Abstract:

One of the difficult issues is to discover the mapping laws among the topological structure, kinematics and dynamics of mechanisms. The previous work shows that reducing the structure coupling degree can reduce the complexity of solutions of kinematics and dynamics, which reveals one of the relations among topological structure characteristics, kinematics and dynamics. Therefore how to reduce the structure coupling-degree will become an important issue for topological structure optimization of mechanism but is little being studied so far. The principle, design methods and application of the structure coupling-reducing (SCR) are studied. A concept of the SCR is defined. The differences and connections between the SCR and motion decoupling are also revealed. From analyzing topological structures both branched chain itself and branched chains layout between the moving and the static platform of parallel mechanism, two principles and three methods for the SCR are proposed. These three methods are hybrid branched chains method, superposing kinematic joints method, and changing position and orientation characteristics branched chains into driving branched chains method, respectively. Corresponding examples of the SCR are given and some novel mechanisms with low coupling degrees are obtained. The principles and methods for the SCR can be applied to all complex planar mechanisms and spatial mechanisms.

Key words: forward position solutions, kinematics, motion decoupling, structure coupling-reducing, topological structure, topological structure optimization, parallel mechanisms