Time-Synchronization Method for CAN–Ethernet Networks with Gateways

Abstract

Time-synchronization technology can provide a common notion of time among the participating nodes on a network. This is essential not only for protocol operation for time-critical services but also for the time stamp for information included in the message. Precise time information can be very crucial for such things as autonomous driving because there are various sensor measurements from multiple cameras, and radio detection and ranging (radar) and light detection and ranging (LiDAR) are used for perceiving the current situation via sensor fusion. A well-known synchronization method, IEEE 1588, denoted as the precision time protocol (PTP), can be used for various applications. For in-vehicle networks of autonomous cars, we have to consider that the network may be comprised of subnetworks based on different protocols such as controller area network (CAN) and Ethernet. However, implementing PTPs on such heterogeneous vehicle networks causes several problems. First, the PTP procedure must be modified to be implement on a CAN network. Second, to calculate the delay and offset for PTP, the processing delay that occurs during message conversion must be considered. In this paper, we propose a synchronization method for CAN–Ethernet networks to solve these problems. The performance of the proposed synchronization method is evaluated by experiments on a real CAN–Ethernet network.

Performance Enhancement of CAN/Ethernet Automotive Gateway with a CAN Data Reduction Algorithm

“…The IVN architecture of modern vehicles employs heterogeneous protocols such as CAN, LIN, FlexRay, and Ethernet, each with distinct characteristics. A gateway is required to enable seamless communication among multiple networks using various protocols [9,[11][12][13][14][15][16][17][18][19][20]. The automotive electric/electronic (E/E) architecture is undergoing a transition from a central gateway to a domain E/E architecture [11,19].…”

“…Various automotive gateways [11][12][13][14][15][16] that use heterogeneous IVN protocols were proposed. A gateway framework for IVNs that includes CAN, FlexRay, and Ethernet was proposed in [11].…”

A Fuzzy-PI Clock Servo with Window Filter for Compensating Queue-Induced Delay Asymmetry in IEEE 1588 Networks

“…IEEE 1588-2008 (PTPv2) [9] supports obtaining hardware timestamps, and the accuracy can reach the sub-microsecond level. It is widely used in most fields, such as Smart Grid [10], Seismic Survey [11], Automotive Electronics [12], and Flight Test [13]. White Rabbit (WR) [14], also known as IEEE 1588-2019 [15], uses optical fiber to transmit time and frequency information.…”

“…Furthermore, it does not provide an estimation method for clock skew. For convenience of comparison, the clock skew directly uses the value of Equation (12) in this paper, with the opposite sign. The exponentially weighted moving average filter factor is set to 1.…”

Software-Based AUTOSAR-Compliant Precision Clock Synchronization Over CAN

“…Proper synchronization is a basic requirement for various functions: from capture-and-replay methods during the development phase of ECUs to the coordination of sensor data acquisition and control actions during normal operation to the recording of error data for diagnostic purposes [4]. In the AUTOSAR (AUTomotive Open System ARchitecture) architecture, clock synchronization therefore plays a central role across the different network domains [5], with different mechanisms adapted to the capabilities of the individual networks and time gateways connecting the time domains [6]. For CAN, AUTOSAR defines a simple oneway reference broadcast scheme with a time master regularly distributing its local time to the connected slaves [7].…”