Radar Sensors Powered by Wireless Charging

Wireless charging of sensors therefore opens up a new range of conceivable sensing solutions. In some cases, it makes it possible to reimagine where and when sensors can be used, and define entirely new types of applications. SINTEF MiNaLab is developing a system for wireless charging using MEMS micromirrors to steer a beam of light towards a photovoltaic cell. The mirrors have some specific and desirable properties that differentiate them from the state-of-the-art of micromirrors, such as high deflection angles, high accuracy, low power consumption and low cost in high volumes.

In a master thesis, we seek to utilize this new power source, combining a high number of sensors to create new “super-sensors” – configurations that would otherwise need cabling or large batteries and therefore be unfeasible in real-life situations. For an illustration, see the figures above and below. Above is an illustration of the system in use. Below, we illustrate how each sensor along the upper wall is used to “interrogate” whether a hypothesized object is indeed present and moving at a specific physical location.

The application we are considering is room mapping. In this situation we are interested in creating a map of the room: where is the furniture? Are the people in the room? Are they moving around and where are they headed? Can we monitor the movement of limbs, hands, feet, and perhaps even capture intent, the direction they are heading or finer movements like gestures?

This information could be used for many different purposes, such as turning on or off light or heating, or in hifi/audio applications, where the best cinematic audio experience depends on knowing where the listener is situated, and “beaming” sound from speaker elements towards the listener. It could also be used to monitor the number of people present in a library or a shop, without resorting to privacy-violating technologies like cameras.

This thesis can be attacked from the signal processing/room mapping angle or from a systems/hardware building angle, where emphasis is more on the processing side or on the hardware building side. To demonstrate performance of the end application, we don’t need to implement the actual wireless charging part. Instead we can ‘fake’ the experience by using cabled or battery powered solution. Completing a thesis therefore doesn’t depend on building or utilizing a full wireless charging system. The CPU needed to create a voxel-based occupancy map of the room could be located remotely from the sensors themselves. Low power wireless technologies like Wi-Fi 6.0 could transfer radar sensor data from each radar node to a PC doing all the number-crunching.

A group of students could work together on different aspects of the solution.

Relevant literature:

• Wireless charging of devices (A SINTEF patent)
• The power of occupancy sensing technologies in offices
• Hand gesture recognition using arrays