Browse Topic: Electronic brake controls
In this study, we introduce an electronically controlled brake system (ECB) that can be applied to electric vehicles (EVs) and internal combustion engine vehicles (ICEVs). The main features of the ECB include maximizing the regenerative energy while maintaining vehicle stability and ensuring redundancy in automatic braking. The brake system consists of upper and lower units. The newly developed upper unit has a brake-by-wire configuration and can control the front and rear wheel pressures separately. Hereinafter, controlling the front and rear wheel pressures separately is referred to as two-channel pressure control. The regenerated energy can be maximized while appropriately maintaining the distribution of the front and rear braking forces based on the two-channel pressure control during regenerative cooperation. The lower unit is a conventional hydraulic unit for executing anti-lock brake control, electronic stability control and so on. Each of the upper and lower units has a pressure source and is connected via a communication bus. Thus, even if one of the pressure sources malfunctions during automatic braking, sufficient brake forces can be ensured by another brake system.
Efficiency testing of hybrid-electric vehicles is challenging, because small run-to-run differences in pedal application can change when the engine fires or the when the friction brakes supplement regenerative braking, dramatically affecting fuel use or energy regeneration. Electronic accelerator control has existed for years, thanks to the popularity of throttle-by-wire (TBW). Electronic braking control is less mature, since most vehicles don’t use brake-by-wire (BBW). Computer braking control on a chassis dynamometer typically uses a mechanical actuator (which may suffer backlash or misalignment) or braking the dynamometer rather than the vehicle (which doesn’t yield regeneration). The growth of electrification and autonomy provides the means to implement electronic brake control. Electrified vehicles use BBW to control the split between friction and regenerative braking. Automated features, e.g. adaptive cruise control, require BBW to actuate the brakes without pedal input. We present a system for computer control of brake and accelerator inputs on a TBW- and BBW-equipped vehicle. The system injects analog signals into the vehicle’s wiring harness, bypassing the pedals and obviating mechanical actuation and brake-by-dyno. The system combines feedforward control based on recorded human pedal application with feedback control based on human-driven speed. This combination produces repeatable driving, enabling precise measurement of the impact (e.g. fuel or battery use) of small changes to the powertrain (e.g. engine calibration or lubricant) or test cycle (e.g. speed or grade). The system’s J2951-defined energy-efficiency rating and absolute speed-change rating were more consistent than a human’s by factors of 6.63 and 4.10, respectively. The effect of braking intensity on braking regeneration is quantified using the system.
In recent years, the development of intelligent vehicle and new energy vehicles has advanced by leaps and bounds, which has further improved the safety requirements of controllers. And more and more component manufacturers are actively promoting the ISO 26262 standard “Road Vehicles-Functional Safety”. At the same time, the electronic parking brake (EPB) system is an indispensable electronic product of the intelligent vehicle, which brings convenience to drivers and improves vehicle safety. So it is necessary to develop an intelligent vehicle pneumatic EPB system based on the ISO 26262 standard to improve reliability and safety. In this paper, the concept phase of the ISO 26262 standard was analyzed and applied to the design of the EPB system. The risk assessment and risk analysis of the EPB system were carried out, and the corresponding safety objectives were formulated. In this paper, a dual MCU scheme was proposed to the EPB system, which contained the core MCU and the monitoring MCU. Then the hardware circuit is designed according to the proposed safety goal, including mutual reset circuit and arbitration circuit. And the three-layer software architecture of the EPB system was designed, including basic function layer, fault detection layer and monitoring layer. Finally, the functional verification experiment and the safety test were carried out. The experimental results show that the designed EPB controller not only meets the design requirements of the intelligent vehicle EPB system, the proposed control strategy can also detect faults accurately and respond in time. The EPB controller satisfies the proposed safety objectives and improves the reliability of the EPB system greatly.
The purpose of this study is to develop a method for evaluating the safety of the braking control algorithm for automated driving under mixed traffic flow of automated driving system and vehicles driven by drivers. We consider that the automated driving system should be controlled such that it blends in with mixed traffic. Therefore, in evaluating the safety of braking control for the automated driving system when following, the influence of the automated driving system on the driver of the following vehicle is an important evaluation index. First, we analyzed past traffic accidents in Japan to determine a suitable traffic environment for evaluating the safety of the braking control algorithm for the automated driving system when following. Second, the driver’s braking operations were measured using actual vehicles in this situation. We developed a method of generating sample algorithms of braking control based on the driver’s braking operations. Finally, we developed a method of identifying the most suitable range of parameters of braking control algorithms by evaluating these sample algorithms based on the results of actual experiments. This evaluation method uses a driving simulator. The automated driving system in which the sample algorithm of braking control is installed runs ahead of the vehicle driven by a subject in the driving simulator. The subject evaluates the sense of danger for braking by the automated driving system.
Vehicle manufacturers are suffering from increasing expenses for fixing software issues. This fact is mainly driving their desire to use mobile communication channels for doing Software Updates Over The Air (SOTA). Software updates today are typically done at vehicle service stations by connecting the vehicles’ electronic network via the On Board Diagnostic (OBD) interface to a service computer. These operations are done under the control of trained technicians. SOTA means that the update process must get handled by the driver. Two critical aspects need to get considered when doing SOTA at Electronic Brake Control (EBC) systems. Both will determine the acceptance of SOTA by legal authorities and by the passengers: The safety and security of the vehicle The availability of the vehicle for the passengers The security aspect includes the necessity to protect the vehicle and the manufacturers IP from unwanted attacks. Existing safety measures ensure safe operation of a vehicle at all times. In general and especially for EBC systems the existing safety measures need extensions for updating software in remote locations. It must be absolutely ensured, that the vehicle will not move while changing the software. In difference to software updates at service stations the SOTA concept must consider any possible level of technical knowhow of any potential driver, who might start an update. This requirement is not just critical for updating the EBC itself but also for updating other ECUs. Vehicles cannot be driven while updating the software and thus they are not available for a certain period of time. In this paper three different approaches are discussed how to execute SOTA and what this means with respect to the duration of the update process. The study starts with a detailed analysis of the operations and activities for updating software within a vehicle and EBC unit. It includes descriptions of data flows and examples of the influences by the various bus options of the vehicles’ networks. Next are explained options for scalable system solutions and implementing security functions within the vehicles network with examples of its implementation by using existing electronic components. Finally we show options for the implementation and how to reduce the downtime of the EBC system. Several aspects of cyber security in vehicles have been studied in the past. This paper concentrates onto the specifics for EBC systems in a holistic system approach.
Vehicle dynamics simulation with Hardware In the Loop (HIL) has been demonstrated to reduce development and validation time for dynamic control systems. For dynamic control systems such as Anti-lock Braking System (ABS) and Electronic Stability Control (ESC), an accurate vehicle dynamics performance simulation system requires the Electronic Brake Control Module (EBCM) coupled with the vehicles brake system hardware. This kind of HIL simulation-specific software tool can further increase efficiency by means of automation and optimization of the development and validation process. This paper presents a method for HIL vehicle dynamics simulator optimization through Brake Response Time (BRT) correlation. The paper discusses the differences between the physical vehicle and the HIL vehicle dynamics simulator. The differences between the physical and virtual systems are used as factors in the development of a Design Of Experiment (DOE) quantifying HIL simulator performance. Finally, the DOE results are used to drive the development of a tool to correlate the HIL system hardware to the physical vehicle BRT. This leads to the development of hardware with improved BRT, and to the design of new HIL simulators with improved brake response.
This recommendation is intended to provide the minimum acceptable criteria for snowmobile hand brake control systems. This recommendation is not intended to cover competition vehicles nor is it intended to limit development of new and/or improved technology in controls. Although these recommendations are primarily addressed to hand control systems using an outer flexible conduit with a multiple strand inner cable or hydraulic type brake control system, the basic requirements of freedom of movement, strength, material, etc. will apply to any system.
It is recognized that a malfunction in any one of the specified areas can degrade intended performance, but that levels of malfunction or combinations thereof must be considered by the vehicle designer in determining the point at which a failure indication is warranted. Consequently, the minimum reaction recommended by this document consists of making available a malfunction signal.
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