RAPID PROTOTYPING OF ROBOTICS SYSTEM

RAPID PROTOTYPING OF ROBOTICS SYSTEM

Abstract

In this paper, the application of Rapid Prototyping in fabricating non-assembly robotic systems is presented. Using the Stereolithography Apparatus SLA 190 of the Department of Mechanical and Aerospace Engineering of Rutgers University, and the Selective Laser Sintering Sinterstation 2000 of DTM Corporation of Austin, TX, prototypes of mechanical joints were fabricated experimentally. The designs of these component joints were then used to fabricate the articulated structure of experimental prototypes for two robotic systems:

1) A three-legged parallel manipulator.
2) A four degree of freedom finger of a five-fingered robotic hand.

Introduction

It is always desirable to evaluate a proposed robot design prior to full prototyping to ensure the swiftest and most cost effective design changes. Even though powerful three dimensional Computer Aided Design and Dynamic Analysis software packages such as Pro-Engineer, IDEAS, ADAMS and Working Model 3-D are now being used, they can not provide important visual, haptic and realistic workspace information for the proposed design. In addition, there is a great need for developing methodologies and techniques that will allow fast design, fabrication and testing of robotic systems. A frame work for the feasibility and usefulness of applying Rapid Prototyping in fabricating robotic systems is presented here.

Rapid prototyping of parts and tools is a rapidly developing technology [1, 2] with many advantages: a) time and money savings, b) quick product testing, c) expeditious design improvements, d) fast error elimination from design, e) increased product sales, and f) rapid manufacturing. Its main advantage is early verification of product designs. Rapid Prototyping is quickly becoming a valuable key for efficient and concurrent engineering. Through different techniques, engineers and designers are now able to bring a new product from concept modeling to part testing in a matter of weeks or months. In some instances, actual part production may even be possible in very short time. Rapid Prototyping has indeed simplified the task of describing a concept to design teams, illustrating details to engineering groups, specifying parts to purchasing departments, and selling the product to customers.

Robotic systems have been used as part of a rapid prototyping process [3, 4]. However, the application of Rapid Prototyping in robot design and fabrication has been very limited. One of the first works to rapidly fabricate robotic systems was made by Professor Gosselin and his group at Laval University who used a Fused Deposition Modeling Rapid Prototyping machine [5]. Several mechanisms were fabricated such as a six-legged six degree-of-freedom parallel manipulator. These rapidly manufactured mechanisms required assembly after Rapid Prototyping of the mechanism parts.

Recently, our group at Rutgers University has fabricated a three-legged, six degree-of-freedom Rapid Prototype of a parallel manipulator in one step, without requiring assembly [6]. To do this, a set of joints that includes revolute, prismatic, universal and spherical joints, was fabricated using the Stereolithography machine model SLA 190, from 3D Systems, CA. Each leg of the three-legged platform was composed of two spherical and one prismatic joint and was connecting two triangular links. To the authors’ knowledge, this is the first successful fabrication of a multi-joint, multi degree of- freedom robotic system that was Rapidly Prototyped without requiring any assembly.

The use of Rapid Prototyping in the fabrication of non assembly type robotic systems is further explored in this paper. The main focus of this investigation is the successful design and construction of articulated structures using another prototyping technique known as Selective Laser Sintering (SLS). Prototype joints similar to those fabricated with the Stereolithography process, are Rapidly Prototyped using the Selective Laser Sintering Sinterstation 2000 of DTM Corporation of Austin, TX. In addition, one four degree of freedom finger of a robotic hand with four fingers, a thumb and a palm is constructed as one non-assembly type mechanism. Rapid actuation of the joints of the rapidly prototyped systems is outside the scope of this paper and will be studied in our future work.

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