Fraunhofer LBF calibrates truck wheel force sensors with high loads
Vehicle development is inconceivable without reliable load data. If this involves the dynamic measurement of forces and moments in the design of chassis, nothing is possible without wheel force sensors. But they have to measure ever higher loads. The test bench for truck measuring wheels developed by Fraunhofer LBF covers radial forces of up to 400 kilonewtons, lateral forces of up to 200 kilonewtons and tangential forces or drive and braking torques of up to 100 kilonewton meters.
“Wheel force sensors today cover much larger load ranges than in earlier years. With the newly developed test stand, wheel force sensors for heavy vehicles can now also be calibrated over the full measuring range at the Fraunhofer LBF. This saves time and money despite the higher forces,” explains Johannes Käsgen, responsible for the development of the calibration test stand at the Fraunhofer LBF. The new test stand is suitable for wheel force sensors from various manufacturers. It can be flexibly adapted to different wheel geometries using adapters.
In contrast to the previous test rigs, only the sensor element is calibrated without the rim and tire. The LBF scientists screw the wheels over the wheel flange onto a lockable turntable. Instead of the rim, they attach a load introduction ring via which they introduce the loads in the directions to be tested. This is done at eight positions of the wheel circumference – not in combination, but one after the other. The loads are increased stepwise or continuously and recorded via a single force measuring element located in the direct load flow. A load calculation is not necessary. This increases accuracy and eliminates sources of error.
The new calibration test bench can be used to determine the sensitivity of the wheel force sensor in the radial, lateral and tangential load directions and to determine the measuring accuracy for each force component. The crosstalk between the determined load components is calculated. “Sensors should be calibrated at least every two years. This ensures measurement accuracy and identifies possible problems with the sensors,” emphasizes Käsgen.
More information: https://www.lbf.fraunhofer.de/en.html
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