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Method and device for measuring the angular velocity of a luminance transition zone and steering aid system for fixation and tracking a target comprising at least one such luminance transition zone

  • US 8,938,324 B2
  • Filed: 12/09/2010
  • Issued: 01/20/2015
  • Est. Priority Date: 12/15/2009
  • Status: Expired due to Fees
First Claim
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1. A method for measuring a time delay between two output signals measured by two adjacent optical sensors, the time delay resulting from a movement of an object moving in a given direction, the method comprising:

  • carrying out a spatial filtering of the first and second signals delivered by a first and a second optical sensor, the optical axes of the first and the second optical sensors forming an inter-receptor angle containing the object;

    calculating a first order derivative and carrying out a temporal low-pass filtering of the first and second signals delivered by the first and second optical sensors in order to obtain respectively a third and a fourth signals;

    calculating the second order temporal derivative of the first and second signals delivered by the first and second sensors in order to obtain respectively a fifth and a sixth signals;

    measuring the delay between the first and second signals delivered by the first and second optical sensors, the delay depending on the angular velocity of the luminance transition zone of the object;

    wherein the step of measuring the delay is a feedback loop based on an estimated delay between the temporally filtered signals delivered by the first and second optical sensors, the feedback loop comprising the steps of;

    estimating a time delay at a first instant between the third and fourth signals;

    calculating the error at the first instant between the fourth signal at the first instant and third signal at the first instant delayed by the estimated time delay at the first instant; and

    estimating whether the error at the first instant is different from 0, namely whether a delay error at the first instant exists;

    if the error at the first instant is different from 0, estimating whether the delay error at the first instant is smaller or bigger than zero on the basis of the error at the first instant and the fifth and sixth signals;

    calculating the evolution of the delay on the basis of the time delay at the first instant and the delay error at the first instant.

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