Articles de périodique

Permanent URI for this collectionhttp://192.168.16.104:4000/handle/123456789/5769

Browse

Filter results by year or month
Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Adaptive empirical distributions in the framework of inverse problems
    (2017) Silva, Tiago A. N.; Loja, Maria A. R.; Carvalho, Alda
  • No Thumbnail Available
    Item
    Analysis Randon Causes Repeatability Errors Inducted by Friction at Joints in Industrial Robots
    (2022-02-01) REZALA, Aicha; ARBAOUI, M
    The present study was carried out to investigate and analyze the positionning repeatability introduced by friction variations based on stochastic ellipsoids. A mixed friction model has been developed with improved properties compared to existing standard models. The contact is presented as a multitude of micro contacts whose nature can be of two types: lubricated and solid. This model is experimentally tested on a reciprocating tribometer under extreme friction conditions, with sliding speed varying from 0.1 to 3 m/s and load modified from 40N to 150N to discuss the effect of speed, the effect of nominal contact pressure and the effect of sliding distance on friction parameters. The results showed how this model can be represented as a sum of functions of the relevant states, which are linear and nonlinear in the friction parameters. Thus, these results were used to evaluate the covariance matrix in order to locate the different ranges of errors which have an impact on the repeatability of position.
  • No Thumbnail Available
    Item
    CONTRIBUTION TO IMPROVING THE MECHANICAL CHARACTERISTICS OF MATERIALS USED IN THE STRUCTURAL COMPONENTS OF INDUSTRIAL ROBOTS BY BOROCARBONITRIDING TREATMENT
    (2024-02-13)
    Knowledge of the mechanisms by which contact surfaces deteriorate is necessary in order to improve the wear behavior of industrial robots. Reducing friction and wear in mechanisms of all kinds is still a sensitive design issue, and remains crucial in cutting-edge technologies where energy savings and reliability must go hand in hand. Determining the tribological behavior of materials would enable us to increase the efficiency and lifespan of industrial robots, etc., which would result in better operation without the risk of equipment damage or breakdown. The robust design of a mechanism aims to ensure that its performance is optimal and unaffected by variations. Hence the economic impact on the user. This paper presents a state of the art review of the methods used in robust mechanism design. Conventional technological solutions involve the formulation of a pair of materials and a contact geometry adapted to the tribological constraints of the mechanical system (pressures, speeds). Thermochemical treatment is a very effective way of remedying the static and dynamic errors caused by the operation of industrial robots. In this research work, we thought of improving the reliability of our industrial robot structure by improving the mechanical characteristics of the tribological systems that make it up. We would therefore apply thermochemical treatments with a rational choice of materials for the various contact surfaces with the aim of ensuring the quality of the robot’s operation and obtaining the lowest possible cost price. Tests were carried out on various ferrous alloys. The results obtained were used to validate the improved additive elements in the base alloys proposed for the construction of robot modules. A comparison of the results obtained with those reported in the literature shows good agreement. Keywords : Borocarbonitriding tr