RF system for tracking objects

• US 7,327,306 B2
• Filed: 05/05/2006
• Issued: 02/05/2008
• Est. Priority Date: 05/06/2005
• Status: Expired due to Fees

• Current Assignee: Orthosoft Inc. (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Orthosoft Inc. (Zimmer Biomet Holdings, Inc.)
• Inventors: Laroche, Jean-Louis
• Primary Examiner(s): Gregory; Bernarr E.
• Application Number:
  US11/418,114
• Publication Number:
  US 20060250300A1
• Time in Patent Office: 641 Days
• Field of Search: 342 27- 51, 342/175, 342/195, 342450-465, 342/59, 342/118, 342/125, 342/126, 342/147, 342/156, 342/146, 342165-174, 606/1, 606 32- 34, 128/897, 600/117, 600/407, 600/424, 600/429
• US Class Current: 342/126
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2090/3975 active
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for
• CPC Class Codes: G01S 13/874 Combination of several systems for attitude determination in general G01C, control of attitude G05D1/49
• CPC Class Codes: G01S 7/4004 of parts of a radar system

Abstract

A system for tracking an object in space for position, comprises a transponder device connectable to the object. The transponder device has one or several transponder aerial(s) and a transponder circuit connected to the transponder aerial for receiving an RF signal through the transponder aerial. The transponder device adds a known delay to the RF signal thereby producing an RF response for transmitting through the transponder aerial. A transmitter is connected to a first aerial for transmitting the RF signal through a first aerial. A receiver is connected to the first, a second and third aerials for receiving the RF response of the transponder device therethrough. A position calculator is associated to the transmitter and the receiver for calculating a position of the object as a function of the known delay and the time period between the emission of the RF signal and the reception of the RF response from the first, second and third aerials. A method is also provided.

Claims

1. A method for tracking an object in space for position, comprising the steps of:

emitting an RF signal from a fixed position;

receiving the RF signal with a transponder device on the object;

emitting from the transponder device an RF return signal consisting of the received RF signal delayed in time by a known time delay;

receiving the RF return signal with at least three aerials associated to the fixed position; and

calculating a position of the object from a distance between each of the at least three aerials and the transponder device as a function of the known delay and the time period between the emission of the RF signal and the reception of the RF return signal from the first, second and third aerials.

2. The method according to claim 1, wherein the step of receiving the RF return signal is performed in three orthogonal axes, such that the step of calculating also involves calculating an orientation of the object.

3. The method according to claim 1, further comprising a step of detecting obstruction before the step of calculating the position of the object, such that position is calculated as a function of the known delay, the time period, and obstruction data.

4. The method according to claim 1, wherein the step of receiving the RF return signal is performed with four aerials, such that the position is calculated as a function of the known delay and the time period between the emission of the RF signal and the reception of the RF return signal from the first, second, third and fourth aerials.

5. The method according to claim 1, wherein the step of calculating the position of the object is performed as a function of a phase difference between the emitted RF signal and the received RF return signal.

6. A system for tracking an object in space for position, comprising:

a transponder device operatively connected to the object, the transponder device having a transponder aerial and a transponder circuit connected to the transponder aerial for receiving an RF signal through the transponder aerial, the transponder device for adding a known delay to the RF signal for thereby producing an RF response for transmitting through the transponder aerial;

first, second and third aerials;

a transmitter connected to the first aerial for transmitting the RF signal through the first aerial;

a receiver connected to the first, second and third aerials for receiving the RF response of the transponder device therethrough; and

a position calculator associated to the transmitter and the receiver and having a cycle counter and a phase comparator for calculating a position of the object as a function of the known delay, a number of cycles between the emission of the RF signal and the reception of the RF response from the first, second and third aerials, and as a function of a phase difference between the emitted RF signal and the received RF response.

7. The system according to claim 6, wherein the transponder aerial comprises three orthogonally oriented transponder aerials whereby an orientation of the transponder device is calculated as a function of the RE response of the three transponder aerials.

8. The system according to claim 6, wherein the position calculator has value data associating a distance between at least one of the first, second and third aerial to a time value, whereby the position calculator is for calculating the position as a function of the known delay, the time period and the distance between the at least one of the first, second and third aerial.

9. The system according to claim 6, further comprising a fourth aerial connected to the receiver for receiving the RF response therethrough, with the time period including the reception of the RF response from the fourth aerial.

10. The system according to claim 6, further comprising an obstruction detector associated with the position calculator, the obstruction detector for producing obstruction data, whereby the position calculator is for calculating the position of the object as a function of the known delay, the time period and the obstruction data.

11. The system according to claim 10, wherein the transponder device is for amplifying the RF response, such that the obstruction detector identifies reflective obstructions.

12. The system according to claim 10, further comprising a fourth aerial connected to the receiver for receiving the RF response therethrough, the obstruction detector for considering the RF response received through all of the four aerials to identify obstruction, whereby the obstruction data filters the RF response received through one of the four aerials upon detection of obstruction for said one aerial.

13. The system according to claim 10, wherein the obstruction detector has a sensor device for visually detecting obstructions.

14. The system according to claim 6, wherein the transponder device has a portable power source.

15. The system according to claim 6, wherein said transponder device is switched between three transponder aerials and a transponder circuit is connected to the transponder aerials for receiving RF signals through the transponder aerials, the transponder devices for adding a known delay to the RF signal for thereby producing RE pulses for transmitting through the transponder aerials, further wherein the three transponder aerials are orthogonally oriented.