Method and apparatus for the evaluation of an angle over an extended range
AssigneeEnertec
InventorMichel Berard
Life of this patent
Estimating the term…
Abstract
A method and device for evaluating an angle A known by at least two trigonometric functions and capable of varying over a range greater than 360.degree.. Two counter integers N.sub.0, N.sub.1 are stored and up-dated, each with respect to the other, as a function of even and odd indicator signals FC.sub.2, FS.sub.2. The value of the angle A, expressed in quarter turns, is given by the first or the second counter number as a function of the value of the even indicator signal FC.sub.2.
Claims8
A method for evaluating the variation, from an initial instant, of an angle A capable of varying over a range greater than 90.degree., by using instantaneous values of at least an even indicator signal FC.sub.2 and an odd indicator FS.sub.2, respectively related to the signs of the cosine and the sine of a double angle 2A, comprising the steps of:
- (a) putting and storing in memory, at an initial instant, two counter numbers, N.sub.0, N.sub.1 ;
- (b) defining a localization parameter X by assigning to it, as a function of the instantaneous value of the even indicator signal, the value of one of the counter numbers N.sub.0, N.sub.1 ;
- (c) reading out the other of the counter numbers N.sub.0, N.sub.1, by assigning it as a new value that of the localization parameter X increased or decreased by one in dependence upon the instantaneous value of the product of the two indicator signals;
- (d) selectively repeating the previous steps (b) and (c) in the course of time;
- and
- (e) producing at least a first output signal related to the localization parameter X, variation of which, expressed in multiples of quarter turns, represents the variation of the angle A since the initial instant in corresponding multiples of 90.degree..
Apparatus for evaluating the variation, from an initial instant, of an angle A that can vary over a range greater than 90.degree., by using at least an even indicator signal FC.sub.2 and an odd indicator signal FS.sub.2 respectively related to the cosine and sine of the double angle 2A, comprising:
- two read/write memories;
- memory reading address means responsive to the even indicator signal and adapted to deliver as a first output of the apparatus a duplication signal X representative of the contents of one of the two memories, selected according to the value of the even indicator signal (FC.sub.2);
- an operator circuit adapted, according to the value of the product of the indicator signals, to increment or decrement the value of the duplication signal X;
- and
- memory writing address means adapted to write in that one of the two memories which was not selected the value of the duplication signal X as modified by the operator circuit.
Dependencies are inferred from the claim text.