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A Prototype Optical Tracking System Investigation and Development - page 23 / 170





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Chapter 2

Design Overview

This chapter provides an overview of the tracking system design. The major system com- ponents are described first followed by a discussion of design considerations. This discus- sion leads to the development of a specification for the system. The final section details the scope of the research.


System components

The design is for an inside-looking-out optical tracking system using camera modules. High intensity LEDs are used to provide feature points for tracking. In this research these are referred to as ‘markers’. collection of markers in a fixed configuration is known as a ‘beacon’. The intention is to place multiple beacons around the periphery of the ‘tracking


Like the IRL system [21] but unlike the HiBall tracker [16], cameras are used to determine the angles between the object being tracked and the markers around the tracking volume. Multiple camera modules with limited FOVs are combined to synthesise a larger angular FOV. This larger FOV allows the system to recover images from the camera modules cor- responding to a range of directions. These images are analysed by the system to detect the presence of markers. The camera modules are to be fixed to a rigid structure known as the ‘hub enclosure’. This is a mechanical housing that keeps the camera modules in fixed and known locations and orientations with respect to a point on the enclosure. Figure 2.1 shows a model of an enclosure design. The camera modules are embedded into the en- closure and their lens assemblies protrude outwards. In this model, the camera modules provide coverage of the entire hemisphere with 45 degree FOVs; this requires 17 camera modules. Using the 2D locations of the markers in each set of images retrieved from the camera modules, a pose estimation algorithm will calculate the pose of the hub enclosure


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