This work presents an algorithm for automated real-time ramp detection using 3D point cloud data in the context of shared-control powered wheelchairs. Limitations in the interfaces available to those with severe motor...
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ISBN:
(纸本)9781509039302
This work presents an algorithm for automated real-time ramp detection using 3D point cloud data in the context of shared-control powered wheelchairs. Limitations in the interfaces available to those with severe motor impairments can make basic maneuvering tasks with powered wheelchairs difficult. Although a significant amount of work has been done on obstacle detection and avoidance, much less attention has been given to algorithms for the safe and reliable detection of ramps and inclines;even though navigating these structures is an important part of urban life. We provide an algorithmic solution for accurately detecting traversable inclines for applications with powered wheelchairs using the Point Cloud Library (PCL) within the Robotics Operating System (ROS) framework. All algorithms are implemented first in simulation and later evaluated on data obtained from indoor and outdoor urban environments. We measure the performance of our algorithm with systematic testing on several different ramp structures, observed from varied viewpoints. Results show that our algorithm is successful in detecting the orientation, slope, and width of traversable ramps with up to 100% accuracy and an average detection accuracy of 88%.
This paper presents a new and robust algorithm for detection of sleep stages by using the lead I of the Electrocardiography (ECG) and a fingertip Photoplethysmography (PPG) sensor, validated using multiple overnight P...
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This paper presents a new and robust algorithm for detection of sleep stages by using the lead I of the Electrocardiography (ECG) and a fingertip Photoplethysmography (PPG) sensor, validated using multiple overnight PSG recordings consisting of 20 human subjects (9 insomniac and 11 healthy). Heart Rate Variability (HRV) and Pulse Transit Time (PTT) biomarkers which were extracted from ECG and PPG biosignals then employed to extract features. Distance Weighted k-Nearest Neighbours (DWk-NN) was used as classifier to differentiate sleep epochs. The validation of the algorithm was evaluated by Leave-One-Out-Cross-Validation method. The average accuracy of 73.4% with standard deviation of 6.4 was achieved while the algorithm could distinguish stages 2, 3 of non-rapid eye movement sleep by average sensitivity of almost 80%. The lowest mean sensitivity of 53% was for stage 1. These results demonstrate that an algorithm based on PTT and HRV spectral analysis is able to classify and distinguish sleep stages with high accuracy and sensitivity. In addition the proposed algorithm is capable to be improved and implemented as a wearable, comfortable and cheap instrument for sleep screening.
Overnight continuous blood pressure measurement provides simultaneous monitoring of blood pressure and sleep architecture. By this means, we are able to investigate whether different sleep events are associated to blo...
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Overnight continuous blood pressure measurement provides simultaneous monitoring of blood pressure and sleep architecture. By this means, we are able to investigate whether different sleep events are associated to blood pressure fluctuations. In this paper, we used the Pulse Transit Time (PTT) to develop and evaluate functions for measurement of blood pressure. We focused on the first and second derivatives of fingertip Photoplethysmography (PPG) recordings to detect PPG critical points. By applying R wave of ECG and PPG critical points, we created two PTT-based models for estimation of systolic and diastolic blood pressure (SBP and DBP). Seven subjects polysomnography datasets that contained PPG, ECG and blood pressure recordings were utilised to validate and compare developed PTT-BP functions. Results found that if the peak of the first derivative of PPG (VPG) was considered as the pulse pressure arrival point, the resulted PTT (PTT V ) would more accurately predict both SBP and DBP. The average R-squared coefficient for SBP and DBP were correspondingly 0.593 and 0.416. The obtained mean error for PTT V based functions in SBP was ±3.96 mmHg with standard deviation of 1.41 mmHg and in DBP was ±6.88 mmHg with standard deviation of 3.03 mmHg. We concluded PTT detected from VPG is a reliable and suitable maker for overnight continuous blood pressure monitoring.
The human metabolome has remained largely unknown, with most studies annotating ~10% of features. In nucleic acid sequencing, annotating transcripts by source has proven essential for understanding gene function. Here...
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Objective 1. To evaluate and optimize commonly used nonlinear deformation algorithms when applied to human brain MRI. 2. To evaluate and optimize accuracy of automated atlas-based segmentation of the two most commonly...
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Objective 1. To evaluate and optimize commonly used nonlinear deformation algorithms when applied to human brain MRI. 2. To evaluate and optimize accuracy of automated atlas-based segmentation of the two most commonly used target regions for deep brain stimulation (DBS), the nucleus subthalamicus (STN) and the internal part of the globus pallidus (GPi). 3. To guide clinicians as to which preoperative MRI sequences to acquire in patients undergoing DBS. Background Translating single-subject imaging into a common reference frame such as the MNI space is a ‘core concept within the field of brain mapping’ (Evans et al., 2012) making an accurate transformation into this space necessary. Here, we evaluated and optimized 6 commonly used deformation algorithms and compared each outcome to manually labeled brain regions of 103 brains. Methods Algorithms evaluated were: New Segment, DARTEL and SHOOT (SPM); FNIRT (FSL); SyN and BSpline (ANTs). Target space was the MNI 2009b NLIN space. An atlas of the STN and GPi in MNI space (Ewert et al., 2017) was transformed to native space by inverting each deformation matrix. The resulting atlas-based segmentations were then compared to expert manual segmentations of the native brains. Overlap between the two was quantified using the Dice coefficient (Dice et al., 1945), mean surface distance and correlation of volumes. Two open source datasets were used: The IXI-dataset ( http://***/ixi-dataset/ ) and the HCP-dataset ( http://***/ ). Results The best performing algorithms were New Segment with a custom tissue probability map (TPM) (1) and ANTs SyN (2) with an additional step to refine subcortical coregistration. Performance is compared to inter-rater results (3) of manual segmentations. Fig. 1 shows results for the HCP data for STN (L, in red) and GPi (R, in blue) separately: median Dice for STN (1): 0.70 (std: 0.1); (2): 0.72 (0.06); (3): 0.76 (0.09). Median of mean surface distance in m
This paper proposes a multilevel shunt active power filter (SAPF) to deal with either harmonic currents compensation or reactive power compensation. Such a device can reduce the harmonic distortion at the grid current...
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ISBN:
(纸本)9781467395519
This paper proposes a multilevel shunt active power filter (SAPF) to deal with either harmonic currents compensation or reactive power compensation. Such a device can reduce the harmonic distortion at the grid currents provided by non-linear loads located in stiff systems. The proposed SAPF is based on three-phase bridge (TPB) converters connected to cascaded single-phase transformers. The transformers arrangement permits the compensator to use a single dc-link unit which simplifies the control strategy and number of sensors. The multilevel waveforms are generated by using a suitable PWM strategy associated with the transformers turns ratio. Modularity and simple maintenance make the proposed SAPF an attractive solution compared to some conventional configurations. The model, PWM technique and control strategy, are presented as well as studies considering harmonic distortion and semiconductor losses estimation. Simulation and experimental results are presented in order to validate theoretical approaches.
Heterointerfaces of SrTiO3 with other transition metal oxides make up an intriguing family of systems with a bounty of coexisting and competing physical orders. Some examples, such as LaAlO3/SrTiO3, support a high car...
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We developed an integrated optical stimulation and optical coherence microscopy imaging system, and demonstrated for the first time optogenetic pacing in Drosophila melanogaster at different developmental stages, incl...
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