TDR-BASED SYSTEM AND METHOD FOR HAND DETECTION ON A STEERING WHEEL WITH ELIMINATION OF AGING AND ENVIRONMENTAL EFFECTS

摘要

A method of detecting a hand positioning on a steering wheel (38) by operating a sensing system (10) including at least one electrically conducting signal line (12) that is arrangeable on a rim of the steering wheel (38) with a priori knowledge about a relation between a distance of any portion of the at least one signal line (12) from a reference point (30) and information on a position on the rim (40), and which comprises an electric impedance change (28) of predefined magnitude that is permanently arranged at a predefined position along the at least one signal line, a signal voltage source (26), and a control and evaluation unit (28). From a received measurement signal traveling along the signal line (12) and having been reflected by the at least one electric impedance change (28) and by another portion or other portions of the signal line (12), a reference travel time is determined. Based on the determined reference travel time and the a priori known relation, a position or positions on the rim (46) of the other portion or portions of the signal line (12) that has or have at least partially reflected the measurement signal is determined by the control and evaluation unit (28).