A method to fabricate complex structure for variable stiffness manipulators based on low-melting-point alloy

Compared to rigid manipulators, the soft manipulator can operate inside some special environments, such as cavity, assembled machine, or other crowded rooms. The movement of soft manipulators is generated by structural deformation instead of joint rotation used by rigid manipulators. Structure of the soft manipulator is often required to be complicated and lightweight to guarantee the load capacity and positional accuracy. 3D printing technology and casting can be applied to fabricate the above structure, but it is also difficult to be applied to fabricate a complex and variable stiffness structure. To solve the problem, we proposed a method to fabricate a complex structure with multiple hollow by assembling mold, which can achieve light weight and high rigidity of the structure. In addition, the molds are low-cost and easily to be assembled and disassembled, and low-melting-point alloys (LPMA) has good liquidity inside the molds. The structure fabricated by this method demonstrates large stiffness variation range and load capability.