[Technology Report]
Four-Wheeled Supercomputers
Automotive safety equipment turns vehicles into the largest collection of mobile computing and sensing equipment you'll own.
Expect to see even more efficient and powerful vision systems in the near future, allowing for better recognition and tracking. They might employ chips like Recognetics’ CM-1K neural network chip, which can apply up to 256 bytes to 1024 neurons in parallel. Furthermore, the chips can be logically stacked so they all operate in parallel.
The chip isn’t being used for automotive applications at this time, but it is performing real-time image recognition for a number of applications. Still, new image-processing architectures such as the CM-1K and IMAPCAR will expand vision-system performance, often with additional sensor support.
3D IMAGING Advances in sensor technology will have as much influence on future active safety systems as parallel-processing improvements have had in computing performance. Shrinking the size of a unique 3D camera could make a difference. Advanced Scientific Concepts has a Flash Ladar 3D camera system that employs a short pulse of laser light to deliver 3D information (Fig. 5). The resulting information can then be used in an automotive setting to identify objects within the environment with a very high degree of accuracy. The current incarnation of the camera can operate at 30 frames/s. The laser is eye-safe, suiting it for automotive applications.
This approach is significant because it provides the accuracy of a laser or radar range finder with the scope of a vision system. The range and accuracy vary depending on the configuration. However, one system has a precision of 3 in. with a range up to 5000 ft. The system also includes much of the computational details within the camera.
Although the system uses optics similar to a camera, the sensing system is significantly different. Essentially, the sensor can detect when the start of the laser pulse is received. It then triggers the subsequent capture of light information at 1-ns intervals. Its synchronization and speed of capture distinguish the system from other 3D approaches.
SENSOR FUSION The ability to combine information from a variety of sources, such as Analog Devices’ MEMS gyroscope, will be key in many automotive safety applications (Fig. 6). Such combinations will provide more accurate information and allow better distribution of sensors because of their lower cost, smaller size, and lower power requirements.
Systems that don’t use technologies like Advanced Scientific Concepts’ Flash Ladar 3D system often use a pair of cameras instead to provide streoscopic viewing that simplifies range analysis. In the future, expect additional cameras to provide the automotive control unit and arm the driver with more data about the car’s interior and exterior. Likewise, multiple sensor modules may be a better solution for covering smaller, possibly overlapping areas.
Some sensors operate differently under different conditions, such as rain or darkness. Multiple sensors with different operating characteristics will often provide better results than a single sensor. For example, a number of techniques can be used to monitor drivers to see if they are falling asleep.
Likewise, using vision alone for a range of information is a gamble at best. Lighting conditions, reflectivity, and other optical illusions can cause problems. Still, radar cannot determine the color of a stoplight, even if it can determine the distance down to the millimeter.
ROLLING SUPERCOMPUTERS Applying computing resources to an individual sensor or a group of sensors can be a daunting challenge by itself. Also, the amount of processor power—even for a single chip like the IMAPCAR—is significant and growing. But you can’t determine the system’s total amount of computing power until you consider the potential number of different networks in a car and the number of different nodes in these networks (see the table). Multicore design arrived just in time for the automotive industry.
From a safety standpoint, a number of systems will be tied together via one or more networks, depending on the sensors and control systems involved. Network interconnects like FlexRay are already being used in braking and drivetrain applications. Networking makes it easier to develop cooperative systems, and it’s leading to centralized safety and environmental management systems.
This makes sensor fusion more practical, especially given a range of configurations where some car models contain a subset of high-end sensors. It also means the performance requirements will rise. Likewise, reliability and redundancy become harder to address.
Several companies are developing custom solutions that will likely move into the mainstream. Freescale has dual-core designs in which the cores check each other. In addition, a triplecore design includes a pair of cores in hardware synchronization, with the third acting as an I/O processor and traffic cop. Redundancy becomes significantly easier with multiple cores, even using standard processors.
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