Smart tyres sense their own roadworthiness adding a new dimension to autonomous vehicles Worn treads and failing tyres play a key role in road traffic accidents, particularly in bad weather conditions. Current ways of testing tyres for road worthiness have drawbacks which one EU-supported project has overcome by a completely new approach, turning the tyre itself into a reliable sensor. Transport and Mobility © Bilanol, Shutterstock There have been several studies showing the role of worn or failing tyres in accidents. The conclusion is that, were we to reduce the number of vehicles whose tyres are inadequate, we could cut the number of accidents by 28.5 %, of which a considerable proportion would be on snow or wet roads. Since 2014, Tyre Pressure Monitoring Systems (TPMS) have been mandatory, but these only measure pressure and the temperature of tyres. The tyre industry is looking for the real-time monitoring of the status of wear to be integrated within new intelligent tyres, enabling preventive maintenance. As the widespread use of autonomous vehicles grows nearer, there is a need to take an equally advanced approach to the tyres used. SMART Tyre, patented by Wriggle Solutions, which is a spin-off company of the Sant’Anna School of Advanced Studies in Pisa, can measure the stress, wear and tear of tyres in real time. Arash Gholamzadeh Nasrabadi, the CEO of Wriggle Solutions says: “Effective solutions were difficult to implement, mainly because they depended on the use of adoption of internal sensors or cameras. These showed a variety of drawbacks, being expensive and not reliable or robust enough.” Smart-tyre’s innovation was to use the tyre itself as a sensor. Wriggle’s system is capable of directly analysing the electrical response of the tyre’s compound which, because of the materials the tyre is made of, is conductive by nature. “This allows the electrical signals that flow through the tyre to be analysed by a micro-controller, which uses the data to measure the tread depth accurately,” adds Nasrabadi. The system comprises two modules: M1 and M2. The former, which detects tyre deformities, relies on the monitoring of the tyre vibrations by employing inertial measurement units. The module has one sensor placed on the axle, near the tyre, and another sensor placed on the axle, far from the tyre, to perform a differential measurement by subtracting the noise generated by vehicle vibrations. The module can be directly powered with the vehicle battery and connected to the vehicle control unit via wired connections, with results appearing on the driver’s dashboard. The M2 sensor monitors the tread depth by measuring the electrical response of the tyre itself, which varies as a function of the quantity of material that composes the tread. This then provides an estimate of the tread depth. To perform the measurement, the module has to be directly connected to the tyre which, being a moving part (e.g. the rim or the tyre itself), requires a wireless power supplier (e.g. a battery or by induction) and the use of a wireless communication infrastructure. As Nasrabadi explains: “The tyre must be already conductive (as in trucks) or made conductive by using Extrinsically Conductive Polymers (ECP) by doping the rubber mixture with carbon black, carbon nanotubes or graphene, which are already used in the tyre manufacturing sector. Hence the collaboration with tyre manufacturer is essential.” Wriggle Solutions developed several minimal viable products in order to test the hypothesis behind the patent, and results were very positive. They reached a fully working prototype through an iterative approach. “Despite the sector’s complexity and the fact that it is hard to secure uptake of innovation, we have been driven mostly by our belief that our patent could have a positive impact on people’s lives and reduce both tyre waste and fuel consumption,” says Nasrabadi. Wriggle Solutions is now seeking potential partners willing to cooperate in the industrialisation of the Smart-tyre technology, which has already been validated through a prototype. Keywords Smart-tyre, Tyre Pressure Monitoring Systems, Wriggle Solutions, tyre deformities, tyre tread, road traffic accidents
