Apparatus for resolving presence and orientation within a defined space

• US 6,066,954 A
• Filed: 01/25/1999
• Issued: 05/23/2000
• Est. Priority Date: 02/03/1994
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Gershenfeld, Neil, Smith, Joshua R.
• Primary Examiner(s): BROWN, GLENN WARNER
• Application Number:
  US09/245,480
• Time in Patent Office: 484 Days
• Field of Search: 324/663, 324/671, 324/672, 324/686, 324/687, 324/715, 324/716, 324/71.1, 324/73.1
• US Class Current: 324/671
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: B60N 2/28 Seats readily mountable on, and dismountable from, existing seats or other parts of the vehicle
• CPC Class Codes: B60N 2/286 forward facing B60N2/2866 takes precedence
• CPC Class Codes: B60N 2/2863 backward facing
• CPC Class Codes: B60R 21/01532 using electric or capacitive field sensors
• CPC Class Codes: B60R 21/01556 Child-seat detection systems
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01B 7/004 for measuring coordinates of points
• CPC Class Codes: G01D 5/24 by varying capacitance
• CPC Class Codes: G01V 3/088 operating with electric fields G01V3/082 takes precedence
• CPC Class Codes: G06F 3/011 Arrangements for interaction with the human body, e.g. for user immersion in virtual reality blind teaching G09B21/00
• CPC Class Codes: G06F 3/017 Gesture based interaction, e.g. based on a set of recognized hand gestures interaction based on gestures traced on a digitiser G06F3/04883
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 2217/94052 with evaluation of actuation pattern or sequence, e.g. tapping
• CPC Class Codes: H03K 2217/960775 Emitter-receiver or "fringe" type detection, i.e. one or more field emitting electrodes and corresponding one or more receiving electrodes

Abstract

Apparatus for resolving movement of a mass within a defined space utilizes at least one electrode proximate to the space to be observed. An AC signal is applied to the electrode, and the current measured from that electrode and also to any other electrodes included in the system, and which are effectively connected to the ground return of the AC-coupled electrode. A person (or object) to be sensed intercepts a part of the electric field extending beween the AC-coupled "sending" electrode and the other "receiving" electrodes, the amount of the field intercepted depending on the size and orientation of the sensed person, whether or not the person provides a grounding path, and the geometry of the distributed electrodes. Given the nonlinear spatial dependence of the field, multiple electrodes can reliably distinguish among a set of expected cases. The invention detects motion by taking sequential measurements at different times and utilizing the time variation in signal magnitudes as well as the absolute magnitudes themselves.

Claims

1. Apparatus for characterizing the position and orientation of a person in a defined space, the apparatus comprising:

a. at least two electrodes distributed proximate to the space, the electrodes having fixed positions relative to each other;

b. an AC source;

c. means for sequentially coupling a plurality of electrodes to the AC source so as to produce a current flowing into each uncoupled electrode;

d. means for measuring the current flowing from the AC-coupled electrode;

e. means for measuring the current flowing into each uncoupled electrode; and

f. means for characterizing position and orientation within the space based on the measurements.

2. The apparatus of claim 1 further comprising, within the defined space, a nonconductive contour having first and second sides opposed to each other, the person resting against the first side and the electrodes being disposed on the second side.

3. The apparatus of claim 2 wherein the contour is a seat comprising a base portion and a back portion angled relative to each other, at least one electrode being located along the base portion and at least one electrode being located along the back portion, the apparatus comprising at least three electrodes.

4. The apparatus of claim 3 wherein the apparatus comprises four electrodes, two electrodes being spaced along the base portion and two electrodes being spaced along the back portion.

5. The apparatus of claim 1 further comprising:

a. a computer memory for storing the (i) the measurements and (ii) a pattern of measurement clusters each associated with a position and an orientation; and

b. a processor for comparing the measurements against the pattern to thereby characterize position and orientation.

6. The apparatus of claim 3 further comprising:

a. a computer memory for storing the (i) the measurements and (ii) a pattern of measurement clusters each associated with a position and an orientation, the clusters including measurements characterizing a seated adult, an infant in a carrier facing away from the back portion and an infant in a carrier facing toward the back portion; and

b. a processor for comparing the measurements against the pattern to thereby characterize position and orientation.

7. The apparatus of claim 1 wherein the coupling means sequentially connects at least one of the electrodes to the AC source a plurality of times.

8. The apparatus of claim 7 comprising at least three electrodes, the coupling means being configured to sequentially connect each of the electrodes to the AC source, and the means for measuring current flowing into each uncoupled electrode being configured to make at least two measurements of current into one of the unconnected electrodes and at least one measurement of current into another of the unconnected electrodes.

9. The apparatus of claim 7 further comprising:

a. a computer memory for storing the (i) the measurements and (ii) a pattern of measurement clusters each associated with a movement; and

b. a processor for comparing the measurements against the pattern to thereby characterize movement of the mass.

10. Apparatus for characterizing the three-dimensional position and orientation of a person in a defined space, the apparatus comprising:

a. at least three electrodes distributed proximate to the space, the electrodes having fixed positions relative to each other;

b. an AC source;

c. means for sequentially coupling each of a plurality of electrodes to the AC source so as to produce a current flowing into each uncoupled electrode;

d. means for measuring the current flowing from the AC-coupled electrode;

e. means for measuring the current flowing into each uncoupled electrode, at least some of the electrodes being switchably connected to the AC source and to the uncoupled-electrode current-measuring means to alternately serve as AC-coupled electrodes and as measurement electrodes; and

f. means for characterizing the person'"'"'s three-dimensional position and orientation within the space based on the measurements.

11. The apparatus of claim 10 wherein said characterizing means comprises a computer memory for storing (i) the measurements and (ii) information representing a pattern of measurements associated with known positions and orientations, and a processor for comparing the measurements against the pattern to thereby characterize position and orientation.

12. The apparatus of claim 10 further comprising a nonconductive contour having first and second sides opposed to each other, the person resting against the first side and the electrodes being disposed on the second opposite side.

13. The apparatus of claim 12 wherein the contour is a seat comprising a base portion and a back portion angled relative to each other, at least one electrode being located along the base portion and at least one electrode being located along the back portion.

14. The apparatus of claim 13 wherein the apparatus comprises four electrodes, two electrodes being spaced along the base portion and two electrodes being spaced along the back portion.