TDK has developed an energy harvesting system to power an AI-enabled tyre sensor and wireless data link.
InWheelSense is a multi-mode power generation and sensing module that attaches to the wheel of a vehicle to convert the force of tyre rotation for battery-free sensing and data collection and transmission from the wheel.
The module enables sensing of road surface conditions, wheel alignment, tyre pressure and other conditions in real-time, and can connect to roadside infrastructure for smart mobility applications, says Dr Rakesh Sethi General Manager at TDK’s US R&D Centre for Sensors and Actuators.
The InWheelSense energy harvesting module uses piezoelectric elements to generate electric power from mechanical motion or force. By placing the device at the boundary between the tyre and wheel, the module generates electricity using the force received from the road surface as the tyre rotates.
The architecture allows multiple devices to be connected along the wheel’s circumference, and achieves an average continuous power output of 1mW when driving at 65mph (105km/h) with a Bluetooth Low energy (BLE) wireless link.
The sensors can be used to add additional information during adverse weather or all terrain conditions for driver safety and autonomous driving applications. Because speed, turning, and other changes in operating conditions can cause variations in the electromotive force characteristics of the device, the module can sense various driving conditions using those power changes through analysis of the waveforms from the piezoelectric effect.
Waveforms are output when the tires contact the road surface, so they are continuously generated as the car begins driving. As the speed increases, the frequency of the waveforms also increases, and when the direction of travel changes, the load on the tires will change, creating different waveforms that reflect the driving characteristics at that time.
Because one waveform is outputted for each wheel revolution, the InWheelSense module is able to detect not only the speed during driving, but also road surface conditions based on the shape