Linking Evaluation Of Subjective Handling Tests On The Road With Objectively Measured Data By Using Fuzzy-Set-Theory 885006

High speed tires were measured on the road and in the lab, both on a rear wheel drive and a front wheel drive vehicle. The tests described refer to standard methods used in the tire industry. They include various tire patterns as well as direction-oriented patterns.

Depending upon vehicle type and driven axle, the subjective test result in varying sequences in the main groups of tested parameters - slalom, curve behaviour, handling characteristics and steering response. Static, quasi-static and dynamic measurements on tires were performed in the Semperit lab. The data obtained in the lab did not result in distinct sequences. In case we have to decide which tire is best suited for the intended purpose, the basis for decisions in neither precise nor clear, and conventional engineering mathematics will not suffice. Therefore, “Fuzziness” has to be introduced. The basis of the Fuzzy-Set-Theory is a maximum/minimum principle. The Fuzzy-Set-Theory is a mathematical structure capable of dealing with inexact decisions. Based upon Fuzzy-Set-Theory, a method is described to correlate subjective driving tests and objective indoor measurements. The end result is a correlation of indoor and outdoor tests.

This basically qualitative evidence of subjective road tests is contrasted by quantitative evidence in the lab. However, for better understanding of the tires evaluated on the road, the data obtained in the lab have to be correlated a posteriori, even though the target a priori correlation cannot be reached.