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Influence of Loading Frequency on Fatigue Properties of Structural Materials
Kašpar, Jan ; Němec, Karel (referee) ; Věchet, Stanislav (advisor)
This thesis analyse the influence of loading frequency on the fatigue of the structural materials. Low frequency loading (to the 200 Hz) has nearly no influence on the fatigue properties in almost all cases. Hight frequency loading (1 and more kHz) has major influence on the fatigue limit of the structural materials. This interference will disply like increasing of the fatigue limit. For example fatigue limit of steel is more affected by hight frequency loading than the cast-iron. Important aspect at hight frequency loading is rising temperature in the loading process. Rising temperature has negative influence on the fatigue limit of materials. Important aspect of the loading high frequency is possibility to achieved gigacycle regime of the fatigue (109 and more cycles), where should appear crack from below surface. This crack is call „ fish eye".
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Automatic environment generator design for mobile robot
Schreiber, Petr ; Krejsa, Jiří (referee) ; Věchet, Stanislav (advisor)
This work deals with design and realization of automatic environment generator, serving for autonomous robot simulations. The author describes various approaches to implementation of interior environment generator and their relation to Open Dynamics Engine physics library and XODE file format. This work also includes verification of generator functionality with participation of virtual mobile robot.
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Basics search for simultaneous localization and mapping.
Gärtner, Jan ; Marada, Tomáš (referee) ; Věchet, Stanislav (advisor)
This work deals with methods of simultaneous localization and mapping using in mobile robotic problems in the world. Main Goal of the work is describe existing and common using methods of simultaneous localization and mapping. The first part of the work deals with parting and description of each subproblems of simultaneous localization and mapping. The second part is note concrete methods of simultaneous localization and mapping. The third part is attending to practical application of simultaneous localization and mapping using in robotic tasks in the world. The last one is devoted to robotic application within the Faculty of Mechaniacal engineering at Brno Technical University and practicability apportionable methods for the applications.
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Covering the Working Space of Mobile Robot
Krejsa, Jiří ; Věchet, Stanislav
Equally distributed covering of working space is essential in some mobile robot applications, such as presentation robotics or security robot patrol. This paper explores a method for such covering based on rapidly exploring random trees (RRT) algorithm. RRTs can cover the working space close to completeness while uncovered areas are quickly reduced. The algorithm can be modified to emphasize certain areas of interest by appropriately generating corresponding goals. Method performance is compared to random walk in simulation experiments.
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Multiple Indoor Robot Localization Using Infrared Beacons
Krejsa, Jiří ; Věchet, Stanislav ; Chen, K.-S.
Mobile robot localization based on active artificial landmarks is well established robust technique in indoor mobile robotics. This paper explores the extension of the method to multiple robot localization, with the key idea of using the robots themselves as the artificial landmarks, supplying other robots in the group with its estimate of position. The method uses nonlinear version of Kalman filter for determination of position estimate in 2D space, x-y coordinates and angle with respect to global coordinate system, with the estimate represented by mean values and corresponding covariances. Simulation results based on model well verified with the real system suggest that while only small reduction of number of fixed active landmarks can be achieved, the main advantage of the method is in increased robustness of localization technique with respect to obscured landmarks fields of view.
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Mobile Robot Tracking Using Image Processing
Krejsa, Jiří ; Věchet, Stanislav ; Ripel, T.
During the evaluation of autonomous mobile robot navigation routines the determination of true robot position on its track is essential. The paper presents simple yet reliable method of tracking robot position using processing of images acquired from the devices positioned above the operation space. The method consists of two steps for each image: detection of the robot in image space and transfer of its coordinates to operation space.
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Concurrent mapping and localization based on potential fields
Věchet, Stanislav ; Krejsa, Jiří
Presented paper deals with Concurrent Mapping and Localization as a method to build the local map for the autonomous mobile robot. Building accurate local map is necessary for the successful navigation through the crowded environment densely populated with dynamic obstacles. The occupancy grid mapping algorithm was used due to the high uncertainty in the measurements of dynamic obstacles. As the occupancy grid algorithm is of probabilistic nature the implementation is straightforward and is also capable to generate the results in real-time.
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Mobile robot motion planner via neural network
Krejsa, Jiří ; Věchet, Stanislav
Motion planning is essential for mobile robot successful navigation. There are many algorithms for motion planning under various constraints. However, in some cases the human can still do a better job, therefore it would be advantageous to create a planner based on data gathered from the robot simulation when humans do the planning. The paper presents the method of using the neural network to transfer the previously gained knowledge into the machine learning based planner. In particular the neural network task is to mimic the planner based on finite state machine. The tests proved that neural network can successfully learn to navigate in constrained environment.
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Experimental Determination of Human Arm Force/Elbow Joint Angle Relation
Krejsa, Jiří ; Zezula, M. ; Věchet, Stanislav
The achievable force at the end of human forearm depends on the forearm position. The actual value of this force is one of the most important variables affecting the design of the motorized splint, but reliable data are hard to find. Sophisticated measuring device was constructed to determine this force. The force is measured during the movement of the forearm, as such method yields better results than static measurement. The trajectory of movement is enforced by the measuring device, so the influence of the subject on the trajectory is eliminated.
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Rychlá metoda srovnávání skenů pro lokalizaci mobilního robotu
Krejsa, Jiří ; Věchet, Stanislav
The paper is focused on fast method which uses subsequent proximity sensor scans of mobile robot environment to determine the robot position and orientation and to build a local map. The environment is supposed to be unknown. The method, based on Potential-Based Scan Matching which gives a measure of scan match is combined with gradient descent in order to find the proper match of two scans in reasonable time. Tests of robustness against the noise in sensor readings are included.
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