TDK Unveils Power-Generating Wheel Sensor

Up to 13 InWheelSense modules can be attached to a wheel to generate electricity from tire movement.

TDK’s piezoelectric module harvests energy from tire/wheel forces and combines a sensor to generate tire-related and driving-environment data. (TDK)

Electronics maker TDK in January introduced its InWheelSense piezo-electronic “energy harvesting and sensing module” that it said can generate power from vehicle wheel movement while also serving as a sensing platform to enable a variety of vehicle data-collection functions. The company said in a media presentation prior to the CES 2021 conference that its energy-harvesting module/sensor (EH-Module) is envisioned as a safety and comfort enhancement for robotaxis and an alternative and backup to any automated vehicle’s (AV’s) perception sensors.

Torque between the tire and the wheel generates the electricity for the module’s operation. (TDK)

The EH-Module “makes wheels and tires intelligent,” said Rakesh Sethi, general manager for sensors and actuators at TDK’s U.S. R&D Center. He said the EH-module’s ability to “analyze what is going on with the car at each wheel” will make forthcoming robotaxi operation safer by providing discrete information to infrastructure-connected systems about driving conditions and valuable vehicle data derived from the wheel/tire interface. The energy-generating module/sensor also will be vital, he said, for generating power for increasingly energy-hungry emerging technologies.

“InWheelSense is a multi-faceted power generation and sensing solution that attaches to the wheel of an automobile to convert the force of tire rotation into piezoelectric power and generate battery-less sensing and data collection and transmission from the wheel – a hostile environment where delivering an electrical source is otherwise difficult” the company said in a release. Sethi confirmed InWheelSense will be in “early production” in 2023 and volume production by 2025. Evaluation kits, including an attachment setup for existing wheels, is available now.

Power-generation with sensor integration

TDK’s InWheelSense module can generate around one milliwatt of power at 65 mph. (TDK)

TDK’s InWheelSense module can sense various road and driving conditions based on the force exerted between the tire and the wheel. The module uses that same force to create average continuous DC power of around one milliwatt in an 18-inch wheel when driving at 105 km/h (65 mph). The unit is just 125 mm (4.9 in.) long and 19 mm (0.75 in.) deep. TDK said as many as 13 EH-Modules could be attached to a single wheel.

The company said the EH-Module can use measurement of the forces on the tire-wheel interface to sense speed, road condition and wheel balance, adding that data directly related to tires and road conditions is vital for driverless robotaxis and other AVs that do not have an operator constantly monitoring driving conditions – or identifying imminent maintenance needs. Sethi added that data from the InWheelSense module also could serve as backup for a vehicle’s perception sensors, which can be affected by weather and other disruptions.

The company said the power available from the modules will be useful for the multiple types of sensors potentially placed in the wheel or even embedded directly in the tire. Those types of sensors – and their connectivity requirements – cannot be adequately powered by batteries or platforms such as today’s tire-pressure monitoring (TPM) sensors, Sethi said.

In answer to globally expanding vehicle-related emissions regulations, the InWheelSense module also has the potential to directly measure particulate emissions from tires and brakes, TDK said. Sethi said the company is collaborating with TPM suppliers to study integration of the InWheelSense module with current TPM functionality.