Permutation entropy (PE) has been recently suggested as a novel measure to characterize the complexity of nonlinear time series. In this paper, we propose a simple method to address some of PE's limitations, mainl...
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Permutation entropy (PE) has been recently suggested as a novel measure to characterize the complexity of nonlinear time series. In this paper, we propose a simple method to address some of PE's limitations, mainly its inability to differentiate between distinct patterns of a certain motif and the sensitivity of patterns close to the noise floor. The method relies on the fact that patterns may be too disparate in amplitudes and variances and proceeds by assigning weights for each extracted vector when computing the relative frequencies associated with every motif. Simulations were conducted over synthetic and real data for a weighting scheme inspired by the variance of each pattern. Results show better robustness and stability in the presence of higher levels of noise, in addition to a distinctive ability to extract complexity information from data with spiky features or having abrupt changes in magnitude.
In this paper design and control of planar cable-driven parallel robots are studied in an experimental prospective. Since in this class of manipulators, cable tensionability conditions must be met, feedback control of...
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In this paper design and control of planar cable-driven parallel robots are studied in an experimental prospective. Since in this class of manipulators, cable tensionability conditions must be met, feedback control of such robots becomes more challenging than for conventional robots. To meet these conditions, internal force control structure is introduced and used in addition to a PID control scheme to ensure that all cables remain in tension. A robust PID controller is proposed for partial knowledge of the robot, to keep the tracking errors bounded. Finally, the effectiveness of the proposed control algorithm is examined through experiments on K.N. Toosi planar cable-driven robot and it is shown that the proposed control structure is able to provide suitable performance in practice.
Tool tip calibration is an important procedure in most surgical navigations. Investigations on tool tip calibration have been done by several commercial navigation systems, such as, Medtronics, GE, BrainLAB and Materi...
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Contact electrification or triboelectric charging has mostly been seen as a negative phenomenon in various engineering applications. In electronic applications, static charge buildup may even destroy some of the compo...
Contact electrification or triboelectric charging has mostly been seen as a negative phenomenon in various engineering applications. In electronic applications, static charge buildup may even destroy some of the components. In this paper, we demonstrate a cantilever based design using triboelectric charging mechanism for energy harvesting applications. The voltage output of triboelectric energy harvester (TEH) continuously increases with increased mass applied force and proof mass loading on the cantilever. The voltage output increases from 0.4 V to 1.8V as the excitation acceleration increases from 0.4g to 1.8g. The design has been shown to demonstrate wide bandwidth characteristics. The FWHM increases from 3.76 to 12.64 Hz as the acceleration increases from 0.4g to 1.8g. The peak power output is found to be 0.18μW at 1.4g.
This paper presents the design, fabrication and characterization of an electromagnetic MEMS energy harvester with ultra-broad operating bandwidth. The beam stretching induced nonlinear spring stiffness enables the res...
This paper presents the design, fabrication and characterization of an electromagnetic MEMS energy harvester with ultra-broad operating bandwidth. The beam stretching induced nonlinear spring stiffness enables the resonance to extend from 65 Hz to 340 Hz and 400 Hz at accelerations of 0.5g and 1.0g, respectively. The ultra-wide bandwidth could benefit the harvester device for more efficient vibration energy harvesting.
This study is an extension to our research on long term deployment of an assistive robot in a shopping mall. In this paper, we have discussed the architecture of robot Neel using rich web interactions and Unified comm...
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This study is an extension to our research on long term deployment of an assistive robot in a shopping mall. In this paper, we have discussed the architecture of robot Neel using rich web interactions and Unified communication methods to stay connected with users in an interpersonal manner. This enables the robot to build rapport among users by assisting shoppers to get offers and deals based on their preferences along with assisting retailers by connecting to their target customers. After the in-person human-robot interaction, both can stay connected with each other by using unified messaging services. Also we discuss the utility of having a robot in such a scenario, where it can aid humans with the strong online recommendation and interaction engines by connecting with potential shoppers and relevant retailers in the mall. The trials provide us valuable information for long term deployment and feasibility of such autonomous, intelligent, interactive robots in our social space for having effective Human robot interactions and communication.
Stereo visual odometry and dense scene reconstruction depend critically on accurate calibration of the extrinsic (relative) stereo camera poses. We present an algorithm for continuous, online stereo extrinsic re-calib...
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Stereo visual odometry and dense scene reconstruction depend critically on accurate calibration of the extrinsic (relative) stereo camera poses. We present an algorithm for continuous, online stereo extrinsic re-calibration operating only on sparse stereo correspondences on a per-frame basis. We obtain the 5 degree of freedom extrinsic pose for each frame, with a fixed baseline, making it possible to model time-dependent variations. The initial extrinsic estimates are found by minimizing epipolar errors, and are refined via a Kalman Filter (KF). Observation covariances are derived from the Cramer-Rao lower bound of the solution uncertainty. The algorithm operates at frame rate with unoptimized Matlab code with over 1000 correspondences per frame. We validate its performance using a variety of real stereo datasets and simulations.
In this paper, we present an inexpensive system for diverless video capture and fast image stitching of image frames for rapid reef assessment of shallow coral reefs. Our system has two main components: 1) Teardrop, a...
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Although machine learning methods, such as random forests, have been developed to correlate survival outcomes with a set of genes, less study has assessed the abilities of these methods in incorporating pathway inform...
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Although machine learning methods, such as random forests, have been developed to correlate survival outcomes with a set of genes, less study has assessed the abilities of these methods in incorporating pathway information for analyzing microarray data. In general, genes that are identified without incorporating biological knowledge are more difficult to interpret. Thus, the pathway-based survival analysis using machine learning methods represents a promising approach for generating new biological hypothesis from microarray studies. The two popular variants of random forests used in this research for survival data are random survival forests and bivariate node-splitting random survival forests. There are three types of datasets used for this research and each dataset with a three-level outcome. This research which compared the four splitting rules available in random survival forests to identify log-rank test is the most accurate in terms of prediction error. To evaluate the accuracy of pathway based survival approach, this research considered employing area under the receiver operating characteristic curve for censored data. The use of random survival forests for survival outcomes in analyzing microarray data allows researchers to obtain results that are more closely tied with the biological mechanism of diseases.
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