A/C Interface Contributing Editor, Raymond Dessy
The following capsule summaries discuss the application of three commercial robot systems to laboratory problems. The Microbot Alpha (Microbot, Inc.) is a revolute design driven by stepping motors in an open-loop configuration. The Zymate robot (Zymark, Inc.) involves a cylindrical geometry, with dc servo motors and potentiometers as position encoders for feedback. The Rhino (Rhino Robot, Inc.) is a revolute spatial design, driven by dc servo motors with digital shaft encoders in the feedback loop. The Microbot Alpha is programmed via a teaching pendant; the Zymate is commanded by a set of soft keys associated with the CRT attached to the microcomputer programming console. The Rhino is progammed via an RS-232 port to its intelligent controller card; any small microcomputer can be used to provide the string of control characters. The three systems range in cost from $2000 to $20,000. Procter & Gamble Company Corporate Technology Division Advanced Instrumentation Group P.O. Box 39175 MVL Cincinnati, Ohio 45247 Contributors: Grower Owens, Rod Eckstein, and Tom Franz
A company engaged in the development and manufacture of many consumer products requires the routine chemical analysis of a large number of samples. Once the analytical method is fully validated and established, its execution is usually a boring, monotonous task. About two years ago, our Advanced Instrumentation Group was in the process of developing and applying powerful microcomputer systems to laboratory control and automation problems. We realized at that time that the full power of the microcomputer in the laboratory environment would not be felt without a flexible, articulate mechanical interface. Using the intelligence supplied by the microcomputer, this mechanical interface could solve the problem of moving samples from place to place. Depending on its complexity and level of
ROBOTS IN THE LABORATORY: PARI II articulation, the mechanical interface might even be able to mimic the human arm and hand in performing sample preparation tasks such as weighing and pipetting. With these considerations in mind, we turned to the rapidly developing field of robotics in search of this mechanical interface. Two years ago the field of industrial robotics was coming of age. A number of robots, or articulated arms, were available commercially. However, the majority of applications at that time were in the heavy manufacturing industries requiring >50-lb payload capacities from large hydraulic robots. Somehow, the thought of a several-ton behemoth bolted to the laboratory floor and leaking hydraulic fluid profusely did not seem appropriate for the analytical laboratory. A few smaller, electrically driven units, notably the Unimate PUMA robots, were available, but their cost exceeded $30,000. Hence, we turned to a small, inexpensive hobbyist-educational robot, the Minimover-5 from Microbot, for use as a development tool. Coupling this unit with an Apple II microcomputer, a pH meter, an electronic balance, a pipettor, and a pressurized solvent dispenser made it pos-
1232 A · ANALYTICAL CHEMISTRY, VOL. 55, NO. 12, OCTOBER
1983
sible to totally automate a pH titration (2). This was an extremely valuable learning experience that resulted in a generalized concept for a laboratory robotic work station. The three obvious components for such a work station are the robot, the microcomputer and its interface hardware, and the specialized instruments that the particular application might require. Two less obvious components are software and special mechanical interfaces. These critical components are the glue that holds the entire system together. The system software supervises the communication and cooperation of the work station elements. The software also schedules the sequence of events and performs whatever computations are required. Special mechanical interfaces encompass any modification of equipment that is required to provide the robot with precise, reliable mechanical coupling with the system elements, including special finger attachments for gripping test tubes, holders for pH electrodes and pipet tips, and racks or magazines for presenting empty test tubes for fresh samples. Desirable attributes for a laboratory robot include: 0003-2700/83/A351-1232$01.50/0 © 1983 American Chemical Society
Figure 1. The Microbot Alpha robot Photo courtesy of Microbot, Inc., Mountain View, Calif.
• positional feedback from each joint, • five or more arm motion axes plus gripper actuation, • three-pound payload capacity, • dedicated microcomputer con troller providing a standard interface protocol for straightforward connec tion to any laboratory computer, • low cost (
