Experimental investigation of tyre dynamics by means of MEMS accelerometers fixed on the liner

Nowadays, many researches exist in the automotive field aimed at improving vehicle active control. Recently, the possibility to exploit sensors fixed inside the tyre (particularly on the liner) has been presented by the authors of this paper [F. Braghin, M. Brusarosco, F. Cheli, A. Cigada, S. Manzoni, and F. Mancosu, Measurement of contact forces and patch features by means of accelerometers fixed inside the tyre to improve future car active control, Vehicle Syst. Dyn. 44(1) (2006), pp. 3–13]. These sensors allow measurements to be obtained from the closest point to the contact patch, making possible the best description of contact phenomena (with respect to the actual situation in which sensors are usually placed on the hub); these data can be sent to the vehicle controller, processed and therefore used for active control. However, there is still a tyre layer between the sensors and the road, therefore a specific study of the transfer functions between tyre input and sensor signals is needed to understand how to correlate signal trends to physical events, taking into account tyre behaviour. This also means that signal features have to be analysed to find how they depend on physical parameters (such as vertical load, camber angle, etc.). A dedicated test facility has been designed and built to perform this task; this is the object of the present paper, which first of all focuses on the choices for this particular design solution. Different tyres have been tested by means of this test bench (the study has been carried out up to 2 kHz and this threshold comes from road test results), looking for eventual differences among their behaviours; in particular, the effects of tyre tread block presence have been investigated.