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Characteristics of Orbit Determination with Short-Arc Observation by an Optical Tracking Network, OWL-Net
摘要： An optical tracking network, the Optical Wide-field patroL Network (OWL-Net), has been developed to maintain the orbital ephemeris of 11 domestic low Earth orbit satellites. The schedule overlapped events were occurred in the scheduling of the OWL-Net with reduction of the optical observation chances. A short-arc observation strategy for the OWL-Net was tested to reduce schedule overlapped events with the optical observation simulation and the orbit determination. In the full-scale optical observation simulation from January 2014 to December 2016, the most frequent overlapped events were occurred 127, 132, and 116 times in the 4th, 34th, and 18th weeks of 2014, 2015, and 2016, respectively. The average number of overlapped event for three years was over 10% for the whole observation chances of five stations. Consequently, the short-arc observation strategy reduced the schedule overlapped events for every observation target of the OWL-Net. In case of the 5 s and 10 s cases, the most schedule overlapped events were removed. The test results of the orbit determination results show that the most maximum orbit prediction errors after seven days are maintained at <10 km in the in-track direction for the short-arc observation simulations. The results demonstrate that the short-arc optical observation strategy is more optimal to maintaining the accuracy of orbital ephemeris with more observation chances.
关键词： short-arc observation,optical tracking network,OWL-Net,orbit determination,LEO satellites
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Krakow (2018.10.16-2018.10.18)] 2018 IEEE International Conference on Imaging Systems and Techniques (IST) - Assessment of a Markerless Optical Tracking Technique for Computer-Assisted Hip Surgery
摘要： This article presents an evaluation of a prototype optical tracking system intended for use in computer-assisted orthopedic surgery. The device is based on a smartphone with a built-in video camera, and an external miniature time-of-flight camera. It is able to automatically recognize a surgical instrument based on its shape and appearance, and to determine its orientation relative to an array of light-reflective markers. The experiments were done in a measurement configuration and with the instruments that are specific to computer-assisted implantation of the acetabular component in total hip replacement surgery. The evaluation included the recognition rate of the instruments, and the angular accuracy of the system. The results show, that the accuracy is comparable to that obtained by conventional tracking devices in clinical settings, and partially meets the requirements specified in the literature for hip surgery.
关键词： optical tracking,surgical navigation,accuracy,computer assisted surgery,time of flight camera
更新于2025-09-23 15:22:29
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[ACM Press the 12th International Conference - Eindhoven, Netherlands (2018.09.03-2018.09.04)] Proceedings of the 12th International Conference on Distributed Smart Cameras - ICDSC '18 - Hand-Eye Camera Calibration with an Optical Tracking System
摘要： This paper presents a method for hand-eye camera calibration via an optical tracking system (OTS) faciltating robotic applications. The camera pose cannot be directly tracked via the OTS. Because of this, a transformation matrix between a marker-plate pose, tracked via the OTS, and the camera pose needs to be estimated. To this end, we evaluate two different approaches for hand-eye calibration. In the first approach, the camera is in a fixed position and a 2D calibration plate is displaced. In the second approach, the camera is also fixed, but now a 3D calibration object is moved. The first step of our method consists of collecting N views of the marker-plate pose and the calibration plates, acquired via OTS. This is achieved by keeping the camera fixed and moving the calibration plate, while taking a picture of the calibration plate using the camera. A dataset is constructed that contains marker-plate poses and the relative camera poses. Afterwards, the transformation matrix is then computed, following a least-squares minimization. Accuracy in hand-eye calibration is computed in terms of re-projection error, calculated based on camera homography transformations. For both approaches, we measure the changes in accuracy as a function of the number of poses used for each calibration, while we define the minimum number of poses required to obtain a good camera calibration. Results of the experiments show similar performances for the two evaluated methods, achieving a median value of the re-projection error at N = 25 poses of 0.76 mm for the 2D calibration plate and 0.70 mm for the 3D calibration object. Also, we have found that minimally 15 poses are required to achieve a good camera calibration.
关键词： optical tracking system,neurosurgery,augmented reality,Hand-eye calibration,endoscope,tracking
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM) - Hong Kong, China (2019.7.8-2019.7.12)] 2019 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM) - Closed loop controlled optical tracking module for free-space optical communications
摘要： In this paper, a closed loop controlled optical tracking module for free-space optical communication is presented. The motion of the optical tracking module is achieved using a pan-tilt mechanical platform driven by two servomotors. The optical tracking module consists of optical elements including beam splitters and quadrant photodiodes to extract the angular parameters of the incident wave. Optical as well as dynamic modeling is performed to confirm the tracking functionality of the system. Furthermore, to validate the concept, experimentation has been carried out by placing a laser emission module in front of a fixed optical tracking module. The laser was moved in free-space with the help of a mechanical structure and the successful tracking of the optical tracking module has been observed.
关键词： pan-tilt mechanical platform,servomotors,quadrant photodiodes,beam splitters,optical tracking module,free-space optical communication
更新于2025-09-12 10:27:22
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CIGuide: in situ augmented reality laser guidance
摘要： Purpose A robotic intraoperative laser guidance system with hybrid optic-magnetic tracking for skull base surgery is presented. It provides in situ augmented reality guidance for microscopic interventions at the lateral skull base with minimal mental and workload overhead on surgeons working without a monitor and dedicated pointing tools. Methods Three components were developed: a registration tool (Rhinospider), a hybrid magneto-optic-tracked robotic feedback control scheme and a modi?ed robotic end-effector. Rhinospider optimizes registration of patient and preoperative CT data by excluding user errors in ?ducial localization with magnetic tracking. The hybrid controller uses an integrated microscope HD camera for robotic control with a guidance beam shining on a dual plate setup avoiding magnetic ?eld distortions. A robotic needle insertion platform (iSYS Medizintechnik GmbH, Austria) was modi?ed to position a laser beam with high precision in a surgical scene compatible to microscopic surgery. Results System accuracy was evaluated quantitatively at various target positions on a phantom. The accuracy found is 1.2 mm ± 0.5 mm. Errors are primarily due to magnetic tracking. This application accuracy seems suitable for most surgical procedures in the lateral skull base. The system was evaluated quantitatively during a mastoidectomy of an anatomic head specimen and was judged useful by the surgeon. Conclusion A hybrid robotic laser guidance system with direct visual feedback is proposed for navigated drilling and intraoperative structure localization. The system provides visual cues directly on/in the patient anatomy, reducing the standard limitations of AR visualizations like depth perception. The custom- built end-effector for the iSYS robot is transparent to using surgical microscopes and compatible with magnetic tracking. The cadaver experiment showed that guidance was accurate and that the end-effector is unobtrusive. This laser guidance has potential to aid the surgeon in ?nding the optimal mastoidectomy trajectory in more dif?cult interventions.
关键词： Optical tracking,Magnetic tracking,Augmented reality,Navigated surgery,Laser guidance,Robotic control,Microscope
更新于2025-09-11 14:15:04
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A new approach of orbit determination for LEO satellites based on optical tracking of GEO satellites
摘要： Ability of autonomous orbit determination (OD) for a satellite is receiving increasing interests due to its considerable value in engineering application. A new OD approach for low earth orbit (LEO) satellites based on tracking geosynchronous orbit (GEO) satellites using space-based optical tracking approach is proposed which can improve the autonomy of LEO satellites and reduce their dependence on ground facilities. Based on the information support of Space Surveillance Network (SSN), several GEO satellites are selected as guidance and calibration functions like beacons for LEO satellites equipped with space-based optical (SBO) sensors, as they are called beacon GEO satellites in this paper. LEO satellites can determine their own orbits by tracking these GEO objects without measures of ground facilities, which only need to provide necessary information of beacon objects for them. Unlike traditional space-based observation, long arcs and high-frequency measurements, which are more bene?cial to determine orbit precisely, are possibly obtained. This paper focuses on demonstrating the feasibility and performance of proposed approach. To determine orbits, batch least-squares (LS) estimator with Tschauner–Hempel (T–H) equation state-transition matrix to estimate the propagation of initial errors is used. Different scenarios are simulated and results show that tracklet length, measurement frequency, and measurement errors are the main factors that in?uence the accuracy of OD.
关键词： T–H equation state-transition matrix,Angles-only measurements,Space-based optical tracking,Autonomous OD
更新于2025-09-10 09:29:36