Positron Emission Tomography (PET) enables functional imaging of deep brain structures, but the bulk and weight of current systems preclude their use during many natural human activities, such as locomotion. The proposed long-term solution is to construct a robotic system that can support an imaging system surrounding the subject's head, and then move the system to accommodate natural motion. This requires a system to measure the motion of the head with respect to the imaging ring, for use by both the robotic system and the image reconstruction software. We report here the design and experimental evaluation of a parallel string encoder mechanism for sensing this motion. Our preliminary results indicate that the measurement system may achieve accuracy within 0.5 mm, especially for small motions, with improved accuracy possible through kinematic calibration.

翻译：正电子发射断层扫描（PET）能够实现深部脑结构的功能成像，但当前系统的体积和重量阻碍了其在许多自然人类活动（如行走）中的应用。提出的长期解决方案是构建一套机器人系统，该系统可支撑环绕受试者头部的成像装置，并通过移动系统来适应自然运动。这需要一套能够测量头部相对于成像环运动的系统，以供机器人系统和图像重建软件共同使用。本文报告了一种用于感知此类运动的平行弦编码器机构的设计与实验评估。初步结果表明，该测量系统可达到0.5毫米以内的精度，尤其适用于小幅度运动，且通过运动学标定可进一步提升精度。