Mikaela Öhman with a wireless stop button for buses.

She is harvesting energy

Using the heat and vibrations generated in a vehicle, it is possible to make sensors and electronic components self sufficient when it comes to energy. Fewer cables also result in lower material costs and less complicated installation.

“Energy harvesting is nothing new. Windmills are an old way of gathering ambient energy and using it for something else. Solar cells are a modern example. This is the next step; gathering energy to power small electronic components,” explains Mikaela Öhman, a development engineer at Volvo Group Trucks Technology and chairman of Volvo’s TC Sensors committee.

She holds up a stop button for buses. Inside the yellow shell, there is a new electromagnetic component the size of a fingertip. Pressing the stop button causes a magnet to move one millimetre inside a coil of copper wire. This is all that is needed to generate the power that is required to send a radio message to a receiver at the front of the bus. The stop sign comes on. As far as passengers are concerned, there is no difference, but, in a bus with 40 buttons, this solution eliminates the need to install 230 metres of cable.

Wireless sensors are already used  in vehicles. They are powered by batteries, but the development of increasingly energy-efficient components has opened the door to energy supply using energy harvesting, with typical effects in the micro- to milliwatt range.

Mikaela Öhman and her colleagues are focusing primarily on utilising vibration energy and thermal energy. This energy can be captured in a number of different ways. There is, for example, material that generates electrical power when it is deformed, otherwise known as piezoelectric energy. Other materials react in the same way when they are exposed to temperature changes.

This work is part of a concept study in which Volvo Group Trucks Technology is collaborating with Chalmers University of Technology and Halmstad University. The next step on the road from laboratory to reality will be to test energy harvesting in a vehicle in operation. One of the main challenges is for the wireless sensors to withstand the gruelling environment in a vehicle.

“We are doing this to increase our knowledge internally but also to make suppliers aware of the needs and requirements of the automotive industry when it comes to energy harvesting. Because this is a development that is in the pipeline, make no mistake!”

 

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