NUWAR Literature
Publications associated with NUWAR

This contribution presents the workspace analysis process leading to the development of the concept of a New University of Western Australia Robot - NUWAR. NUWAR is a variation of the well-known Delta parallel robot. It is of particular interest to determine, for given dimensions of a manipulator, how the size and shape of the robot workspace vary with values of two angles defining the orientation of motor axes. Finding the optimal values of these angles, from the point of view of the workspace volume has been an objective of this study. Computer simulations indicated that the configuration described by motor axis inclination to the horizontal plane a degrees and the angle between the motor axis and the sides of the base triangle b degrees - known as the New University of Western Australia Robot - NUWAR - is advantageous over Delta configuration in terms of workspace volume and shape.

Parallel robots, unlike serial, traditional ones, have the end effector connected to the base by several kinematic chains in parallel. Research into the field of parallel robots documented in the literature dates back to the year 1938, when Pollard patented his mechanism for car painting [Pollard 1938]. In 1947 McCough proposed a 6-degree-of-freedom platform, which was later used by Stewart in his flight simulator [Stewart 1966]. Parallel manipulators are particularly suited to a number of typical industrial applications and have presented a lot of interest to various researchers over the years. In recent years, several new structures and mechanisms have been proposed, developed for a variety of both established and novel applications, such as packaging, assembly, haptic interfaces, etc [Arai and Tanikawa, 1996; Badano et al. 1993; Clavel 1988; Pierrot et al. 1991; Tsumaki et al. 1998].

Parallel manipulators possess a number of advantages when compared to traditional serial arms. They offer generally a much higher rigidity and smaller mobile mass than their serial counterparts. These features alow much faster and more precise manipulations. A catalogue of a large variety of parallel configurations can be found in the book by Merlet and at his internet page [Merlet, 1990, 1998].

The Delta robot [Clavel 1988] is an original design that arose from the need detected in the production and manufacturing sectors for manipulators better suited to the fast execution of light-duty tasks. As seen from the figure 1, the three closed kinematic chains consisting of arms and parallel rods, are identical and actuated by three revolute electric motors rigidly mounted to the top (robot base), and closed below at the common tool-base by ball joints. The combination of the constrained motion of these three chains results in three translatory degrees of freedom for the robot tool-base. Capable of achieving 500m/s², the direct drive DELTA robot is one of the fastest robots in the world.

This study considers the feasibility of other configurations for three degree of freedom parallel robots, and discusses the potential advantages of a particular arrangement. Like the Delta, the robot considered in this paper consists of three kinematic chains in parallel, which connect the base to the end effector. It is of particular interest to determine, for given dimensions of a manipulator, how the size and shape of the robot workspace varies with values of two angles defining the orientations of motor axes. An objective of this study was investigating, whether the kinematic configuration with motor axes perpendicular to one another is advantageous ove the Delta configuration.

Department of Mechanical and Materials Engineering
The University of Western Australia
Nedlands, Perth, Western Australia  6009
 

WEB DESIGN: ZEIKE TAYLOR
zeike@tartarus.uwa.edu.au