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In recent years we have seen drastic improvements of the accuracy of wheel force transducer (WFT) systems /1, 2 and 3/. These systems in most cases are calibrated just statically. What is the dynamic behaviour of the sensor? What can we expect towards the accuracy of the measured loads on real road surfaces as they are influenced by a number of parameters? In the present paper quantitative results are reported out of a broad investigation of the effects of the following parameters road surface, rim stiffness, tire air pressure, velocity and wet road conditions. The unique Wheel and Tire Testing Vehicle (“Universal Skid Resistance Measurement Device”) of Stuttgart University was used for the measurements on two highways. The WFT-signals are referenced to the multiaxial force sensing of this vehicle. These findings are compared to results derived from a rolling road flatbelt test stand reported in /6/.

Wheel force transducers (WFT) play an increasing role in endurance evaluation of road vehicles, ride and handling optimization, tire development and vehicle dynamics. With paper 980262 part I of an investigation of seven WFT–systems was presented. After a general evaluation two systems were compared in more detail. From a more basic interest deeper consideration was given to Angle Error Correction and material selection. This paper reports on part II of the investigation. The general evaluation of present systems on the market is updated and refined including new systems and updated versions. Thus an unique and quick overview is provided mirroring the present status of WFT technology. Special attention is given to systems best suited for applications in tire development, for driving dynamics optimization, active safety and active suspension development as well as in the ride and handling area.

Wheel force transducers (WFT) play an increasing role in endurance evaluation of road vehicles, ride and handling optimization, tire development and vehicle dynamics. Seven WFT-systems, which split basically into three design categories: strain gaged beam and spoke, individual load cells and mechanically separated load components are looked at in this investigation. After a general evaluation the two systems which seem to be most promissing are compared in more detail: Angle error correction and material selection (Titanium alloy versus carbon fibre composite) appeared to be the most significant differences of these two systems. FE-temperature analysis shows that during downhill braking temperature limits of the carbon fibre material are reached or exceeded. As in addition manufacturing of the special wheels (also partly made of carbon fibre) is expensive and cannot be done by the customer, using light weight metals seems to be the better choice.

Vehicle weight optimization is a time and cost consuming step in vehicle development. Significant improvements of this iterative process are possible through integration of numerical and experimental simulation technologies as well as testing on the road. One of the key elements in that optimization is to use wheel forces instead of other physical quantities. This paper discribes essential elements of an integrated process and illustrates that with the experiences of Porsche AG, which in 1996 stepped forward to latest technology in this field by implementation of wheel force measurements into its product development and endurance evaluation process.

An important part of vehicle development are design evaluation and validation processes based on testing in the laboratory. At present there are many complete vehicle, body and suspension road simulator configurations. They all are compromised with respect to complexity and cost. They all have certain advantages and disadvantages. Examples for the evolution of such systems will be discussed. It becomes apparent that new solutions are required if not just the optimization of components and subassemblies is aimed at but the exact evaluation of service life in terms of proving ground kilometers. The new concept is a complete car test rig with an active restraint system which restrains the car during maneouvre load simulation and leaves it otherwise relatively uninfluenced. The test rig has in total 20 actuators, four at each wheel and another four at the restrained system. This test rig will be described in some detail.