Search results for "Motion compensation"
showing 10 items of 16 documents
Inverse kinematic control of an industrial robot used in Vessel-to-Vessel Motion Compensation
2017
An increased level of complex offshore load handling operations is expected due to an increased amount of floating wind turbines, remote fish farms, and autonomous shipping, and in general more advanced operations to be carried out at sea. A common problem for these applications is that both equipment and personnel have to be transported between two floating vessels at sea. An investigation of the Vessel-to-Vessel Motion Compensation (VVMC) problem may increase the efficiency and safety of such operations in the future. In this paper, a control algorithm has been developed and experimentally tested in the Norwegian Motion Laboratory featuring two Stewart platforms (SPs), an industrial robot…
Testing of wireless sensor performance in Vessel-to-Vessel Motion Compensation
2016
Relative Vessel-to-Vessel Motion Compensation (VVMC) between two floating vessels can be considered an extension of existing Active Heave Compensation (AHC), which is current state-of-the-art in the offshore industry. In this paper, the experimental results from a small-scale experimental setup of a VVMC scenario are presented. The work focuses on the kinematics related to VVMC, sensor accuracy of Motion Reference Units (MRUs), and the communication delay related to wireless transmission of MRU data between two floating vessels. The accuracies of the MRU sensors are good and verified to be less than 5% of the heave amplitude. The wireless communication link had a typical time-delay of 8ms. …
Semantic Analysis of the Driving Environment in Urban Scenarios
2021
Understanding urban scenes require recognizing the semantic constituents of a scene and the complex interactions between them. In this work, we explore and provide effective representations for understanding urban scenes based on in situ perception, which can be helpful for planning and decision-making in various complex urban environments and under a variety of environmental conditions. We first present a taxonomy of deep learning methods in the area of semantic segmentation, the most studied topic in the literature for understanding urban driving scenes. The methods are categorized based on their architectural structure and further elaborated with a discussion of their advantages, possibl…
Optical Flow with Theoretically Justified Warping Applied to Medical Imaging
2015
International audience; Motion induced artifacts represent a major obstacle in the correct malignant lesion detection in medical imaging especially in MRI. The goal of this paper is to evaluate the performance of a new non-rigid motion correction algorithm based on the optical flow method. The proposed algorithm specifically addresses three major problems in MRI: the induced gaps in 3D images, the constancy assumption of current optical flow algorithms and the existence of large non-linear movement. In this paper, we compare the performance of extracted kinetic features from the tumor regions under consideration of several 2-D or 3-D motion compensation parameters for the differential diagn…
Tecsis: Low-Cost Methodology To Distinguish Archaeological Findings
2006
The automatic or semi-automatic research of archaeological findings includes some methodologies and algorithms of the Computer Vision. Reconstruction of a scene is one of the key step to get the solution to that challenge. This paper will address a methodology to reconstruction underwater scenes with mosaicing techniques. The reconstruction of scene will be the video-mosaic of sea bottom landscapes starting from single video frames. The methodology is based on the evaluation of the optic °ow in between frames, and its motion estimation has been evaluated on the extracted features from the common areas of consecutive pairs frames. This approach carried out the motion model from a geometric p…
Real-time 6-DOF Vessel-to-Vessel Motion Compensation using laser tracker
2017
The industry state-of-the-art offshore motion compensation is today carried out by offshore cranes equipped with Active Heave Compensation (AHC) systems, meaning that a hanging load is positioned at a certain height above the seafloor, even though the floating vessel carrying both the crane and the load is moving due to wave disturbances. Lately, there has been an increased interest among the industry also to compensate for the movement of a secondary vessel, which indicates that a more detailed investigation of the Vessel-to-Vessel Motion Compensation (VVMC) problem is required. The primary motivation for such compensation technique is influenced by the demand for load transfer between shi…
Efficient smart-camera accelerator: A configurable motion estimator dedicated to video codec
2013
Smart cameras are used in a large range of applications. Usually the smart cameras transmit the video or/and extracted information from the video scene, frequently on compressed format to fit with the application requirements. An efficient hardware accelerator that can be adapted and provide the required coding performances according to the events detected in the video, the available network bandwidth or user requirements, is therefore a key element for smart camera solutions. We propose in this paper to focus on a key part of the compression system: motion estimation. We have developed a flexible hardware implementation of the motion estimator based on FPGA component, fully compatible with…
Hardware Implementation of a Configurable Motion Estimator for Adjusting the Video Coding Performances
2012
International audience; Despite the diversity of video compression standard, the motion estimation still remains a key process which is used in most of them. Moreover, the required coding performances (bit-rate, PSNR, image spatial resolution, etc.) depend obviously of the application, the environment and the network communication. The motion estimation can therefore be adapted to fit with these performances. Meanwhile, the real time encoding is required in many applications. In order to reach this goal, we propose in this paper a hardware implementation of the motion estimator which enables the integer motion search algorithms to be modified and the fractional search and variable block siz…
Relative Vessel Motion Tracking using Sensor Fusion, Aruco Markers, and MRU Sensors
2017
This paper presents a novel approach for estimating the relative motion between two moving offshore vessels. The method is based on a sensor fusion algorithm including a vision system and two motion reference units (MRUs). The vision system makes use of the open-source computer vision library OpenCV and a cube with Aruco markers placed onto each of the cube sides. The Extended Quaternion Kalman Filter (EQKF) is used for bad pose rejection for the vision system. The presented sensor fusion algorithm is based on the Indirect Feedforward Kalman Filter for error estimation. The system is self-calibrating in the sense that the Aruco cube can be placed in an arbitrary location on the secondary ve…
Video Indexing Using MPEG Motion Compensation Vectors
2003
In the last years a lot of work has been done on color, textural, structural and semantic indexing of "content-based" video databases. Motion-based video indexing has been less explored, with approaches generally based on the analysis of optical flows. Compressed videos require the decompression of the sequences and the computation of optical flows, two steps computationally heavy. In this paper we propose some methods to index videos by motion features (mainly related to camera motion) and by motion-based spatial segmentation of frames, in a fully automatic way. Our idea is to use MPEG motion vectors as an alternative to optical flows. Their extraction is very simple and fast; it doesn't r…