Inductive sensor for angular measurement of the position of a moving part and measuring method using such a sensor

1. An inductive sensor for measuring the angular position of a rotating part, the inductive sensor comprising:

a primary winding associated with at least one secondary winding; and

a target rigidly connected with the rotating part rotating about a central axis,

the primary winding being centered about an axis that is coincident with the central axis of the target, and carrying a high-frequency alternating current which induces a voltage in each secondary winding,

each secondary winding, which is centered about the central axis, is made up of a number k (k≧2) of substantially identical loops, forming angular sectors, with opening SB, which are successively crossed and arranged opposite the primary winding, and

the target is made up of p (p≧1) angular sectors having a same angular opening α of value α0equal to the opening SB of the loop sectors and which are regularly distributed opposite the primary and secondary windings,

wherein the opening α of each target angular sector is reduced by an adjustment angular sector SA which is equal to the fraction

C

(

h

*

r

)

,

 such that a α=SB−SA,

wherein:

C = an angular scanning course of the sensor between two target successive positions that are identical,

h= an order of the harmonic to be eliminated in a linearity deviation Fourier decomposition, which is defined between measured and real angular values for positions of the target over the course C, and

r = the number k of loops per secondary winding relative to the number p of sectors of the target:

r

=

k

p

.

2. The inductive sensor according to claim 1 , wherein the harmonic to be eliminated is of the 4th order and the adjustment angular sector SA is equal to a quarter of the angular opening of each winding loop.

3. The inductive sensor according to claim 2 , wherein the sensor includes two secondary windings.

4. A method for measuring the angular position of a rotatable part using an inductive sensor according to claim 2 , the method comprising:

successively masking each of the angular sectors of each secondary winding with an angular opening SB with each angular sector of the target with an opening α that is less than the angular opening SB, an opening reduction being adjusted such that the voltage induced in each secondary winding has a sinusoidal variation;

measuring the voltage at the terminals of each secondary winding;

combining the amplitudes of the measured voltages using a same sinusoidal function; and

providing a positional measurement for the target at each moment as a function of the amplitude of the sinusoidal function at the respective moment.

5. The inductive sensor according to claim 1 , wherein the sensor includes two secondary windings.

6. The inductive sensor according to claim 5 , wherein the secondary windings are offset by half a loop.

7. A method for measuring the angular position of a rotatable part using an inductive sensor according to claim 6 , the method comprising:

successively masking each of the angular sectors of each secondary winding with an angular opening SB with each angular sector of the target with an opening α that is less than the angular opening SB, an opening reduction being adjusted such that the voltage induced in each secondary winding has a sinusoidal variation;

measuring the voltage at the terminals of each secondary winding;

combining the amplitudes of the measured voltages using a same sinusoidal function; and

providing a positional measurement for the target at each moment as a function of the amplitude of the sinusoidal function at the respective moment.

8. A method for measuring the angular position of a rotatable part using an inductive sensor according to claim 5 , the method comprising:

successively masking each of the angular sectors of each secondary winding with an angular opening SB with each angular sector of the target with an opening α that is less than the angular opening SB, an opening reduction being adjusted such that the voltage induced in each secondary winding has a sinusoidal variation;

measuring the voltage at the terminals of each secondary winding;

combining the amplitudes of the measured voltages using a same sinusoidal function; and

providing a positional measurement for the target at each moment as a function of the amplitude of the sinusoidal function at the respective moment.

9. A method for measuring the angular position of a rotatable part using an inductive sensor according to claim 1 , the method comprising :

successively masking each of the angular sectors of each secondary winding with an angular opening SB with each angular sector of the target with an opening α that is less than the angular opening SB, an opening reduction being adjusted such that the voltage induced in each secondary winding has a sinusoidal variation;

measuring the voltage at the terminals of each secondary winding;

combining the amplitudes of the measured voltages using a same sinusoidal function; and

providing a positional measurement for the target at each moment as a function of the amplitude of the sinusoidal function at the respective moment.

10. The method for angular position measurement according to claim 9 , wherein the used function is the arc tangent of the ratio of the amplitudes of the sinusoidal voltages measured at the terminals of two secondary windings, in phase quadrature.