Teleoperation of the Thaw Telescope at the Allegheny Observatory: A Case Study

François E. Cellier
Institute of Computational Science
ETH Zürich
CH-8092 Zürich
Switzerland
Email: FCellier@Inf.ETHZ.CH

Abstract

It is planned to equip the THAW telescope with capabilities for remote operation. This will allow us to study the requirements for teleoperation of the forthcoming Astrometric Telescope Facility (ATF), a payload of the U.S. Space Station.

The following steps are foreseen in this project:

Simulation of the THAW telescope on a MicroVax (under VMS, using Ada), and control of the telescope simulation from another MicroVax (under VMS, using OASIS), both here in Tucson.
```
                 TUCSON               |               PITTSBURGH
                 ******               |               **********
                                      |
 /-\  I------------I   I------------I |
 \-/  |            |   |            | |
  |   | Commanding |   | Simulation | |
--+-->|  MicroVax  |-->|  MicroVax  | |
  |   |   (OASIS)  |   |    (Ada)   | |
 /-\  |            |   |            | |
/   \ I------------I   I------------I |
                                      |
      
```
This testbed will allow us to investigate convenient means for man/machine communication, it will also allow us to define the intermediary language (for computer/computer communication), and it will allow us to study the data flow (communication parameters) between the two computers. This stage will be completed by April 1988.

Simulation of the THAW telescope on the MicroVax located in Pittsburgh, and control from another MicroVax located in Tucson.

                 TUCSON               |               PITTSBURGH
                 ******               |               **********
                                      |
 /-\  I------------I                  |                       I------------I
 \-/  |            |                                          |            |
  |   | Commanding |                 /|                       | Simulation |
--+-->|  MicroVax  |--------------->/ | /-------------------->|  MicroVax  |
  |   |   (OASIS)  |                  |/                      |    (Ada)   |
 /-\  |            |                                          |            |
/   \ I------------I                  |                       I------------I
                                      |

This second phase will teach us which problems we have to solve in order to communicate over long distance through 9600 Baud dial up modems and/or through the NSI data communication network. This phase will be completed by August 1988.

In this phase, we shall replace the telescope simulation by the real instrument. However, in order to minimize the problems, we plan to use now the second MicroVax (in Pittsburgh) to run the command software locally. The controlling computer will be a PS/2 model 80. The intermediary language will remain the same.

                 TUCSON               |               PITTSBURGH
                 ******               |               **********
                                      |
                                      |  /-\  I------------I   I-------------I
                                      |  \-/  |            |   |             |
                                      |   |   | Commanding |   | Controlling |
                                      | --+-->|  MicroVax  |-->|  PS/2 (Ada) |
                                      |   |   |   (OASIS)  |   | + Telescope |
                                      |  /-\  |            |   |             |
                                      | /   \ I------------I   I-------------I
                                      |

In this third phase, we shall learn to deal with the real hardware in a multiprocessing environment with simultaneous activities, timeouts, interrupts, etc. Due to the necessary modifications of the telescope hardware, e.g. the installation of a remotely controllable detector head (medusa), it is difficult to predict when this phase of the project can be completed.

Remote control of the THAW telescope with constant operator surveillance at the remote site.

                 TUCSON               |               PITTSBURGH
                 ******               |               **********
                                      |
 /-\  I------------I                  |                       I-------------I
 \-/  |            |                                          |             |
  |   | Commanding |                 /|                       | Controlling |
--+-->|  MicroVax  |--------------->/ | /-------------------->|  PS/2 (Ada) |
  |   |   (OASIS)  |                  |/                      | + Telescope |
 /-\  |            |                                          |             |
/   \ I------------I                  |                       I-------------I
                                      |

In this phase, we shall learn how to overcome communication difficulties, how to solve emergencies, and how to make the hardware/software configuration as robust as possible.

Automated remote control with scheduled task execution. The hardware configuration is similar to step 4, but now, the monitoring operator is gone. Work schedules will be preprogrammed for an entire week, and the telescope will take series of observations without any human intervention.
```
                 TUCSON               |               PITTSBURGH
                 ******               |               **********
                                      |
      I------------I                  |                       I-------------I
      |            |                                          |             |
      | Commanding |                 /|                       | Controlling |
      |  MicroVax  |--------------->/ | /-------------------->|  PS/2 (Ada) |
      |   (OASIS)  |                  |/                      | + Telescope |
      |            |                                          |             |
      I------------I                  |                       I-------------I
                                      |
      
```
The fifth phase will teach us how to deal with questions of artificial intelligence, in particular automated planning. Ultimately, we could feed the commanding computer with a list of stars to be observed, and leave it up to the computer to decide, weather the weather is good enough for observation, and if there are several candidates, which star would be assigned the highest priority (perhaps the one that has not been observed for the longest time span).

It is this mode of operation that most closely resembles the type of operation foreseen for the ATF instrument. We shall be able to learn which controls, sensors, and safeguards (harware) need to be included in the ATF design, and we shall be able to deliver a software system which could be easily adapted for remote control of the ATF instrument.

The remainder of this report is organized as follows. Section II describes the parts of the Allegheny Observatory and the Thaw telescope, and lists the major functions and constraints associated with the current (manual) mode of operation. Section III discusses a strawman design for the intermediary language to be used for the computer-to-computer communication. It should be EMPHASIZED that this language will be used between the two MicroVax workstations in the simulation phases and between the commanding MicroVax and the controlling PS/2 in the teleoperation phase. Almost all of these commands and responses will be TRANSPARENT to the user. The (OASIS based) command set for man-machine interface will be the subject of a future report. An example, however, is given in part D of this section.

Section IV gives a list of control loops and motors that must be in place for (fully automated) teleoperation. Similarly, section V lists the required sensors. Finally, section VI discusses the present avoidance zones and necessary safeguards (both hardware and software) and section VII gives a (very preliminary) list of error messages.

Homepage