Computer Animation of Modular Robotic Systems

Introduction - Computer animation provides a means of viewing robot motion to aid in human perception and decision making for both design and operation. Current applications of computer animation to robotics have focused on the simulation and programming of existing robots. The most common uses are workcell design, offline programming and the promotion of research programs. Since robots are usually purchased in their final configuration, there has been little demand for computer applications that aid in the design of the robot itself. The development of a modular reconfigurable robotic architecture presents an excellent opportunity to apply computer animation to the early stages of the robot design. Interactive software packages that generate computer animations have found wide acceptance for programming and simulating industrial robots. Animated workcell design involves graphically placing the robot in its environment, also called the workcell. Machines, tools, parts and any other objects that the robot will interact with are also placed in the workcell. Computer animation is then used to visually simulate these interactions as the robot performs its task. Offline programming uses animation to replace the actual robot while programming the robot's motion and its interactions with its environment. This allows the actual robot to remain in service while motion programs are being developed and thus decreases costly downtime. Research program promotion is also a very important application of computer animation. Computer animation can be used to effectively convey ideas while an impressive graphical simulation of a robot performing a complex maneuver will enhance a company's or research program's high-tech image.

Current robots are purchased in their final configuration from the robot manufacturer. These robots are typically designed to perform a specific class of tasks, and if the application changes significantly the robot is rendered obsolete. The development of a generalized modular robotic architecture using a set of one, two and three degree of freedom joint modules and generic links greatly reduces the threat of obsolescence to the robotic system.' A modular architecture also represents an excellent opportunity to use interactive computer animation in the development of robot technology through research enhanced by the use of three dimensional computer animation as a visualization tool. Available graphics workstations can produce very smooth animations of a robot manipulator moving in a complex environment. Dedicated graphics hardware performs the calculations necessary to display solid-surface models on the computer screen. These images can be displayed in color, three dimensions, perspective and with hidden surfaces removed, resulting in very realistic animations. The main drawback to using these graphics workstations is that writing the programs for computer animation is complex and quite time consuming, often requiring thousands of lines of code to produce a single animation. The difficulty and significant time investment in writing the computer animation code has led to the development of application programs that aid in the production of computer animations on graphics workstations.

A software package under consideration in this article has been developed to interactively assemble and animate robotic systems. This package, which is based on a generalized modular and reconfigurable robotic architecture, facilitates the application of computer animation to robotics research, design and operation. The possible uses of computer animation in robotics research are many. They include the development of obstacle avoidance techniques, redundant inverse kinematics algorithms, dynamic simulations, real-time calculations, manual controllers, serial configurations, parallel configurations, mobile robots, hybrid systems, layered structures with several input scales and world model databases.

Modularity - Modular design is the construction of large systems from smaller discrete units. The benefits to approaching the design of robotic systems from a modular perspective are numerous. From a finite set of one, two and three degrees of freedom joint modules and generic links, a general robotic architecture can be developed. The modular robot is reconfigurable to perform varied tasks and thus reduce obsolescence. The design of the robot is simplified and cost can be reduced by using the same modules in a wide variety of configurations. The integration of technology is facilitated because a new robot does not have to be built in order to test a new idea. The cost of sending payload into space is tremendously expensive, thus making very attractive a robot that could perform many different tasks. Every robot that is sent into a nuclear environment immediately becomes contaminated and must be decontaminated or disposed of. This reality also makes attractive the use of a robot that can be reconfigured to perform many tasks.  Next Page ->