Transfer force perception skills to robot‐assisted laminectomy via imitation learning from human demonstrations

A comparative study of two force perception skill learning approaches for robot‐assisted spinal surgery,the impedance model method and the imitation learning(IL)method,is presented.The impedance model method develops separate models for the surgeon and patient,incorporating spring‐damper and bone‐grinding models.Expert surgeons'feature parameters are collected and mapped using support vector regression and image navi-gation techniques.The imitation learning approach utilises long short‐term memory networks(LSTM)and addresses accurate data labelling challenges with custom models.Experimental results demonstrate skill recognition rates of 63.61%-74.62%for the impedance model approach,relying on manual feature extraction.Conversely,the imitation learning approach achieves a force perception recognition rate of 91.06%,outperforming the impedance model on curved bone surfaces.The findings demonstrate the potential of imitation learning to enhance skill acquisition in robot‐assisted spinal surgery by eliminating the laborious process of manual feature extraction.

Dynamic targets searching assistance based on virtual camera priority

Background When a user walks freely in an unknown virtual scene and searches for multiple dynamic targets,the lack of a comprehensive understanding of the environment may have a negative impact on the execution of virtual reality tasks.Previous studies can help users with auxiliary tools,such as top view maps or trails,and exploration guidance,for example,automatically generated paths according to the user location and important static spots in virtual scenes.However,in some virtual reality applications,when the scene has complex occlusions,and the user cannot obtain any real-time position information of the dynamic target,the above assistance cannot help the user complete the task more effectively.Methods We design a virtual camera priority-based assistance to help the user search dynamic targets efficiently.Instead of forcing users to go to destinations,we provide an optimized instant path to guide them to places where they are more likely to find dynamic targets when they ask for help.We assume that a certain number of virtual cameras are fixed in virtual scenes to obtain extra depth maps,which capture the depth information of the scene and the locations of the dynamic targets.Our method automatically analyzes the priority of these virtual cameras,chooses the destination,and generates an instant path to assist the user in finding the dynamic targets.Our method is suitable for various virtual reality applications that do not require manual supervision or input.Results A user study is designed to evaluate the proposed method.The results indicate that compared with three conventional navigation methods,such as the top-view method,our method can help users find dynamic targets more efficiently.The advantages include reducing the task completion time,reducing the number of resets,increasing the average distance between resets,and reducing user task load.Conclusions We presented a method for improving dynamic target searching efficiency in virtual scenes by virtual camera priority-based path guidance.Compared with three conventional navigation methods,such as the top-view method,this method can help users find dynamic targets more effectively.

基于矩阵半张量积方法的带有敌对输入的异步时序机控制

本文基于矩阵半张量积方法研究了带有敌对输入的异步时序机的控制问题.首先,利用矩阵半张量积,给出了带有敌对输入的异步时序机动态行为的代数表示.接着,通过分析具体的控制过程设计了具有最小状态集的控制器并给出了控制器状态转移结构矩阵和输出结构矩阵的赋值算法.其次,基于带有敌对输入的异步时序机的代数表示和控制器的赋值算法给出了整个闭环系统的动态行为的代数表示,从而验证本文理论结果的正确性.最后,利用具体实例说明了本文所提方法的的可行性和有效性.

Guidelines for navigation-assisted spine surgery

Spinal surgery is a technically demanding and challenging procedure because of the complicated anatomical structures of the spine and its proximity to several important tissues.Surgical landmarks and fluoroscopy have been used for pedicle screw insertion but are found to produce inaccuracies in placement.Improving the safety and accuracy of spinal surgery has increasingly become a clinical concern.Computerassisted navigation is an extension and application of precision medicine in orthopaedic surgery and has significantly improved the accuracy of spinal surgery.However,no clinical guidelines have been published for this relatively new and fast-growing technique,thus potentially limiting its adoption.In accordance with the consensus of consultant specialists,literature reviews,and our local experience,these guidelines include the basic concepts of the navigation system,workflow of navigation-assisted spinal surgery,some common pitfalls,and recommended solutions.This work helps to standardize navigation-assisted spinal surgery,improve its clinical efficiency and precision,and shorten the clinical learning curve.

3D corrective nose reconstruction from a single image

There is a steadily growing range of applications that can benefit from facial reconstruction techniques,leading to an increasing demand for reconstruction of high-quality 3D face models.While it is an important expressive part of the human face,the nose has received less attention than other expressive regions in the face reconstruction literature.When applying existing reconstruction methods to facial images,the reconstructed nose models are often inconsistent with the desired shape and expression.In this paper,we propose a coarse-to-fine 3D nose reconstruction and correction pipeline to build a nose model from a single image,where 3D and 2D nose curve correspondences are adaptively updated and refined.We first correct the reconstruction result coarsely using constraints of 3D-2D sparse landmark correspondences,and then heuristically update a dense 3D-2D curve correspondence based on the coarsely corrected result.A final refinement step is performed to correct the shape based on the updated 3D-2D dense curve constraints.Experimental results show the advantages of our method for 3D nose reconstruction over existing methods.

Decompression and fusion combined with rehabilitation training for the foot drop secondary to lumbar degenerative disease:Case report and literature review

Foot drop(FD)secondary to lumbar degenerative disease is a relatively uncommon finding in spinal practice.Although only a part of patients with FD can obtain satisfactory recovery of their muscle strength after operation,most of the articles still advocate surgical intervention at early stage.Despite the double roots compression is one of the accepted causes for FD,we describe an extremely rare case of a middle-age man presenting with a severe foot drop(tibialis anterior=0/5)resulted from three roots compression(L4-S1),who had undergone pedicle screws fixation(L3-S1),transforaminal lumbar interbody fusion(TLIF)at L4/5,laminotomy and discectomy at L5/S1 with laminotomy at L3/4 as well as conventional rehabilitation training postoperatively,which included strength training of the active and antagonistic muscles in the week lower extremity.Twelve months after surgery,the patient recovered from his deficit(tibialis anterior improved from 0/5 to 4/5).Therefore,we discuss the possible pathological mechanism and surgical option for the foot drop due to the lumbar degenerative disease as well as the potential risk factors portending prognosis postoperatively.