Method for robotic motion compensation during PET imaging of mobile subjects

Studies of the human brain during natural activities, such as locomotion, would benefit from the ability to image deep brain structures during these activities. While Positron Emission Tomography (PET) can image these structures, the bulk and weight of current scanners are not compatible with the desire for a wearable device. This has motivated the design of a robotic system to support a PET imaging system around the subject's head and to move the system to accommodate natural motion. We report here the design and experimental evaluation of a prototype robotic system that senses motion of a subject's head, using parallel string encoders connected between the robot-supported imaging ring and a helmet worn by the subject. This measurement is used to robotically move the imaging ring (coarse motion correction) and to compensate for residual motion during image reconstruction (fine motion correction). Minimization of latency and measurement error are the key design goals, respectively, for coarse and fine motion correction. The system is evaluated using recorded human head motions during locomotion, with a mock imaging system consisting of lasers and cameras, and is shown to provide an overall system latency of about 80 ms, which is sufficient for coarse motion correction and collision avoidance, as well as a measurement accuracy of about 0.5 mm for fine motion correction.Comment: 2023 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS

Calibration and evaluation of a motion measurement system for PET imaging studies

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.Comment: arXiv admin note: text overlap with arXiv:2311.1786

GRACE: Online Gesture Recognition for Autonomous Camera-Motion Enhancement in Robot-Assisted Surgery

Camera navigation in minimally invasive surgery changed significantly since the introduction of robotic assistance. Robotic surgeons are subjected to a cognitive workload increase due to the asynchronous control over tools and camera, which also leads to interruptions in the workflow. Camera motion automation has been addressed as a possible solution, but still lacks situation awareness. We propose an online surgical Gesture Recognition for Autonomous Camera-motion Enhancement (GRACE) system to introduce situation awareness in autonomous camera navigation. A recurrent neural network is used in combination with a tool tracking system to offer gesture-specific camera motion during a robotic-assisted suturing task. GRACE was integrated with a research version of the da Vinci surgical system and a user study (involving 10 participants) was performed to evaluate the benefits introduced by situation awareness in camera motion, both with respect to a state of the art autonomous system (S) and current clinical approach (P). Results show GRACE improving completion time by a median reduction of 18.9s (8.1% ) with respect to S and 65.1s (21.1% ) with respect to P. Also, workload reduction was confirmed by statistical difference in the NASA Task Load Index with respect to S (p < 0.05). Reduction of motion sickness, a common issue related to continuous camera motion of autonomous systems, was assessed by a post-experiment survey ( p < 0.01 )

Learning Deep Nets for Gravitational Dynamics with Unknown Disturbance through Physical Knowledge Distillation: Initial Feasibility Study

Learning high-performance deep neural networks for dynamic modeling of high Degree-Of-Freedom (DOF) robots remains challenging due to the sampling complexity. Typical unknown system disturbance caused by unmodeled dynamics (such as internal compliance, cables) further exacerbates the problem. In this paper, a novel framework characterized by both high data efficiency and disturbance-adapting capability is proposed to address the problem of modeling gravitational dynamics using deep nets in feedforward gravity compensation control for high-DOF master manipulators with unknown disturbance. In particular, Feedforward Deep Neural Networks (FDNNs) are learned from both prior knowledge of an existing analytical model and observation of the robot system by Knowledge Distillation (KD). Through extensive experiments in high-DOF master manipulators with significant disturbance, we show that our method surpasses a standard Learning-from-Scratch (LfS) approach in terms of data efficiency and disturbance adaptation. Our initial feasibility study has demonstrated the potential of outperforming the analytical teacher model as the training data increases

Fully Immersive Virtual Reality for Skull-base Surgery: Surgical Training and Beyond

Purpose: A virtual reality (VR) system, where surgeons can practice procedures on virtual anatomies, is a scalable and cost-effective alternative to cadaveric training. The fully digitized virtual surgeries can also be used to assess the surgeon's skills using measurements that are otherwise hard to collect in reality. Thus, we present the Fully Immersive Virtual Reality System (FIVRS) for skull-base surgery, which combines surgical simulation software with a high-fidelity hardware setup. Methods: FIVRS allows surgeons to follow normal clinical workflows inside the VR environment. FIVRS uses advanced rendering designs and drilling algorithms for realistic bone ablation. A head-mounted display with ergonomics similar to that of surgical microscopes is used to improve immersiveness. Extensive multi-modal data is recorded for post-analysis, including eye gaze, motion, force, and video of the surgery. A user-friendly interface is also designed to ease the learning curve of using FIVRS. Results: We present results from a user study involving surgeons with various levels of expertise. The preliminary data recorded by FIVRS differentiates between participants with different levels of expertise, promising future research on automatic skill assessment. Furthermore, informal feedback from the study participants about the system's intuitiveness and immersiveness was positive. Conclusion: We present FIVRS, a fully immersive VR system for skull-base surgery. FIVRS features a realistic software simulation coupled with modern hardware for improved realism. The system is completely open-source and provides feature-rich data in an industry-standard format.Comment: IPCAI/IJCARS 202