GB2399965A

GB2399965A - System for determining the three dimensional position of an article

Info

Publication number: GB2399965A
Application number: GB0306811A
Authority: GB
Inventors: Alan Begg
Original assignee: Morgan Crucible Co PLC
Current assignee: Morgan Crucible Co PLC
Priority date: 2003-03-24
Filing date: 2003-03-24
Publication date: 2004-09-29
Also published as: GB0306811D0

Abstract

A system is disclosed for determining the position of an article in a room and comprises a number of transmitters arranged about the room, one or more transponders secured to or within the article capable of receiving and responding to the transmitted signals, and a processing means capable of interpreting responses to the transmitted signals and presenting three dimensional positional information for the or each transponder. The transmitters may operate at a frequency that is shielded by the structure of the room and may be GPS type transmitters. The transponder may comprise a processing means so that its response may comprise the positional information. The transponder response may further provide orientation information. Each transponder may hold identification information so that the processing means may discriminate between transponders. The position or orientation information may be presented as a computer generated image and the image may further comprise detail of the area surrounding the article. The transmitters may be mounted on a frame surrounding the article. The articles may be medical or surgical tools.

Description

Position Sensing System, Components Therefor and Uses Thereof This

invention relates to systems for accurately positioning articles, sensors used for such systems, and uses of such systems.

Global Positioning Systems (GPS) are well known as means of accurately establishing the position of a user. A series of orbiting satellites transmit signals and from phase information received from said signals a GPS receiver can calculate its position to within meters.

Receivers for such systems were until recently quite bulky. The use of resonantly coupled lo dielectric ceramic aerials has reduced the size of such receivers considerably. Receivers still need to contain a power supply of sufficient capacity to operate the electronics. For GPS transponders (which need to have sufficient power to transmit their location) the power supply needs to be larger.

Buildings shield the frequency of signals used by GPS systems. It has been proposed to use a low frequency navigation system called a Building Positioning System (BPS) to provide navigation within a building (to within 5cm accuracy for a coverage area of 50m).

There are many applications that require positioning to a higher accuracy within a room. A demanding application requiring high positional accuracy is machine assisted surgery. As an example, US-B-6332891 discloses a system and method for performing image guided surgery in which a sensor on a surgical tool receives signals from a transmitter secured in known relationship to the patient such that a computer generated image of the tool can be overlaid on a computer generated image of the patient enabling location of the tool tip to be seen.

US-B-6332891 discloses the use of a single sensor and does not clearly disclose how positioning infonnation other than along one axis is achieved.

2s US-A-6024695 discloses a system in which several transmitters are securely located on the patient to provide datum points, these transmitters being LEDs, and images of the patient from several different cameras are processed to provide the positioning information for surgical apparatus. This requires pins to be attached to the patient and requires a wiring loom to transmit identifying signal patterns to each pin so that it can be identified in image processing. Such a system requires clear line of sight access between the pins and the cameras.

Such surgical techniques of course require the utmost precision of location. A deviation of millimetres can be critical.

There are other applications where the ability to precisely locate objects or parts of objects will be of great importance and these include robot controlled machinery. A positioning system that permitted location to within l cm, preferably to within +0.25cm, more preferably TO. I cm would be of great value in such applications.

Accordingly the present invention provides a system for accurately positioning articles in a room, comprising: o a) a plurality of transmitters capable of emitting signals and arranged about the room b) one or more transponders capable of receiving said signals and responding thereto, and capable of being secured to or within an article c) processing apparatus capable of interpreting responses to said signals and presenting three-dimensional positional information for the or each transponder.

In the alternative, but less desirably, the transmitters may be secured to or within the articles and the transponders may be arranged about the room.

Further details of the invention are set out in the claims in the light of the following illustrative

description.

The transmitters may be (]PS type transmitters (operating in the same or similar range of frequencies) so that the structure of the building shields the system from interference.

Part of the processing apparatus may be in the transponders so that the transponder response comprises the positional information.

If the responses of the transponders are capable of providing information on orientation of the transponder then the response from a single transponder may be processed to provide three- 2s dimensional orientation information.

If the responses of the transponders are not capable of providing information on orientation of the transponder, then the response from two or more transponders on an article may be processed to provide threedimensional orientation information.

The transponders may hold identifying information so that the processing apparatus may discriminate between transponders.

L l

One or more transponders may be fitted to one part of an article and the location of the remainder of the article calculated from the positional information of the or each transponder.

If the article has two or more relatively moving parts then each part may have one or more transponders so that the position of the different parts may be calculated.

s The positional and/or orientation information produced by the system may presented as a computer generated image. The computer-generated image may also be presented with an image of the area surrounding the article. For example, a surgeon can have scanned images of a patient overlain with an image of a medical tool such as a surgical tool generated from positional information obtained from the positioning system.

0 If full area cover of a room is not required, and for improved accuracy, the transmitters may be mounted close to the article whose position is required. For example, the transmitters may be mounted on a frame surrounding the article.

Because the distance the signal has to travel is small' then the ponder needs of the transponder are correspondingly smalh so allowing for a much smaller transponder than is used for general GPS. A transponder can readily be provided that is less than 2crn on each side. By appropriate selection of aerial materials is will be possible to produce a transponder that could be swallowed, which may be of help in diagnostic methods.

Provision of such sensors on other sensors (e.g. on cameras) permits close integration of images with sensed positional inforrrat.on. This can be of assistance in generating new presentations of information. It can also assist in the motion picture industry to enable closer control of cameras.

The above description has referred to use of GPS type technology. Similar results may be achievable using infrared, ultrasonic' or other signals. /

Claims

1. A system for accurately positioning articles in a room, comprising: a) a plurality of transmitters capable of emitting signals and arranged about the room b) one or more transponders capable of receiving said signals and responding thereto, and capable of being secured to or within an article c) processing apparatus capable of interpreting responses to said signals and presenting three-dimensional positional information for the or each transponder.

2. A system as claimed in Claim 1, in which the transmitters are mounted in the room and 0 operate at a frequency shielded by the structure of the room.

3. A system as claimed in Claim 1, or Claim 2, in which the transmitters are GPS type transmitters.

4. A system as claimed in any one of Claims 1 to 3, in which part of the processing apparatus is in the transponders so that the transponder response comprises the positional information

5. A system as claimed in any one of Claims 1 to 4, in which the responses of the or each transponder is capable of providing information on orientation of the transponder and the response from a single transponder is processed to provide three-dimensional orientation information

6. A system as claimed in any one of Claims 1 to 4, in which the responses of the or each transponder is not capable of providing information on orientation of the transponder, and the response from two or more transponders on an article is processed to provide three- dimensional orientation information.

7. A system as claimed in any one of Claims 1 to 6, in which there is more than one as transponder each holding identifying information so that the processing apparatus may discriminate between transponders

8. A system as claimed in any one of Claims I to 7, in which one or more transponders are fitted to one part of an article and the location of the remainder of the article is calculated from the positional information of the or each transponder.

9. A system as claimed in Claim 8, in which said one part is a handle for the article.

10. A system as claimed in any one of Claims I to 9, in which the article has two or more relatively moving parts and each part has one or more transponders.

I 1. A system as claimed in any one of Claims 1 to 10, in which the positional information produced by the system is presented as a computer generated image

12. A system as claimed in any one of Claims I to 1 1, in which the orientation information produced by the system is presented as a computer generated image

13. A system as claimed in Claim 11, or Claim 12, in which the computer generated image is presented with an image of the area surrounding the article lo

14. A system as claimed in any one of Claims I to 13, in which the transmitters are mounted close to the article whose position is required

15. A system as claimed in Claim 14, in which the transmitters are mounted on a frame surrounding the article.

16. A system as claimed in any one of Claims I to 15, in which the transmitters and transponders are transposed, the transmitters being secured to or within the articles and the transponders being arranged about the room.

17. A system as claimed in any one of Claims 1 to 16, in which the articles are patients and medical tools.

18. A tool having one or more transponders as mentioned in any preceding claim.

19. A tool as claimed in Claim 18, in which the tool is a medical tool.

20. A tool as claimed in Claim 19, in which the tool is a surgical tool.

21. A transponder designed for use in the system of any of claims 1 to 17.

22. A frame mounted set of transmitters for use in the system of any of claims I to 17.

23. A room incorporating mounted transmitters for the system of any of claims I to 17. 2s