Abstract
A New hybrid cylinder/wire drive parallel arm (simply called“hybrid arm”) for manipulating heavy materials in construction and ship building works is proposed. The total number of cylinder and wire is fixed to seven based on the force closure principle, and the kinematics and statics are formulated for hybrid arms with arbitrary combination of cylinders and wires. Various hybrid arms with different combination of cylinders and wires are compared with the conventional Stewart platform and a multi wire drive mechanism, evaluating their workspace with orientation. The workspace is determined under the constraints on the interference between the links and the limitation of the cylinder force and wire tension. As a result, the most suitable hybrid arm for heavy material handling is the mechanism with three cylinders, four wires, and one connecting rod between the cylinders and the end plate. Furthermore, this hybrid arm is modified into the mechanism with variable length rod for the application of manipulating a precasting concrete board with the size of 3×6×0.2 [m] and the weight of 10 [t], which is used in automatic building construction systems; the prototype of this arm is designed and developed.
