Method and apparatus for determining three-dimensional position, orientation and mass distribution

Apparatus for quantifying at least one unknown parameter pertaining to a property selected from size, position and orientation of an electrically conductive mass within a defined space and having a predetermined mass distribution, each parameter representing an independent degree of freedom, the apparatus comprising:

• a. a plurality of electrodes disposed proximate to the space and with defined positions relative to each other, the electrodes being sufficient in number to resolve the unknown parameter;
• b. an AC source;
• c. means for connecting the AC source to one of the electrodes to create an electric field around the mass;
• d. means for measuring current levels through a plurality of the electrodes to produce a measurement set;
• and
• e. processor means for inferring, from the measurement set, a value of the unknown parameter which, according to a forward model relating a plurality of instances of the parameter to corresponding expected current levels through a plurality of the electrodes given an AC signal through one of the electrodes, produces expected current levels closest to the measured levels.

Apparatus for obtaining the distribution of an electrically conductive mass within a defined space, the mass having a size within a predetermined range, the apparatus comprising:

• a. a plurality of electrodes disposed proximate to the space and with defined positions relative to each other, the electrodes being sufficient in number to resolve the unknown parameter;
• b. an AC source;
• c. means for connecting the AC source to one of the electrodes to create an electric field around the mass;
• d. means for measuring current levels through a plurality of the electrodes;
• and
• e. processor means configured to (i) for each measurement, localize the mass within a spatial region spanning first and second spatial boundaries corresponding to first and second iso-signal shells, the iso-signal shells being established by the predetermined size range of the mass and the measured current level, and (ii) combine the spatial regions into a representation of a composite spatial region containing the mass, the composite spatial region approximating the distribution of the mass.

A position-sensing device for sensing a three-dimensional position of an electrically conductive mass, the apparatus comprising:

• a. at least three electrodes disposed proximate to the space and with defined positions relative to each other;
• b. an AC source;
• c. means for connecting the AC source to one of the electrodes to create an electric field around the mass;
• d. means for measuring current levels through a plurality of the electrodes to produce a measurement set;
• and
• e. processor means for inferring, from the measurement set, the three-dimensional position of the mass, the processor being configured to infer the three-dimensional position according to a forward model relating position to corresponding expected current levels through a plurality of the electrodes given an AC signal through one of the electrodes, the inferred position producing expected current levels closest to the measured levels.

A method of sensing a three-dimensional position of an electrically conductive mass, the method comprising the steps of:

• a. disposing at least three electrodes proximate to the space and with defined positions relative to each other;
• b. providing an AC source;
• c. connecting the AC source to one of the electrodes to create an electric field around the mass;
• d. measuring current levels through a plurality of the electrodes to produce a measurement set;
• and
• e. inferring, from the measurement set, the three-dimensional position of the mass according to a forward model relating three-dimensional position to corresponding expected current levels through a plurality of the electrodes given an AC signal through one of the electrodes, the inferred position producing expected current levels closest to the measured levels.

A position-sensing device for sensing a two-dimensional position of an electrically conductive mass and an offset, with respect to the two-dimensional position, along a third dimension, the apparatus comprising:

• a. at least three electrodes disposed proximate to the space and with defined positions relative to each other;
• b. an AC source;
• c. means for connecting the AC source to one of the electrodes to create an electric field around the mass;
• d. means for measuring current levels through a plurality of the electrodes to produce a measurement set;
• and
• e. processor means for inferring, from the measurement set, the two-dimensional position of the mass and the existence of an offset, along a third dimension, exceeding a predetermined threshold, the processor being configured to infer the two-dimensional position and the offset according to a forward model relating position to corresponding expected current levels through a plurality of the electrodes given an AC signal through one of the electrodes, the inferred position and offset producing expected current levels closest to the measured levels.

A method of sensing a two-dimensional position of an electrically conductive mass and an offset, with respect to the two-dimensional position, along a third dimension, the method comprising the steps of:

• a. disposing at least three electrodes proximate to the space and with defined positions relative to each other;
• b. providing an AC source;
• c. connecting the AC source to one of the electrodes to create an electric field around the mass;
• d. measuring current levels through a plurality of the electrodes to produce a measurement set;
• and
• e. inferring, from the measurement set, the two-dimensional position of the mass and the existence of an offset, along a third dimension, exceeding a predetermined threshold,
• wherein the inferring step comprises providing a forward model relating position to corresponding expected current levels through a plurality of the electrodes given an AC signal through one of the electrodes, and identifying a two-dimensional position and offset producing expected current levels closest to the measured levels.

A method of characterizing at least one property selected from mass distribution, position and orientation of an electrically conductive mass within a defined space, the method comprising the steps of:

• a. disposing a plurality of electrodes proximate to the space and with defined positions relative to each other;
• b. providing an AC source;
• c. connecting the AC source to one of the electrodes to create an electric field around the mass;
• d. measuring current levels through a plurality of the electrodes to produce a measurement set;
• and
• e. inferring, from the measurement set, the instance of the property which, according to a forward model relating a plurality of instances of the property to corresponding expected current levels through a plurality of the electrodes given an AC signal through one of the electrodes, produces expected current levels closest to the measured levels.

A method of quantifying at least one unknown parameter pertaining to a property selected from size, position and orientation of an electrically conductive mass within a defined space and having a predetermined mass distribution, each parameter representing an independent degree of freedom, the method comprising the steps of:

• a. disposing a plurality of electrodes proximate to the space and with defined positions relative to each other, the electrodes being sufficient in number to resolve the unknown parameter;
• b. providing an AC source;
• c. connecting the AC source to one of the electrodes to create an electric field around the mass;
• d. measuring current levels through a plurality of the electrodes to produce a measurement set;
• and
• e. inferring, from the measurement set, a value of the unknown parameter which, according to a forward model relating a plurality of instances of the parameter to corresponding expected current levels through a plurality of the electrodes given an AC signal through one of the electrodes, produces expected current levels closest to the measured levels.

A method of obtaining the distribution of an electrically conductive mass within a defined space, the mass having a size within a predetermined range, the method comprising the steps of:

• a. disposing a plurality of electrodes proximate to the space and with defined positions relative to each other, the electrodes being sufficient in number to resolve the unknown parameter;
• b. providing an AC source;
• c. connecting the AC source to one of the electrodes to create an electric field around the mass;
• d. measuring current levels through a plurality of the electrodes;
• e. for each measurement, localizing the mass within a spatial region spanning first and second spatial boundaries corresponding to first and second iso-signal shells, the iso-signal shells being established by the predetermined size range of the mass and the measured current level;
• and
• f. combining the spatial regions into a representation of a composite spatial region containing the mass, the composite spatial region approximating the distribution of the mass.