| Although spatial mechanisms are more general in structure than planar mechanisms, their applications are few due to the limited number of practical design tools and the complexity of those available. It is in fact the task of the future to develop effective, but practical design tools for spatial mechanisms. This research presents several new methods for synthesizing adjustable spatial mechanisms.; The first method involves the kinematic synthesis of spatial mechanisms for multi-phase motion generation. Using this method, spatial four and five-bar mechanisms can be synthesized to achieve different phases of prescribed rigid body positions. The theory of this approach has also been extended to incorporate rigid body tolerance problems. Using the tolerance problem method, spatial four-bar mechanisms can be synthesized to achieve the prescribed precise rigid body positions and also satisfy the rigid body positions within the prescribed tolerances. Both approaches use the R-R, S-S, R-S and C-S dyad displacement equations.; The second method involves the kinematic synthesis of spatial mechanisms for multi-phase multiply separated positions. Using this method, spatial four and five-bar mechanisms can be synthesized to achieve different phases of prescribed rigid body positions, velocities and accelerations. The theory of this approach has also been extended to incorporate instantaneous screw axis (ISA) parameters. Using ISA parameters, spatial four-bar mechanisms can also be synthesized to achieve different phases of prescribed rigid body positions, velocities and accelerations. Both approaches use the R-R, S-S, R-S and C-S dyad displacement, velocity and acceleration equations.; For each method, the maximum number of prescribed rigid positions is determined for each mechanism for two and three phase problems. The spatial four and five-bar mechanisms considered in this research are the RRSS, RRSC, RSSR-SS and RSSR-SC. |
