Design Article
How to meet driver assistance requirements
Wolfgang Bott, MOST Corperation
2/12/2013 7:52 AM EST
Multi-channel approach
Driver assistance systems typically have to deal with a variety of sensor data. In order to cope with the complexity, you often find a hierarchical approach with different abstraction levels and timing constraints. On the lower level there is a high amount of raw data, where high bandwidth as well as coherent and fast transmission are required. On the medium level, objects and attributes need to be transported. Finally, on the highest level, interpretation data will flow. A typical mapping to MOST is shown in Figure 2 MOST Data Transport Mechanisms.
A multi-channel network allows the parallel usage of all services for control data, streaming data and packet data through one network. These services are easily synchronized, if necessary, in a highly deterministic way.
The third generation of the MOST Specification [1] introduces MOST with 150 Mbit/s. MOST150 enables IP data communication, providing the automotive-ready Ethernet channel according to IEEE 802.3 with freely configurable bandwidth from 0 to nearly 150 Mbit/s. In this way, MOST is open to a broad variety of IP protocol based applications, including the seamless integration of wireless mobile devices or car-to-car and car-to-infrastructure communication.
The MOST Framework, with its function block concept, comprises a clear application programming interface. It is able to standardize both interfaces between infotainment applications and sensor interfaces such as cameras in driver assistance applications.
Hard real-time and low latency requirements
Driver assistance systems in a hierarchical approach with sensor fusion applications lead to hard real-time and low latency requirements. Severe jitter restrictions need to be met over an automotive environment temperature range from -40°C to 95°C (or even 105°C).
To this purpose, the MOST system concept is based on inherent synchronicity on the physical layer level. Clear distinction between transfer jitter (relevant on the system level) and alignment jitter (only relevant on the single link level) leads to a robust system design. The specification limits are testable and can be checked during compliance verification.
Next: Flexible topology
Driver assistance systems typically have to deal with a variety of sensor data. In order to cope with the complexity, you often find a hierarchical approach with different abstraction levels and timing constraints. On the lower level there is a high amount of raw data, where high bandwidth as well as coherent and fast transmission are required. On the medium level, objects and attributes need to be transported. Finally, on the highest level, interpretation data will flow. A typical mapping to MOST is shown in Figure 2 MOST Data Transport Mechanisms.
Figure 2: MOST data transport mechanisms
A multi-channel network allows the parallel usage of all services for control data, streaming data and packet data through one network. These services are easily synchronized, if necessary, in a highly deterministic way.
The third generation of the MOST Specification [1] introduces MOST with 150 Mbit/s. MOST150 enables IP data communication, providing the automotive-ready Ethernet channel according to IEEE 802.3 with freely configurable bandwidth from 0 to nearly 150 Mbit/s. In this way, MOST is open to a broad variety of IP protocol based applications, including the seamless integration of wireless mobile devices or car-to-car and car-to-infrastructure communication.
The MOST Framework, with its function block concept, comprises a clear application programming interface. It is able to standardize both interfaces between infotainment applications and sensor interfaces such as cameras in driver assistance applications.
Hard real-time and low latency requirements
Driver assistance systems in a hierarchical approach with sensor fusion applications lead to hard real-time and low latency requirements. Severe jitter restrictions need to be met over an automotive environment temperature range from -40°C to 95°C (or even 105°C).
To this purpose, the MOST system concept is based on inherent synchronicity on the physical layer level. Clear distinction between transfer jitter (relevant on the system level) and alignment jitter (only relevant on the single link level) leads to a robust system design. The specification limits are testable and can be checked during compliance verification.
Next: Flexible topology
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