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In recent years wheel dynamometer measuring systems,using strain gauge and quartz technologies, have been optimised and are mature now. For specific fields of application the use of sensors based on either of the two measuring technologies would be the technically optimal choice. For technical, practical and economic reasons often two systems in parallel couldn't be used and thus limitations needed to be accepted. In order to overcome these limitations Kistler integrated sensors with both measurement technologies into one product family. Using results from practical applications and investigations the paper describes the new potential to get better test results faster. Kistler continously works towards a better integration of engineering processes (numerical simulation, testing on benches and in the vehicle).

Since decades KISTLER is contiuously innovating in the field of piezoelectric sensor technology. This paper describes major technological progresses in the field of rotating wheel dynamometers: the six-component Rotating Wheel Dynamometer RWD and the Rotating Wheel Torque Meter RWT. First the systems are explained in detail, then outstanding applications in vehicle development, tire power loss determination and tire deformation investigation are given. An outlook on upcoming innovations concludes the paper.

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.

During the design, evaluation and optimization process of automotive brake systems brake torque measurements are often crucial. Known brake torque sensors lead to differences in terms of mass, inertia, stiffness and brake cooling compared to a vehicle without measurement equipment. In this contribution a new brake torque sensor is described which proved to be superior to known systems. Either the hub itself is turned into the sensing element or is replaced by a sensing element. Thus mass, inertia, stiffness and cooling conditions are nearly unchanged. A modification of this sensor allows measurement of residual brake torques in a low range (20....50 Nm) with high sensivity and features at the same time a high range (up to 2.000 Nm) with lower sensivity. The application of the sensor in a study to lower energy loss caused by residual brake friction in a passenger car is described.

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.

If a company wants to start to develop vehicles, to build new models or to grow into new markets, the question is always the same: How to choose, to measure, to evaluate road profiles to generate load profiles which have to be endured by the vehicle in question? This paper describes steps of the process from a practical point of view and gives guidelines and examples how to solve this important problem. Special attention is given to instrumentation. It is clearly stated that this question cannot be solved over night. Each company has to build up own standards as company philosophy and strategy contributes much to this question.

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.