Reference Position Research Articles

Deep-Learning Image Stabilization for Adaptive Optics Ophthalmoscopy

An adaptive optics scanning laser ophthalmoscope (AOSLO) has the characteristics of a high resolution and a small field of view (FOV), which are greatly affected by eye motion. Continual eye motion will cause distortions both within the frame (intra-frame) and between frames (inter-frame). Overcoming eye motion and achieving image stabilization is the first step and is of great importance in image analysis. Although cross-correlation-based methods enable image registration to be achieved, the manual identification and distinguishing of images with saccades is required; manual registration has a high accuracy, but it is time-consuming and complicated. Some imaging systems are able to compensate for eye motion during the imaging process, but special hardware devices need to be integrated into the system. In this paper, we proposed a deep-learning-based algorithm for automatic image stabilization. The algorithm used the VGG-16 network to extract convolution features and a correlation filter to detect the position of reference in the next frame, and finally, it compensated for displacement to achieve registration. According to the results, the mean difference in the vertical and horizontal displacement between the algorithm and manual registration was 0.07 pixels and 0.16 pixels, respectively, with a 95% confidence interval of (−3.26 px, 3.40 px) and (−4.99 px, 5.30 px). The Pearson correlation coefficients for the vertical and horizontal displacements between these two methods were 0.99 and 0.99, respectively. Compared with cross-correlation-based methods, the algorithm had a higher accuracy, automatically removed images with blinks, and corrected images with saccades. Compared with manual registration, the algorithm enabled manual registration accuracy to be achieved without manual intervention.

Clinical Experience and Feasibility of Using 2D-kV Image Online Intervention in the Ultrafractionated Stereotactic Radiation Treatment of Prostate Cancer

<h3>Purpose/Objective(s)</h3> This study reports the clinical experience and feasibility of using 2D-kV image system with online intervention in the ultra-fractionated stereotactic radiation treatment of prostate cancer. <h3>Materials/Methods</h3> 15 low/intermediate risk prostate patients, all with three transperineally implanted fiducial markers, received 40 Gy in 5 fractions to a PTV with margins of 3 mm posteriorly and 5 mm in other directions with online 2D-kV image tracking and manual beam interruption strategy with a 2 mm-threshold. A total of 180 kV paired setup images and 1272 intraoperative radiotherapy (IORT) 2D-kV images were analyzed to evaluate the setup deviation and intra-treatment target deviation. Elapsed time at different timestamps of different treatment, target deviation from planning position at different timestamps, and prostate motion during treatment, were calculated against beam interruption to evaluate their correlation. A subset of data from 22 fractions were re-evaluated to check the differences between using planning position and using pre-treatment setup position as reference. Margins based on the derived system and random errors were calculated to evaluate the feasibility of the workflow in ensuring prostate coverage during treatment. <h3>Results</h3> 50 out of 75 fractions were found to require interruption. Interruption had a strong correlation with prostate motion along longitudinal direction and had moderate correlations with prostate motion along vertical direction and prostate's prior-treatment setup along vertical direction. Using pre-treatment position as reference for IORT monitoring, the magnitude of motion deviation from reference position was reduced by 0.3 mm at vertical direction and 0.4 mm at lateral and longitudinal directions. The 3D margin calculated was 3.7 mm, 4.6 mm, 5.0 mm at lateral, vertical, longitudinal directions, respectively. <h3>Conclusion</h3> It is feasible to use a 2D-kV online IORT monitoring system with a proper intervention scheme to perform ultra-fractionated stereotactic radiation treatment for prostate cancer. High quality and safe delivery can be achieved by minimizing the elapsed time between setup image and the start of treatment beam-on, increasing the imaging frequency, and shortening the treatment time.

Real-time vehicle identification and tracking during agricultural master-slave follow-up operation using improved YOLO v4 and binocular positioning

The identification and positioning of a master is essential for the master-slave cooperative operation of agricultural machinery. This study aimed to develop an agricultural vehicle dynamic identification and tracking method for agricultural master-slave follow-up operation using improved YOLO v4 and binocular positioning. The regular pruning algorithm was used to trim the original YOLO v4 channel to achieve a fast and accurate identification of master vehicle. The principle of binocular vision positioning was used to calculate the position of the master. The method (IYO-BPO) proposed in this study fused target detection and binocular vision positioning together, which was used to identify and track the master vehicle in real time. To evaluate the performance of the developed method, RTK-GPS and a gyroscope were installed on the master vehicle to obtain the reference position and heading angle. Identification and tracking experiments of both the linear and S-shaped movement of the master were conducted. The RMS errors were 0.067 m, 0.203 m, and 2.602° in terms of the longitudinal, lateral, and heading angle deviation, respectively, when the master moved along a straight line. The results show that the master vehicle could be identified and tracked by the IYO-BPO correctly and effectively.

Global Incremental Flight Control for Agile Maneuvering of a Tailsitter Flying Wing

This paper proposes a novel control law for accurate tracking of agile trajectories using a tailsitter flying wing unmanned aerial vehicle that transitions between vertical takeoff and landing and forward flight. The global control formulation enables maneuvering throughout the flight envelope, including uncoordinated flight with sideslip. Differential flatness of the nonlinear tailsitter dynamics with a simplified aerodynamics model is shown. Using the flatness transform, the proposed controller incorporates tracking of the position reference along with its derivatives velocity, acceleration, and jerk, as well as the yaw reference and yaw rate. The inclusion of jerk and yaw rate references through an angular velocity feedforward term improves tracking of trajectories with fast-changing accelerations. The controller does not depend on extensive aerodynamic modeling but instead uses incremental nonlinear dynamic inversion to compute control updates based on only a local input–output relation, resulting in robustness against discrepancies in the simplified aerodynamics equations. Exact inversion of the nonlinear input–output relation is achieved through the derived flatness transform. The resulting control algorithm is extensively evaluated in flight tests, where it demonstrates accurate trajectory tracking and challenging agile maneuvers, such as sideways flight and aggressive transitions while turning.

Trajectory Tracking and Collision Avoidance on Smart Wheel Chair

There have been many developments of wheelchairs as mobility aids, including electric wheelchairs. Wheelchairs sometimes still require manual steering. Therefore, in this research, a smart wheelchair is developed that can move automatically to the destination position from a predetermined position with a trajectory tracking system. The system deploys the odometry method, orientation angle using the output of the IMU-9DOF sensor with Kalman filter, and collision avoidance to avoid collisions with obstacles in front of it. The use of the Kalman filter improves the angle output that is close to the reference. In the trajectory tracking test, the wheelchair can approach the given reference position with a maximum error of 20 cm for the x-axis and 2 cm for the y-axis. The wheelchair collision avoidance test has been able to avoid collisions, as it successfully detects an obstacle less than 40 cm and avoids the collision correspondingly.

Backstepping control of gliding robotic fish for pitch and 3D trajectory tracking

Underwater gliders are known for their energy-efficiency and long-duration operations, with demonstrated applications in ocean exploration, fish tracking, and environmental sampling. Many applications such as exploring a large area of underwater ruins would benefit from accurate trajectory tracking. Trajectory tracking is particularly challenging for underwater gliders due to their under-actuated, highly nonlinear dynamics. Taking gliding robotic fish as an example, a backstepping-based controller is proposed to track the desired pitch angle and reference position in the 3D space. In particular, under-actuation is addressed by exploiting the coupled dynamics and introducing a modified error term that combines pitch and horizontal position tracking errors. Two-time-scale analysis of singularly perturbed systems is used to establish the convergence of all tracking errors to a neighborhood around zero. The effectiveness of the proposed control scheme is demonstrated via simulation and experimental results, and its advantages are shown via comparison with a PID controller and a baseline backstepping controller that does not use the modified error. This paper is accompanied by a video available at: https://youtu.be/D8Vej3weeGc.

Mapping Information in the Wild: An Archivist’s Approach to Liaison Librarianship

ABSTRACT How do archivists who find themselves in dual librarian/archivist positions approach library instruction and reference services? This case study examines the instructional experiences of an archivist serving in an interim role as a liaison librarian to a public affairs college at a large, public university in the United States. Utilizing action research methodology to study and inform their instruction approach and philosophy, the archivist created an instructional model which incorporates archival principles and concepts into a landscape mapping exercise. Archivists can make material contributions to library instruction through their unique knowledge, skills, and perspectives.

Robust and Decoupled Position and Stiffness Control for Electrically-Driven Articulated Soft Robots

The control of articulated soft robots, i.e. robots with flexible joints and rigid links, presents a challenge due to their intrinsic elastic elements and nonlinear force-deflection dependency. This letter first proposes a discrete-time delayed unknown input-state observer based on a nominal robot model that reconstructs the total torque disturbance vector, resulting from the imperfect knowledge of the elastic torque characteristic, external torques, and other model uncertainties. Then, it introduces a robust controller, that actively compensates for the estimated uncertainty and allows bounded stability for the tracking of independent link position and joint stiffness reference signals. The convergence of the disturbance estimator and the overall system’s stability in closed loop is proven analytically, while the effectiveness of the proposed control design is first evaluated in simulations with respect to large uncertainty conditions, and then demonstrated through experiments on a real multi-degree-of-freedom articulated soft robot.

A Shared Autonomy Reconfigurable Control Framework for Telemanipulation of Multi-Arm Systems

Teleoperation is a widely adopted strategy to control robotic manipulators executing complex tasks that require highly dexterous movements and critical high-level intelligence. Classical teleoperation schemes are based on either joystick control, or on more intuitive interfaces which map directly the user arm motions into one robot arm's motions. These approaches have limits when the execution of a given task requires reconfigurable multiple robotic arm systems. Indeed, the simultaneous teleoperation of two or more robot arms could extend the workspace of the manipulation cell, or increase its total payload, or afford other advantages. In different phases of a reconfigurable multi-arm system, each robot could act as an independent arm, or as one of a pair of cooperating arms, or as one of the fingers of a virtual, large robot hand. This manuscript proposes a novel telemanipulation framework that enables both the individual and combined control of any number of robotic arms. Thanks to the designed control architecture, the human operator can intuitively choose the proposed control modalities and the manipulators that make the task convenient to execute through the user interface. Moreover, through the tele-impedance paradigm, the system can address complex tasks that require physical interaction by letting the robot mimic the arm impedance and position references of the human operator. The proposed framework is validated with 8 subjects controlling 4 Franka Emika Panda robots with 7-DoFs to execute a telemanipulation task. Qualitative results of the experiments show us the promising applicability of our framework.

Practical Position Tracking for 3D Unicycle Model

This paper considers practical position tracking for the 3D unicycle model. In contrast to the existing hand position coordinate transformation, a novel modified hand position coordinate transformation is proposed for the 3D unicycle model which can guarantee that the induced velocity transformation matrix is nonsingular for all the possible orientations. By employing the proposed modified hand position coordinate transformation, the nonlinear 3D unicycle position kinematics can be converted into the single integrator form, which enables arbitrary position reference trajectory tracking given any prespecified upper bound for the steady-state tracking error. The control performance is examined by numerical examples.

Constrained remote control of construction machine with time-varying delay and packet loss

This study developed a constrained remote control system for a crawler dump (C50-R, YANMAR Co.), which was experimentally validated in the testing field of Kajima Corporation. The remote-controlled crawler dump fulfilled the input constraints and tracked to a reference position and rotation angle in the presence of time-varying transmission delays and consecutive packet losses. The developed autonomous and remote control technology is expected to contribute to the compensation for the labor shortage in the construction industry and improve the workplace environment.

"It Works for Me": Pseudotherapy Use is Associated With Trust in Their Efficacy Rather Than Belief in Their Scientific Validity.

Objectives: To identify how perceptions, attitudes, and beliefs towards pseudotherapies, health, medicine, and the public health system influence the pseudotherapy use in Spain. Methods: We carried out a cross-sectional study using the Survey of Social Perception of Science and Technology-2018 (5,200 interviews). Dependent variable: ever use of pseudotherapies. Covariables: attitude towards medicine, health and public health system; perceived health; assessment of the scientific character of homeopathy/acupuncture. The association was estimated using prevalence ratios obtained by Poisson regression models. The model was adjusted for age and socioeconomic variables. Results: Pseudotherapy use was higher in women (24.9%) than in men (14.2%) (p < 0.001). The probability of use in men (p < 0.001) and women (p < 0.001) increases with the belief in pseudotherapies’ usefulness. Among men, a proactive attitude (reference: passive) towards medicine and health (RP:1.3), and a negative (reference: positive) assessment of the quality of the public health system increased use-probability (RP:1.2). For women, poor health perceived (referencie: good) increased likelihood of use (RP:1.2). Conclusion: Pseudotherapy use in Spain was associated with confidence in its usefulness irrespective of users’ assessment of its scientific validity.

Motion correction and its impact on quantification in dynamic total-body 18F-fluorodeoxyglucose PET

BackgroundThe total-body positron emission tomography (PET) scanner provides an unprecedented opportunity to scan the whole body simultaneously, thanks to its long axial field of view and ultrahigh temporal resolution. To fully utilize this potential in clinical settings, a dynamic scan would be necessary to obtain the desired kinetic information from scan data. However, in a long dynamic acquisition, patient movement can degrade image quality and quantification accuracy.MethodsIn this work, we demonstrated a motion correction framework and its importance in dynamic total-body FDG PET imaging. Dynamic FDG scans from 12 subjects acquired on a uEXPLORER PET/CT were included. In these subjects, 7 are healthy subjects and 5 are those with tumors in the thorax and abdomen. All scans were contaminated by motion to some degree, and for each the list-mode data were reconstructed into 1-min frames. The dynamic frames were aligned to a reference position by sequentially registering each frame to its previous neighboring frame. We parametrized the motion fields in-between frames as diffeomorphism, which can map the shape change of the object smoothly and continuously in time and space. Diffeomorphic representations of motion fields were derived by registering neighboring frames using large deformation diffeomorphic metric matching. When all pairwise registrations were completed, the motion field at each frame was obtained by concatenating the successive motion fields and transforming that frame into the reference position. The proposed correction method was labeled SyN-seq. The method that was performed similarly, but aligned each frame to a designated middle frame, was labeled as SyN-mid. Instead of SyN, the method that performed the sequential affine registration was labeled as Aff-seq. The original uncorrected images were labeled as NMC. Qualitative and quantitative analyses were performed to compare the performance of the proposed method with that of other correction methods and uncorrected images.ResultsThe results indicated that visual improvement was achieved after correction of the SUV images for the motion present period, especially in the brain and abdomen. For subjects with tumors, the average improvement in tumor SUVmean was 5.35 ± 4.92% (P = 0.047), with a maximum improvement of 12.89%. An overall quality improvement in quantitative Ki images was also observed after correction; however, such improvement was less obvious in K1 images. Sampled time–activity curves in the cerebral and kidney cortex were less affected by the motion after applying the proposed correction. Mutual information and dice coefficient relative to the reference also demonstrated that SyN-seq improved the alignment between frames over non-corrected images (P = 0.003 and P = 0.011). Moreover, the proposed correction successfully reduced the inter-subject variability in Ki quantifications (11.8% lower in sampled organs). Subjective assessment by experienced radiologists demonstrated consistent results for both SUV images and Ki images.ConclusionTo conclude, motion correction is important for image quality in dynamic total-body PET imaging. We demonstrated a correction framework that can effectively reduce the effect of random body movements on dynamic images and their associated quantification. The proposed correction framework can potentially benefit applications that require total-body assessment, such as imaging the brain-gut axis and systemic diseases.

Research on Oil Painting Layout and Expression Form Based on Multi Data Visual Communication

Multi records visible conversation plan combines modern-day digital technology, offers a new capacity of verbal exchange and a new way of expression for visible verbal exchange design, and has the twin position of innovative notion and reference. The emergence and popularization of visible verbal exchange technology and the integration and utility of visible conversation technological know-how in oil portray introduction are additionally heating up. Combined with multi-information visible conversation science and the strategies of sketching in typical oil portray creation, oil portray advent can continue to play a special creative allure in the visible era and preserve the symbiosis, interplay, and practical transformation of visible subculture represented by using standard portray varieties and images. Aiming at the search for on oil painting design and expression structure based totally completely on multi-information seen communication, this paper analyzes the facts transmission characteristics, seen language characteristics and aesthetic psychological features of multi-information seen verbal trade design. The oil portrays format and expression structure based totally on multi records visible communication. Through experiments and analysis, it is proven that the overall performance of 1500 ms is the fantastic when inspecting the dynamic alternate of time sequence information.

An identification and positioning method for coal gangue based on lightweight mixed domain attention

ABSTRACT The intelligentization of coal mines is the only approach to the high-quality development of the coal industry. Detection, identification, and sorting of coal gangue is an important part of the intelligentisation of coal mines. For the problems of traditional target detection algorithm model, such as high complexity, difficult training, and poor identification and positioning effect on coal and gangue under complex conditions, an identification and positioning method for coal gangue based on lightweight mixed domain attention was proposed. First, a mixed domain attention model was constructed through residual connection of spatial attention and efficient channel attention, and the MobileNetv3 network was optimized to improve its detection effect on coal and gangue under different conditions. Secondly, the optimized network was used to replace the feature extraction network in YOLOv4, and lightweighted using depthwise separable convolution to reduce model complexity and thereby obtain the ECSMv3_YOLOv4. Then the relationship between the actual position of coal and gangue on the conveyor belt was derived. Finally, after an experimental device was set up, a multi-condition coal and gangue dataset was built, the model was trained, as well as the identification and positioning results of the model under different sizes and light intensities were tested, and compared with those of other algorithms. Experiment results showed that the algorithm has the highest detection accuracy and efficiency, and can correctly identify and position coal and gangue under complex conditions with high confidence values. Compared with other algorithms, the mAP value of the proposed method is increased by 2.84% at most. The FLOPs was only 2,610,046, and the FPS of detection reached 28.8. Accordingly, this research is considered to be of certain theoretical value and technical reference for identification and positioning of coal gangue.

Considering Lumpectomy Cavity PTV Expansions: Characterization of Intrafraction Lumpectomy Cavity Motion

PurposeAccelerated partial breast irradiation and lumpectomy cavity boost radiation therapy plans generally use volumetric expansions from the lumpectomy cavity clinical target volume to the planning target volume (PTV) of 1 to 1.5 cm, substantially increasing the volume of irradiated breast tissue. The purpose of this study was to quantify intrafraction lumpectomy cavity motion during external beam radiation therapy to inform the indicated clinical target volume to PTV expansion. Methods and MaterialsForty-four patients were treated with a whole breast irradiation using traditional linear accelerator-based radiation therapy followed by lumpectomy cavity boost using magnetic resonance (MR)-guided radiation therapy on a prospective registry study. Two-dimensional cine-MR images through the center of the surgical cavity were acquired during each boost treatment to define the treatment position of the lumpectomy cavity. This was compared with the reference position to quantify intrafraction cavity motion. Free-breathing technique was used during treatment. Clinical outcomes including toxicity, cosmesis, and rates of local control were additionally analyzed. ResultsThe mean maximum displacement per fraction in the anterior-posterior (AP) direction was 1.4 mm. Per frame, AP motion was <5 mm in 92% of frames. The mean maximum displacement per fraction in the superior-inferior (SI) direction was 1.2 mm. Per frame, SI motion was <5 mm in 94% of frames. Composite motion was <5 mm in 89% of frames. Three-year local control was 97%. Eight women (18%) developed acute G2 radiation dermatitis. With a median follow-up of 32.4 months, cosmetic outcomes were excellent (22/44, 50%), good (19/44, 43%), and fair (2/44, 5%). ConclusionsIn approximately 90% of analyzed frames, intrafraction displacement of the lumpectomy cavity was <5 mm, with even less motion expected with deep inspiratory breath hold. Our results suggest reduced PTV expansions of 5 mm would be sufficient to account for lumpectomy cavity position, which may accordingly reduce late toxicity and improve cosmetic outcomes.

Geometric Integral Attitude Control on SO(3)

This article proposes a novel integral geometric control attitude tracking scheme, utilizing a coordinate-free representation of attitude on the Lie group of rigid body rotations, SO(3). This scheme exhibits almost global asymptotic stability in tracking a reference attitude profile. The stability and robustness properties of this integral tracking control scheme are shown using Lyapunov stability analysis. A numerical simulation study, utilizing a Lie Group Variational Integrator (LGVI), verifies the stability of this tracking control scheme, as well as its robustness to a disturbance torque. In addition, a numerical comparison study shows the effectiveness of the proposed geometric integral term, when compared to other state-of-the-art attitude controllers. In addition, software-in-the-loop (SITL) simulations show the advantages of utilizing the proposed attitude controller in PX4 autopilot compared to using PX4’s original attitude controller.

Attitude tracking control for reentry vehicles using centralised robust model predictive control

In this work, a centralised robust model predictive control (CRMPC) algorithm is proposed for reentry vehicles to track reference attitude trajectories subject to state/input constraints and uncertainties. In contrast to most designs that apply a cascade control structure for the two-timescale attitude dynamical systems, the proposed control scheme utilises a centralised structure to avoid additional controller development and parameter turning. By designing a nonlinear feedback law and tightening the system constraints, robust constraint satisfaction can be ensured for all admissible uncertainties. In addition, to guarantee the recursive feasibility and closed-loop stability of the proposed CRMPC, a terminal controller, along with a terminal region, is introduced. The validity of using the proposed approach to solve the considered problem is confirmed by executing several experimental studies, which were compared against two other established methods.

Nonlinear disturbance observer-based compliance error compensation in robotic milling

Robotic machining is of growing interest around the world, but the joint deflection from the reference trajectory due to the robot’s low rigidity restricts the use of robots only to machining with low cutting force. This paper proposes a new method for compensating the compliance error based on the nonlinear disturbance observer to reduce the deflection of robot joints against cutting forces. The disturbance observer designed in the joint spaces allows estimating the cutting forces online without any transformation between spaces so that the cutting forces could be obtained with high accuracy. The low-pass filter of the observer is optimized to reduce the effect of model uncertainty arising from the identification process. The deviation obtained by multiplying the joint compliances by the estimated cutting torques can be used to modify the reference position of robot joints. The proposed approach has the benefit to correct the robot's deflection in real time without a sensor. The experimental results reveal that the nonlinear disturbance observer can correctly estimate the cutting forces. Also, they show that the tool center point (TCP) deviation from the predefined path has been reduced using the proposed compliance error compensation.

Three-Dimensional Quantitative Evaluation of the Scapular Skin Marker Movements in the Upright Posture.

Motion capture systems using skin markers are widely used to evaluate scapular kinematics. However, soft-tissue artifact (STA) is a major limitation, and there is insufficient knowledge of the marker movements from the original locations. This study explores a scapular STA, including marker movements with shoulder elevation using upright computed tomography (CT). Ten healthy males (twenty shoulders in total) had markers attached to scapular bony landmarks and underwent upright CT in the reference and elevated positions. Marker movements were calculated and compared between markers. The bone-based and marker-based scapulothoracic rotation angles were also compared in both positions. The median marker movement distances were 30.4 mm for the acromial angle, 53.1 mm for the root of the scapular spine, and 70.0 mm for the inferior angle. Marker movements were significantly smaller on the superolateral aspect of the scapula, and superior movement was largest in the directional movement. Scapulothoracic rotation angles were significantly smaller in the marker-based rotation angles than in the bone-based rotation angles of the elevated position. We noted that the markers especially did not track the inferior movement of the scapular motion with shoulder elevation, resulting in an underestimation of the marker-based rotation angles.