SYSTEMS, METHODS, AND APPARATUS FOR PROVIDING INDOOR NAVIGATION USING MAGNETIC SENSORS

• US 20130261964A1
• Filed: 03/15/2013
• Published: 10/03/2013
• Est. Priority Date: 12/22/2011
• Status: Active Grant

• Current Assignee: Applabz, LLC
• Original Assignee: Applabz, LLC
• Inventors: Goldman, David Allan, Patel, Nirav Balkrishna
• Granted Patent: US 9,243,918 B2
• Time in Patent Office: Days
• US Class Current: 701/500
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01C 21/12 executed aboard the object being navigated; Dead reckoning
• CPC Class Codes: G01C 21/1654 with electromagnetic compass
• CPC Class Codes: G01C 21/1656 with passive imaging devices, e.g. cameras
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01C 21/265 constructional aspects of navigation devices, e.g. housings, mountings, displays G01C21/3688 takes precedence
• CPC Class Codes: G05D 1/0259 using magnetic or electromagnetic means
• CPC Class Codes: G05D 1/0268 using internal positioning means
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00
• CPC Class Codes: G05D 1/0276 using signals provided by a source external to the vehicle involving a plurality of vehicles G05D1/0287; automatically controlling vehicle speed responsive to externally generated signals B60K31/0058

Abstract

An indoor navigational system determines a location of a moveable object in an indoor area and displays this location to a user. The system includes an absolute position sensor coupled to a case attached to a moveable object including a motion sensor coupled to a case including a first magnetic field sensor configured to detect a polarity of a magnet as the magnet passes in proximity to the first magnetic field sensor, a code wheel having two or more magnets alternately oriented with north and south polarities facing toward the first magnetic sensor, the code wheel positioned to rotate in unison with a wheel of the moveable object, and encoder circuitry configured to determine an amount of rotation of the wheel of the moveable object based on an output of the first magnetic field sensor.

Claims

1. An apparatus comprising:

an absolute position sensor coupled to a case attached to a moveable object including;

a light detecting sensor which detects uniquely timed pulses of light emitted from a light emitting device in proximity to the moveable object; and

circuitry configured to determine an identity of the light emitting device in proximity to the moveable object based on the sensed uniquely timed pulses of light; and

a motion sensor coupled to the case including;

a first magnetic field sensor configured to detect a polarity of a magnet as the magnet passes in proximity to the first magnetic field sensor;

a code wheel having two or more magnets alternately oriented with north and south polarities facing toward the first magnetic sensor, the code wheel positioned to rotate in unison with a wheel of the moveable object; and

encoder circuitry configured to determine an amount of rotation of the wheel of the moveable object based on an output of the first magnetic field sensor.

2. The apparatus of claim 1, wherein the motion sensor is configured to transmit a quadrature encoded signal indicative of the determined amount of movement, and the absolute position sensor is configured to transmit an absolute positioning signal including a unique identifier identifying the specific light emitting device in the proximity of the moveable object.

3. The apparatus of claim 1, further comprising a second motion sensor coupled to a second case attached to the moveable object including:

a second magnetic field sensor configured to detect a polarity of a magnet as the magnet passes in proximity to the second magnetic field sensor;

a second code wheel having two or more magnets alternately oriented with north and south polarities facing toward second the second magnetic field sensor, the second code wheel positioned to rotate in unison with a second wheel of the moveable object; and

second encoder circuitry configured to determine the direction and distance of rotation of the second wheel of the moveable object based on an output of the second magnetic field sensor,

wherein the second motion sensor is configured to operate in conjunction with the first motion sensor to detect the direction and amount of rotation of the two wheels of the moveable object.

4. The apparatus of claim 3, wherein the first amount of rotation is used by a processor in conjunction with the second amount of rotation to determine a change in position and orientation of the moveable object.

5. The apparatus of claim 1, wherein the light emitting device is configured to output a collimated beam of light that is detectable by the light detecting sensor as the moveable object passes through the collimated beam.

6. The apparatus of claim 5, wherein one or more light emitting devices are placed throughout an indoor environment and each of the light emitting devices output different, uniquely identifiable timed pulses of light.

7. The apparatus of claim 1, wherein the motion sensor includes a second magnetic field sensor configured to detect the polarity of a magnet as the magnet passes in proximity to the second magnetic field sensor and the encoder circuitry is configured to determine a direction and an amount of movement the moveable object based on the output of the first magnetic field sensor and the second magnetic field sensor.

8. The apparatus of claim 1, wherein the light emitting device includes a vertical cavity surface emitting laser.

9. An apparatus comprising:

a motion sensor connected to a case attached to a moveable object including;

a first magnetic field sensor configured to detect a polarity of a magnet as the magnet passes in proximity to the first magnetic field sensor;

a second magnetic field sensor configured to detect a polarity of a magnet as the magnet passes in proximity to the second magnetic field sensor; and

a code wheel having at least two magnets alternately oriented with north and south polarities facing toward the first and second magnetic field sensors, the code wheel positioned to rotate in unison with a wheel of the moveable object;

wherein the locations of the first and second magnetic field sensors are located at positions within the case such that their alignment with the code wheel corresponds to a quadrature encoder output.

10. The apparatus of claim 9, wherein the moveable object is a shopping cart.

11. The apparatus of claim 9, wherein the quadrature encoder output includes signal changes that are associated with an error-corrected amount of rotation of the wheel

12. The apparatus of claim 9, wherein the first and second magnetic field sensors include hall-effect sensors.

13. The apparatus of claim 9, wherein the first and second magnetic field sensors are encapsulated within the case.

14. The apparatus of claim 9, wherein the code wheel includes an insert tray configured to position the magnets to be evenly spaced apart from each other.

15. A method of operating an indoor navigation system, the method comprising:

detecting, in a light detecting sensor coupled to a moveable object, uniquely timed pulses of light emitted from a proximately located emitting device; and

transmitting from the light detecting sensor an absolute positioning signal including an identifier corresponding to the uniquely timed pulses of light enabling an absolute position of the moveable object to be determined;

determining a first movement of a wheel of the moveable object based on detected changes in polarity of magnets alternately orientated with north and south polarities by a first magnetic field sensor;

determining a second movement of the wheel of the moveable object based on detected changes in polarity of the magnets by a second magnetic field sensor;

determining an amount of movement and a direction of movement of the moveable object based on the first and second movements; and

transmitting a dead-reckoning signal indicative of the determined amount of movement and the direction.

16. The method of claim 15, further comprising:

detecting an error in the timing between changes in polarity of magnets; and

compensating for the error using a correction factor applied to at least one of the amount of movement and the direction.

17. The method of claim 16, wherein the error is based on an amount of misalignment of at least one of the first magnetic field sensor and the first magnetic field sensor with the magnets.

18. The method of claim 16, wherein detecting the error:

monitoring a first waveform including changes in polarity detected by the first magnetic sensor for a time period;

monitoring a second waveform including changes in polarity detected by the second magnetic sensor for the time period; and

determining that the first waveform is substantially less than or greater than 90 degrees out of phase with the second waveform.

19. The method of claim 18, wherein determining the correction factor for the first and the second waveforms includes:

Determining that the moveable object is moving at a constant rate;

determining a first value of a time between positive polarity transitions;

determining a second value of a time of the negative polarity between the positive polarity transitions; and

calculating the correction factor as a ratio of the second value divided by the first value.

20. The method of claim 19, wherein compensating for the error using the correction factor includes:

determining a positive polarity distance as a distance the wheel moved between positive polarity transitions as measured by one of the magnetic sensors multiplied by the correction factor;

determining a negative polarity distance as a distance the wheel moved during the negative polarity between the positive polarity transitions as measured by one of the magnetic sensors multiplied by one minus the correction factor; and

determining the amount of movement based on the determined positive polarity distance and the negative polarity distance.