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This paper presents an efficient feature detection algorithm based on the classical SURF (Speeded Up Robust Feature) detector. The image features are represented and scored with respect to its local symmetry property. The local symmetry has natural properties of scale and transformation invariants, and also insensitive to illumination change and local noise. By the proposed feature descriptor, the...
Loop-closure detection, which is the ability to recognize a previously visited place, is of primary importance for robotic localization and navigation problems. We here introduce SAIL-MAP, a method for loop-closure detection based on vision only, applied to topological simultaneous localization and mapping (SLAM). Our method allows the matching of camera images using a novel saliency-based feature...
In many robotic applications, especially long-term outdoor deployments, the success or failure of feature-based image registration is largely determined by changes in lighting. This paper reports on a method to learn visual feature point descriptors that are more robust to changes in scene lighting than standard hand-designed features. We demonstrate that, by tracking feature points in time-lapse...
This paper proposes a motion planning approach for non-holonomic mobile robots. Firstly, motion planning using i-PID controller is presented. Then we improve the old potential field function to produce smooth repulsive force. Finally a new repulsive function of robot orientation and angular velocity is proposed to improve the performance of obstacle avoidance. The effectiveness and the robustness...
Visual markers are useful tools assisting visual recognition of object pose in robotic applications. But they have two fundamental problems in orientation estimation. One is degradation of orientation accuracy in frontal observation. The other is “pose ambiguity” that the orientation cannot be determined uniquely. We previously developed a novel visual marker “LentiMark” which solves the former problem...
In this paper, the stabilization problem of loaded double inverted pendulum using an optimized state feedback sliding mode control is investigated. ADAMS/Matlab co-simulation environment is used for building a virtual nonlinear model for loaded double inverted pendulum system and the state feedback sliding mode control law is designed for stabilizing the system. Mismatched uncertainties represented...
Two-dimensional blood velocity estimation has shown potential to solve the angle-dependency of conventional ultrasound flow imaging. Clutter filtering, however, remains a major challenge for large beam-to-flow angles, leading to signal drop-outs and corrupted velocity estimates.
Spectral angle mapping is used to identify materials in Terahertz images. We test the performance of several spectral characteristics derived from the measured spectra. Robustness is studied by investigating the Receiver-Operating-Characteristics.
Despite the fundamental variability of human appearance, the last several years have seen considerable advances in age estimation from images of faces. Many of these advances have been made possible by artificially removing external sources of variability—they focus on highly constrained images from datasets such as the MORPH face database and FG-NET. We introduce a novel approach to estimating age...
A novel RB-WC-FI-FB (robust worst-case frequency invariance forward-backward) wideband beam former is proposed in this paper. It is developed to improve the robustness against estimation errors of direction of arrival (DOA) and limited sample number, as well as reduce the number of constraints. By incorporating forward-backward estimation and worst-case performance optimization method into the linearly...
In the framework of the angular metric, robust stability margin is used to characterize the stability robustness of the closed-loop system. The mixed H2/H8 robust controller with degree constraint is designed, whose degree is not larger than that of the plant. The characteristics of mixed H2/H8 controller with degree constraint are discussed, and the form of the controller is parameterized. After...
Interest points matching for aerial visual odometry using quadrotor MAV is tackled in this work. First, a set of sparse feature points are extracted using ORB detector. These are then grouped using Gradient Vector Flow (GVF) fields by finding points of high symmetry within the image. A robust matching strategy is introduced to improve the motion estimation. In order to validate ORB features matches,...
This paper presents a new super-twisting sliding modes direct torque and flux controller (STSM-DTC) for induction motor (IM) drives. The STSM is a second-order (type two) variable-structure control which operates without high-frequency chattering. The proposed STSM scheme is a torque and stator flux magnitude controller implemented in the stator flux reference frame, and it does not employ current...
To improve the robustness against variation in shooting angles, we previously proposed using an asymptotic expansion of the Gabor transform of ear images to compute the Gabor features of other poses and using these estimates in multiple linear discriminant analysis to enhance feature discriminability. Extending this study, the accuracies are compared with other standard methods that can be used to...
Based on joint iterative optimization, a robust widely linear (WL) reduced-rank minimum variance distortion less response (MVDR) beam forming algorithm is proposed for noncircular signals. To handle the issue of the mismatch between the presumed array steering vector and actual array steering vector, a diagonal loading technique is devised. As the proposed beam former takes advantage of the noncircular...
In the present paper, we propose a gray-level image watermarking algorithm with high capacity based on bit decomposition and spread transform. To implement this algorithm, the gray-level digital watermark image is bit decompounded into a series of binary digital images, then the cover data extracted from the original cover image are projected to multiple orthogonal directions, while a binary image...
A novel combined sliding mode adaptive observer for flux and speed estimation of direct thrust controlled surface mounted Linear Permanent Magnet Synchronous Motor (LPMSM) without using position sensors is proposed. The observer comprises a linear state observer combined with a novel nonlinear sliding mode component. The sliding mode component is improved by using two boundary layers which reduce...
Pose graph optimization is an elegant and efficient formulation for robot localization and mapping. Experimental evidence suggests that, in real problems, the set of measurements used to estimate robot poses is prone to contain outliers, due to perceptual aliasing and incorrect data association. While several related works deal with the rejection of outliers during pose estimation, the goal of this...
This paper considers the problem of modeling complex motions of pedestrians in a crowded environment. A number of methods have been proposed to predict the motion of a pedestrian or an object. However, it is still difficult to make a good prediction due to challenges, such as the complexity of pedestrian motions and outliers in a training set. This paper addresses these issues by proposing a robust...
Camera calibration constitutes a basic problem in many robot applications. In this paper two algorithms tailored to the calibration of the parameters of a depth camera are proposed. More precisely, a closed form solution that requires the coordinates of three corresponding points in the world and the camera coordinates systems, for the noise free case is proposed. Moreover, a robust algorithm that...
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