, for vehicular economy maximization. Specifically, for the first time, we leverage this method to optimize an electric bus powertrain configuration with front-and-rear-axle dual motors and a clutch, as a case study. Numerous analysis results, as well as comparisons with common design/control practice, demonstrate the effectiveness and computational benefit of the proposed scheme. IEEE
... Brake-by-wire system, which mechanically decouples the brake pedal from the actuation of the mechanical brake devices, can make the braking force distribution and modulation between the front and the rear axles more flexible [6,7,8]. It was initially developed to improve the dynamic performance of conventional ICE vehicles and has been Regenerative Braking Control Algorithm for an Electrified Vehicle Equipped with a By-Wire Brake System applied in some commercialized cars. ...
... When the driver depresses the brake pedal, the total brake demand (T b_need ) can be detected via pressure sensor in the pedal unit, as equation (7) shows. (7) where, p m is the hydraulic cylinder pressure of the pedal unit, μ b is the friction coefficient of the brake disc, r f is the radius of the piston of the front wheel cylinder, R e_ f is the effective friction radius of the brake disc and β is the real-time front-rear braking force distribution coefficient. ...
Regenerative braking, which can effectively improve vehicle's fuel economy by recuperating the kinetic energy during deceleration processes, has been applied in various types of electrified vehicle as one of its key technologies. To achieve high regeneration efficiency and also guarantee vehicle's brake safety, the regenerative brake should be coordinated with the mechanical brake. Therefore, the regenerative braking control performance can be significantly affected by the structure of mechanical braking system and the brake blending control strategy.
By-wire brake system, which mechanically decouples the brake pedal from the hydraulic brake circuits, can make the braking force modulation more flexible. Moreover, its inherent characteristic of ‘pedal-decouple’ makes it well suited for the implementation in the cooperative regenerative braking control of electrified vehicles.
With the aims of regeneration efficiency and braking performance, a regenerative braking control algorithm for electrified vehicles equipped with a brake-by-wire system is researched in this paper. The layout of the adopted brake-by- wire system is introduced. The proposed regenerative braking control algorithm is illustrated. To validate the control performance of the algorithm, hardware-in-the-loop simulations are carried out. The simulation results show that, based on brake-by-wire system, the proposed control algorithm, coordinating regenerative brake and hydraulic brake well, can further improving the regeneration efficiency of electrified vehicle and guarantee the braking performance in the meantime.
... The development of initial EMB has been actively conducted in the automotive field to replace hydraulic brake [1,2]. Automotive hydraulic brake systems have a complex hardware structure owing to oil pumps, solenoid valves, hydraulic piping, and additional braking function devices such as an anti-lock braking system (ABS) and electric parking brake (EPB), making maintenance increasingly difficult. ...
Recently, with the emergence of electro-mechanical brake (EMB) devices, a control method for an electric motor to replace the existing pneumatic actuator has been studied. The clamping force estimation control method (ECM) from the rotor position of the motor is primarily used because sensor installation is difficult owing to the temperature increase of the friction surface of the brake disk. However, to accurately control the clamping force according to the change in the friction surface and hysteresis characteristics of the motor, it is necessary to consider the installation of a force sensor. This study deals with the installation of force sensors and the sensor compensation control method (SCCM) for the clamping force of an EMB for high-speed train applications. To evaluate the proposed method, that is, the SCCM of the EMB, static control with the wheel in the non-rotating state and dynamic control with the wheel in the rotating state were performed. In addition, static control performance evaluation was performed under the maximum clamping force reference and continuous step reference input. Comparing the two control methods, the error rate of the SCCM was improved by up to 5 %. The results of evaluating the dynamic braking performance with the wheels rotating at 300 km/h showed that the SCCM had an improved deceleration pattern, and the braking speed was more than 3 s faster than that of the pneumatic braking system and ECM of the EMB.
... At present, the most reliable and widely used vehicle braking system is hydraulic brake-based, which takes hydraulic oil as the transmission medium. 1 The hydraulic brake is composed of a master cylinder, hydraulic tubes, valves, wheel cylinders, a brake caliper body, brake pads, and a brake disk. When a braking demand is wanted, braking pressure is generated by the master cylinder and transmitted through the hydraulic tubes to the wheel cylinders, which push the brake pads clamping the brake disks to realize the braking of the vehicle. 2 However, the complex hydraulic tubes and numerous valve components of the hydraulic brake system result in a complex structure, bulky, and further the braking pressure hysteresis in transmission cannot be ignored, which would cause longer braking distance. ...
Electro-mechanical brake (EMB), driven by a motor to push the brake pads to clamp the brake disk for braking, is considered as the future of vehicle braking system, because of its simple structure and controllable braking force. However, EMB must face the problem of motor blocking when it works in a long-time continuous braking condition. When the motor is blocking, the current in the coil windings is large enough to burn the motor down, leading to the failure of EMB, which is a great threat to driving safety. To solve the problem, a new brake-by-wire actuator featuring magnetorheological (MR) clutch (MRC) – an EMB combining with an MRC, i.e., BBW-MRC, is presented in this paper. Specifically, the BBW-MRC is composed of a driving motor, an MRC, a planetary gear reducer, a ball screw, brake pads, and a brake disk. The motor output is transmitted to the MRC through the reducer, and it is controlled in real-time, continuously, and as expected by the MRC via controlling its applied current. The ball screw is driven by the MRC and pushes the brake pads to clamp the brake disk to realize braking in time. The small-scaled BBW-MRC system and the corresponding test bench are developed, and a hierarchical control strategy applied to the BBW-MRC system is designed. Based on the test bench, a series of tests are carried out on the BBW-MRC system, including the stability test of the BBW-MRC system under a long-time braking condition, the braking force response test of the BBW-MRC, and the braking force tracking test. Research results show that: (1) the BBW-MRC system has a quick and accurate performance to track desired braking forces; (2) under long-time braking conditions, the braking force keeps stable and the surface temperature of the motor has a normal change; and (3) the braking force response time has a 53.5% improvement over the EMB that driven by the motor directly.
... Four-motor DDSs are typically comprised of in-wheel motors, that can independently drive each wheel. Articles [8]- [26] describe dual-motor DDSs, [27], [28] describe threemotor systems, and [29]- [37] describe four-motor configurations. ...
Multi-Motor Electric Vehicles (MMEVs) have been identified as a solution to the current disadvantages of Single Motor Electric Vehicles (EVs) in energy consumption and driving range. These improvements are achieved by operating each motor in its peak efficiency region, as appropriate for the driving scenario. Although MMEVs have increased efficiency, the extent is highly dependent on the sizes of the motors. Thus, some researchers have begun to determine the optimal motor sizes. This paper reviews existing literature on motor sizing techniques and analyzes their performance through overall powertrain dynamic and efficiency performance.
... The electromechanical brake (EMB) uses the rotational motion of the motor to move the caliper to exert clamping force on the brake disc. The development of the initial EMB was actively carried out in the automotive field to replace the hydraulic brake [1,2]. ...
This paper deals with efficient operation method for the electromechanical brake (EMB). A three-phase interior permanent magnet synchronous motor (IPMSM) is applied to the EMB operation. A current controller, speed controller, and position controller based on proportional-integral (PI) control are used to drive the IPMSM. Maximum torque per ampere (MTPA) control is applied to the current controller to perform efficient control. For MTPA control, the angle β is calculated from total input current, and the synchronous frame d–q axis current reference is determined by the angle β. The IPMSM is designed and analyzed with finite element analysis (FEA) software and current control is simulated by Matlab/Simulink using a motor model designed by FEA software. The simulation results were verified to compare with experimental results that are input current and clamping force of caliper. In addition, the experimental results showed that the energy consumption is reduced by MTPA.
... Due to the problems of hydraulic brakes with respect to the maintenance of oil and oil pressure lines, as well as the efficiency of hydraulic pump operation in conventional brake systems in the automotive field, EMB is drawing more attention [1,2]. ...
This paper deals with clamping force simulation and experimental result of the Electro Mechanical Brake (EMB) for the High-Speed-Train (HST). Three phase Surface Permanent Magnet Synchronous Motor (SPMSM) is applied to the clamping force control of EMB. At the initial development stage, Proportional Integral (PI) current control under synchronous d-q axis frame was applied to the SPMSM torque control. In addition, an anti-windup controller, which is advantageous for fast current tracking, is proposed to improve the torque output. Matlab/Simulink simulation results were compared with the experimental results measured by the clamping force sensors of the EMB test rig. The experimental results were verified compared to the brake design specification of the High-Speed Electric Multiple Unit-430 Experimental (HEMU-430X) train.
... Furthermore, Drive-by-Wire (DBW), Steer-by-Wire (SBW) and Brake-by-Wire (BBW) systems for the automotive industry have attracted researchers in the past two decades (Johansen, et al. 2003;HoseinNezhad, Bab-Hadiashar and Harding 2004;Hoseinnezhad and Bab-Hadiashar 2005;Hoseinnezhad 2006;Park and Heo 2004;Hoseinnezhad and Bab-Hadiashar 2006). Several types of automotive X-by-Wire systems such as SBW and BBW have been developed (Sundar and Plunkett 2006). Such systems solely rely on microcomputer systems communicating with sensors and actuators to maintain the required functionalities. ...
Anti-Lock Braking Systems (ABS) and Brake-by-Wire Systems (BBW) are safety-critical applications by nature. Such systems are required to demonstrate high degrees of dependability. Fault-tolerance is the primary means to achieve dependability at runtime and has been an active research area for decades. Fault-tolerance is usually achieved in in traditional embedded computing systems through redundancy and voting methods. In such systems hardware units, actuators, sensors, and communication networks are replicated were special voters vote against faulty units. In addition to traditional hardware and software redundancy, hybrid and reconfiguration-based approaches to fault-tolerance are evolving. In this paper, we present a reconfiguration-based fault-tolerant approach to achieve high dependability in ABS BBW braking systems. The proposed architecture makes use of other components of less safety-critical systems to maintain high dependability in the more safety-critical systems. This is achieved by migrating safety-critical software tasks from embedded computer hardware that runs into a malfunction to other embedded computing hardware running less-critical software tasks. Or by using a different configuration in terms of the used speed sensors and type of ABS. The proposed architecture is on average 20% more reliable than conventional ABS architectures assuming equal reliabilities of different components.
... Modern automotive vehicles are highly complex systems, containing a large number of mechanical, electrical and electronic components. Recent development trends in the automotive industry have seen a steady move towards an increased usage of electronically controlled components, with concepts such as brake-by-wire and steer-by-wire becoming increasingly common [1]. The electric and electronic (E/E) signal architecture of a vehicle is controlled by a large number of Electronic Control Units (ECUs), communicating with each other over a bus network spanning the entirety of the vehicle[2] [3]. ...
The complexity of electrical and electronic automotivesystems have increased steadily over the previous decades, with modern vehicles containing as many as 50-70 Elec-tronic Control Units, and several CAN-communication net-works. In order to address the increasing complexity of these safety-critical embedded systems, safety standards such as ISO 26262 are making their way to the market, posing strong restrictions on the development process of automotive systems in order to ensure safety. With cur-rent automotive actors possessing large existing source codebases for their ECUs, primarily written in the C program-ming language, the demands posed on software architec-tural models by ISO 26262 are proving to be a challenge tomeet given the difficulties of modelling low-level languages such as C. This thesis aims to survey currently existingmodelling formalisms with regards to their ability to modelautomotive embedded C source code in a way that facili-tates ISO 26262 compliance. A delimitation is made to theuse of the MISRA-C:1998 subset of the C programminglanguage, a safer subset commonly used in automotive in-dustry. A short ontology is proposed, coupled with a metric for evaluating the completeness of a modelling formalism. Requirements are posed on suitable modelling formalisms,and AADL, Lustre, SysML and Promela are identified as promising candidates for modelling embedded C code. Se-mantic constructions present in the C language are iden-tified, and a mapping between these constructions and se-mantic constructions present in the selected modelling for-malisms is made and analyzed using the completeness eval-uation framework that was proposed. Architectural De-scription Languages (ADL), such as AADL, are identifiedas being the most promising with regards to modelling em-bedded C code. Control Flow Graphs are identified as a promising augmentation to ADLs in order to deal with theirlack of control flow semantics.
The electromechanical braking is a novel braking mode, which is the development direction of the electrification and intelligent train braking system. In this paper, a coupled-rigid-flexible model of the EMB unit is developed, and dynamic characteristics of the EMB unit are analysed based on the model. Firstly, assumed mode method is used to describe the axial and torsional vibration of the screw in nut-screw assembly, and lumped mass method is used to describe motions of other components in the EMB unit. Secondly, the EMB unit model is established and simulated in Matlab/Simulink software based on electro-mechanical and rigid-flexible coupling characteristics. Then the model parameters are calibrated by experiment. Finally, the simulated model is studied to analyse the influence of various factors on the dynamic characteristics of the EMB unit. The results indicate that an increment in viscous damping flats the fluctuation of the pushout force. The maximal pushout force decreases and the changing trend of force is different along with the rotational structure damping increases. The flexible vibration of the screw results in higher pushout force, meanwhile the fluctuation of the force is greater with higher braking instruction current value. When the ratio of the screw length to the screw cross-sectional diameter is 30, the pushout force varies along with the friction pairs wear under vibration. The study can provide references for structure design, control design and fault diagnosis of EMB units.
A new brake-by-wire system based on direct-drive electro-hydraulic brake (DDEHB) unit was designed for vehicle to improve braking performance. A comprehensive brake-by-wire system including this new unit which was set up and its structure and principles were introduced detailed in part II. Then the dynamic model of DDEHB was studied by detailed studying the movement of piston and plunger when braking in part III. At last a Simulink model based on section III was established using Mathlab/Simulink and Mathlab/Stateflow in part IV, and the reliability of model was testified by simulation. The simulation results showed that this novel brake unit can rapidly respond and improve braking performance significantly.
The contribution introduces a modular and flexible experimental vehicle for investigation of novel vehicle electronics. The experimental vehicle features 4-wheel-drive, 4-wheel-steering and electric brakes. Each wheel can be actuated individually. All actuators are controlled by-wire without mechanical or hydraulic fall-back layer. To evaluate the safety of the experimental vehicle on the topmost functional layer (“vehicle layer”), a novel approach for targeted safety analysis is introduced. The approach especially aims at by-wire vehicles with a high degree of functional redundancy between different actuation units and strong integration of driving functionalities as steering or braking. For demonstration, the results of a simplified hazard analysis according to ISO 26262 for operation of the experimental vehicle in a well defined environment are presented. The results serve as a basis for safety evaluation of the vehicle using the introduced approach.
The automotive industry paradigm shift from convention internal combustion engine vehicles to electric vehicles brought new technical challenges for automotive OEMs. During this shifting period, electric vehicles are expected to be produced on small volumes, requiring new design and production processes. In order to have a more flexible and efficient production system, OEMs and suppliers are working on modularity as a design tool to reduce the time to market, reduce the complexity of supply chains and reduce the total vehicle production cost. One of these modular components will be the chassis, which was introduced as a skate by GM on the Sequel concept. On this concept all the crashworthy components were included in the skate, over which an autobody was assembled. This skate-chassis included all the powertrain components, batteries, power electronics and motors, as well as braking and suspension systems. This skate concept was applied to a new small urban electric vehicle and was focused on three main requirements: low production cost, low weight and modularity, assuring the accomplishment of all security and integrity requirements applicable to such a component. On an electric vehicle the optimal position of batteries shall be on a central and low position in the car. In order to take advantage of this configuration a single central beam was used as a structural element providing torsion and bending stiffness to the overall structure, with the batteries placed on both sides of this beam. The use of bended sheet metal allows for a reduction on the production costs, adequate for the manufacturing on small production series. Additionally, the possibility of using different sheet thickness on different chassis parts allowed for a reduction on the overall weight of the chassis.
Featuring compact structure, short transmission chain and high efficiency, the distributed drive electric vehicle has arisen great attention worldwide. In this paper, the research and development status of distributed drive electric vehicle chassis configuration is summarized. Specifically to suppress the negative effects of unsprung mass of the distributed drive electric vehicle, several novel schemes are introduced based on methods of lightweight design, mass transfer, dynamic vibration absorber and active suspension. Combined with some novel technologies, the developing trend of distributed drive electric vehicle chassis is discussed.
This paper describes an overview of the general structure and working principle of brake-by-wire and steer-by-wire platform at first. We design a real-time hardware and software the system. And We use Matlab/xPC Target real-time platform to build the hardware in-the-loop platform for brake-by-wire and steer-by-wire system, we select typical operating conditions to conduct the hardware-in-the-loop test, the results show that the by-wire system testing capabilities of the platform.
A dry Brake-By-Wire (BBW) system is one in which the existing hydraulic system is replaced by motor driven electro-mechanical calipers. Although it has yet to be introduced into series production, the attractive benefits of BBW have kept it in the mainstream of brake research for a number of years. In the current investigation, the BBW system is configured with electric wedge brakes in the front axle where high braking forces are required, while conventional electro-mechanical brakes are used in the rear axles. This paper will examine the feasibility of the current BBW system configuration through lab and vehicle performance tests including ABS (anti-lock braking system).
A new control algorithm of a wedge brake system has been developed. The proposed control algorithm is based on the position control and current control of electronic wedge brake(EWB). The EWB control system in rear wheel has both active braking functions like ABS and ESC and convenient function such as EPB. In this paper, development of control algorithm was performed using hybrid brake system(HBS) which consists of hydraulic brake in front wheel and electronic brake in rear wheel. At first, the configuration of EWB system is explained. Next, structure of electronic control in HBS is explained. And then ABS/ESC/EPB control algorithms are shown. ABS control algorithm has wheel slip calculation, wheel error calculation, wheel slip control, position control, current control, and duty control. ESC algorithm consists of yaw error calculation, yaw moment control, wheel slip control, position control, current control, and duty control. EPB algorithm is made up of apply/release interface, auto or static/dynamic interpretation, driver interpretation, position control, current control, and duty control. To verify the feasibility of the proposed control algorithm, vehicle tests were carried out with the HBS test vehicle equipped with EWB actuators for two rear wheels as well as rig tests and HILS tests. From this research, we have obtained core technologies to develop the ABS/ESC/EPB logic of rear EWB system which can be applied to BBW system in advanced vehicles such as hybrid vehicles, fuel cell vehicles, and electrical vehicles.
This paper presents an fault-tolerant yaw moment control for a vehicle with steer-by-wire (SBW) and brake-by-wire (BBW) devices. SBWs and BBWs can give active front steering (AFS) and electronic stability control (ESC) functions, respectively. Due to motor-driven devices, actuator and sensor faults are inherent in SBW and BBW, and can cause a critical damage to a vehicle. Simple direct yaw moment control is adopted to design a vehicle stability controller. To cope with actuator failure, weighted pseudo-inverse based control allocation (WPCA) with variable weights is proposed in yaw moment distribution procedure. Simulations on vehicle simulation software, CarSim®, show the proposed method is effective for fail safety.
This paper presents an integrated chassis control system with fail safety using optimum yaw moment distribution for a vehicle with steer-by-wire and brake-by-wire devices. The proposed system has two-level structure: upper- and lower-level controllers. In the upper-level controller, the control yaw moment is computed with sliding mode control theory. In the lower-level controller, the control yaw moment is distributed into the tire forces of active front steering(AFS) and electronic stability control(ESC) with the weighted pseudo-inverse based control allocation(WPCA) method. By setting the variable weights in WPCA, it is possible to take the sensor/actuator failure into account. In this framework, it is necessary to optimize the variables weights in order to enhance the yaw moment distribution. For this purpose, simulation-based tuning is proposed. To show the effectiveness of the proposed method, simulations are conducted on a vehicle simulation package, CarSim.
Next generation drive-by-wire automotive systems enabling autonomous driving will build on the fail-operational capabilities of electronics, control and software (ECS) architectural solutions. Developing such architectural designs that would meet dependability requirements and satisfy other system constraints is a challenging task and will possibly lead to a paradigm shift in automotive ECS architecture design and development activities. This aspect is becoming quite relevant while designing battery-driven electric vehicles with integrated in-wheel drive-train and chassis subsystems.In such highly integrated dependable systems, many of the primary features and functions are attributed to the highest safety critical ratings. Brake-by-wire is one such system that interfaces with active safety features built into an automobile, and which in turn is expected to provide fail-operational capabilities. In this paper, building up on the basic concepts of fail-silent and fail-operational systems design we propose a system-architecture for a brake-by-wire system with fail-operational capabilities. The design choices are supported with proper rationale and design trade-offs. Safety and reliability analysis of the proposed system architecture is performed as per the ISO 26262 standard for functional safety of electrical/electronic systems in road vehicles.
A discrete-time model is used to simulate performance of PM brushless DC motor drives under normal and faulty operations. Normal conditions included perfect and imperfect commutations as well as noisy operation. Faulty operation was considered an open-circuit fault on one phase of the stator windings. Current waveform of the motor-DC link is monitored and processed using continuous wavelet transform to derive suitable diagnostic indices. An adaptive neuro-fuzzy inference system (ANFIS) is trained based on indices extracted under various operating conditions in order to automate the diagnosis process. The developed ANFIS yielded a perfect diagnosis of the fault. A good agreement between simulation and experimental results is achieved.
Cogging torque is produced in a permanent magnet machine by the
magnetic attraction between the rotor mounted permanent magnets and the
stator. It is an undesired effect that contributes to the machines
output ripple, vibration, and noise. This paper analyzes various cogging
torque minimization techniques as applied to a permanent magnet machine
used in an electric power steering system. A six pole, eighteen slot,
surface mounted, rare earth type, brushless permanent magnet machine is
analyzed. The resultant cogging torque values are computed using a two
dimensional finite element analysis package