트러스를 이용한 중력 보상기구의 합성방법

Abstract

This research presents a synthesis method by which a static balancer of a truss is transformed into static balancers of various mechanisms. For conventional design methods the kinematics and potential energy of every mechanism should be computed to design a static balancer. To overcome this limitation the concepts of kinematic syntheses (e.g., Baranov truss and associated linkage) are adopted to the design of a static balancer. The space mapping method is used to design a static balancer in this paper. A sliding mechanism can be derived from a Baranov truss combining two concepts of the Baranov truss and associated linkage. For example, elimination of a link at the 5-link Baranov truss results in a 4-bar linkage and a slider-crank mechanism can be derived from a 4-bar linkage when replacing a revolute joint by a prismatic joint. Variations of kinematic parameters and joint variables are investigated in the viewpoint of the static balancing during transforming a truss (or an associated linkage) to an associated linkage (or a sliding mechanism). The conversion rules are determined in which variations of kinematic parameters and joint variables are summarized in the viewpoint of the potential energy or gravitational torques. When applying the conversion rules to the design equation of the space mapping method, successive deletions of row and column vectors of the design equation occur. These deletion procedures are referred as the deletion rules in this paper. Static balancers of various mechanisms (four-bar linkage, Watt mechanism, Stephenson mechanism and sliding mechanisms) are derived from those of the five-link and seven-link Baranov trusses using the deletion rules. Thus, no computation of kinematics and potential energy is necessary to obtain static balancers of various mechanisms, once a static balancer of a truss has been designed. Simulations results showed that complete gravity compensation is achieved for all derived mechanisms from Baranov trusses. Experiments are conducted with the sliding mechanism derived from the seven-link Braranov truss and show that gravitational torques are effectively counterbalanced.