Search

CN-121971169-A - Tracer identification method and system for optical navigation camera

CN121971169ACN 121971169 ACN121971169 ACN 121971169ACN-121971169-A

Abstract

The invention relates to the technical field of optical navigation, in particular to a tracer identification method and system of an optical navigation camera. The method comprises the steps of controlling an optical navigation camera to send a trigger signal with specific frequency to selectively enable a target tracer, carrying out fast time sequence coarse recognition, collecting low-resolution images through pre-exposure operation, carrying out time-sharing exposure based on characteristic time of different tracer surfaces, rapidly obtaining coarse position information of the tracer and screening an optimal tracer surface, then carrying out slow time sequence accurate recognition, guiding formal exposure based on the coarse position information, carrying out high-resolution image collection and local pixel level recognition on a target area, and finally realizing accurate calculation of the pose of the tracer. The invention breaks through the limitation of the singularity of the traditional layout depending on the mark points, obviously improves the identification instantaneity to microsecond level, achieves the positioning precision of ten micrometers level, supports the miniaturized design of the tracer, and effectively overcomes the bottleneck of instantaneity, precision and reliability of multi-target tracking in operation navigation.

Inventors

  • DENG MINGMING

Assignees

  • 北京天智航医疗科技股份有限公司

Dates

Publication Date
20260505
Application Date
20260209

Claims (15)

  1. 1. A tracer recognition method of an optical navigation camera, comprising: S100, controlling an optical navigation camera to send out a trigger signal so as to selectively enable at least one tracer; S200, performing pre-exposure operation, and acquiring images of the at least one tracer to obtain coarse position information; And S300, performing formal exposure operation, and accurately identifying the at least one tracer based on the coarse position information.
  2. 2. The method of claim 1, wherein the issuing a trigger signal comprises issuing a carrier infrared signal at a particular frequency, and only tracers that match the carrier infrared signal frequency are enabled.
  3. 3. The method of claim 2, wherein the pre-exposure operation comprises time-division exposure based on characteristic times of different tracer surfaces to distinguish between similar tracers.
  4. 4. A method according to claim 3, wherein the time-sharing exposure includes exposing at a plurality of preset time points respectively, and setting the states of the tracing surfaces according to the exposure time correspondingly to screen the optimum tracing surfaces.
  5. 5. The method of claim 1, wherein the pre-exposure operation employs a high speed exposure and a low image resolution, and the formal exposure operation employs a long exposure and a high image resolution.
  6. 6. The method of claim 1, wherein only mark points within a target area are identified in a formal exposure operation based on the coarse position information to reduce processing complexity.
  7. 7. The method of claim 3, further comprising the step of screening an optimal tracking surface in the field of view based on the result of the time-shared exposure, the screening fitting a residual based on tracking angle and marker points.
  8. 8. The method of claim 7, wherein the screening step includes recording coarse positions of marker points of the optimal tracking surface and obtaining imaging positions of the marker points on a camera CCD based on projective transformation.
  9. 9. The method of claim 1, wherein the pre-exposure operation and the formal exposure operation are coordinated by a control module in an optical navigation camera, the control module further configured to output tracer location information to a companion device.
  10. 10. The method of claim 5, wherein the high-speed exposure has an exposure time on the order of microseconds or nanoseconds.
  11. 11. The method of claim 6, wherein the target area is determined based on coarse position information acquired by pre-exposure and only the target area is pixel-level identified in a formal exposure.
  12. 12. The method of claim 4, wherein the predetermined time points correspond to delayed illumination characteristic times of different trace planes to achieve coarse recognition in a fast timing phase.
  13. 13. The method of claim 1, further comprising updating pose information of the tracer after the precise recognition and encoding the output.
  14. 14. The method of claim 9, wherein the control module is further configured to designate a trigger mode to control the frequency at which the trigger signal is sent.
  15. 15. A tracer recognition system for an optical navigation camera, comprising: The optical navigation camera comprises a triggering module, an exposure module and a control module; at least one tracer module comprising a receiving module and a lighting module; Wherein the control module is configured to control the trigger module to issue a trigger signal to selectively enable the at least one tracer module; the exposure module is configured to perform pre-exposure to obtain coarse position information and perform formal exposure to perform precise identification based on the coarse position information; the receiving module of the tracer module is configured to enable the light emitting module to emit light in response to the trigger signal.

Description

Tracer identification method and system for optical navigation camera Technical Field The invention relates to the technical field of optical navigation, in particular to a tracer identification method and system of an optical navigation camera. Background The surgical navigation system plays an increasingly important role in modern orthopedic surgery, and by accurately correlating medical image data of a patient with a real-time physiological structure, a surgeon is assisted to conduct accurate surgical planning and instrument operation, so that the accuracy, efficiency and safety of the surgery are remarkably improved. Among the many navigation systems, optical navigation cameras have become the mainstay of choice due to their high precision and non-contact nature, relying on tracers attached to the patient's surgical field or instruments to achieve positional tracking. The tracer is typically equipped with a plurality of optical marker points whose spatial positions are captured by a camera to infer the pose of the tool or anatomy. However, with the increasing complexity of the orthopedic operation, the clinical requirement on the navigation system is that on one hand, the number of tracers to be used simultaneously in the operation is increased to meet the tracking requirement of multi-instrument cooperation or complex anatomical structure, on the other hand, in order to reduce the interference to the operation, the tracers need to be designed in a miniaturized manner, but miniaturization often leads to the increase of the similarity of the mark point layout and the difficulty in distinguishing, and in addition, the popularization of the mechanical arm auxiliary technology makes the real-time requirement of the system on the identification of the tracers extremely high, for example, the frame rate needs to reach hundreds of hertz to ensure the continuity of dynamic tracking. The current optical navigation system has the core bottleneck that the tracer identification link is that the traditional method relies on the singularity of the tracer marking point layout (namely, each tracking surface has a unique layout) to avoid confusion, but the tracer size is increased, the operation convenience is affected, meanwhile, the image quality is improved by a high-resolution CCD camera, the image processing time (such as 2D marking point identification, 3D coordinate reconstruction and tool identification) is exponentially increased along with the number of marking points, so that the real-time performance is reduced, for example, when the exposure time is only about 100 microseconds, the post-processing time is as long as a few milliseconds, and the system performance is short. In the prior art, the efficiency is improved mainly by optimizing an image processing algorithm, but under the challenges of coexistence of high real-time performance, high resolution and multiple tracer scenes, the contradiction among identification effectiveness, real-time performance and precision is increasingly prominent, and an innovative scheme is needed to break through the limitations. Thus, the prior art is still to be further developed. Disclosure of Invention The invention aims to overcome the technical defects and provide a tracer identification method and a tracer identification system for an optical navigation camera, so as to solve the problems in the prior art. To achieve the above object, according to a first aspect of the present invention, there is provided a tracer recognition method for an optical navigation camera, including: S100, controlling an optical navigation camera to send out a trigger signal so as to selectively enable at least one tracer; S200, performing pre-exposure operation, and acquiring images of the at least one tracer to obtain coarse position information; And S300, performing formal exposure operation, and accurately identifying the at least one tracer based on the coarse position information. Specifically, the sending out the trigger signal includes sending out a carrier infrared signal with a specific frequency, and only a tracer matched with the carrier infrared signal in frequency is enabled. Specifically, the pre-exposure operation includes time-sharing exposure, which is performed based on the characteristic times of different tracer surfaces, to distinguish similar tracers. Specifically, the time-sharing exposure includes exposing at a plurality of preset time points respectively, and correspondingly setting the states of the tracing surfaces according to the exposure time to screen the optimal tracing surfaces. Specifically, the pre-exposure operation employs high-speed exposure and low image resolution, while the formal exposure operation employs long exposure and high image resolution. Specifically, based on the coarse position information, only the mark points within the target area are identified in the formal exposure operation to reduce the processing complexity. The method comprises