METHOD TO DETERMINE A DIRECTION AND AMPLITUDE OF A CURRENT VELOCITY ESTIMATE OF A MOVING DEVICE
First Claim
1. A method to determine the direction and the amplitude of a current velocity estimate of a moving device comprising at least an optic-flow sensor producing at least a 2D optic-flow vector and an inertial sensor producing a linear acceleration vector, said optic-flow sensor having a predefined viewing direction relative to the moving device, said method comprising the steps of:
- a. initializing to a default value a direction and amplitude of a current velocity estimate,b. acquiring a linear acceleration vector from the inertial sensor,c. calculating a velocity estimate prediction from the current velocity estimate and the linear acceleration vector by integrating the linear acceleration over time,d. acquiring an optic-flow vector from at least one optic-flow sensor,e. determining at least one measured direction value, a mathematical representation of the optic-flow direction from each optic-flow vector without using the amplitude of the optic-flow vector,f. calculating at least one direction prediction value, a mathematical representation of an optic-flow direction prediction in function of a velocity estimate prediction and a predefined viewing directiong. calculating at least one error value between each measured direction value and the corresponding direction prediction value,h. applying a correction to the velocity estimate prediction to obtain a new velocity estimate, said correction being determined thanks an optimization process so as to reduce the error value(s)i. defining the current velocity estimate equal to the new velocity estimatej. repeating the steps b to i.
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Abstract
A new method for the estimation of ego-motion (the direction and amplitude of the velocity) of a mobile device comprising optic-flow and inertial sensors (hereinafter the apparatus). The velocity is expressed in the apparatus'"'"'s reference frame, which is moving with the apparatus. The method relies on short-term inertial navigation and the direction of the translational optic-flow in order to estimate ego-motion, defined as the velocity estimate (that describes the speed amplitude and the direction of motion). A key characteristic of the invention is the use of optic-flow without the need for any kind of feature tracking. Moreover, the algorithm uses the direction of the optic-flow and does not need the amplitude, thanks to the fact that the scale of the velocity is solved by the use of inertial navigation and changes in direction of the apparatus.
8 Citations
10 Claims
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1. A method to determine the direction and the amplitude of a current velocity estimate of a moving device comprising at least an optic-flow sensor producing at least a 2D optic-flow vector and an inertial sensor producing a linear acceleration vector, said optic-flow sensor having a predefined viewing direction relative to the moving device, said method comprising the steps of:
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a. initializing to a default value a direction and amplitude of a current velocity estimate, b. acquiring a linear acceleration vector from the inertial sensor, c. calculating a velocity estimate prediction from the current velocity estimate and the linear acceleration vector by integrating the linear acceleration over time, d. acquiring an optic-flow vector from at least one optic-flow sensor, e. determining at least one measured direction value, a mathematical representation of the optic-flow direction from each optic-flow vector without using the amplitude of the optic-flow vector, f. calculating at least one direction prediction value, a mathematical representation of an optic-flow direction prediction in function of a velocity estimate prediction and a predefined viewing direction g. calculating at least one error value between each measured direction value and the corresponding direction prediction value, h. applying a correction to the velocity estimate prediction to obtain a new velocity estimate, said correction being determined thanks an optimization process so as to reduce the error value(s) i. defining the current velocity estimate equal to the new velocity estimate j. repeating the steps b to i. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification