Three-Degree-of-Freedom Parallel Mechanical Linkage

Figure 1 depicts a mechanical linkage that converts rotational motion about three base joints (A, B, and C) to translational motion of an end effector (D) in three dimensions. The linkage is fully forward- or back-driveable: It can be driven by motors at joints A, B, and C to obtain a desired translation of end effector D, or else it can be driven in translation at end effector D to generate rotations that can be measured (for example, by use of shaft-angle encoders) at joints A, B, and C. Mechanisms based on this one could be particularly useful as compliant robotic manipulators, force-reflecting hand controllers for such manipulators, and manual position-input devices for computers and other systems (see Figure 2).