Multi-motion-platform parallel robot construction method and parallel robots for same

A method of construction a multiple-movable-platform parallel robot, characterized in that:

• the parallel robot is composed of a fundamental parallel mechanism and N1 (N1≥1) branch parallel mechanism(s), each parallel mechanism having the same N2 (2≤N2≤6) degrees-of-freedom (DOFs) and the same DOF property;
• the fundamental parallel mechanism comprises a fundamental base platform, a fundamental movable platform and N2 (2≤N2≤6) main chains connecting the fundamental base platform with the fundamental movable platform, each main chain being composed of two or more generalized kinematic pairs which are connected in series;
• the branch parallel mechanism comprises a branch base platform, a branch movable platform and N2 (2≤N2≤6) branch chains connecting the branch base platform with the branch movable platform;
• the method comprising the steps of:
• (1) constructing the fundamental parallel mechanism:
• wherein the fundamental parallel mechanism meets the following five requirements:
• (a) the fundamental base platform is a planar base platform;
• (b) a first generalized kinematic pair in each main chain is an active pair;
• each main chain has only one active pair;
• an input end of the first kinematic pair of the main chain is a revolute pair or a sliding pair;
• (c) the input end axes of the first generalized kinematic pairs are arranged in one or two or three orientations of:
• being parallel to the plane of the base platform, lying in the base platform plane, or being perpendicular to the base platform plane;
• (d) in two or three preceding generalized kinematic pairs of the main chain, at least one generalized kinematic pair is an expandable output kinematic pair;
• (e) the fundamental movable platform is located at one side of the plane of the fundamental base platform or is co-planar with the fundamental base platform plane;
• in the main chain, a portion for connecting the expandable output kinematic pair with the fundamental movable platform is called as downstream main chain;
• (2) constructing the branch parallel mechanism(s):
• a) selecting and constructing a multiple-output kinematic pair and constructing the branch base platform:
• in each main chain of the fundamental parallel mechanism, selecting an expandable kinematic pair, the expandable kinematic pair being also called as boundary kinematic pair;
• to this expandable kinematic pair, adding an output end which is called as an auxiliary output end, the original output end being called as main output end;
• totally N1 auxiliary output ends being added, the auxiliary output ends having the same function and symmetrical structure with the main output end;
• the symmetricity includes equivalent symmetricity, translational symmetricity, rotational symmetricity, reflective symmetricity, slidingly reflective symmetricity, as well as scaled symmetricity;
• the expandable kinematic pair becomes a multiple-output kinematic pair which has one more output end than the original generalized kinematic pair;
• in the branch chain, a portion for connecting the boundary generalized kinematic pair with the branch movable platform is called as downstream branch chain;
• the downstream branch chain is also called as auxiliary branch chain;
• a lower end point of the branch chain is a hinge point between the branch chain and the branch base platform;
• the hinge points of the N2 branch chains form the branch base platform;
• the branch base platform has the same, similar or substantially the same shape with the fundamental base platform;
• the symmetricity includes equivalent symmetricity, translational symmetricity, rotational symmetricity, reflective symmetricity, slidingly reflective symmetricity, as well as scaled symmetricity;
• b) constructing the auxiliary branch chains:
• to each newly added auxiliary output end, connecting an auxiliary branch chain or an auxiliary branch rod element (the auxiliary branch chain and the auxiliary branch rod element will both be called as auxiliary branch chain below);
• the downstream main chain in this auxiliary branch chain is the same or substantially the same with that of the main chain;
• all the auxiliary branch chains form a group of N2 auxiliary branch chains;
• the auxiliary branch chain is symmetrical with the downstream main chain;
• the symmetricity includes translational symmetricity, rotational symmetricity, reflective symmetricity, slidingly reflective symmetricity, as well as scaled symmetricity;
• c) connecting the branch movable platform:
• to an tip end of each one of the group of the auxiliary branch chains, a branch movable platform is connected, the branch movable platform has the same, similar or substantially the same shape with the fundamental movable platform, and the branch movable platform is symmetrical with the fundamental movable platform;
• in this way, a branch parallel mechanism symmetrical with the fundamental parallel mechanism is formed;
• the symmetricity between the branch movable platform and the fundamental movable platform includes translational symmetricity, rotational symmetricity, reflective symmetricity, slidingly reflective symmetricity, as well as scaled symmetricity;
• (3) repeating substeps a), b) and c) of step (2);
• in this way, one more new symmetrical branch movable platform is obtained, and one more new symmetrical branch parallel mechanism is also obtained;
• repeating the above operation by N1-1 times;
• in this way, N1 new symmetrical branch movable platforms and N1 new symmetrical branch parallel mechanisms are obtained.