American engineers have developed a sensor capable of real-time monitoring of the wear of the tires. It has a radar that emits a millimeter wave and the reflection determines the remaining tread depth with an accuracy of 0.68 mm, and is also able to detect the foreign objects protector. Article on the development was presented at the MobiSys conference in 2020.
Bus is one of the main factors that affect how the car moves on the road, handles and brakes. These parameters are directly dependent on the condition of the wheels: tyre wear and pressure. In many countries, all new cars must be equipped with monitoring system of tire pressure, which directly or indirectly monitors the pressure and indicates that one or more tires decreased. To control the state of the tire being either the standard intervals (mileage, after which it is recommended to replace the tires) or visual inspection.
Engineers from the University Carnegie Mellon, under the leadership of Anthony Rowe (Anthony Rowe) has developed a system that allows real-time tracking of the status of protector: wear and foreign objects. It is based on automotive radar operating in the millimeter range at frequencies from 77 to 81 GHz and intended for obstacle detection. According to the authors, the radar can be placed in the wheel arches. Also during part of the tests they put it on the test bench close to the horizontal wheel.
The radar emits signals and receives reflections and makes a depth map of the surface of the tire. Engineers have increased the original resolution of the radar in two ways. First, the radar has eight antennae, and it allows you to sum the signals, for improved accuracy. Second, they used radar inverse synthetic aperture (ISAR), in which the resolution of the subject increases due to its movement. In this case the authors used to increase the resolution of the rotation of the tire, whereby the same elements reflect the signals from different positions.
The ISAR limitation of the method lies in the fact that the radar needs to know the angle of rotation of the wheel at every moment. The developers have used aluminum strips of a certain length, pasted on the longitudinal recess of the tread. Since the strips have different and known in advance the length, the radar may at any time at their location to identify a fragment of the bus, which he removes at the moment. In addition, the stripes allow to filter the signal objects stuck in the tread.