Study On Lighthouse Based Wide Range Optical Tracking Technique

In the field of Virtual Reality,tracking as a basic technology for the construction of Virtual Reality System,which is also the key factor to determine the system's performance.Tracking not only affects the reality of users' experience,but also limits the application and development of Virtual Reality technology.At present,the tracking system which could acquire 6-DOF of the target still have many drawbacks,such as high delay,large accumulated error,computeintensive,low precision,high cost and requiring external components.In 2015,HTC and Valve launched a virtual reality headset empowered with Lighthouse,the cutting-edge space positioning technology.Although Lighthouse is superior in terms of accuracy,latency and refresh rate,while Lighthouse has two main problems: one is that its algorithms do not support base station expansion,the tracking area will be limited,and the other is the occlusion problem in moving targets,that is,it is unable to calculate their poses with a small set of sensors,resulting in the loss of optical tracking data.To address these problems,the main contents of this paper include:1)Aiming at the occlusion problem in the process of target moving in the tracking system,an improved pose estimation algorithm is proposed.When the number of the photoelectric sensors scanned by all base stations is less than 3,as long as the sum of the total number of sensors scanned by all base stations is greater than 3 and the recognized space points are not collinear.Our algorithms can be used to complete the tracker's pose estimation in such situation.The result of experiment shows that our algorithm has improved the robustness of the optical tracking system while ensure the high precision.2)Proposed a new base station expansion method that can effectively expand the tracking area without reducing the refresh rate.We added a controller and a stroboscope to the base station to realize the signal synchronization of multiple base stations.We also proposed a novel method of base stations arranging—“Preset Offset Method”.This method effectively solves the problem of multiple base stations identification.The acquisition and analysis of the laser scanning signal are discussed.The customized infrared receiving module has been developed independently.3)A purely optical tracking system and an optical-inertial hybrid tracking system have been developed and implemented.The latter successfully solved the problem of data loss in optical tracking.Optical rail,high-speed camera and other implements have been used to build the test system to assessing the performance of our system.Such as the accuracy,delay and jitter test.The existing problems in the system are analyzed and summarized.