Kinematic analysis and design of a new 3T1R 4-DOF parallel mechanism with rotational pitch motion

Less degree-of-freedom robots are useful for special applications. Specifically, practical application of 4-DOF parallel mechanism has been rare, though synthesis on this type has been conducted quite a few. Recently, we proposed a revolute joint-based 3T1R 4-DOF parallel mechanism having Schonflies motions whose output rotational motion is a roll motion. This work proposes another type of a new 3T1R 4-DOF parallel mechanism having Schonflies motions whose rotational motion is a pitch motion. The position analysis and kinematic modeling for the mechanism are performed, and its workspace size and kinematic characteristic with respect to the kinematic isotropic characteristic are examined. To support high potential of the mechanism for real applications, three different versions are suggested and each motion capability is verified through its simulator. Finally, a prototype is developed to verity its actual motion capability.