Browse Topic: Electric vehicles
Electrical vertical takeoff and landing (eVTOL) vehicles for urban air mobility (UAM) are garnering increased attention from both the automotive and aerospace industries, with use cases ranging from individual transportation, public service, cargo delivery, and more. Distributed electric propulsion systems are their main technical feature; they determine vehicle size and propulsion efficiency and provide distributed thrust to achieve attitude control. Considering the intended role of eVTOL vehicles, ducted-fan systems are ideal choice for the propulsor, as the duct provides a physical barrier between the rotating blades and the human, especially during the take-off and landing phases. Key Technology Challenges of Electric Ducted Fan Propulsion Systems for eVTOL introduces the main bottlenecks and key enablers of ducted-fan propulsion systems for eVTOL applications. Based on the introduction and discussion of these important issues, this report will help eVTOL engineers understand the key technical issues and inspire them to develop the ideal solutions that will enable eVTOL vehicle deployment for UAM operations. Click here to access the full SAE EDGETM Research Report portfolio.
Driving cycles are usually defined by vehicle speed as a function of time and they are typically used to estimate fuel consumption and pollutant emissions. Currently, certification driving cycles are mainly used for this purpose. Since they are artificially generated, the resulting estimates and analyzes can generally be biased. In order to address these shortcomings, recent research efforts have been directed towards development of statistically representative synthetic driving cycles derived from recorded real-world data. To this end, this paper focuses on synthesis of multidimensional driving cycles using the Markov chain-based method and particularly on their validation. The synthesis is based on Markov chain of fourth order, where the road slope is accounted, as well. The corresponding transition probability matrix is implemented in the form of a sparse matrix parameterized with a rich set of recorded city bus driving cycles. A wide collection of statistical features, including the frequency domain indicators, unique cross-correlation velocity-acceleration-slope indicators, and indicators related to bus stops at stations are considered for the purpose of driving cycle validation. To prove the synthesis method validity, a comparative statistical analysis of distributions of the nominated statistical features of synthetic and recorded driving cycles is carried out. Finally, a multi-criteria method of driving cycle validation based on lumped metrics is outlined and examined.
Automotive systems have become increasingly more complex, interconnected and prone to cyberattacks in recent years. With larger software bases and multiple external communication interfaces, the risks for new vulnerabilities and attack vectors on vehicles also increase. Therefore, modern cybersecurity validation is highly stressed for finding security vulnerabilities and robustness issues early and systematically at every stage of the product development process. The integration of a sophisticated fuzz testing program within the overall cybersecurity validation strategy allows for accommodating towards these challenging demands. In this paper, we review a general automotive cybersecurity engineering process containing functional testing, vulnerability scanning and penetration testing, and highlight shortcomings that can be complemented by fuzz testing. We present how fuzz testing is not only beneficial to improve product security directly by detecting weaknesses, but also indirectly by providing input to allow enhancing other testing activities. Finally, we provide a suggestion for an updated cybersecurity engineering process, which gives guidance on when fuzz testing should be performed and how fuzz testing should interface with other testing activities. Our approach is compliant to the ISO/SAE DIS 21434 cybersecurity engineering process. The approach uses Threat Analysis and Risk Assessment (TARA) together with Cybersecurity Assurance Levels (CALs) for the systematic identification of high-priority attack vectors and assignment of testing priorities. With this knowledge, it is possible to decide where, when and how often fuzz testing shall be applied for both finding unknown vulnerabilities and regressions in an automatized manner. This approach identifies issues earlier and with greater coverage than functional testing, vulnerability scanning and penetration testing could achieve on their own. As a result, by following this approach, the overall cybersecurity engineering process is more comprehensive, security remediation costs are lower, and resources for manual activities such as penetration testing are used more efficiently.
Increasing adoption of connected vehicles has led the vehicle manufacturers to deal with security issues in a vehicle-embedded system. In order to secure the security critical instructions/operations such as security functions, cryptographic credentials in a connected embedded system Arm Trustzone Technology is widely used in automotive embedded system across Cockpit, ADAS, V2X, etc. The Arm Trustzone technology protects the security critical operations by executing them in a trusted execution environment (TEE) parallelly by isolating them through hardware from classic rich execution environment (REE) using the shared hardware resources by protecting the confidentiality and integrity of the system. The Arm Trustzone technology uses secure configuration register (SCR) to switch between secure and non-secure worlds by providing two execution environments with different privileges through secure monitor call (SMC) and arm trusted firmware (ATF) across the resources e.g., memory, interrupts, peripherals etc. with different exception levels (EL). The enhanced security provided by Arm Trustzone technology is biased by resource constraints to the operations running in the REE when the resource isolation switches to the TEE through SCR. Hence, for the limited resource embedded automotive cockpits the driver assisting functions such as navigation system, which are running, in the REE gets void of resources due to the TEE, which in turn affects the functional safety of the overall driving system. Here, in order to eliminate the ambiguity between security and safety for the limited resource automotive cockpits where the addition of TEE is cannot be done, an efficient secure storage system is proposed without TEE in Arm Trustzone technology. The proposed approach stores the RPMB (Replay Protected Memory Block) key in the specialized memory of Arm Trustzone Technology during the vehicle provisioning with its encrypted version stored in the RPMB block of MMC. During the Harman secured boot loader based booting of the cockpit system, the derived key is generated from this key after decryption, and the application data based operations are executed in kernel space through an introduced secure storage kernel module in kernel, thereby providing the secured storage of the security critical operations in the Arm Trustzone Technology without TEE.
Practical encryption is an important tool in improving the cybersecurity posture of vehicle data loggers and engineering tools. However, low-cost embedded systems struggle with reliably capturing and encrypting all frames on the vehicle networks. In this paper, implementations of symmetric and asymmetric algorithms were used to perform envelope encryption of session keys with symmetric encryption algorithms while logging vehicle controller area network (CAN) traffic. Maintaining determinism and minimizing latency are primary considerations when implementing cryptographic solutions in an embedded system. To satisfy the timing requirements for vehicle systems, the memory-mapped Cryptographic Acceleration Unit (mmCAU) on the NXP K66 processor enabled 6.4Mb/sec symmetric encryption rates, which enables logging of multiple channels at 100% bus load. Using AES-128 in Cipher Block Chaining (CBC) mode provides the encryption for data confidentiality. Errors and integrity checks are handled by a Cyclic Redundancy Check (CRC) checksum withing the data and digitally signed SHA256 hash values of the overall encrypted record secured the integrity of the data. A hardware security module (HSM) is utilized to store asymmetric key pairs for key management. The HSM implements Elliptic-Curve Cryptography (ECC) algorithms for key exchanges and digital signatures. Secure collection and secure data uploads to a central server are demonstrated. This work and the source code are open source with the goal of inspiring improved secure communications for vehicle networks.
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