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Development of a tyre monitoring system

Gouw, R.H. van der (2017) Development of a tyre monitoring system.

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Abstract:The thesis studies the feasibility of a Tyre Monitoring System (TMS) within a tyre. The goal is to find and validate features based on strain measurements at the Inner Liner (IL) that describe tyre road interaction. With the application of a TMS the behaviour between the tyre and road is monitored directly, which can be used to implement in safety systems of the vehicle. First an overview is constructed that gives the parameters of in uence to describe the tyre road interaction. From this overview two key features are selected to investigate, these are the contact length and the transition from stick to slip of the tread. Experiments in quasi-static conditions are performed to validate these features. To identify the contact length the maximum change in curvature of the IL is used. Whenever in contact, the radius of the tyre changes to a horizontal area. The maximum changes in curvature are used as identifiers for the leading- and trailing edge. With the distance between these maxima known, the length of the footprint is approached using the tyre velocity. With the length measured, an estimation can be made for the full contact area. An algorithm, currently used at Apollo Global R&D, is adapted to estimate the area using the measured length as input. Both the footprint length as the area are validated by experiments using a footprint scan (FPS). The second feature is the transition point from stick to slip of a local tread block. With the distance to the LE known, the effective contact area that generates grip is determined. To validate this feature a test set-up is developed at a tensile tester where the normal force and road condition can be varied. The tensile tester extracts a tread specimen from a road surface which is clamped while monitoring the extraction force. At the moment of slip the tread should relax slightly which should be captured by the TMS signal. The point of slip can be validated by the force signal of the tensile tester. The performed experiments at the FPS showed that the identification of a footprint length is possible. However, the comparison with the FPS result showed that the length by TMS is consistently lower with approximately 20 %. The reason for this difference is the position of the TMS at the IL. The maximum change in curvature of the IL occurs later than the first contact of the tread block. With this difference at both sides of the footprint an error in length arises. Whenever the area estimation is applied based on this length, the same error has its influence. Nevertheless the used algorithm is found feasible for the error estimation. Simulations with the measured length by FPS showed a maximum error of 3% in the estimated area and thus this algorithm is feasible. Calculations based on the minimum sample rate for the quasi-static experiments showed that a sample frequency of 100 kHz is required for the TMS system to measure at 80 km/h. The point of slip is identified with the developed test set-up at the tensile tester. Each test showed a drop in strain measured by the TMS, however the moment of slip occurs before full slippage of the specimen. The set-up simulates a driving situation where the load case shifts slightly forward, leading to a lower normal force at the trailing edge. For the lower load slippage occurs earlier than the full slip of the specimen, this clarifies the shifted strain drop compared to the full slippage. Absolute strain values cannot be compared using this set-up. The alignment and the normal force cannot be applied exactly similar to secure the reproducibility. This leads to mutual variations in strain results.
Item Type:Essay (Master)
Clients:
Apollo Global R&D, Enschede, Netherlands
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
Link to this item:http://purl.utwente.nl/essays/74016
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