In response, SRI is working on ‘sensing core’, a maintenance-free, software-based indirect system, which detects pressure loss by analysing the wheel speed signals, Lowenhaupt said at the ERJ Future Tire Conference 2018.
As part of its “smart tire concept”, the Japanese tire maker is working on indirect deflation warning systems (DWS), the SRI boss told the top-level meeting, held 30-31 May in Cologne, Germany.
This technology, explained the European MD, can detect tire pressure loss, while also estimating road conditions, the load applied to each tire, and other tire dynamic characteristics in real-time.
The technology which is in the development phase has two software modules: dynamic loaded radius (DLR) and resonance frequency method (RFM).
The DLR module monitors the tire dynamic loaded radius. If a tire deflates, the dynamic loaded radius decreases, and the wheel speed of deflated tire increases.
Differences in these measurements are monitored by relative comparison between wheel positions and conveyed to the driver, said Lowenhaupt.
With RFM, if a tire deflates, the stiffness of deflated tire decreases, and there is a shift in the torsional resonance frequency peaks.
Within SRI’s sensing core system, the DLR and RFM software modules run in parallel, allowing for up to four distinct tire-deflation conditions to be detected.
When a car is running, tires need to slip at a certain level in order to generate a driving force, which balances with running resistances, explained Lowenhaupt.
During a normal driving situation, he pointed out, the slip-ratio versus driving-force has a linear relationship. And the slope varies with the slipperiness, meaning the slope can be used as slip indicator.
More specifically, sensing core monitors the road condition, such as traction coefficients. This, said the presenter, is very important in determining vehicle performance.
“For example, the system can detect the slippery conditions of thin ice on asphalt, or detect low traction conditions and can anticipate tire hydroplaning,” said the SRI managing director.
While the information is transmitted to the driver or vehicle system as a warning, data about road conditions can also be collected and shared on the Cloud with other vehicles.
As a special function, the system can also be linked to the GPS, and the driving route can be shown with the detected road condition.
Lowenhaupt went on to detail another developmental technology – for maintaining tire performance. This work is focused on the loss of ‘suppleness’ as softening agent seeps out of rubber due to the effects of heat and pressure over time.
Key to this advance is SRI’s use of liquid farnesene rubber supplied by Kuraray. Among other characteristics, this softener avoids migration due to the much larger size of its molecules and by bonding with the base polymer.
Also on the way from SRI is ‘active tread’ technology, whereby tire rubber becomes softer upon detecting water. This effect enables the tire to cling to surface irregularities in the road, thereby enhanced grip.
Under the roadmap presented by Lowenhaupt, the Japanese tire maker aims to introduce tires combining these smart tire concepts within the next decade.