Apparatus and method for determining absolute position with steering path and steering angle sensors
AssigneeRuf Electronics GmbH
InventorDieter Schödlbauer
Life of this patent
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Abstract
A process and device for determining absolute position by means of two coupled individual sensors which in the measuring range generate saw tooth-shaped output signals with a number of periods (k1 and k2) varying by “1,” and use of a third sensor, which in the measuring range also generates a saw tooth-shaped output signal with a third number of periods (k3) in which k3 differs from k1 and k2 by the absolute value ½. If the first or second sensor fails, a differential signal is generated between the output signal of the remaining functional sensor and the third sensor.
Claims12
A process for determining absolute position by means of two mechanically coupled individual sensors of which the first in the measuring range generates an output signal Φ1 with a first number of periods k1, and the second sensor in the same measuring range generates an output signal Φ2 with a second number of periods k2, in which the two numbers (k1, k2) of periods differ by “1” and in which a differential signal (δΦ) is generated to generate a monotone, clear, absolute position signal, characterized by the fact that at least a third sensor in the same measuring range generates an output signal Φ3 with a third number k3 of periods, which differ from the first (k1) and second (k2) number by a value of ½, and that if the first or second sensor fails, in an analogous manner a differential signal (Φ1−Φ3 or Φ2−Φ3) is generated between the output signal of the remaining functional sensor to generate a position signal.
A device for implementing the process provided with two mechanically coupled sensors which in the measuring range generate an essentially linear saw tooth-shaped output signal (Φ1, Φ2) each of which has a number of periods (k1, k2), in which the number of periods of the two sensors differ by “1” and with an evaluation circuit which from a differential signal (Φ1−Φ2) transmits a monotone, clear, absolute position signal to an output, characterized by the fact that at least a third sensor is provided which in the measuring range also generates an essentially linear, saw tooth-shaped output signal with a third number of periods (k3), wherein the period number (k3) of the third sensor differs from that of the first and second sensor by the value ½, and wherein, in the case of failure of the first or second sensor, the evaluation circuit evaluates analogously the differential signal (Φ1−Φ3 or Φ2−Φ3) between the output signal of the remaining functional first or second sensor and the third sensor to generate a position signal.
An apparatus for determining the absolute position of a shaft having a measuring range comprising:
- a first sensor that generates a first output signal as a function of the location of the shaft and having a first number of periods in said measuring range;
- a second sensor mechanically coupled to said first sensor that generates a second output signal as a function of the location of the shaft and having a second number of periods in said measuring range differing from the first number of periods of the first output signal by a value 1;
- a third sensor mechanically coupled to said first and second sensors that generates a third output signal as a function of the location of the shaft and having a third number of periods in said measuring range differing from the first and second number of periods by a value ½;
- and
- a first evaluation circuit to which the first, second and third output signals are transmitted, said first evaluation circuit transmitting a position signal as a function of the difference between the first and second output signals and in the case of failure of the first or second sensors, transmitting the position signal as a function of the difference between the third output signal and the remaining functional first or second output signals.
Dependencies are inferred from the claim text.