Machine Design

Anticollision radar uses lower frequencies

A radar-safety system for autos works at 5.8 GHz rather than 24 or 77 GHz as is the case in other systems.

The lower frequency allows use of much cheaper components than alternative radar reversing and anticollision technology.

The inventors, Cambridge Consultants Ltd., in the U.K., call the system the CCL-Softcar project. The radar's field of view is completely programmable, so a system can intelligently adapt as steering wheels change direction. “Building a radar for road use has been technically feasible for many years. The core issue is how to make one for a tiny fraction of the costs usually involved,” says Gordon Oswald of Cambridge Consultants. “The design principles in this system draw on defense technology, but have been heavily reengineered to work in a frequency band that's becoming commonplace for wireless consumer gadgets, providing the required performance in a form capable of meeting the aggressive cost targets of the high-volume automotive arena,” he adds.

The CCL-Softcar uses only four radar modules and one electronic-control unit (ECU) to provide 360° protection. Alternative approaches can require two or more modules be installed on every side of a vehicle.

By using a single transmitter and a closely spaced antenna array, echo scatters are more closely matched, letting the system determine distance and trajectory with greater accuracy. This not only reduces the number of radar modules required for anticollision warning, it also minimizes the computation required to analyze the echoes. This approach is particularly important when dealing with multiple objects. For example, when two or more objects are in the field-of-view of conventional radar with widely spaced transmitters and sensors, the math required to determine positions and trajectories can demand supercomputer-style performance.

The transmit/receive module measures less than 3 X 5 in. The system's antenna is broad beam and programmed with software to provide the desired horizontal and vertical coverage. Rear and side-view CCL-Softcar systems have ranges of 16 ft and an angular resolution of less than 2°. Forward-looking radars have a range of 81 ft.

The proof-of-concept CCL-Softcar system is a rear-view radar module with a 16-ft range, mounted inside a typical compact car bumper, that provides intelligent anticollision impact warning. A DSP-based ECU processes the echoes, and communicates the results over a CAN bus to the central controller containing the driver interface. The concept is being used to demonstrate the technology to automotive manufacturers.

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