Carbon Fiber Components with Integrated Wiring for Millirobot Prototyping

We are developing a process to quickly prototype millirobotic systems in which the approach is to identify and develop a construction kit for fabricating almost any design, similar to the kits that are available for larger-scale robots. Two of the basic elements of the kit, the links and flexure joints, have been identified, and an assembly method has been developed. This paper deals with the problem of integrating the wiring in these parts, a significant task on this size scale. This novel feature is achieved through the use of a flexible ribbon cable consisting of three wires made out of patterned copper foil and polyimide. Low melting point solder has been tested successfully to make the electrical interconnect between the parts. We discuss the issues that must be addressed in designing the flexure-wiring combination. In addition, the paper presents the methodology for fabricating structures with integrated wiring using a simple four bar mechanism as an example. Finally, the tests show that the wiring loop over a flexure connecting a distally located sensor on the mechanism maintains both its electrical and mechanical integrity even during large motions. Future work will include the automated assembly of the parts with a low cost assembly tool.