Potential and Limitations of an Improved Method to Produce Dynamometric Wheels

Abstract

A new methodology for the estimation of tyre-contact forces is presented. The new procedure is an evolution of a previous method based on harmonic elimination techniques developed with the aim of producing low cost dynamometric wheels. While the original method required stress measurement in many rim radial lines and the fulfillment of some rigid conditions of symmetry, the new methodology described in this article significantly reduces the number of required measurement points and greatly relaxes symmetry constraints. This can be done without compromising the estimation error level. The reduction of the number of measuring radial lines increases the ripple of demodulated signals due to non-eliminated higher order harmonics. Therefore, it is necessary to adapt the calibration procedure to this new scenario. A new calibration procedure that takes into account angular position of the wheel is completely described. This new methodology is tested on a standard commercial five-spoke car wheel. Obtained results are qualitatively compared to those derived from the application of former methodology leading to the conclusion that the new method is both simpler and more robust due to the reduction in the number of measuring points, while contact forces’ estimation error remains at an acceptable level.

Research on Rotational Angle Measurement for the Smart Wheel Force Sensor

“…where ( ) represents sin + ∆ + sin − (∆ + ∆ ). Equation (15) shows that the evaluation error changes with angle even when the ∆ ( = 1,2) is constant. By calculating the derivative of ( ), the maximum of appears when ( ) reaches its minimum, that is,…”

“…Now that in-wheel motors are finding increasingly utilization in new intelligent vehicles, the need for high precision measurement and control of the wheel forces is becoming more important than ever [11][12][13]. Since the SWFS is installed on the wheel and moving with it [14,15], the direct output force of the SWFS and the real wheel force are in separate wheel coordinates and vehicle coordinates [16,17], thus the direct output force of the SWFS should be converted to the vehicle coordinates, and the Since the SWFS is installed on the wheel and moving with it [14,15], the direct output force of the SWFS and the real wheel force are in separate wheel coordinates and vehicle coordinates [16,17], thus the direct output force of the SWFS should be converted to the vehicle coordinates, and the rotational angle of the wheel is critical to identify the relative motion of the two coordinates. The usage of an encoder is the traditional way to measure the rotational angle, but it brings extra errors during the steering of the wheel [18,19].…”