Analysis of a Novel 6-DOF, 3-PPSP Parallel Manipulator

Abstract

A novel kinematic structure for a parallel manipulator with 6 DOF is proposed. It consists of a platform that is connected to a fixed base by means of 3-PPSP (P—prismatic joint, Sspherical joint) subchains. Each subchain is connected to a passive prismatic joint at the one end, and a passive spherical joint at the other. The spherical joint is then attached to perpendicularly arranged prismatic actuators that are fixed to the base. Due to the efficient architecture, the closed-fonn solutions of the inverse and forward kinematics can be easily obtained.As a consequence, this new kinematic structure can be servo controlled using simple inverse kinematics, because forward kinematics allows for measuring the platform 's position and orientation in Cartesian space. Manipulator workspace determination is carried out through the computation of displacements in the prismatic joints. A Jacobian matrix for the proposed structure is derived so the relationship between actuator forces and output forces/moments of the mechanism can be analyzed. A series of simulations were performed to verify the results of the kinematics analyses and to evaluate the load characteristics of the system.

A new 6-DOF parallel robot with simple kinematic model

“…There are different avenues for solving (10)(11)(12)(13), including the use of Gröbner basis, but the following approach is by far the most elegant one. We obtain four new equations by − subtracting (12) and (13) from the sum of (10) and (11); − subtracting (11) and (13) from the sum of (10) and (12); − subtracting (11) and (12) from the sum of (10) and (13); − adding (10), (11), (12) and (13).…”

“…Of course, the Hexapteron is not the only 6-DOF parallel robot with trivial direct kinematics. However, virtually all other such parallel mechanisms are either three legged (e.g., [11][12][13]) or asymmetrical (e.g., [14][15]) or require double or triple spherical joints (e.g., [15]). …”

Some New Parallel Mechanisms Containing the Planar Four-Bar Parallelogram

“…At the same time, they also suffer problems of complex forward kinematics, relatively small useful workspace, especially limited rotational capability for the reason of at least six kinematic chains and more multi-DoF joints. There are also some 6-DoF parallel mechanisms with three legs, in each of which two actuators are attached, e.g., the 3-PRPS mechanism (Behi 1988;Alizade and Tagiyev 1994), 3-PPSP (Byun and Cho 1997), 3-RSPR (Sima'an, Glozman, and Shoham 1998), and, especially, a mechanism with the 2-DoF planar actuator (Ben-Horin and Shoham 1996). Compared with a 6-DoF mechanism with six legs, such a mechanism has a much larger workspace, very simple forward and inverse kinematic solutions, fewer moving parts and joints.…”

A Six Degree of Freedom Epicyclic-Parallel Manipulator

“…A number of three-legged manipulators have been reported, such as Refs. [17][18][19][20][21][22][23], however, very few of them have all actuators allocated on the ground, [19,22,23] being some examples. Cleary and Brooks [19] used a differential drive system, Lee and Kim [22] used a gimbal mechanism and Monsarrat and Gosselin [23] used five-bar mechanisms as input drivers to allow for all actuators to be mounted on the base of a three-legged six-dof parallel mechanism.…”