Daniela Coman

Role Selection Mechanism for the Soccer Robot System using Petri Net

Robot soccer is a challenging platform for multi-agent research, involving topics such as real-time image processing and control, robot path planning, obstacle avoidance and machine learning. The system consists of a supervisory controller, and controllers for defending and goalkeeping robots. These controllers are designed using Petri net. The robot soccer game presents an uncertain and dynamic environment for cooperating agents. Dynamic role switching and formation control are crucial for a successful game. A soccer robot has to take an appropriate decision based on environment situation. With the role of a robot fixed as goalkeeper, the supervisor, according to the game situation, assigns the role of attacking or defending to the other robots and then respective controllers control the robots. The Petri net model is implemented in Petri net toolbox under MATLAB environment.

Control Strategy of a 3-DOF Walking Robot

The paper presents the mathematical model of a walking robot where the active pair of legs has three free joints. The mathematical model of the robot is determined considering a systemic approach of the robot as variable causality dynamic systems (VCDS). Taking into account a possible symmetrical structure, only the vertical xz-plane evolution is considered. The results can be extended to three-dimensional space. The approach is best on variable dynamic systems, considering that each leg of the pair can change the state depending of the causality order. It is considered that the first leg has both joints free and the second leg has the second joint free. The model is implemented in MATLAB environment and some evolutions examples are presented.

Active solar panel tracking system actuated by shape memory alloy springs

The unique properties (e.g. Shape memory effects) exhibited by shape memory alloys (SMAs) offer the possibility of producing Smart Sun Tracking Mechanisms (SSTMs) for photovoltaic panels. The paper presents an experimental model of an active solar panel tracking system, conceived by authors. This model uses SMA springs as actuators. The SMA springs work as linear actuators by contracting with great strength and speed when heated. The SMA springs attached to this structure can be activated to accurately change the position of the solar panel, following, this way, the motion of the sun throughout the day (appropriately tilted to directly face the sun during the day time). The active shape-change control of SMA spring, the possibilities for miniaturization, easy integration in system structure can effectively increase the efficiency of such SSTM.

Computational analysis of the Cauchy problem associated to the kinematic model of a mobile robot

Recently, the specific problems arising to mobile robots are the following: determining the position and orientation of the robot on the field, planning an optimal path of motion and stationary or moving objects avoidance.This paper realizes a computational analysis of the Cauchy problem associated to a mobile robot kinematics. The ‘phase portrait’ graphical tool of the mathematical soft MAPLE11 points out the influence of the initial conditions: the initial velocities of the driving (left and right) wheels of the robot on the robot trajectory. Considering a pair of two simulation cases for the initial conditions brings a good reliability of the analysis.MSC:68T40, 70B15, 70B10, 37M05.

Motion Control of the Soccer Robot Based on Fuzzy Logic

Robot soccer is a challenging platform for multi‐agent research, involving topics such as real‐time image processing and control, robot path planning, obstacle avoidance and machine learning. The conventional robot control consists of methods for path generation and path following. When a robot moves away the estimated path, it must return immediately, and while doing so, the obstacle avoidance behavior and the effectiveness of such a path are not guaranteed. So, motion control is a difficult task, especially in real time and high speed control. This paper describes the use of fuzzy logic control for the low level motion of a soccer robot. Firstly, the modelling of the soccer robot is presented. The soccer robot based on MiroSoT Small Size league is a differential‐drive mobile robot with non‐slipping and pure‐rolling. Then, the design of fuzzy controller is describes. Finally, the computer simulations in MATLAB Simulink show that proposed fuzzy logic controller works well.

Finite Element Analysis of a Lumbar Vertebra Reconstructed by Biocomposite Alloplastic Grafts

This research approaches the fourth lumbar (L4) vertebra reconstruction by a tronconic alloplastic graft fabricated by a powder metallurgy technology using Ca5(PO4)3(OH) (hydroxyapatite), TiH2 (titanium hydride) and CaCO3 (calcium carbonate) particles as initial powder mixture. The high frequency of the L4 vertebra fractures due to motor vehicle traffic accidents justify the necessity of vertebral reconstruction. This approach simulates the biomechanical behavior of the ANSYS model consisting in the L4 vertebra and the tronconic biocomposite graft during the frontal impact load. The von Misses stress and strain responses from the model depend on the physical and mechanical properties of the biocomposite grafts, experimentally determined. The best simulated mechanical behavior corresponds to the mechanical shielding phenomenon occurring from the biocomposite graft on behalf of the L4 vertebra.

Mobile Robot Trajectory Analysis Using Computational Methods

This paper presents some considerations regarding the trajectory analysis for a class of mobile robots, namely two-wheeled differential drive mobile robots, one of the most utilized mechanical structures now in mobile robotics practice. The paper is continuing the computational analysis of the Cauchy problem associated to a mobile robot kinematics. The phaseportrait graphical tool of the mathematical soft MAPLE11, points out the influence of the initial conditions the initial velocities of the driving (left and right) wheels of the robot on the robot trajectory. Considering a pair of few simulation cases for the initial conditions brings a good reliability of the analysis. The issue of repetitive phenomena is very important to notice in this context, as in the analysis it is repeated a specific allure of the trajectory. It brings important features, both from mathematical and robotic analysis standpoint. The further changes are due to the initial conditions variations. Repetitive phenomena can be collected in order to realize a global panel of random distributed events in the kinematics of two wheeled differential drive mobile robot and to use the statistical observations in the further analysis.

New approaches in computational dynamics of the mixing flow

Abstract Between the most mature interdisciplinary areas, computational fluid dynamics (CFD) comes recently into focus. In the same time, it becomes more and more difficult to contribute fundamental research to it. However, although it remains unpredictable how CFD develops, it is part of what makes it an exciting and attractive discipline. This paper aims to exhibit some part of recent work in CFD. It concerns the qualitative approach of the turbulent behaviour of a mixing flow in an excitable media. Studying a mixing for a flow implies the analysis of successive stretching and folding phenomena for its particles, the influence of parameters and initial conditions. In the previous works, the study of the 3D non-periodic models exhibited a quite complicated behaviour. In agreement with experiments, there were involved some significant events, the so-called “ rare events ”. The variation of parameters had a great influence on the length and surface deformations. The experiments were realized with a special vortex installation, it was used a well-known aquatic algae as biologic material, and the water as basic fluid. In the paper there are presented some features of a qualitative comparative analysis of the model associated to the vortex flow technology. In the computational analysis there were used the fast analysis tools of MAPLE11 soft, in order to check the “rare events” and to complete the statistical analysis of the behaviour of the model.

Modeling and Analysis of Soccer Robot Tasks Using Generalized Stochastic Petri Nets

Robot soccer competition provides an excellent opportunity for robotics research. In particular, the soccer robots must perform real-time visual recognition, navigate in a dynamic field, avoid the obstacle, collaborate with teammates, and kick the ball in the correct direction. All these tasks demand robots that are autonomous (sensing, thinking, and acting as independent creatures), efficient (functioning under time and resource constraints), cooperative (collaborating with each other robot to accomplish tasks that are beyond individual’s capabilities), and intelligent (reasoning and planing actions and perhaps learning from experience). This paper proposes a method of defining and analysing the attacking robot tasks using Petri nets. Attacking soccer robot behaviors are modeled using the generalized stochastic Petri nets. Using Petri nets allows qualitative and quantitative analysis of the task execution. Petri net model is implemented in Petri Net Toolbox under MATLAB environment. Therefore, it is validated the net topology, the evolution of (their dynamics), the structural and behavioral properties (corresponding to checking if resources usage is stable and the model have no deadlocks), as well as the stochastic performance.

Computational Features of Flow Modeling in Nanostructured Sensors

Nowadays the productivity of the welding processes represents an important factor in economy concepts. The technologies which are developed by the researchers are oriented to the increasing of the welding processes’ productivity and to the improvement of the products’ quality.