WIRELESS POSITION SENSING IN THREE DIMENSIONS USING ULTRASOUND

• US 20110026363A1
• Filed: 03/28/2007
• Published: 02/03/2011
• Est. Priority Date: 03/28/2006
• Status: Active Grant

• Current Assignee: Performance Designed Products LLC
• Original Assignee: In2Games Ltd. (Performance Designed Products LLC)
• Inventors: Lavache, Steven David
• Granted Patent: US 9,791,547 B2
• Time in Patent Office: Days
• US Class Current: 367/127
• CPC Class Codes: G01S 11/16 using difference in transit time between electrical and acoustic signals
• CPC Class Codes: G01S 5/30 Determining absolute distances from a plurality of spaced points of known location

Abstract

The present invention provides a method of position sensing between a wireless mobile component carrying a mobile ultrasonic transducer and a fixed component carrying a plurality of fixed ultrasonic transducers in a predetermined spaced-apart relationship, the method comprising turning off all the transducers to establish a period of silence, activating one or more of the fixed transducers to transmit an ultrasonic signal, starting a plurality of timers corresponding to the respective plurality of fixed transducers generally simultaneously with transmitting the signal, receiving the signal at the mobile transducer, transmitting a signal from the mobile transducer responsive to the received signal, receiving the signal transmitted by the mobile transducer at each fixed transducer and stopping the respective timer generally at the time of reception of an edge of the received signal found within the first twenty received edges and preferably within the first ten received edges and more preferably at the first received rising edge, calculating the distance between the mobile transducer and each fixed transducer based on a predetermined constant representative of the speed of sound and the time taken for transit of the signal to each fixed transducer as measured by the respective timers, and performing trigonometric calculations using the calculated distances in order to determine the 3-dimensional position of the mobile component relative to the fixed component.

Claims

1. A method of position sensing between a wireless mobile component carrying a mobile ultrasonic transducer and a first rf transducer and a fixed component carrying a plurality of fixed ultrasonic transducers in a predetermined spaced-apart relationship and a second rf transducer, comprising;

(a) sending an rf trigger signal from the second rf transducer,

(b) starting a plurality of timers corresponding to the respective plurality of fixed transducers generally simultaneously with transmitting the trigger signal,

(c) receiving the trigger signal at the first rf transducer,

(d) transmitting a signal from the mobile ultrasonic transducer responsive to the received trigger signal,

(e) receiving the signal transmitted by the mobile ultrasonic transducer at each fixed ultrasonic transducer and stopping the respective timer generally at the time of reception of an edge of the received signal found within the first twenty received edges and preferably within the first ten received edges and more preferably at the first received rising edge,

(f) calculating the distance between the mobile ultrasonic transducer and each fixed ultrasonic transducer based on a predetermined constant representative of the speed of sound and the time taken for transit of the signal to each fixed transducer as measured by the respective timers, and

(g) performing trigonometric calculations using the calculated distances in order to determine the 3-dimensional position of the mobile component relative to the fixed component.

2. A method according to claim 1 comprising clipping the signal received by the fixed ultrasonic transducers to produce a substantially square waveform.

3. A method according to claim 2, wherein the signal transmitted by the second rf transducer is modulated to embed a unique code selected from a predetermined set of codes, and wherein the first rf transducer is responsive only to a received signal containing a predetermined one of the predetermined set of codes, whereby several mobile components may be used with a single fixed component.

4. A method of position sensing using a wireless mobile component carrying an ultrasonic transducer and a fixed component carrying a plurality of ultrasonic transducers in a predetermined spaced-apart relationship, the method including selecting the said mobile component from a plurality of similar mobile components by modulating a signal transmitted by the fixed component with a unique code selected from a predetermined set of codes, and arranging for the mobile component to be responsive to a subset of, and preferably only one of, the codes from the said set of codes.

5. A method according to claim 4, wherein the modulation is amplitude modulation.

6. A method according to claim 5, wherein the modulation is carried over 8 cycles of the signal and each cycle represents a single bit of an 8 bit binary number.

7. A method of position sensing using a wireless mobile component carrying an ultrasonic transducer and a fixed component carrying a plurality of ultrasonic transducers in a predetermined spaced-apart relationship, the method including selecting the said mobile component from a plurality of similar mobile components by modulating a signal transmitted by the fixed component with a unique code selected from a predetermined set of codes, and arranging for the mobile component to be responsive to a subset of, and preferably only one of, the codes from the said set of codes and further including activating one or more of the fixed transducers to transmit an ultrasonic signal, receiving the signal at the mobile transducer, transmitting a signal from the mobile transducer responsive to the received signal, and listening between transmission cycles to the fixed transducers to receive a turn-off signal at the mobile transducer to cause the mobile transducer to stop transmitting.

8. A method of position sensing using a wireless mobile component carrying an ultrasonic transducer and a fixed component carrying a plurality of ultrasonic transducers in a predetermined spaced-apart relationship, the method including selecting the said mobile component from a plurality of similar mobile components by modulating a signal transmitted by the fixed component with a unique code selected from a predetermined set of codes, and arranging for the mobile component to be responsive to a subset of, and preferably only one of, the codes from the said set of codes and wherein the mobile component is arranged to stop transmitting after a predetermined period of time such as 8 cycles.

9. A method of calibrating an ultrasonic position sensing arrangement having a fixed component carrying a plurality of ultrasonic transducers in a predetermined spaced-apart relationship, the method comprising activating a first and second of the fixed transducers, transmitting an ultrasonic signal from the first to the second transducer, measuring the time taken for the ultrasonic signal to travel from the first to the second transducer and deducing a first calibration measure based on the known distance between the transducers and the measured time.

10. A method according to claim 9, including activating a third transducer, measuring the time taken for the ultrasonic signal to travel from the first to the third transducer, deducing a second calibration measure based on the known distance between the first and third transducers and the measured time and averaging the first and second calibration measures.

11. A method of position sensing between a wireless mobile component carrying a mobile ultrasonic transducer and a first rf transducer and a fixed component carrying a plurality of fixed ultrasonic transducers in a predetermined spaced-apart relationship and a second rf transducer, comprising;

(a) sending an rf trigger signal from the second rf transducer,

(b) starting a plurality of timers corresponding to the respective plurality of fixed transducers generally simultaneously with transmitting the trigger signal,

(c) receiving the trigger signal at the first rf transducer,

(d) transmitting a signal from the mobile ultrasonic transducer responsive to the received trigger signal,

(e) receiving the signal transmitted by the mobile ultrasonic transducer at each fixed ultrasonic transducer and stopping the respective timer generally at the time of reception of an edge of the received signal found within the first twenty received edges and preferably within the first ten received edges and more preferably at the first received rising edge,

(f) calculating the distance between the mobile ultrasonic transducer and each fixed ultrasonic transducer based on a predetermined constant representative of the speed of sound and the time taken for transit of the signal to each fixed transducer as measured by the respective timers, and

(g) performing trigonometric calculations using the calculated distances in order to determine the 3-dimensional position of the mobile component relative to the fixed component.

(h) repeating the position sensing method at least one hundred times a second.

12. A method of position sensing according to claim 11, comprising carrying out a method of calibrating an ultrasonic position sensing arrangement having a fixed component carrying a plurality of ultrasonic transducers in a predetermined spaced-apart relationship, the method comprising activating a first and second of the fixed transducers, transmitting an ultrasonic signal from the first to the second transducer, measuring the time taken for the ultrasonic signal to travel from the first to the second transducer and deducing a first calibration measure based on the known distance between the transducers and the measured time, between substantially every repetition of the position sensing method.

13. An ultrasonic position sensor arrangement having a fixed component carrying a plurality of fixed ultrasonic transducers in a predetermined spaced-apart arrangement and a wireless mobile component carrying a mobile ultrasonic transducer, the fixed component including a plurality of Class C amplifiers coupled to the respective outputs of the fixed transducers, and a plurality of timers arranged to be triggered by respective outputs of the class C amplifiers.

14. An ultrasonic position sensor according to claim 13, wherein the gain of the amplifiers is selected to ensure that the output is saturated at the respective normal operating points of the fixed transducers.

15. An ultrasonic position sensor according to claim 13, further including a modulator arranged to modulate a signal transmitted by the fixed ultrasonic transducers to embed a unique code in the signal selected from a predetermined set of codes.

16. An ultrasonic position sensor according to claim 15, wherein the modulation is amplitude modulation.

17. An ultrasonic position sensor according to claim 13, wherein the mobile component comprises at least two members, each member carrying a mobile ultrasonic transducer and being connectable to another member using attachment means.

18. An ultrasonic position sensor according to claim 17, wherein the attachment means is magnetic, a hook and loop fastener or a clip.

19. An ultrasonic position sensor according to claim 17, wherein the members include a detecting means adapted to determine whether the member is connected to another member and cause only one member to transmit a signal when two or more members are connected.

20. A mobile component comprising at least two members, each member being connectable to another member using attachment means and including communications means for transmitting information to a fixed unit.

21. A mobile component according to claim 20, wherein the attachment means is magnetic, a hook and loop fastener or a clip.

22. A mobile component according to claim 20, wherein the communications means transmits information to the fixed unit through a wire or through a wireless connection.

23. A mobile unit according to claim 22 wherein the communications means is an ultrasonic transducer.

24. A mobile unit according to claim 22 wherein the communications means is an rf transducer.

25. A mobile component comprising at least two members, each member being connectable to another member using attachment means and including communication means for transmitting information to a fixed unit, wherein the fixed component is adapted to determine the position of each mobile component.

26. A mobile component comprising at least two members, each member being connectable to another member using attachment means and including communication means for transmitting information to a fixed unit, wherein the members include a detecting means adapted to determine whether the member is connected to another member and cause only one member to transmit a signal when two or more members are connected.

27. A method of position sensing between a wireless mobile component carrying a mobile ultrasonic transducer and a fixed component carrying a plurality of fixed ultrasonic transducers in a predetermined spaced-apart relationship, the method comprising:

(a) turning off all the transducers to establish a period of silence,

(b) activating one or more of the fixed transducers to transmit an ultrasonic signal,

(c) starting a plurality of timers corresponding to the respective plurality of fixed transducers generally simultaneously with transmitting the signal,

(d) receiving the signal at the mobile transducer,

(e) transmitting a signal from the mobile transducer responsive to the received signal,

(f) receiving the signal transmitted by the mobile transducer at each fixed transducer and stopping the respective timer generally at the time of reception of an edge of the received signal found within the first twenty received edges and preferably within the first ten received edges and more preferably at the first received rising edge,

(g) calculating the distance between the mobile transducer and each fixed transducer based on a predetermined constant representative of the speed of sound and the time taken for transit of the signal to each fixed transducer as measured by the respective timers, and

(h) performing trigonometric calculations using the calculated distances in order to determine the 3-dimensional position of the mobile component relative to the fixed component.

28. A method according to claim 27 comprising clipping the signal received by the fixed ultrasonic transducers to produce a substantially square waveform.

29. A method according to claim 28, wherein the ultrasonic signal transmitted by the fixed component is modulated to embed a unique code selected from a predetermined set of codes, and wherein the mobile ultrasonic transducer is responsive only to a received signal containing a predetermined one of the predetermined set of codes, whereby several mobile components may be used with a single fixed component.

30. (canceled)

31. (canceled)

32. (canceled)

33. A method of calibrating an ultrasonic position sensing arrangement having a fixed component carrying a plurality of ultrasonic transducers in a predetermined spaced-apart relationship, the method comprising activating a first and second of the fixed transducers, transmitting an ultrasonic signal from the first to the second transducer, measuring the time taken for the ultrasonic signal to travel from the first to the second transducer and deducing a first calibration measure based on the known distance between the transducers and the measured time, wherein the calibration is carried out between substantially every repetition of a position sensing method.