After-notes in Kinematics
Y.M. Ram
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1.2 Mobility The MobilityMdefines the number of degrees of freedom of a system. For 1≥Mthe system is a mechanism with Mdegrees of freedom. If 0=Mthe system is a statically determinate structureand generally no relative motion between the links is possible. If 0<Mthen the system is a statically indeterminate structure. The mobility may be determined by the Grubler’s equation ()21213ffnM−−−=, (1.2.1) where nis the total number of links (including the ground) 1fis the number of one-degree-of freedom joints 2fis the number of two-degree-of freedom joints Pure rotation joints, pure sliding joints, and pure rolling contact joints are of 1fcategory. Rolling & sliding contact joints are 2ftype. Example 1.2.1 Using the Grubler’s equation determine the mobility for the devices shown in Figure 1.2.1