Papers by Author: Serban Olaru

Abstract: The most important in the study of the robots is the kinematic and dynamic analyze. Many researchers studied the kinematics or dynamics without simulation and assisted analyze that it is very heavy to understand the behavior and to show some characteristics. The paper shows one assisted method by using the virtual proper LabVIEW instrumentation (VI). For the forward kinematics (FK) and for direct dynamics (DD) was used one recurrent matrix method which was developed with quaternion algebra, that will be possible to use in many different other types of robots, only by initial settings of the type of joints, the movement axis, the home position, the dimension of each robot’s body, the application point in the working space of the manufacturing cells and the internal coordinates in each joint. For the inverse kinematics (IK) we used the Iterative Pseudo Inverse Jacobian Matrix Method (IPIJMM) coupled with the proper Sigmoid Bipolar Hyperbolic Tangent Neural Network with Time Delay and Recurrent Links (SBHTNN-TDRL). The paper describe all steps in one case study to obtain the space curve in different Euller planes by using one arm type robot and the proposed VI-s. The presented method and the LabVIEW VI-s are generally and they can be used in all other robots types and for all other conventional and unconventional space curves.

Abstract: One of the most precise method solving the inverse kinematics problem in the redundant cases of the robots is the coupled method. The proposed method use the Iterative Pseudo Inverse Jacobian Matrix Method (IPIJMM) coupled with the proper Sigmoid Bipolar Hyperbolic Tangent Neural Network with Time Delay and Recurrent Links (SBHTNN-TDRL). One precise solution of the inverse kinematics problem is very difficult to find, when the degree of freedom increase and in many cases this is impossible because the redundant solutions. In all these cases must be used the numerical iterative approximation, like the proposed method, with artificial intelligence algorithm. The paper describe all the steps in one case study to obtain the space circle curve in different planes by using one arm type robot and the proposed method. The errors of the space movement of the robot end-effecter, after applying the proposed method, was less than 0,01. The presented method is general and it can be used in all other robots types and for all other conventional and unconventional space curves.

Abstract: This paper explains and demonstrates how can designed one multi robots application with many tasks and some different type of modular collaborative robots. Was described the general mathematical model for the direct and inverse kinematics to controlling the robots and how can solve the inverse kinematics of multiple tasks by using the priority of tasks or serial tasks composed by sum of the weighted several tasks. Some collaborative multi robots applications with parallel, serial or composed robots configurations were shown. The general mathematical matrix model of the robot application point with three translations and three rotations to the world Cartesian coordinates of the application map was defined. The designed method, the animation programs and the used LabVIEW proper virtual instruments open the way to easily define the multi robots application map, establish the constraints of the used robots and of the environment to avoid the singular points and tests the manipulation programs for collaborative application.

Abstract: Finding the better solution of the inverse kinematics problem, with the minimum of the trajectory errors, is very difficult because there are many variable parameters and many redundant solutions. The presented paper show the assisted solving of the inverse kinematics with the goal to minimize the final end-effector trajectory errors, by optimizing the distance between the and-effector final position and the target. All obtained results were been verified by applying the proper forward kinematics virtual LabVIEW instrumentation. The paper tries to answer at the inverse kinematics problem for one known mathematical trajectory and identifying the cinematic errors after the establishing and applying the proper assisted solving method using the Cycle Coordinate Descent Method coupled to the proper Neural Network Sigmoid Bipolar Hyperbolic Tangent (CCDM-SBHTNN). We were shown one complete study case to obtain one circle space trajectory using one arm type robot fixed on the ceiling. The presented method is general and can be used in all other robots types and in all other conventional and unconventional space curves.

Abstract: In the industrial robots research one of the most important problem is to know cinematic and dynamic behavior to use them in the optimization process of the 3D space trajectory. Now, in the world, the results of the dynamic behavior research where obtained by research without one complex matrix model and without LabVIEW virtual instrumentation. In this paper it is show one assisted method and mathematical modeling with quadratic 6x6 matrix equations in the theoretical and experimental cinematic and dynamic analyze of didactical robot. For that where realized and used many virtual LabVIEW instruments (VI) and one didactical robot. All VI-s work on-line with the possibility to change some constructive and functional parameters of the structure or of the command low and see what is happened with the position, velocities, accelerations, forces and moments in all robot’s joints It is possible to try different control low of the movements like: simultaneously, successive or successive and simultaneously in all joints. The most important of the results is the possibility to know in every moment what is the better velocity characteristic for the dynamic behavior, validate easily the dynamic model and to know what is the variation of the absolute joint’s moments, forces, accelerations and velocities to can calculate all mechanical parts in each joints.

Abstract: The most important things in the dynamic research of industrial robots are the vibration behavior, the transfer function and the vibration power spectral density between some of the robot joints and components. In the world this research is made without the assisted research. In each of the study cases in this paper was used the proper virtual Fourier analyzer and was presented one new method of the assisted vibration analysis. With this research it is possible the optimal choosing the base modulus type to avoid the frequencies from the robot spectrum. In the manufacturing systems, the most important facts are the vibration behavior of the robot, the compatibility with some other components of the system. All the VI where achieved in the LabVIEW soft 8.2 version, from National Instruments, USA. This method and the created virtual LabVIEW instrumentation are generally and they are possible to apply in many other dynamic behavior research.

Abstract: The actual required productivity, accuracy and reliability impose that the robots must be optimized concerning the dynamic behavior. The joints and robots bodies are necessary to be optimized for their usability performance to assure the productivity requirements. The global dynamic compliance (GDC) is one of the most important dynamic parameters of the dynamic behavior of the industrial robots. The viscose global dynamic damper coefficient (VGDDC) is other important parameter of the dynamic behavior what must be optimized to obtain the desired dynamic behavior, the avoiding of the resonance frequencies. The paper shows one new assisted method of the GDC analyzes of the industrial robot with LabVIEW virtual instrumentation (VI) in three different cases: with/without smart magnetorheological damper (MRD) and with aero damper. The created VI-s assures to obtain the assisted research of the dynamic behavior. With this research was possible to determine in the frequencies domain, the robot GDC and the viscose global dynamic damper equivalent coefficient (VGDDEC) value in a case with MRD and finally the transmission of the vibration from the floor to the robot’s tool center point (TCP). This method and the created virtual LabVIEW instrumentation are generally and they are possible to apply in many others dynamic behavior researches.

Abstract: The paper showed the assisted research of one new model of digital dynamic neural network by using the LabVIEW proper virtual instrumentation and proper mathematical model. In the research were used some different way to optimize the convergence process, for example: using one time- delay of the first and second output from the neural layers; using the recursive link and time- delay; using the bipolar sigmoid hyperbolic tangent sensitive function replacing the sigmoid simple sensitive function. By on-line simulation of the neural network it is possible to know what will be the influences of all network parameters like the input data, weight, biases matrix, sensitive functions, closed loops and time- delay, to the gradient errors, in a convergence process. By on-line using the proper virtual LabVIEW instrumentation, were established some influences of the network parameters: number of input vector data, number of neurons in each layers, to the number of iterations before canceled the mean square error to the target. In the optimization research we used the minimization of the gradient error function between the output and the target.

Abstract: In the control of the position of the robots systems one of the more important is to assure the minimum errors between the output and the target. All advanced researches in the word propose to use the neural network (NN) and the learning algorithm like Widrow and Hoff, or Levenberg-Marquard by using the least mean square (LMS) of errors and Delta rule, or back propagation training algorithm. Present paper is showing the mathematical model and numerical simulation of some important neurons types used in many applications that require extreme precision and neural network. All assisted researches were made with the owner LabVIEW virtual instrumentation. The research results and virtual LabVIEW instrumentation can be used in many other mechatronics applications.

Abstract: In the optimization of the trajectory or of the guidance of mobile robots one of the more important things is to assure one small difference between the output data of the system and the target. This paper show how on-line will be possible to establish one convergence way to the target without any influences of the input data or initial conditions of the weights or biases. The paper show the general components and the mathematical model of some more important neurons and one numerical simulation of the linear neural network. In the paper was used the least mean square (LMS) error algorithm for adjusting the weights and biases and incremental training by different training rate, finally to obtain one minimum error to the target.