blind person walking across the road

Portable radar device could help visually impaired people ‘see’ their environment

Image credit: DT

A portable radar device has been developed that could give visually impaired people or unmanned moving devices the ability to detect objects in real time.

Researchers at KAUST, in collaboration with scientists at the VTT Technical Research Centre of Finland, say the radar can be produced at low-cost and also has potential applications in healthcare and personal security.

Radar provides detailed information about the size, distance and speed of moving objects.

However, for close-range applications, the transmitted radio waves must have short wavelengths to pick up as much detail as possible about its immediate environment. Such sensors could help visually impaired people translate radar reflections into useful information about their environment.

“Current radar modules are large and bulky. They also lose out on key details because they operate using long radio wavelengths,” said Seifallah Jardak, who worked on the project.

“We wanted to develop a low-power, portable radar. Colleagues at VTT brought the necessary experience in millimetre-wave and hardware design, while I focused on the signal processing side and developed modular radar software.”

The earliest prototype performed a single scan every two seconds, making it difficult to acquire enough input data. Jardak optimised the signal processing modules and improved the performance to eight scans per second, providing better real-time monitoring.

The device design incorporates a frequency-modulated continuous wave (FMCW) radar. This means the radar produces continuous pulses of millimeter-wavelength radio waves which have a frequency that varies during each pulse. The small wavelength means that the time taken for pulses to reach an object and reflect back, and therefore the distance to the object, are calculated accurately.

“To limit the size of our system, we chose an operating frequency of 24GHz. This enabled us to reduce the size of the microstrip antenna,” Jardak said. “Our design also has one transmitting and two receiving antennae, meaning it can better estimate the angular location of a target.”

The device fits into a 10cm box, weighs less than 150g and is powered by a 5V battery. Initial trials suggest it is capable of target detection, speed estimation and tracking at ranges of up to 12 metres. The team even used it to detect whether a person was breathing when sitting in a chair.

“Our prototype may also be useful for unmanned robotic and quadcopter applications where a collision avoidance system is required,” Jardak added.

In 2016, St Andrews University researchers developed a system based on radar that can recognise various objects, including body parts, makes of smartphone and food.

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