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, calibration, and experimental evaluation of a parallel string encoder mechanism for sensing this motion. Our results indicate that with kinematic calibration, the measurement system can achieve accuracy within 0.5mm, especially for small motions.

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，但现有扫描系统的体积和重量限制使其无法在行走等自然人体活动中使用。长期解决方案是构建一套可环绕受试者头部支撑成像系统，并能够随自然运动调整位置的机器人系统。这要求配备一套能测量头部相对于成像环运动的系统，以供机器人与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、校准与实验评估。结果表明，经过运动学校准后，该测量系统在小幅度运动场景下能达到0.5毫米以内的精度。