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IV W
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sho
p o
n R
ob
otic
Au
ton
om
ou
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bse
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(To
rre
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s, M
ála
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, Sp
ain
, Se
pte
mb
er
28-
Oc
tob
er
2, 2015)
Edito
rs: M
. D
. C
ab
alle
ro-G
arc
ía, S.
B. P
an
de
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. H
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A. J.
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RevMexAA (Serie de Conferencias), 48, 29–30 (2016)
AUTONOMOUS DOME FOR A ROBOTIC TELESCOPE
Akash Kumar1, Anand Sengupta1, and Shashikiran Ganesh2
RESUMEN
El Laboratorio de Investigacion de Fısica opera un telescopio robotico de 50 cm de diametro ubicado en elMonte Abu (Rajsthan, India). El Telescopio Automatizado para Estudios Variables (ATVS) usa el sistemade control de observatorio RTS2 para las operaciones automatizadas. El observatorio alberga una cupula de3,5 m de diametro realizada por Sirius Observatories. Nosotros hemos desarrollado la electronica haciendouso de tarjetas con la logica necesaria y el software para controlar las operaciones. Estamos en el proceso decompletar los “drivers” para conectar nuestro Arduino con RTS2. Este trabajo es una breve descripcion de lasfases diversas en relacion al desarrollo y su integracion para alcanzar el objetivo necesario.
ABSTRACT
The Physical Research Laboratory operates a 50 cm robotic observatory at Mount Abu (Rajsthan, India). ThisAutomated Telescope for Variability Studies (ATVS) makes use of the Remote Telescope System 2 (RTS2) forautonomous operations. The observatory uses a 3.5 m dome from Sirius Observatories. We have developedelectronics using Arduino electronic circuit boards with home grown logic and software to control the domeoperations. We are in the process of completing the drivers to link our Arduino based dome controller withRTS2. This document is a short description of the various phases of the development and their integration toachieve the required objective.
Key Words: instrumentation: miscellaneous
1. INTRODUCTION
The Physical Research Laboratory operates arobotic 50 cm telescope. This is an autonomoustelescope for variability studies (ATVS) in its obser-vatory at Mount Abu (latitude : 24◦ 39m 9s North,longitude: 72◦ 46m 47s East, altitude : 1680m).The operating conditions are quite tough in termsof range in humidity, temperature and wind. Thetelescope is protected from the environment by afibre glass dome manufactured by Sirius Observato-ries.
2. DOME CONTROLLER FOR AUTONOMOUSOPERATIONS
The telescope operates in the robotic mode(Ganesh et al. 2013) and efforts are made in orderto fully automate it using Remote Telescope System(RTS2, http://rts2.org/). The observatory hasover 200 clear nights in a year but needs to becompletely closed and sealed during the Indianmonsoon season (generally mid June to September)each year. Apart from this there are occasions when
1Indian Institute of Technology, Village Palaj, Shimkhera,Gandhinagar, Gujarat, India-382355 ([email protected]).
2Physical Research Observatory, Navrangpura, Ahmed-abad, Gujarat, India ([email protected])
the skies become cloudy and/or wind conditionsalso become drastically worse. Therefore, forautonomous operations to succeed, we need thedome controller to be very reliable with redundantweather sensors so that the shutters can be closedautomatically in case of bad weather.
Humidity is a major cause of repeated failures ofelectronic boards. We have not found commerciallyfeasible solutions available for controlling the dome.Hence we have decided to go for a locally engineeredsolution using cheap, general purpose, electronicboards available easily. The objective of this workwas to make an autonomous dome controller for arobotic telescope using easily replaceable electronics.The controller is in charge of the dome functions likeclosing and opening of the shutter and clockwise andcounter-clockwise motion of the dome to track thetelescope. It also keeps the record of the position ofthe dome and can be controlled by a Windows orLinux based computer using appropriate drivers.
We built the dome controller using the ubiqui-tous Arduino boards. An Arduino is an open sourcephysical computing platform based on a simplemicro-controller board. It consists of a physicalprogrammable circuit board. It can be programmed
29
IV W
ork
sho
p o
n R
ob
otic
Au
ton
om
ou
s O
bse
rva
tori
es
(To
rre
mo
lino
s, M
ála
ga
, Sp
ain
, Se
pte
mb
er
28-
Oc
tob
er
2, 2015)
Edito
rs: M
. D
. C
ab
alle
ro-G
arc
ía, S.
B. P
an
de
y, D
. H
iria
rt &
A. J.
Ca
stro
-Tira
do
30 KUMAR, SENGUPTA, & GANESH
Fig. 1. View of Sirius Dome housing the PRL 50cm tele-scope at Mount Abu (left panel). Block diagram of domeand shutter control logic (right panel).
via the USB port of the computer using the ArduinoIDE (integrated Development Environment) builtwith a software platform known as Processing. TheArduino IDE includes support for various electroniccomponents such as encoders and other sensors,relay boards etc. We used one Arduino board tocontrol the shutter movement of the dome (openingand closing) and another one to control the domerotation (clockwise or counter-clockwise). Boththe boards communicate with each other usingRF transceivers. This is needed because the domerotation controller is connected to the PC andthe shutter controller is connected via the domecontroller. The shutter controller, powered by abattery, is mounted in a box on the dome androtates with it. Thus wireless communication ismandatory. For monitoring the orientation of thedome we use an incremental rotation encoder whichconverts the angular motion of the dome into aseries of digital pulses which encode the movementof it. To control the motion of the motors of theshutter and the dome, we have used semiconductorrelay boards with physical limit switches. Thesesemiconductor relay boards are operated usingdigital pulses from the Arduino microcontrollerboard.
3. DRIVE DEVELOPMENT PHASES
The work was divided in different phases and thework of all the phases was accomplished one by oneand finally integrated to make the drive. The differ-ent phases were the following:
1. Making a programmable controller of thedome’s shutter.
2. Making a programmable controller of thedome’s rotation.
3. Conversion of the motion of the dome into dig-ital code.
4. Setting up a wireless connection between the ro-tation controller and the shutter of the dome.
5. Making it compatible with RTS2.
In the first phase, a mechanical controller circuitfor the shutter of the dome was made using limitswitches and was successfully tested. After that aprogrammable control circuit was made using anArduino board and semiconductor relays to controlthe motors and was coded for opening, intermediatestop and closing operations of the shutter. Work onthe position encoder was also started to record theposition of the dome.
Simultaneously, work on the rotation part ofthe dome was started and a programmable controlcircuit was made using another Arduino board andwas coded for clockwise, counter-clockwise motionand for detecting home position. Then the positionencoder was integrated with this controller andthe code was modified accordingly. Work on thewireless communication between dome rotation andshutter controllers was started using radio frequencytransceivers and a communication protocol was es-tablished and encoded for transferring the commandto the controller boards.
The electronic circuits have been tested at theobservatory and software coding has been developedfor synchronizing the dome orientation with theazimuth being pointed by the telescope. We planto integrate the shutter control board with inde-pendent(redundant) cloud, rain and wind sensorsto allow quick closure of the shutters withoutcomputer/manual intervention.
Acknowledgements. The first author wouldlike to acknowledge support received from the or-ganizers towards local hospitality which enabled hisparticipation in the workshop. His travel to Malagawas funded by IIT Gandhinagar. Work at PRL isfunded by the Dept of Space, Govt. of India. Wethank colleagues at PRL for their support of thiswork.
REFERENCESGanesh, S., Baliyan, K. S., Chandra, S., Joshi, U. C.,
Kalyaan, A., Mathur, S. N, ASI Conference Series,2013, 9, 99
