Liviu Ciupitu

The static balancing of the industrial robot arms: Part II: Continuous balancing

The paper presents some new constructional solutions for the balancing of the weight forces of the robot arms, using the elastic forces of the helical springs. The balancing is exactly realised in all points of work field by using the elastic system which contains the high pair mechanisms. For the performance study of the static balancing mechanisms, a new notion, namely efficaciousness coefficient, is defined. This coefficient is equal to the ratio of the mechanical work consumed for acting the unbalanced arm and the mechanical work consumed for moving the balanced arm. The static balancing mechanism is useful if the efficaciousness coefficient is greater than one. Finally, the results of solving a numerical example are presented.

The static balancing of the industrial robot arms: Part I: Discrete balancing

The paper presents some new constructional solutions for the balancing of the weight forces of the industrial robot arms, using the elastic forces of the helical springs. For the balancing of the weight forces of the vertical and horizontal arms, many alternatives are shown. Finally, the results of solving a numerical example are presented.

Optimum Design of Balancing Systems with Cylindrical Helical Extension Springs

The static balancing of the weight forces is necessary to any mechanical system which is not working in horizontal plane. The effect is the decrease (until to vanishing) of the acting power. From practical point of view two main ways of static balancing could be taken into consideration: by mass redistribution of components or/and by adding counterweights, and by elastic forces of the springs or of the gases. The first solution is not always possible due to the dimensions of mechanical systems and due to increasing of the dynamic stresses of components. Second solution is more and more used to various mechanical systems.The complexity of balancing systems with springs comes from the need of using zero-free length springs. In any case the mathematical model has not a unique solution. Present paper is an extension of a paper of first author [1] and is presenting a method to find the optimum solution of the simplest elastic system which is using a real helical extension spring with finite-free length. Design variables are the position of spring’s joints, as well as the constructional parameters of a extension spring. Finally some examples are presented.

Static Balancing of Mechanical Systems Used in Medical Engineering Field – Continuous Balancing

In medical field are used many categories of mechanical systems, from simple mechanisms to the complex mechatronic systems. Present paper is focused to those mechanical systems that are working in vertical plane by supporting loads or by lifting weights. The targets are both patients and medical workers. Paper is proposing some new devices and mechanisms for supporting the weights that are hanged to the ceiling. These mechanical systems are called too with zero-stiffness because the balancing force does not depend to elongation of elastic system. For all the presented solutions the balancing of the weight forces will be done by using the elastic forces of torsion spiral springs and cylindrical helical springs with straight characteristics. The balancing is made exactly for all positions throughout the work field.

Optimum Design of Balancing Systems with Real Springs

The static balancing of the weight forces of any mechanical system which is not working in horizontal plane is considered in order to decrease the acting power. From practical point of view two main ways of balancing could be taken into consideration: by mass redistribution of components and/or by adding counterweights, and by elastic forces of the springs or of the gases.The first solution is not always possible due to the clearance diagram of mechanical systems and due to increasing of the dynamic stresses of components. Second solution is more and more used to various mechanical systems and many constructive solutions were proposed in last time. The complexity of balancing systems with springs comes from the need of using zero-free length springs.In any case the mathematical model has not a unique solution. Present paper is continuing a former paper of author and is presenting a method to find the optimum solution of the simplest elastic system which is using a real spring. Design variables are the position of spring’s joints, as well as the constructional parameters of a real spring.

Robotic Arm with 9 DOF Driven by Spherical Ultrasonic Motors

Abstract Research team of Prof. Shigeki TOYAMA is developing at Tokyo University of Agriculture and Technology a new type of ultrasonic motor. Its spherical shape confers 2 or 3 DOF in a single joint which makes it suitable for mechatronics field and especially for industrial robots of articulated kind. In that paper is presented a robotic arm with 9 DOF driven by 3 Spherical Ultrasonic Motors (SUM) which can by used in assembly and manipulating operations.

Optimization of the Robot's Position Base Point by Using the Proper Algorithm and Iterative Pseudo Inverse Jacobian Neural Network Matrix Method

In the robotized production one of the more important think is to choose the optimal solution to use the robots with respect an objective function which represents, for example, minimum time of motion during a application, or minimum consumption of energy, or maximum precision, or combination of these. Some objective functions could results from the specificity of the application like is the case of casting of forging, where the minimum of the accumulation of heat could be one of the optimization criteria. In the controlling of the space movement of the end effecter and the robot’s joints of the all robots from the applications, one of the most important think is to know, with the extreme precision, the joints relative displacements of all robots. One of the most precise method to solve the inverse kinematics problem in the robots with redundant chain is the complex coupled method of the neural network with Iterative Pseudo Inverse Jacobian Matrix Method. In this paper was used the proper coupled method Iterative Pseudo Inverse Jacobian Matrix Method (IPIJMM) with Sigmoid Bipolar Hyperbolic Tangent Neural Network with Time Delay and Recurrent Links (SBHTNN-TDRL) to establish the optimal position of the application point of the robots base with respect simultaneously two objective functions: the extreme precision and the minimum of the movements time. The paper shown how can be changed the multi robots application in to one application with parallel robot structure with three independent robots, all of them with optimal location point with respect the obiective function. The presented method and the virtual instrumentations (VI) are generally and they can be used in all other robots application and for all other conventional and unconventional space curves.

Optimal Location of Robot Base with Respect to the Application Positions by Using Proper Neural-Network Method

Usual the location of robot base with respect to positions (configurations) of an application that the robot must reach is choose in such a way that the application points to be into working space of robot by avoiding the obstacles. Or the application is build from the very first beginning in such a way that all application points to be in the working space of robot because usual the robot base is fixed to the ground. But this is not the optimal solution with respect to an objective function which represents for example minimum time of motion during a cycle, or minimum consumption of energy, or maximum precision, or combination of these. Some objective functions could results from the specificity of the application like is the case of casting of forging where the accumulation of heat for example could be one of the optimization criteria. For example in the automotive industry the owners prefer to replace the whole robotized line when the product is changed instead of reprogramming robots because the prices of robots is decreasing and the price of reprogramming is increasing. For such a situation the placing of robot base in an optimum location from the very first beginning so that the time or/and energy consumption to be minimum is an essential initial task, especially for large series productions. The proposed paper is dealing with the subject of moving the base of robot with respect to the application points so that an objective function representing the minimum time of motion during a cycle to be fulfilled.

Active Static Balancing of Mechatronic Systems - An Overview

Static balancing of a mechanical system can be regarded as the total or partial cancellation of the mechanical effects (force or moment) of static loads to the actuating system of it, in all configurations, respectively in a finite number of configurations, from functioning domain, under quasi-static conditions. Active balancing is taking into consideration the variation of static loads during the functioning of mechanical systems. As a consequence the active balancing requires an adaptive controlling system and a dynamic model of mechatronic system. In this article, some aspects of the active static balancing problem of mechanical systems are surveyed.

Educational Model for the Kinematic Study of Non-Circular Gears

The noncircular gears are used more and more in industrial applications. The paper presents an educational test rig for the kinematic study of non-circular gears. Two gears are studied from kinematic theoretically point of view: a gear with identically oval spur gears and another gear with identically elliptical spur gears, and simulation diagrams are presented. As for the testing rig, a gear with identically oval spur gears has been used. The researchers are able to draw with high precision the variation curve of output angle with respect to input angle. By using numerical methods for integration and differentiation other diagrams could be drawn and a comparation with simulation diagrams could be made.