Design , Fabrication and Analysis of Automatic Telescopic Mount

The major advantage of the project is the ease with which a celestial body may be tracked in the night sky. This gives us access to proper imaging and exploring new systems in the night sky. The telescope has an 8’ aperture .This is achieved by attachment of worm-worm gear arrangement mounted of the shafts of the RA and Dec axes of the telescopic mount. To this a controlling system using PLC programmed with PLC language is used which is controlled by using an HMI. The project aims to have high accuracy and precision in object tracking. A Nema 23 Stepper motor with a 4.25 reduction gearbox has been selected. This arrangement is controlled by a 24V SMPS and 48V DC power supply. The project is economically affordable thus making it more available to the local enthusiasts. Index Terms – Equatorial Mount, RA and Dec axis, PLC, HMI, Nema 23 Motor, SMPS, gearbox, Celestial


I. INTRODUCTION
Automatic Equatorial Mount is made to automatically track celestial bodies in the night sky using a HMI and the entire process will be automated to obtain high end imagery and exposures ranging from 5 minutes to 6 hours easily.

A. Working
Automatic Equatorial Mount has been designed to be on two axes, Right Ascension and Declination axis specifically.The shafts are controlled by a worm and worm gear arrangement made upon them.The worm is controlled by a gear box which is given motion by a stepper motor of 27.2 RPM.This motion is reduced to 0.05 RPM from a 4.25:1 reduction ratio gearbox attached to the output shaft of the motor.This is then connected to the worm with the help of a bronze coupling arrangement.The motors are given Pulses by a PLC which are controlled by a programmed display custom manufactured.The Motors are given 48 V DC.
The PLC is given 24V DC; both are different power supply units.Thus the shaft motion is controlled.
On the Axes of the shaft, perpendicular to the shaft is a scale for angular measurements for tracking celestial bodies using a reference.Once the Celestial object to be tracked is viewable from the telescope, the RPM from Maximum to the desired 0.05 RPM has been change.The RPM is specifically 0.05 or 1 degree in 4 minutes.This gives us the diameter of shaft 20mm; otherwise the shaft diameter changes causing problems.Polaris is a star that doesn't seem to move when viewing from the Earth.This is due to the fact that it is aligned with the axis of the Earth.So Polaris acts as a point from which one can easily trace other celestial bodies using their generally known RA and Dec angles.

A. Objectives
1. To fabricate and analyze the tracking of celestial bodies.
2. To find the accuracy with time of tracking and improving the accuracy.

B. Concepts
Angle: Angles are permissible in the range of 0 0 -180 0 only on the RA-shaft.This is due to the hemisphere being 180 0 visible from any position on the earth

C. Components Description
The body of the mount on the lower section is made     There is heat dissipation caused by the gears.There is a camera fit on the lens of the telescope which captures the deep space images connected to a laptop that gets the data feed constantly from it.In this manner the basic functioning is started.This setup can stay up to 180 0 from start to end of the process, but that is the maximum viewable hemisphere so that is the limitation of it.The Dec shaft can rotate 360 0 if needed.This goes on to prove that our selected gear and worm material has comparatively are successfully able to withstand the load and can thus be selected motion transmission.The force is distributed to the worm from the transmission in the form of horizontally distributed force

III. RESULT AND CONCLUSION
The motor RPM is 27.12.The desired RPM on shaft is 0.05 which is successfully available after transmission from worm to worm gear on both the shafts.This testing is done in normal atmospheric conditions.
There is constant motion available when the telescope moves in any of the required directions.The objective is focused properly in the lens of the telescope and is viewable from the lens of the camera.
When readings were taken for more objects it was seen that there is minor jerking occurring leading to distortion of images which is to be eliminated.This Effectiveness: The effectiveness is given by the trail marks occurring with respect to time of tracking of the object by the telescope.It has been done by placing a camera at the lens of the telescope and then continuously clicking pictures and then using external software for compiling them all together.This gives us a high exposure clear image of deep space.
up of mild steel.There are three legs which are supported additionally by attachment of horizontal supports from the central cylindrical frame.Above the frame there is housing of shafts and bearings for supporting them.The rubber foot can withstand up to 50Kilograms individually.The shafts are selected of stainless steel for their high capacity to bear load and withstand the bending moment acting upon them.The motors preferred in this sensitive operation are stepper motors with a low RPM and a gear box.Stepper motor has coil windings that help enhance the smooth motion transmission without jerking the motion.The PLC is a custom programmed unit that provides the designated RPM by relaying information to the motor controller that produces pulses for the designated RPM.The power supply is for providing the proper supply to the PLC setup and the motors individually.The standard voltage of 230V AC is converted to 24V DC and 48V DC respectively.Worm and worm gear are a special arrangement for constant motion.There is heat dissipation and no significant crushing load acting due to material being phosphor bronze.Bearings enable smooth motion transmission by making interference fit with the shaft and thus, remove the chances of impurities present in the actual hole for the shaft.Bearing used is needle bearing to withstand high radial load in our case.

Figure 1 .
Figure 1.Working of Equatorial Mount

Figure 2 .
Figure 2. Experimental Setup of the Mount and Analysis of Automatic Telescopic Mount © 2018 RAME IJAEFEA 11 Research Association of Masters of Engineering www.rame.org.inOn market survey and checking catalogues for the selection of motor capable of rotating the telescope with the speed of the Earth the main factor that comes into consideration is the driving speed of the shaft.Generally all motors are designed for high torque transmission with a high power supply.If a DC motor would've been use then a spur gear would've come into implementation.When spur gears engage or disengage there is a jerk that moves the telescopes which eliminates the selection of spur gear or DC motor drive regardless of its speed of rotation.On market survey, founds a lot of catalogues and select a suitable motor with the least driving speed which can further be reduced by use of reduction gear drive at the exit of stepper motors driving shaft.Thus reducing the total output as per our requirement.All of the components used have been analyzed in ANSYS software before their fabrication or purchase to estimate the load that would be acting upon them to get the general idea if the component would be actually be able to sustain it or should there be any changes made to dimensions or to choose a different material respectively.Major Force Diagrams acting upon RA and Dec Shafts:

Figure 3 .Figure 4 .
Figure 3. Vertical Force Diagram For RA shaft Diameters for the Ra and Dec shaft are 20mm respectively.

Figure 7 .
Figure 7. ANSYS Analysis of Worm and Worm Gear occurs when the telescope moves from centre 0hours to left or right maximum side.IV.ACKNOWLEDGEMENT Authors are very much thankful to Pawaskar Engineering Works Chakala, Andheri (E) for permission to work in their workshop and technical support.

TABLE 4 LOCATION
F. Analysis of Major Components

TABLE 9 BENDING
MOMENTS OF DEC SHAFT HORIZONTALLY