Abstract:This paper presents an approach to visual obstacle avoidance and reactive robot navigation for outdoor and indoor environments. The obstacle detection algorithm includes an image feature tracking procedure followed by a feature classification process based on the IPT (Inverse Perspective Transformation). The classifier discriminates obstacle points from ground points. Obstacle features permit to draw out the obstacle boundaries which are used to construct a local and qualitative polar occupancy grid, analogous… Show more
“…Measuring systems equipped with one camera are also not rare [4]. The camera then performs two to eight photos of the object [4], and the distance is determined on the basis of the inverse perspective transformation [5]. There is also a T measuring system variant with a camera equipped with autofocus.…”
Abstract-The article presents new results achieved during researching the distance measuring method that is a part of Depth From Defocus techniques. The method has been developed to determine the shape of the flaccid diaphragm used in the Ventricular Assist Device (VAD). The shape is determined on the basis of distance measured between the CCD sensor plate of the camera and objects (markers) located on the flaccid diaphragm. Experiments were carried out using a stationary camera and circular markers with a diameter from 3 mm to 9 mm.The goal of this paper is to present the influence of the object (marker) size on the distance range measured between the camera and diaphragm used in the external pneumatic prosthetic heart.
“…Measuring systems equipped with one camera are also not rare [4]. The camera then performs two to eight photos of the object [4], and the distance is determined on the basis of the inverse perspective transformation [5]. There is also a T measuring system variant with a camera equipped with autofocus.…”
Abstract-The article presents new results achieved during researching the distance measuring method that is a part of Depth From Defocus techniques. The method has been developed to determine the shape of the flaccid diaphragm used in the Ventricular Assist Device (VAD). The shape is determined on the basis of distance measured between the CCD sensor plate of the camera and objects (markers) located on the flaccid diaphragm. Experiments were carried out using a stationary camera and circular markers with a diameter from 3 mm to 9 mm.The goal of this paper is to present the influence of the object (marker) size on the distance range measured between the camera and diaphragm used in the external pneumatic prosthetic heart.
“…Measuring systems equipped with one camera are also used [4]. The distance to the object in these systems is determined using, for example, a perspective inverse transform [5]. A single camera configuration with an autofocus function is also possible.…”
Abstract-The article presents the results achieved while researching a distance measuring method belonging to Depth From Defocus techniques. The method has been developed to determine the shape of a flaccid diaphragm used in the Ventricular Assist Device (VAD). The shape is determined on the basis of distance measured between the CCD sensor plate of a camera and the markers located on the flaccid diaphragm. The goal of this paper is to present the influence of marker size on distance range measured between the camera and the diaphragm used in a pneumatic prosthetic heart.The article presents the impact of marker size on the result of a distance measurement method [1,2]. The method was developed for a video sensor to determine the instantaneous stroke volume of blood SV from a pneumatic pump heart assist device (VAD), Fig. 1a. When measuring SV, the flaccid diaphragm is equipped with markers which position and orientation in 3D space is subject to change in relation to the camera position. What is important in the method is that when measuring the position of the camera and all settings: the lens and the camera (focus, aperture, focal length) are invariable. Method [1, 2] also defines in 3D space the position of all the markers on the basis of analysis of only one image frame. In this respect, it has no equivalent in the literature. The vision systems mentioned in the literature typically create a stereoscopic system [3]. The distance in such a system is calculated knowing the optical parameters of the cameras and their mutual position. Measuring systems equipped with one camera are also used [4]. The distance to the object in these systems is determined using, for example, a perspective inverse transform [5]. A single camera configuration with an autofocus function is also possible. The distance to the object is then determined with a lens equation [6]. Other methods used to measure the distance are photogrammetry [7][8] and a fringe projection technique [9][10][11]. Their use, however, depends on: the scope of measured distances, required measurement speed, required image sensor resolution, light source type as well as target size and sensor weight.When determining the shape of a flaccid diaphragm, real time operation is particularly important (the shape of the diaphragm may change with a frequency of up to 3Hz) as * E-mail: Krzysztof.Murawski@wat.edu.pl well as simultaneous multipoint measurement of the position in 3D space in respect to all of the markers, Fig. 1b. The development of a soft-sensor for measuring the SV of a pulsating heart assist pump results from the needs and problems mentioned in [12]. In [12][13] it was demonstrated that SV can be determined by using the acoustic Helmholtz resonator theory. This method, however, has substantial limitations. For this reason the search for techniques of determining SV is still valid. The knowledge of changes dynamics in SV will enhance the safety of VAD usage, which currently depends on visual inspection: "One of the main advantages of the extracorporeal, po...
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