As humans and robots work closer together than ever,anthropomorphic robotic arms with intuitive human-robot interaction interfaces have drawn massive attention to improving the quality of robot-assisted manipulation.I...As humans and robots work closer together than ever,anthropomorphic robotic arms with intuitive human-robot interaction interfaces have drawn massive attention to improving the quality of robot-assisted manipulation.In pursuit of this,we designed a dedicated 7-degrees-of-freedom(DoF)anthropomorphic robotic arm having three compact differential joints and a head-mounted gaze tracker enabling head-pose-tracked 3D gaze estimation.Moreover,two key challenges were addressed to achieve accurate robot-assisted manipulation of the object indicated by the direction of human gaze.First,a novel predictive pupil feature was proposed for 3D gaze estimation.Differing from most existing features subjected to the common paraxial approximation assumption,the proposed novel predictive pupil feature considered the light refraction at two corneal surfaces with a more realistic eye model,significantly improving the 3D gaze estimation accuracy when the eyeball rotates at large angles.Second,a novel optimization-based approach was developed to efficiently compensate for the posture errors of the designed 7-DoF anthropomorphic robotic arm for accurate manipulation.Compared with the existing Jacobian-based or optimization-based approaches with nominal joint values as iteration initial,the proposed approach computed the optimal iteration initial and realized faster convergence for real-time posture error compensation.With the posture error compensation in real time and 3D gaze estimated accurately,the human can command accurate robot-assisted manipulation using his eyes intuitively.The proposed system was successfully tested on five healthy subjects.展开更多
Optical imaging techniques provide low-cost,non-radiative images with high spatiotemporal resolution,making them advantageous for long-term dynamic observation of blood perfusion in stroke research and other brain stu...Optical imaging techniques provide low-cost,non-radiative images with high spatiotemporal resolution,making them advantageous for long-term dynamic observation of blood perfusion in stroke research and other brain studies compared to non-optical methods.However,high-resolution imaging in optical microscopy fundamentally requires a tight optical focus,and thus a limited depth of field(DOF).Consequently,large-scale,non-stitched,high-resolution images of curved surfaces,like brains,are difficult to acquire without z-axis scanning.To overcome this limitation,we developed a needle-shaped beam optical coherence tomography angiography(NB-OCTA)system,and for the first time,achieved a volumetric resolution of less than 8μm in a non-stitched volume space of 6.4 mm×4 mm×620μm in vivo.This system captures the distribution of blood vessels at 3.4-times larger depths than normal OCTA equipped with a Gaussian beam(GB-OCTA).We then employed NB-OCTA to perform long-term observation of cortical blood perfusion after stroke in vivo,and quantitatively analyzed the vessel area density(VAD)and the diameters of representative vessels in different regions over 10 days,revealing different spatiotemporal dynamics in the acute,sub-acute and chronic phase of post-ischemic revascularization.Benefiting from our NB-OCTA,we revealed that the recovery process is not only the result of spontaneous reperfusion,but also the formation of new vessels.This study provides visual and mechanistic insights into strokes and helps to deepen our understanding of the spontaneous response of brain after stroke.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52027806,52435005,92248304,52075191).
文摘As humans and robots work closer together than ever,anthropomorphic robotic arms with intuitive human-robot interaction interfaces have drawn massive attention to improving the quality of robot-assisted manipulation.In pursuit of this,we designed a dedicated 7-degrees-of-freedom(DoF)anthropomorphic robotic arm having three compact differential joints and a head-mounted gaze tracker enabling head-pose-tracked 3D gaze estimation.Moreover,two key challenges were addressed to achieve accurate robot-assisted manipulation of the object indicated by the direction of human gaze.First,a novel predictive pupil feature was proposed for 3D gaze estimation.Differing from most existing features subjected to the common paraxial approximation assumption,the proposed novel predictive pupil feature considered the light refraction at two corneal surfaces with a more realistic eye model,significantly improving the 3D gaze estimation accuracy when the eyeball rotates at large angles.Second,a novel optimization-based approach was developed to efficiently compensate for the posture errors of the designed 7-DoF anthropomorphic robotic arm for accurate manipulation.Compared with the existing Jacobian-based or optimization-based approaches with nominal joint values as iteration initial,the proposed approach computed the optimal iteration initial and realized faster convergence for real-time posture error compensation.With the posture error compensation in real time and 3D gaze estimated accurately,the human can command accurate robot-assisted manipulation using his eyes intuitively.The proposed system was successfully tested on five healthy subjects.
基金supported by the National Key R&D Program of China(No.2022YFB4702902)National Natural Science Foundation of China(Nos.61831014,62275023,and 32021002)+2 种基金Beijing Municipal Natural Science Foundation(No.4232077)Overseas Expertise Introduction Project for Discipline Innovation(No.B18005)STI2030-Major Projects(No.2022ZD0212000).
文摘Optical imaging techniques provide low-cost,non-radiative images with high spatiotemporal resolution,making them advantageous for long-term dynamic observation of blood perfusion in stroke research and other brain studies compared to non-optical methods.However,high-resolution imaging in optical microscopy fundamentally requires a tight optical focus,and thus a limited depth of field(DOF).Consequently,large-scale,non-stitched,high-resolution images of curved surfaces,like brains,are difficult to acquire without z-axis scanning.To overcome this limitation,we developed a needle-shaped beam optical coherence tomography angiography(NB-OCTA)system,and for the first time,achieved a volumetric resolution of less than 8μm in a non-stitched volume space of 6.4 mm×4 mm×620μm in vivo.This system captures the distribution of blood vessels at 3.4-times larger depths than normal OCTA equipped with a Gaussian beam(GB-OCTA).We then employed NB-OCTA to perform long-term observation of cortical blood perfusion after stroke in vivo,and quantitatively analyzed the vessel area density(VAD)and the diameters of representative vessels in different regions over 10 days,revealing different spatiotemporal dynamics in the acute,sub-acute and chronic phase of post-ischemic revascularization.Benefiting from our NB-OCTA,we revealed that the recovery process is not only the result of spontaneous reperfusion,but also the formation of new vessels.This study provides visual and mechanistic insights into strokes and helps to deepen our understanding of the spontaneous response of brain after stroke.
