[PDF][PDF] Dynamic balancing of mechanisms by using an actively driven couter-rotary counter-mass for low mass and low inertia
Second international workshop on fundamental issues and future …, 2008•research.utwente.nl
Dynamic balancing of mechanisms still goes together with a considerable increase of mass
and inertia. The goal of this article is to actively balance various useful 1-, 2-, and 3-degree-
of-freedom planar and spatial, serial and parallel mechanisms and to show that active
balancing is a good alternative for low mass and low inertia dynamic balancing. It is
proposed to force balance mechanisms with the minimum number of countermasses and to
use the inertia of these counter-masses to balance the moment by actively controlling them …
and inertia. The goal of this article is to actively balance various useful 1-, 2-, and 3-degree-
of-freedom planar and spatial, serial and parallel mechanisms and to show that active
balancing is a good alternative for low mass and low inertia dynamic balancing. It is
proposed to force balance mechanisms with the minimum number of countermasses and to
use the inertia of these counter-masses to balance the moment by actively controlling them …
Abstract
Dynamic balancing of mechanisms still goes together with a considerable increase of mass and inertia. The goal of this article is to actively balance various useful 1-, 2-, and 3-degree-of-freedom planar and spatial, serial and parallel mechanisms and to show that active balancing is a good alternative for low mass and low inertia dynamic balancing. It is proposed to force balance mechanisms with the minimum number of countermasses and to use the inertia of these counter-masses to balance the moment by actively controlling them with an additional actuator. The counter-masses then are driven such that they counterrotate with respect to the mechanism and the dynamic balance is obtained. Herewith the advantages for low mass and low inertia of the counter-rotary counter-mass (CRCM-) principle and the principle of duplicate mechanisms (DM) where a mechanism is balanced altogether (instead of link by link), are combined. A double pendulum is actively balanced, compared with other balancing principles, and used for the synthesis of various actively balanced manipulators.
It was found that dynamic balancing by active control of the CRCM (ACRCM) results into a better total mass-inertia relation then balancing with nonactive CRCMs or using separate counterrotations for the moment balance. The DM-principle still is better, however the size of the ACRCM-balanced mechanism is considerably smaller. For a low mass and low inertia addition, the ACRCM should have a large inertia and a low mass. Active control of the ACRCM has the advantage of being able to compensate for disturbances that affect the moment balance, such as drift, belt elasticity or external forces. Disadvantages are the addition of a controlled actuator and difficulty to handle high accelerations as for example due to impact. It is shown that a planar 3-RRR parallel manipulator and a spatial 3-RRR parallel manipulator can be dynamically balanced with respectively one and two ACRCMs. It is also shown that a 3-DOF planar 1-RRR serial manipulator can be completely dynamically balanced by a single ACRCM.
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