Anti-crash radar comes closer for all vehicles

A British company, Cambridge Consultants, claims to have made a breakthrough in radar safety systems for vehicles, with the potential to make sophisticated reversing and anti-collision safety aids an affordable accessory for the mass market.

The design and development consultancy has solved major electronic challenges to allow it to use lower frequency - and lower cost - components than alternative radar reversing and anti-collision technology.

The radar's field of view is also completely programmable, allowing a system to dynamically and intelligently adapt as the vehicle's steering wheels change direction.

Dubbed the CCL-Softcar project, the radar is said to solve the performance and cost issues that have stalled progress in this area.

"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 defence technology, but have been heavily re-engineered to work in a frequency band that is 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."

CCL-Softcar is a pulsed radar system working in the 5.8 GHz band, rather than the 24 or 77 GHz frequencies of alternative approaches.

Working at this lower frequency reduces the cost of the components required to build a system, and avoids the time and cost overheads which precision assembly of higher frequency equipment imposes.

Just four radar modules and one electronic control unit are required to provide 360° protection - further reducing the bill of materials compared with alternative approaches which can require two or more modules to be installed on every side of a vehicle.

The technical feat has been achieved without resorting to large directional antennas normally required to operate at the lower frequency. The CCL-Softcar transmit/receive module measures less than 8 x 12 cm.

The antenna provides a further major safety benefit. Instead of focusing on a limited field of view, the antennas are all broad beam, and are software programmed to provide the desired horizontal and vertical coverage.

By changing the mathematical 'filter' applied to echo reception, the field of view changes. This allows the radar to adapt in real-time as the steering wheels change direction: in the case of a rear view system for example, it provides smart feedback when backing into a space between automobiles.

The company has constructed a proof-of-concept CCL-Softcar to demonstrate the technology to vehicle manufacturers. Rear and side-view systems have ranges of 5 m and an angular resolution of less than two degrees. Forward-looking radars have a range of 25 m.

Just one module is required to implement rear, side or front view safety. Alternative approaches typically require two or more transmit/receive modules spaced widely apart for each view to allow the system to determine object position using a form of triangulation ('trilateration').

Conventional wisdom dictates that the further apart the sensors are, the higher the accuracy. But CCL has proved that for automobile radar, the exact opposite can be true.

This is because the exterior surfaces of the typical automobile result in a complex scattering of echoes that make it very hard to accurately determine distance and trajectory, a problem exacerbated when measurements are being taken from different positions and directions.

By using a single transmitter and a closely-spaced antenna array, echo scatters are more closely matched, allowing the system to determine distance and trajectory with greater accuracy.

This approach not only reduces the number of radar modules required for anti-collision warning, but reduces the computation required to analyse the echoes - further reducing system costs.

This is especially important for dealing with multiple objects.

When two or more objects are in the field of view of a radar system with widely spaced transmitters and sensors for example, the mathematical analysis required to determine their positions and trajectories is so great that it can demand supercomputer-style performance.

This is one of the major reasons why anti-collision radars have been so long in development. Conversely, the echo separations between multiple objects appearing in the field of view of CCL-Softcar will always tend to be more clearly defined.

The demonstration unit comprises a rear-view radar module with a range of 5 m, mounted inside a typical compact car bumper, and providing intelligent anti-collision impact warning.

A DSP-based electronic control unit (ECU) processes the echoes, and communicates the results to the central controller containing the driver interface, over a CANbus vehicle network.

The same ECU will control further transmitter/receiver modules for side- and front-view protection. An identical radar transmitter and antenna receiver - programmed for a different field of view - is used for side view protection.

The same basic module - but with a different signal waveform - is used for frontal view systems, to accommodate the extended range. This architecture allows four-quadrant vehicle protection to be implemented with just four radar modules and a single ECU.

This compares with the eight or more radar modules required by some alternative systems.