Machine efficiency determined using graph and screw theories with application in robotics. (June 2020)

• Record Type: Journal Article
• Authors: Laus, L.P.; Simas, H.; Martins, D.
• Is Part Of: Mechanism and machine theory. Volume 148(2020)
• Publication Date: 2020-06
• Subjects: Efficiency -- Parallel robots -- Closed kinematic chain; Machine theory -- Periodicals; Machinery -- Periodicals; Machines -- Périodiques; Génie mécanique -- Périodiques; Machine theory; Machinery; Periodicals; 621.81
• DOI: 10.1016/j.mechmachtheory.2019.103748
• Languages: English
• ISSNs: 0094-114X

Abstract

Highlights: Paper proposes a new generic method to determine the efficiency of complex mechanical systems. The approach combines graph and screw theories. Examples of application to slider-crank and parallel robot are provided. Loss sources like friction can be included in the model. A new and efficient algorithm for solving the non-linear system of equations is depicted; this rendes huge reduction in computational effort. Abstract: A new method to determine the efficiency of complex machines, including parallel robots, based on graph and screw theories is presented. The method can be used with any arbitrary set of joints connected in any possible way. Graph theory is used to describe the topology and screw theory, the joints geometric features. It is an extension of the Davies' Method in which active coupling is used to model power entering and leaving a kinematic chain. An increase in accuracy is obtained by splitting up prismatic joints, which results in a more realistic model. The slider-crank linkage and the 3-UPU spatial manipulator are used as examples and details on modelling prismatic, revolute and universal joints are presented.