ABSTRACT
Spatial mechanisms can execute three-dimensional or spatial motion. Spatial mechanism motion is predominantly determined by the degrees of freedom of the mechanism joints used and spatial orientation of the joints. The cylindrical joint can enable spatial mechanism motion because this joint has a translational degree(s) of freedom (DOF) along the z-axis in addition to the planar rotational DOF about the z-axis. Like planar mechanisms, there are also many different types of spatial mechanisms. The chapter considers three types of four-bar spatial mechanisms: the RRSS, 4R Spherical, and RSSR mechanisms. The passive DOF of the coupler link about its own axis of symmetry makes the RSSR linkage ineffective for spatial rigid-body guidance. C. H. Suh and C. W. Radcliffe introduced function generation equations to synthesize RSSR and 4R Spherical mechanisms to approximate six and four precision points, respectively. The MATLAB and SimMechanics files enable the user to efficiently conduct spatial mechanism kinematic analysis and simulation.
