Comparison of Various Dynamic Balancing Principles Regarding Additional Mass and Additional Inertia

Abstract

The major disadvantage of existing dynamic balancing principles is that a considerable amount of mass and inertia is added to the system. The objectives of this article are to summarize, to compare, and to evaluate existing complete balancing principles regarding the addition of mass and the addition of inertia and to introduce a normalized indicator to judge the balancing performance regarding the addition of mass and inertia. The balancing principles are obtained from a survey of literature and applied to a double pendulum for comparison, both analytically and numerically. The results show that the duplicate mechanisms principle has the least addition of mass and also a low addition of inertia and is most advantageous for low-mass and low-inertia dynamic balancing if available space is not a limiting factor. Applying countermasses and separate counter-rotations with or without an idler loop both increase the mass and inertia considerably, with idler loop being the better of the two. Using the force-balancing countermasses also as moment-balancing counterinertias leads to significantly less mass addition as compared with the use of separate counter-rotations. For low transmission ratios, also the addition of inertia then is smaller.

Double Pendulum Balanced by Counter-Rotary Counter-Masses as Useful Element for Synthesis of Dynamically Balanced Mechanisms

“…The double pendulum of Fig. 1 is balanced with the two CRCMs m * 1 and m * 2 as described in [9]. Mass m 2 is force balanced about A by CRCM m * 2 which is a lumped mass with inertia I * 2 .…”

“…One way to reduce the mass and inertia is by using the counter-masses necessary for the force balance of the linkage also for balancing the moment, as shown by Berestov [7]. In [8][9][10] this principle is compared with other balancing principles, showing indeed a reduction of the additional mass and inertia.…”

Enhanced active dynamic balancing of the planar robots using a three-rotating-bar balancer

“…According to what is determined by mechanic, two methods are applied eliminating the adverse impact of the vibrations: passive dynamic balancing (without computer control) and active dynamic balancing (with computer control). 4 Passive dynamic balance of a robot can be achieved by 1 adjusting kinematic parameters such as the length or the mass of a link. 5 With the operation of passive dynamic balancing mechanism, side effects inevitably are produced.…”

Methodology for analysis and synthesis of inherently force and moment-balanced mechanisms: theory and applications

“…Therefore two main approaches have evolved, referred to here as the link-by-link approach where each link is considered for balance individually and the leg-by-leg approach where each leg (connecting the moving platform and the base) of a parallel mechanism is considered for balance individually [59,9,93]. It was shown that these approaches lead to a significant, if not huge, addition of mass and inertia and also to complex designs [94,102,98,97,93,92]. An increase of mass and inertia by a factor four as best result showed already to be challenging to obtain.…”

“…1.10b. Since this counter-rotating inertia is both used as force balance mass and as moment balance inertia, it is regarded a counterrotating countermass which is known to be an advantageous balance solution for low mass and low inertia [102].…”