POSITION DETERMINATION SYSTEM, TRANSMISSION DEVICE AND RECEPTION DEVICE, AND POSITION DETERMINATION METHOD

• US 20100286949A1
• Filed: 12/19/2008
• Published: 11/11/2010
• Est. Priority Date: 12/28/2007
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Kajitani, Hiroshi, Miyamoto, Junichi
• Granted Patent: US 8,498,839 B2
• Time in Patent Office: Days
• US Class Current: 702/150
• 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
• CPC Class Codes: G01S 7/5273 using digital techniques
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/0433 in which the acoustic waves are either generated by a movable member and propagated within a surface layer or propagated within a surface layer and captured by a movable member

Abstract

Positions of a plurality of transmission devices are precisely detected by a direct wave arriving first at a reception device without being affected by other ultrasonic signals from the transmission device.

Provided are a moving body including a transmission device which simultaneously sends out a trigger signal and an ultrasonic signal modulated by pseudo random sequence data having high self-correlativity, and a reception device which detects a position of the moving body, in which the reception device includes at least two ultrasonic reception units which receive the ultrasonic signal, a unit which calculates a correlation value between a waveform of the ultrasonic signal and a modulation reference waveform of a pseudo random sequence determined in advance according to the moving body, a unit which calculates a time of propagation of the ultrasonic to arrive at the two ultrasonic reception units from a time point of reception of the trigger signal and a time point of detection of a first peak of the correlation value, and a unit which calculates a position of the moving body based on the ultrasonic propagation time and an interval length between the ultrasonic reception units, and as the pseudo random sequence, different sequences whose cross-correlativity is low are used.

Claims

1. A position detection system, comprising:

at least one moving body including a transmission device which simultaneously sends out a trigger signal indicative of transmission timing and an ultrasonic signal modulated by pseudo random sequence data having high self-correlativity; and

a reception device which receives said trigger signal and said ultrasonic signal to detect a position of said moving body, wherein

said reception device comprising;

at least two ultrasonic reception units provided with a predetermined interval which receive said ultrasonic signal;

a unit which calculates a correlation value between a waveform of said ultrasonic signal and a modulation reference waveform of said pseudo random sequence determined in advance according to said moving body;

a unit which detects a first peak of said correlation value calculated and calculates a time of propagation of the ultrasonic to arrive at said two ultrasonic reception units from a time point of reception of said trigger signal and a time point of detection of the correlation peak; and

a unit which calculates a position of said moving body based on said ultrasonic propagation time calculated and the interval length between said ultrasonic reception units, wherein

as said pseudo random sequence, different sequences whose cross-correlativity is low are used.

3. The position detection system according to claim 1, wherein said trigger signal is an electromagnetic wave signal which enables identification of said transmission device.

4. The position detection system according to claim 3, wherein said trigger signal is a signal whose band is divided to prevent overlap with respect to each said transmission device.

5. The position detection system according to claim 1, wherein

said trigger signal is an electromagnetic wave signal modulated by a pseudo random signal having high self-correlativity which differs with each said transmission device, and

said reception device calculates a correlation value between a waveform of a received trigger signal and a modulation reference waveform set in advance and detects a top of the trigger signal differing with each said transmission device to generate timing as a start point of an arrival time of the ultrasonic signal.

6. The position detection system according to claim 1, wherein

said transmission device transmits a plurality of said ultrasonic signals based on a plurality of said pseudo random sequences which can be set, and

said reception device, at every reception of said plurality of ultrasonic signals, obtains values of correlation with modulation reference waveforms of all said pseudo random sequences to be used for said ultrasonic signal and checks a cross-correlation value between different M sequences to determine and assign said pseudo random sequence to be assigned to said moving body according to a predetermined reference.

7. The position detection system according to claim 6, wherein

said reception device comprises a display unit which displays information of said pseudo random sequence determined, and

the transmission device of said moving body comprises a setting switch which sets said pseudo random sequence for use for said ultrasonic signal based on the information of said pseudo random sequence displayed on the display unit of said reception device.

8. The position detection system according to claim 1, wherein as a pseudo random sequence, an M sequence is used.

9. The position detection system according to claim 1, wherein as a pseudo random sequence, a partial string of an M sequence is used.

10. The position detection system according to claim 1, wherein said moving body is an electronic pen.

11. The position detection system according to claim 1, wherein said moving body is a robot comprising said transmission device.

2. A position detection system, comprising:

at least one moving body including a transmission device which simultaneously sends out an ultrasonic signal modulated by a pseudo random signal having high self-correlativity; and

a reception device which receives said ultrasonic signal to detect a position of said moving body, wherein

said transmission device of said moving body comprising;

a unit which receives a trigger signal indicative of transmission timing; and

a unit which transmits said ultrasonic signal at the timing of reception of said trigger signal,

said reception device comprising;

a unit which sends out said trigger signal;

at least two ultrasonic reception units provided with a predetermined interval which receive said ultrasonic signal;

a unit which calculates a correlation value between a waveform of said ultrasonic signal and a modulation reference waveform of said pseudo random sequence determined in advance according to said moving body;

a unit which detects a first peak of said correlation value calculated and calculates a time of propagation of the ultrasonic to arrive at said two ultrasonic reception units from a time point of reception of said trigger signal and a time point of detection of the correlation peak; and

a unit which calculates a position of said moving body based on said ultrasonic propagation time calculated and the interval length between said ultrasonic reception units, wherein

as said pseudo random sequence, different sequences whose cross-correlativity is low are used.

12-23. -23. (canceled)

24. A position detection method, wherein

at least one transmission device executes a step of simultaneously transmitting a trigger signal indicative of transmission timing and an ultrasonic signal modulated by a pseudo random signal having high self-correlativity,

a reception device which receives said trigger signal and said ultrasonic signal to detect a position of said moving body executes the steps of:

receiving said ultrasonic signal by at least two ultrasonic reception units provided with a predetermined interval;

calculating a correlation value between a waveform of said ultrasonic signal and a modulation reference waveform determined in advance according to said moving body;

detecting a first peak of said correlation value calculated and calculating a time of propagation of the ultrasonic to arrive at said two ultrasonic reception units from a time point of reception of said trigger signal and a time point of detection of the correlation peak; and

calculating a position of said moving body based on said ultrasonic propagation time calculated and the interval length between said ultrasonic reception units, wherein

as a sequence of a pseudo random signal of said ultrasonic signal sent by said transmission device, different sequences whose cross-correlativity is low are used.

26. The position detection method according to claim 24, wherein said trigger signal is an electromagnetic wave signal which enables identification of said transmission device.

27. The position detection method according to claim 26, wherein said trigger signal is a signal whose band is divided to prevent overlap with respect to each said transmission device.

28. The position detection method according to claim 24, wherein said trigger signal is an electromagnetic wave signal modulated by a pseudo random signal having high self-correlativity which differs with each said transmission device, and

said reception device calculates a correlation value between a waveform of a received trigger signal and a modulation reference waveform set in advance and detects a top of the trigger signal differing with each said transmission device to generate timing as a start point of an arrival time of the ultrasonic signal.

29. The position detection method according to claim 24, wherein

said transmission device transmits a plurality of said ultrasonic signals based on a plurality of said pseudo random sequences which can be set, and

said reception device, at every reception of said plurality of ultrasonic signals, obtains values of correlation with modulation reference waveforms of all said pseudo random sequences to be used for said ultrasonic signal and checks a cross-correlation value between different M sequences to determine and assign said pseudo random sequence to be assigned to said moving body according to a predetermined reference.

30. The position detection method according to claim 29, wherein

said reception device comprises a display unit which displays information of said pseudo random sequence determined, and

the transmission device comprises a setting switch which sets said pseudo random sequence for use for said ultrasonic signal based on the information of said pseudo random sequence displayed on the display unit of said reception device.

31. The position detection method according to claim 24, wherein as a pseudo random sequence, an M sequence is used.

32. The position detection method according to claim 24, wherein as a pseudo random sequence, a partial string of an M sequence is used.

25. (canceled)

33-34. -34. (canceled)