Platform Robots: Gradation of Mechanisms Based on Their Structural Error Performance

Robot arms which received greater attention in the recent past are open chain linkages. Each joint in these robot arms, is actuated independently. While possessing many advantages such as large workspace and maneuverability, they do suffer from disadvantages like less rigidity, accumulation of mechanical errors from shoulder to end effector, control problems etc. The alternative to the open chain robot arms is the in - parallel actuator arrangement often referred to as the platform-type whose successful application is reported by many investigators. Multi-degree-of-freedom linkage Mechanisms are now receiving active consideration for application as platform type robots. In fact in the literature, a number of distinct multi degree of freedom planar linkage mechanisms are available and all of them can be considered as platform type Robots. In this paper numerical measures are proposed to compare all the distinct planar linkage mechanisms at the conceptual stage of design in the category of 9 link, 2 degree of freedom and 10 link,3 degree of freedom, from the view point of structural error performance. The proposed method is based on the deployment of design parameters in different topological features of the chain Viz., links, Joints and loops.