Rapid Prototyping for Robotics

The design of robotic mechanisms is a complex process involving geometric, kinematic, dynamic, tolerance and stress analyses. In the design of a real system, the construction of a physical prototype is often considered. Indeed, a physical prototype helps the designer to identify the fundamental characteristics and the potential pitfalls of the proposed architecture. However, the design and fabrication of a prototype using traditional techniques is rather long, tedious and costly. In this context, the availability of rapid prototyping machines can be exploited in order to allow designers of robotic mechanisms or other systems to build prototypes rapidly and at a low cost. This chapter summarizes the research experience of two research groups, one at Universit ́e Laval, the other at Georgia Tech, concerning the rapid prototyping of mechanisms. The two groups employed two different types of RP technology, Fused Deposition Modeling (FDM) and Stereolithography (SL), respectively, and the use of both is described in this chapter. The two types of Rapid Prototyping technologies considered here, FDM and SL, are both based on the principle of Additive Fabrication, i.e. parts are built by adding material to the whole, as opposed to subtracting material from the whole (as is done in traditional machining processes). FDM and SL both build three-dimensional parts from a CAD model by building one layer after the other, which facilitates the construction of parts with any desired internal and external geometry in a fraction of the time and cost necessary to build them using a conventional process (Ashley, 1995). Additive Fabrication therefore provides several advantages for the quick and efficient construction of mechanical prototypes: • Quick turn-around time, thus facilitating many design iterations; • No limits on part complexity, as parts with complex geometry can be built just as quickly and cheaply as parts with simple geometry; • Since most components are “self-made”, there are no issues of components being available only in certain sizes from a manufacturer; • Since the designer has access to the interior of the part during the build process, Additive Fabrication provides novel design possibilities (Binnard, 1999). These capabilities can be exploited to yield short-cuts that eliminate the need for fasteners and the need for assembly of the prototypes.