Conductive system for measuring the linear and angular positions of one object relative to another

Position measurement system of the relative position between two objects. The system comprises a first and a second inductive system. The first inductive system comprises a transmitting coil and a first detector, with the attribute that the pattern of conductors that form the coil extends along a longitudinal axis. A second inductive system comprises a second transmitting coil and a second detector, with the attribute that the coil extends essentially in the longitudinal direction. The second trasmitter coil can be realised as a Meander pattern of conductive material, with return path in its center-line. Using the detectors, it is possible to accurately determine the linear and/or angular position(s) of two bodies relative to each other.

The invention is explained below with reference to the drawings, wherein

FIG. 1 shows a cylinder in a three-dimensional system of co-ordinates;

FIG. 2 shows a Meander-coil and a ring-coil;

FIG. 3 is a sectional view through a number of electrical conductors that carry a current and thus generate an electromagnetic field;

FIG. 4 is a sectional view of two parallel conductors carrying a current and the thus generated electromagnetic field,

FIG. 5 is a sectional view of the Meander-coil and a detector with position signals in a detector made with two coils;

FIG. 6 shows two parallel conductors and a detector in the embodiment with two detector coils, and the position signals associated with a displacement;

FIG. 7 shows two detectors and their positions relative to the Meander and ring coils;

FIG. 8 shows a cylinder tilted around a z-axis and an x-axis and two detector-mounts;

FIG. 9 shown the locations of two detector-mounts relative to a cylinder ring in normal position;

1. A system for measurement of the positioning of a first object relative to a second object, where said measurement is performed for at least two degrees of freedom simultaneously,

2. A system according to claim 1 wherein said second direction is a rotational direction around an axis parallel with said first direction, where said rotational direction corresponds to a first of said at least two degrees of freedom.

3. A system according to claim 1 wherein said first direction comprises a translational direction along said second axis.

4. A system according to claim 2 wherein said first direction comprises a rotational direction around a first axis, where said first axis is perpendicular to said second axis and parallel to the plane of the winding of said first detector coil.

5. A system according to claim 2 wherein said system comprises a third detector with a third electrically conducting detector coil that is perpendicular to said first detector coil, said detector being operable to detect magnetic flux through that third detector coil, where measurement of said first magnetic flux with said third detector is indicative of a third component of said positioning, said third component pertaining to a third direction, where said third direction comprises a translational direction along said second axis and/or a rotational direction around a third axis, where said third axis is perpendicular to said first and second axis.

6. A system according to claim 1 wherein said first magnetic flux due to said first electric current and said second magnetic flux due to said second electric current are mutually distinguishable due to differences between said first and said second electric current, where said differences are at least one from the group consisting of different frequencies and different modulations.

7. A system according to claim 1 wherein said first transmitter coil has at least two parallel first conductor sections, said parallel first conductor sections being perpendicular to said first direction, wherein the direction of said first electric current in said parallel first conductor sections is alternating for subsequent parallel first conductor sections.

8. A system according to claim 1 wherein said second transmitter coil has at least two parallel second conductor sections, said parallel second conductor sections being perpendicular to said second direction, wherein the direction of said second electric current in said second conductor sections is alternating for subsequent sections.

9. A system according claim 8 wherein said second transmitter coil is a Meander coil with a central conductor extending parallel with said second direction, said second electric current in said sentral conductor producing a further magnetic flux counteracting the magnetic flux produced by further conductor sections, where said further conductor sections connect said parallel second conductor sections in said Meander coil.

10. A system according to claim 1 wherein said second detector coil has a width not larger than half a period of said certain periodicity and a length substantially longer than the lengths of said parallel second conductor sections.

11. A system according to claim 1 wherein said second detector comprises at least one further detector coil, where this at least one further detector coil has an orientation and shape substantially equal to the orientation and shape of said second detector coil, and where the center of said at least one further detector coil as compared to the center of said second detector coil is displaced along said second direction by a fractional amount of the period of said certain periodicity.

12. A system according to claim 11 wherein said second detector comprises two coils, the centers of which having a mutual displacement of half a period of said certain periodicity.

13. A system according to claim 1 wherein said first detector comprises at least one additional coil, where said at least one additional coil has an orientation and shape substantially equal to the orientation and shape of said first detector coil and where the center of said at least one additional detector coil as compared to the center of said first detector coil is displaced along the first direction.

14. A system according to claim 13 wherein the center of said at least one additional detector coil is displaced by a distance equal to half the distance between said parallel first detector sections.

15. A system according to claim 1 wherein said system comprises a third transmitter coil that is electrically conducting, where said third transmitter coil is driven by a third electric current to produce a third magnetic flux, which is varying in time and alternating spatially with a further periodicity along said second direction.

16. A system according to claim 15 wherein said further periodicity is different from said certain periodicity by a rational fraction of the period of said certain periodicity.