| Closed-form forward/reverse
position solutions for a 6-degree-of-freedom (DoF) parallel mechanism that
has some type of nonsymmetric geometry are derived in this study. Particularly,
the derived forward-position analysis is applicable to the mechanisms in
which three passive joints are constrained to move parallel to the moving
plate. Its kinematic and dynamic characteristics are investigated via isotropic
index of the Jacobian matrix and isotropic index of the output effective
inertia matrix, respectively. From this investigation, it is found that
the mechanism has fairly uniform kinematic/dynamic characteristics throughout
its workspace. To examine the effectiveness of the proposed 3-PPSP-type
mechanism, a prototype is designed, implemented, and tested experimentally
under various operating conditions. A simple PID controller is applied to
the system, and its joint positions are servo-controlled. The controlled
system showed a good trajectory performance. Noting that a more advanced
controller requiring a forward- and/or reverse-position solution can be
applied to the system in real time, it can be contended that the manipulator
is a candidate for the high-precision manipulator. |
