Welcome to the McGrath Brothers'

Overview


Operation

The remote user downloads the necessary software (videoconferencing software and custom drawing software). The user then executes these programs and attempts to connect to the RTS (Robot Terminal Server) via Internet. If the robot is available for use, the user receives an indication that the connection is sucessful. The robot moves to a home position, activating the room lights. The user now selects a color pen and begins drawing on a "virtual canvas" that simulates the resulting lines (the robot grabs a real pen and begins drawing on the board). Left clicking the mouse causes the pen to press on the board, right clicking the mouse lifts the pen for travel without drawing. The user is free to change color pens at will. The connection is closed after a timeout period or when the user closes the drawing application.

Background

While searching for a suitable senior project for the Electromechanical Engineering Technology program at VTC, a suggestion was made to increase the utility of a robot arm donated by IBM. After considering other project ideas, Scott and Bill McGrath decided to pursue this idea. In their tradition of interfacing things to the web (see the WVTC WEB-DJ project), a scheme for operating the robot arm remotely was developed. The activity chosen to demonstrate was drawing.

A siginificant amount of programming, circuit design and construction, and mechanical design and fabrication was required to implement such functionality. This meant that the project met the criterion set forth for senior projects as well as satisfying the McGraths' desire to challenge themselves.

Description

The project's problem statement reads:

Design, build, and develop a system that will enhance the utility of and demonstrate the capabilities of the PUMA 562 robot arm.

The chosen solution statement:

Interface the PUMA 562 with a common PC, allowing it to be remotely operated over the network and perform such tasks as allowing an Internet user to draw on a canvas. Create a software package, interface circuits, a versatile end effector, and a standardized tool holder to do this.

The robot will allow users anywhere in the world to connect to the robot through the Internet using customized software. These users will then be able to draw on a board using various pens. Additional consideration will be given to making the robot easier to re-use for other applications by improving the interface to the robot.

The budget for this project is very small, so techniques to reduce the cost of the project will be employed wherever possible.

Theory of operation

The custom drawing application is executed on the remote user's computer. A connection is established over TCP/IP (Internet) with the RTS (Robot Terminal Server). The RTS, running a custom Windows 95 program, sends this data through RS-232 and the parallel port, and communicates with the URC (Unival Robot Controller). The URC has software written in the VAL-II language which accepts these commands, confirms the safety of each command, and translates the location information to points on the board in the physical world. The URC provides power and control of the motors in the robot arm and maneuvers the arm to comply with the command.

The RTS also selects television camera views and converts the video signals to data for delivery by the videoconferencing software.

An interface box that uses optoisolators and is attached to the RTS allows system supervisors to remotely monitor the URC's front panel, indicating arm power, program run, and fault conditions. This also allows the remote supervisor to enable and disable the robot, to execute programs, and to energize or remove arm power.

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© Copyright 1998-1999 by Bill McGrath and Scott McGrath. All rights reserved.
Questions/Comments: smcgrath@vtc.vsc.edu
Last Revised: Thursday, March 18, 1999