Anca Petrisor

Modelling and simulation of a variable speed air-conditioning system

This work presents two models to simulate the transient and steady state behavior of a vapour compression air-conditioning system. The condenser and the evaporator were divided into a number of control volumes. Time dependent partial differential equations system was obtained from the mass, energy and momentum balances for each control volume. As the expansion valve and the compressor both have very small thermal inertia, the steady state models were applied for these components. Transient and steady state models numerical predictions were compared and good agreement was found. Further simulations were performed with the objective of verifying the possibility of controlling the refrigeration system and the superheating of the refrigerant in the evaporator outlet by varying the compressor speed and the throttling valve sectional area. The results indicate that the proposed models can be used to formulate an algorithm for controlling a refrigeration system.

Using GUI of Matlab to create a virtual laboratory to study an induction machine

Recently, appeared the powerful data-processing tools, which allows simulating the dynamic systems in a simple way, in graphic environment. The article briefly presents how to use the software of Graphical User Interfaces (GUI) of MATLAB and shows its application to a traditional problem of dynamics of the electric machines: the simulation of the starting of an asynchronous machine. The goal of this paper is to provide electrical engineers and students with an introduction to the GUI. The same approach can be used to solve more difficult problems.

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.

Hybrid petri nets as a new formalism for modeling electrical drives

The purpose of this paper is to present the hybrid Petri nets formalism, as a description for a class of hybrid dynamics systems, with several applications, explanations and comments concerning some hybrid models of DC electrical drives. Starting from a generic mathematical model and using the Visual Object Net ++ software tool, several simulation scenarios was proposed, in order to verifying the Petri nets structures achieved. The simulation results can be used for building a modular hierarchical structure of the models.

Control systems for robotic gloves

A robotic glove designed to help stroke patients regain movement of their hands has been developed as part of a collaborative project in Romania. The robotic glove has been designed to facilitate repetitive movement and exercise of the hand of patients within the chronic stage of illness and after they have been released from hospital. A method for the analysis of flexion-extension movement of both human and anthropomorphic robotic finger is presented. Two types of control systems developed for robotic gloves and two implemented methods of recuperative actions are presented, too.

Post-stroke assistive rehabilitation robotic gloves

This paper presents the research activities and results which have been obtained to develop robotic gloves and its control system to be used for post-stroke hand rehabilitation. The practical results for robotic gloves development are shown from a mechanical, sensorial and control point of view. This work is focused on developing a lightweight and low-cost robotic glove used by patients in order to regain their hand movements. Robotic glove tele-operation was implemented with a tele-operation glove, having attached blending sensors, or a mobile device (phone) with Android.

Post-stroke Hand Rehabilitation Using a Wearable Robotic Glove

The paper presents the research work done for development of a lightweight and low-cost robotic glove that post-stroke patients can use to recover hand functionality. The work focused on two directions for the robotic glove structure (exoskeleton and wearable soft robotic glove) and on two types of recuperative actions (tele-operation and program based actions). Given the performance tests ran for the robotic gloves, better results were shown with the wearable soft robotic glove that could also be combined with Functional Electrical Stimulation in order to improve the post-stroke hand rehabilitation.

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.

Fuzzy control for shape memory alloy tendon-actuated robotic structure

Shape memory alloy offers an interesting solution, using the shape transformation of the wire/structure in the moment of applying a thermal-type transformation able to offer the martensitic temperature. In order to assure an efficient control of SMA actuator applied to inverted pendulum, a mathematical model and numerical simulation of the resulting model are required. Due to a particular possibility of SMA actuator connection, a modified dynamics for wire or tendon actuation is presented. For an efficient study, a Simulink block set was developed (block for user configurable shape memory alloy material, configurable block for dynamics of single-link robotic structure, block for user configurable wire/tendon actuation). As conventional control possibilities were explored, the fuzzy control structure applied in this chapter. offers an improved response. A more compact SMA actuation is proposed and experimented. The results are commented.