True Motion Research Articles

Available acceleration set for the study of motion capabilities for cable-driven robots

The study of the ability of a cable driven robot (CDR) to generate motion between poses (motion generation capability) is important for many purposes such as motion planning and manipulator design. Existing analysis approaches that study CDR capability primarily do so by evaluating the mechanism's wrench generation abilities. Due to the nonlinear relationship between wrench and motion generation, these methods typically underestimate the true motion generation capability of a CDR and can result in conservative restrictions in operation. In this paper, two new metrics derived from the available acceleration set are proposed to better understand CDR motion generation capability. Using these metrics and the known properties of the static workspace, the maximum acceleration and speed capabilities of the CDR are quantified. This new information serves to better inform other technical aspects in the design, analysis and operation of CDRs, such as in workspace design and motion planning. To illustrate the application of the proposed metrics, two example robots are considered: a 2 link 2 DoF 4 cable CDR and a 6 DoF 7 cable CDR. The results show the insights into motion generation and how it provides new information to be used within motion planning and task scaling.

A GAUSSIAN PROCESS BASED MULTI-PERSON INTERACTION MODEL

Abstract. Online multi-person tracking in image sequences is commonly guided by recursive filters, whose predictive models define the expected positions of future states. When a predictive model deviates too much from the true motion of a pedestrian, which is often the case in crowded scenes due to unpredicted accelerations, the data association is prone to fail. In this paper we propose a novel predictive model on the basis of Gaussian Process Regression. The model takes into account the motion of every tracked pedestrian in the scene and the prediction is executed with respect to the velocities of all interrelated persons. As shown by the experiments, the model is capable of yielding more plausible predictions even in the presence of mutual occlusions or missing measurements. The approach is evaluated on a publicly available benchmark and outperforms other state-of-the-art trackers.

A GAUSSIAN PROCESS BASED MULTI-PERSON INTERACTION MODEL

Online multi-person tracking in image sequences is commonly guided by recursive filters, whose predictive models define the expected positions of future states. When a predictive model deviates too much from the true motion of a pedestrian, which is often the case in crowded scenes due to unpredicted accelerations, the data association is prone to fail. In this paper we propose a novel predictive model on the basis of Gaussian Process Regression. The model takes into account the motion of every tracked pedestrian in the scene and the prediction is executed with respect to the velocities of all interrelated persons. As shown by the experiments, the model is capable of yielding more plausible predictions even in the presence of mutual occlusions or missing measurements. The approach is evaluated on a publicly available benchmark and outperforms other state-of-the-art trackers.

Neck Pain and Proprioception Revisited Using the Proprioception Incongruence Detection Test.

Proprioceptive imprecision is believed to contribute to persistent pain. Detecting imprecision in order to study or treat it remains challenging given the limitations of current tests. The aim of this study was to determine whether proprioceptive imprecision could be detected in people with neck pain by testing their ability to identify incongruence between true head motion and a false visual reference using the Proprioception Incongruence Detection (PID) Test. A cross-sectional study was conducted. Twenty-four people with neck pain and 24 matched controls repeatedly rotated to specific markers within a virtual world and indicated if their true head rotation was more or less than the rotation suggested by the visual feedback. Visual feedback was manipulated at 6 corrections, ranging from 60% of true movement to 140% of true movement. A standard repositioning error (RPE) test as undertaken for comparison. Healthy controls were better able to detect incongruence between vision and true head rotation (X̅=75.6%, SD=8.5%) than people with neck pain were (X̅=69.6%, SD=12.7%). The RPE test scores were not different between groups. The PID Test score related to self-reported pain intensity but did not relate to RPE test score. Causality cannot be established from this cross-sectional study, and further work refining the PID Test is needed for it to offer clinical utility. Proprioceptive precision for neck movement appears worse in people with neck pain than in those without neck pain, and the extent of the deficit appears to be related to usual pain severity. The PID Test appears to be a more sensitive test than the RPE test and is likely to be useful for assessment of proprioceptive function in research and clinical settings.

Blind identification of the Millikan Library from earthquake data considering soil-structure interaction

The Robert A. Millikan Library is a reinforced concrete building with a basement level and nine stories above the ground. Located on the campus of California Institute of Technology (Caltech) in Pasadena California, it is among the most densely instrumented buildings in the U.S. From the early dates of its construction, it has been the subject of many investigations, especially regarding soil–structure interaction effects. It is well accepted that the structure is significantly interacting with the surrounding soil, which implies that the true foundation input motions cannot be directly recorded during earthquakes because of inertial effects. Based on this limitation, input–output modal identification methods are not applicable to this soil–structure system. On the other hand, conventional output-only methods are typically based on the unknown input signals to be stationary whitenoise, which is not the case for earthquake excitations. Through the use of recently developed blind identification (i.e. output-only) methods, it has become possible to extract such information from only the response signals because of earthquake excitations. In the present study, we employ such a blind identification method to extract the modal properties of the Millikan Library. We present some modes that have not been identified from force vibration tests in several studies to date. Then, to quantify the contribution of soil–structure interaction effects, we first create a detailed Finite Element (FE) model using available information about the superstructure; and subsequently update the soil–foundation system's dynamic stiffnesses at each mode such that the modal properties of the entire soil–structure system agree well with those obtained via output-only modal identification. Copyright © 2015 John Wiley & Sons, Ltd.

Touchless Optical Finger Motion Tracking Based on 2D Nanosheets with Giant Moisture Responsiveness.

A new optical touchless positioning interface based on ultrasensitive humidity responsive 1D photonic crystals utilizing the giant moisture dependent swelling capacity of 2D phosphatoantimonate nanosheets is presented. The spatially confined, full spectral color change combined with reversible transparency switching induced by the humidity sheath of a human finger allows for real time, true color lateral finger motion tracking under touchless conditions.

An effiicient full frame algorithm for object-based error concealment in 3D depth-based video

In real-time video transmission, the loss of packet results in visual quality degraded for the succeeding frames. This paper proposes an efficient full frame algorithm for depth-based 3-D videos. Each frame can be regarded as combination of objects. True motion estimation (TME) and depth map are exploited to calculate the motion vector (MV) for each object. In this paper, the object is defined as the pixels with the same MV and similar depth value. The object-based MV can extrapolate each object in reference frame to reconstruct the damage frame. In the consideration of computational complexity, in this method, only the high frequency regions need to execute TME. In this paper, we provide a new method to obtain the objects according to temporal and depth information. From the simulation results, our algorithm gives better visual quality and PSNR in most case with lower complexity.

Extending the Applicability of POMDP Solutions to Robotic Tasks

Partially observable Markov decision processes (POMDPs) are used in many robotic task classes from soccer to household chores. Determining an approximately optimal action policy for POMDPs is PSPACE-complete, and the exponential growth of computation time prohibits solving large tasks. This paper describes two techniques to extend the range of robotic tasks that can be solved using a POMDP. Our first technique reduces the motion constraints of a robot and, then, uses state-of-the-art robotic motion planning techniques to respect the true motion constraints at runtime. We then propose a novel task decomposition that can be applied to some indoor robotic tasks. This decomposition transforms a long time horizon task into a set of shorter tasks. We empirically demonstrate the performance gain provided by these two techniques through simulated execution in a variety of environments. Comparing a direct formulation of a POMDP to solving our proposed reductions, we conclude that the techniques proposed in this paper can provide significant enhancement to current POMDP solution techniques, extending the POMDP instances that can be solved to include large continuous-state robotic tasks.

SU-E-J-60: Evaluation of Temporal Lag in Radiotherapy Gating for Tumor Motion Trajectories

Purpose: Evaluating timing differences between LINAC beam ON/OFF and the estimation of tumor positioning using gating systems is essential for establishing confidence when treating with gating during radiotherapy, and is an annual requirement of TG-142. Temporal discrepancies between the trajectories of external marker surrogates and beam delivery may vary depending upon the type of external marker motion, which is quantified in this work for several trajectories. Methods: A precise robotic 3D motion stage performed several trajectories typically used for gating phantoms, including sinusoidal and Lujan-type motion; a commercial respiratory motion simulator was also employed. The true motions were monitored using variable resistors. The beam ON/OFF was controlled separately by two RPM (Varian) systems, an integrated version delivered by a Varian Truebeam LINAC and version 1.6 delivered by a Varian Trilogy, and measured using a diode. The resistor and diode signals were read by a multichannel digital oscilloscope, and timing differences between beam ON/OFF as measured by the diode and the phantom motion were determined using a peak detection algorithm. Results: Timing differences between beam ON/OFF and 3D stage motion peaks (diode—true motion timing) were computed to be 79.4 & 57.7ms for sinusoidal motion and 109.1 & 63.6ms for Lujan-type motion on the Truebeam LINAC, for beam ON and OFF, respectively. Timing differences for the Trilogy LINAC were 34.4 & 55.2ms for the sinusoidal motion and 29.0 & 26.3ms for the Lujan-type motion, for beam ON and OFF, respectively. With the commercial motion simulator, the timing differences were found to be −9ms and −78ms for beam ON/OFF, respectively, with the Truebeam, and −97.6ms and −60.9ms for beam ON/OFF, respectively, with the Trilogy. Conclusion: Setup-dependent temporal lags were found using this methodology. These discrepancies have the potential to influence quality assurance on gating systems and ultimately the treatment dose during radiotherapy. NIH National Institute of Biomedical Imaging and Bioengineering grant T32 EB002103-21

SU‐E‐T‐509: Inter‐Observer and Inter‐Modality Contouring Analysis for Organs at Risk for HDR Gynecological Brachytherapy

PurposeThis study quantifies errors associated with MR‐guided High Dose Rate (HDR) gynecological brachytherapy. Uncertainties in this treatment results from contouring, organ motion between imaging and treatment delivery, dose calculation, and dose delivery. We focus on interobserver and inter‐modality variability in contouring and the motion of organs at risk (OARs) in the time span between the MR and CT scans (∼1 hour). We report the change in organ volume and position of center of mass (CM) between the two imaging modalities.MethodsA total of 8 patients treated with MR‐guided HDR brachytherapy were included in this study. Two observers contoured the bladder and rectum on both MR and CT scans. The change in OAR volume and CM position between the MR and CT imaging sessions on both image sets were calculated.ResultsThe absolute mean bladder volume change between the two imaging modalities is 67.1cc. The absolute mean inter‐observer difference in bladder volume is much lower at 15.5cc (MR) and 11.0cc (CT). This higher inter‐modality volume difference suggests a real change in the bladder filling between the two imaging sessions. Change in Rectum volume inter‐observer standard error of means (SEM) is 3.18cc (MR) and 3.09cc (CT), while the inter‐modality SEM is 3.65cc (observer 1), and 2.75cc (observer 2). The SEM for rectum CM position in the superior‐inferior direction was approximately three times higher than in other directions for both the inter—observer (0.77 cm, 0.92 cm for observers 1 and 2, respectively) and inter‐modality (0.91 cm, 0.95 cm for MR and CT, respectively) variability.ConclusionBladder contours display good consistency between different observers on both CT and MR images. For rectum contouring the highest inconsistency stems from the observers’ choice of the superior‐inferior borders. A complete analysis of a larger patient cohort will enable us to separate the true organ motion from the inter‐observer variability.

The nonlinear behaviors of movement of electron in the atoms

In view of difficulties and questions of quantum mechanics in description of motion of electrons in hydrogen atom, we here established their nonlinear theory of motion based on the true motions of electron and nucleon and the real interactions between them, in which the motion of electron is depicted by a nonlinear Schrödinger equation with a Coulomb potential, the nonlinear interaction b∣φ∣2φ is produced by the change of Coulomb interaction between nucleon and electron due to the motion of nucleon. Thus the natures of the electron are thoroughly changed relative to those in quantum mechanics due to the nonlinear interactions, it not only is stable and localized, but also possesses a wave–corpuscle duality. Meanwhile, if its eigenenergy is still quantized and distributed in accordance with the energy levels, then we can use the new theory to explain perfectly the spectrum features of hydrogen atom, which resembles quantum mechanics, but its sizes of eigenenergy are depressed relative to that in quantum mechanics. This means that the nonlinear interaction enhances the localized and stable nature of the electron. Therefore, the new nonlinear theory is successful and correct to the hydrogen atom.

True-Motion Estimation and Compensation with Multitemporal Block-Matching Search

in de-interlacing algorithms are fundamental to explore image quality potential on modern TV screen technologies. This paper presents a true motion vector verification algorithm based on multi temporal block matching strategy, applied to video de-interlacing. During field scanning, a block of pixels is selected, then a block with the same reference coordinates is extracted but in the future field. A searching process runs in the previous field, looking for the most similar block; the best fit block and their coordinates are extracted from the previous field, and a new searching process is done but in the future field. If the searching process in the future field results back to the original block coordinates, the motion vector is validated; in other case, a correction over the motion vectors is done. Error calculation showed that the proposed algorithm presents image quality improvement, when compared to a classical motion compensation algorithm.

Frame Rate Up-Conversion Using Linear Quadratic Motion Estimation and Trilateral Filtering Motion Smoothing

Frame rate up-conversion (FRUC) is a widely used technique to enhance the visual quality of low frame rate video presented on liquid crystal displays. One decisive factor for an effective FRUC algorithm is to obtain true motion vectors (MVs) for motion compensated interpolation. However, many current block-based motion estimation methods cannot always provide reliable MVs. In this paper, a new FRUC algorithm employing linear quadratic motion estimation and trilateral filtering motion smoothing is presented to estimate true MVs. The MV obtained by minimizing matching error is modeled as the measurement of true MV with noise. To remove the noise, the measured MV is updated with the corresponding predicted MV by using linear quadratic estimation. In motion smoothing stage, a trilateral filter which considers local smoothness, neighboring motion reliability as well as motion diversity at motion boundary, is used to further improve the accuracy and density of motion vector field (MVF). Experimental results demonstrate that the proposed algorithm outperforms the conventional FRUC algorithms with better objective and subjective image quality.

Frame Rate Up-Conversion Method for Video Processing Applications

In this paper, a new low-complexity frame rate up-conversion (FRUC) method is proposed for video processing applications. In the proposed FRUC method, true motion estimation (TME) is used to track motion trajectories by imposing smoothness constraints on block-matching algorithm (BMA). In order to produce high-quality interpolated frames, TME is performed in both forward and backward directions; then, the reliable dense motion vector field is obtained by using the multistage motion vector (MV) post-processing method. The constraints of low computational complexity and low memory bandwidth are also considered in our method. We use a histogram-based predictive search to impose smoothness constrains and reduce the number of search points. Furthermore, a complexity-simplified improvement of the proposed method is introduced to reduce computational complexity with slight quality degradation. In addition, a new scan order of BMA and a pipelining of MV post-processing are presented to guarantee the causality of the system and improve the pixel data reuse, which reduces the memory bandwidth. The experiment results show that the proposed FRUC method achieves not only better video quality, but also low computational complexity and memory bandwidth compared to the conventional methods.

Deep shading buffers on commodity GPUs

Real-time rendering with true motion and defocus blur remains an elusive goal for application developers. In recent years, substantial progress has been made in the areas of rasterization, shading, and reconstruction for stochastic rendering. However, we have yet to see an efficient method for decoupled sampling that can be implemented on current or near-future graphics processors. In this paper, we propose one such algorithm that leverages the capability of modern GPUs to perform unordered memory accesses from within shaders. Our algorithm builds per-pixel primitive lists in canonical shading space. All shading then takes place in a single, non-multisampled forward rendering pass using conservative rasterization. This pass exploits the rasterization and shading hardware to perform shading very efficiently, and only samples that are visible in the final image are shaded. Last, the shading samples are gathered and filtered to create the final image. The input to our algorithm can be generated using a variety of methods, of which we show examples of interactive stochastic and interleaved rasterization, as well as ray tracing.

Adaptation of the modified Bouc-Wen model to compensate for hysteresis in respiratory motion for the list-mode binning of cardiac SPECT and PET acquisitions: testing using MRI.

Binning list-mode acquisitions as a function of a surrogate signal related to respiration has been employed to reduce the impact of respiratory motion on image quality in cardiac emission tomography (SPECT and PET). Inherent in amplitude binning is the assumption that there is a monotonic relationship between the amplitude of the surrogate signal and respiratory motion of the heart. This assumption is not valid in the presence of hysteresis when heart motion exhibits a different relationship with the surrogate during inspiration and expiration. The purpose of this study was to investigate the novel approach of using the Bouc-Wen (BW) model to provide a signal accounting for hysteresis when binning list-mode data with the goal of thereby improving motion correction. The study is based on the authors' previous observations that hysteresis between chest and abdomen markers was indicative of hysteresis between abdomen markers and the internal motion of the heart. In 19 healthy volunteers, they determined the internal motion of the heart and diaphragm in the superior-inferior direction during free breathing using MRI navigators. A visual tracking system (vts) synchronized with MRI acquisition tracked the anterior-posterior motions of external markers placed on the chest and abdomen. These data were employed to develop and test the Bouc-Wen model by inputting the vts derived chest and abdomen motions into it and using the resulting output signals as surrogates for cardiac motion. The data of the volunteers were divided into training and testing sets. The training set was used to obtain initial values for the model parameters for all of the volunteers in the set, and for set members based on whether they were or were not classified as exhibiting hysteresis using a metric derived from the markers. These initial parameters were then employed with the testing set to estimate output signals. Pearson's linear correlation coefficient between the abdomen, chest, average of chest and abdomen markers, and Bouc-Wen derived signals versus the true internal motion of the heart from MRI was used to judge the signals match to the heart motion. The results show that the Bouc-Wen model generated signals demonstrated strong correlation with the heart motion. This correlation was slightly larger on average than that of the external surrogate signals derived from the abdomen marker, and average of the abdomen and chest markers, but was not statistically significantly different from them. The results suggest that the proposed model has the potential to be a unified framework for modeling hysteresis in respiratory motion in cardiac perfusion studies and beyond.

Analysis of hip range of motion in everyday life: a pilot study.

Patients undergoing total hip arthroplasty are increasingly younger and have a higher demand concerning hip range of motion. To date, there is no clear consensus as to the amplitude of the "normal hip" in everyday life. It is also unknown if the physical examination is an accurate test for setting the values of true hip motion. The purpose of this study was: 1) to precisely determine the necessary hip joint mobility for everyday tasks in young active subjects to be used in computer simulations of prosthetic models in order to evaluate impingement and instability during their practice; 2) to assess the accuracy of passive hip range of motion measurements during clinical examination. A total of 4 healthy volunteers underwent Magnetic Resonance Imaging and 2 motion capture experiments. During experiment 1, routine activities were recorded and applied to prosthetic hip 3D models including nine cup configurations. During experiment 2, a clinical examination was performed, while the motion of the subjects was simultaneously captured. Important hip flexion (mean range 95°-107°) was measured during daily activities that could expose the prosthetic hip to impingement and instability. The error made by the clinicians during physical examination varied in the range of ±10°, except for flexion and abduction where the error was higher. This study provides useful information for the surgical planning to help restore hip mobility and stability, when dealing with young active patients. The physical examination seems to be a precise method for determining passive hip motion, if care is taken to stabilise the pelvis during hip flexion and abduction.

An Artifact Information Based Motion Vector Processing Method for Motion Compensated Frame Interpolation

Motion compensated frame interpolation (MCFI) is a technique used extensively to enhance the visual quality of low frame rate videos. It requires true motion vectors (MVs) to ensure the high quality of the interpolated image. However, many current motion estimation techniques are block-based, which cannot always provide reliable MVs. In this paper, a novel motion vector processing method is presented to obtain the reliable MVs for MCFI. By introducing the interpolated artifact information of each MV as a new reliability metric, the proposed method first classify the input motion vector field (MVF) into reliable and possibly unreliable groups. A correlation-based MV reliability determination method is then used to identify the unreliable MVs from the possibly unreliable group with the reference of the reliable MVs. In the motion correction stage, these unreliable MVs are corrected properly with an region classification method. By using the updated MVF as new input, the above processes are performed iteratively until no new MV reliability changes. Finally, an occlusion handling process is performed to solve the unreliable MVs within the occluded areas and remove the small motion inconsistencies. Experimental results demonstrate the superior performance of the proposed method. Compared with existing benchmark algorithms, the frames interpolated by the proposed method provide better image quality both subjectively and objectively.

Frame rate up-conversion method based on texture adaptive bilateral motion estimation

In this paper, a new frame rate up-conversion scheme is proposed in order to overcome motion blur problems of liquid crystal displays caused by slow responses. Conventional bilateral motion estimation methods used in the frame rate upconversion scheme present a major drawback of missing true motion vectors if there are blocks with simple textures in search range. To solve this problem, a texture adaptive bilateral motion estimation method increasing the cost value of a block with simple texture is proposed. Also a motion estimation scheme that utilizes neighboring motion vector effectively is proposed to reduce computation time required to estimate motion. Since the proposed scheme does not apply all available motion vectors within search range, the execution time of frame rate up conversion can be reduced dramatically. Experimental results show that the interpolated frame image quality is improved as well as the processing time of the proposed method is greatly reduced compared with those of conventional methods.

질감 활성도 기반 양방향 움직임 추정과 인접 움직임 정보를 이용한 프레임률 증가 기법

In this paper we propose a new frame rate up conversion scheme which is used to overcome the motion blur problem of liquid crystal display caused by its slow response. The conventional bilateral motion estimation method which is mainly used in the frame rate up conversion scheme has a drawback that it cannot find true motion vector if there are blocks with simple texture in the search range. To solve this problem, a texture adaptive bilateral motion estimation method that increases cost value of block with simple texture is proposed. Also a motion estimation scheme that utilizes neighboring motion vector effectively is proposed to reduce computation time required to estimate motion. Since the proposed scheme does not apply all available motion vectors within the search range, the execution time of frame rate up conversion can be reduced dramatically. Experimental results show that the interpolated frame image quality of the proposed method is improved in subjective as well as objective view point compared with that of the conventional method.