Ion Simionescu

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.

Mobil Mechatronic System with Applications in Agriculture and Sylviculture

Abstract Walking mechatronic systems protected much better the environment when their contact with the soil is discrete, a fact that limits appreciately the area that is crushed. In order to make and to control a walking robot, one needs the knowledge of all walking potentialities since the choice of the number of legs as well as of their structures depend on the type of gait that has been selected. In the Mobil Robots Laboratory of the POLITEHNICA University of Bucharest, a four-legged modular mechatronic system has been built and tested, while a hexapod one is being tested.

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 Industrial Robot Grippers

Of all feasible designs, some are “better” than others. If this is assumed as true, then there must be some quality that the better designs have more of than the lees desirable ones do. This quality must be expressed as a computable function of the design variables, and it can consider optimizing to obtain a “best” design. The function with respect to which the design is optimized is called the objective function. In some design situations, there may appear to be two or more quantities which should be objective functions. The goal of the kinematics synthesis of the linkages is to establish the kinematics dimensions of the component elements provided that some conditions are imposed regarding movements of some points or elements. As a rule, only conditions about the positions of the points or elements are imposed. In the other words, only the transmission functions of the positions are used to write the synthesis equations. The solving of the kinematics synthesis problems is reduced to the solving of some nonlinear equation systems. As a result, the problems of the kinematics synthesis of linkages do not have the unique solutions. Only in some very simples particular cases the system of synthesis equations is linear and problem has a single solution. In the optimum synthesis of the gripper mechanisms, the objective function may express the positioning precision of the work pieces, the magnitude of the driving force, the domain of the stable fastening of the work pieces etc. In the work, some considerations about the optimum synthesis of the two fingered self centering grippers are shown.

The Modular Walking Machine, Platform for Technological Equipments

Walking robots represent a special category of robot, characterized by having the power source and technological equipment on-board the platform. A walking robot can traverse most natural terrains. The advantages of a legged system for off-road use have been gradually recognized. One of the most important advantages is mobility.

Autonomous Robot for Mining Exploration: A Structomatical and Kinematical Model for Uneven Ground

This paper deals with the analysis of the mechanical system of a self-propelled vehicle on the tires able to move on an uneven ground whilst his platform stays horizontally. It is question to simulate the movement of a desmodromic robot which moves in an environment represented by a 3D surface. The robot has a mechano-hydraulic system which is able to modify the geometry of chassis in the aim of maintaining the platform always at horizontal while in movement, no matter the soil configuration (of course between some limits).The horizontalisation mechanism with the rolling train hydraulically driven presents some difficulties because of the non holonomic constraints of the wheels ([1, 2]). In order to make the application of the multipoles theory in the structomatical model must be introduce some simplifications in the contact joint. Thus, the non holonomic joints are presented like gamma active joints (with the condition of controlled rolling/skidding).This is an extension of the general principle of mechanism formation ([3]) according who any mechanical structure can be broken in genes upon an unique formula (the genetic code of the mechanism).Because of the complexity of the calculus the study of mechanism was divided in a few chapters: geometrics, structomatics, kinematics, kinetostatics and dynamics etc. The uttermost important and difficult part is the kinematical model because of the non-linearity of the equations. This article presents the first two items; the others will be the matter of future papers.

On the Singularities of DELTA Parallel Robots

The major disadvantage of the parallel robot is that the singular positions are comprised into the work space. The singular positions are the particular poses for parallel robot DELTA where the mobility of the structure is not longer zero when the actuators are locked. Present analysis is focused on the determinant value of the Jacobian matrix of the kinematic analysis equation system, written using Denavit – Hartenberg transformation matrices. The kinematic equations possess the algebraic and trigonometric character, so that the inverse singularity analysis can be formulated. By instantaneous mobility analysis of the moving platform of the parallel robots, the geometric conditions for the forward singularity configurations are identified. Finally, a numerical example is solved in order to illustrate the variation of the Jacobian determinant in the proximity of a singular position.

A Comparative Study on Geometric and Kinematic Parameters of Serial (4R) and Parallel (3T) Robots

A geometric and kinematic study between two structures of robots was performed, respectively a mechanical anthropomorphic structure, with bars and gears, with four degree of freedom, (dof), redundant (4R), which canavoid obstacles and a parallel manipulator with translation on three axes (3T). This 3T structural solution allows rapid and precise movements, which are important characteristics for machine building industry. All these features make the parallel manipulator to be an attractive alternative to the serial ones for high precision operations in a limited workspace.