P17310: RIT Observatory Telescope Dome Controls
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Detailed Design

Table of Contents

Team Vision for Preliminary Detailed Design Phase

Progress Report

Completed

In Progress

Prototyping, Engineering Analysis, Simulation

Encoder

The new encoder was tested on the dome system and data was collected using a myDAQ device. Channels A and B were recorded on the Analog In ports with 100001 Samples per Channel with a Sample rate of 3000 (dt=0.0003333,Total time=33.333, Data points collected/Channel=100001). The following figure shows the results after processing the data:

public/Detailed Design Documents/128PPR_Encoder_DAQ.png

The first plot does not agree with the end position compared to the other plots due to the fact data collection had started after the dome had started rotating already but the slope agrees within two decimal places. The slopes of each plot determined that the shaft rotating around 2.93 rotations per second in either direction which is within operating capabilities of the encoder.

It is also about 65 shaft rotations to reach a 90 degrees of rotation for the dome. From this, one shaft rotation is about 1.3846 degrees for the dome. This also means, one pulse from the encoder is about .0108 degrees of rotation for the dome. This means we have greater than 1/2 a degree of accuracy for controlling the dome which meets our engineering requirements.

Looking closely at the data, there was a change in pulses about every 2.3ms to 2.6ms. If was rotating at a constant 3 Rev/sec, then it should be outputting at a rate of 2.6 ms/pulse which agrees with experiment.

If we use the NI USB-6001 for the final control system, it has a max sampling rate of 20Ksamples/second which translates to a maximum read rate of 1 sample every 50microseconds which exceeds our expected sampling rate of 2.6ms.

I/O Integration Circuit

The relay system schematic was merged with the I/O integration circuit to show the general layout of the finalized control system.

Control System Schematic

Control System Schematic

Schematic File

Both 9 position and 4 position circular connectors were purchased with female contacts to mount the I/O integration circuit to the relay system.

Connector Mounting

Connector Mounting

Initially the relay system was debugged as to see why none of the relays were flipping after applying bias to the coils. It was found that a 24VDC reference was never connected to the system. To continue with testing a power supply was set to 24VDC and jerry-rigged to the relay system.

24VDC Power Supply

24VDC Power Supply

The I/O integration was built and connected to the relay system. An Arduino was used as a stand in DAQ until a unit is purchased.

Integration Circuit

Integration Circuit

The links below show the dome rotating as well as the shutter opening and closing by means of the I/O Integration circuit. Future tests will utilize a LabVIEW interface rather physical buttons to control digital signals. All relays were properly engaged by the digital signal which gives validity to our selected concept.

Dome Rotation

Shutter Open

Shutter Close

Telescope Communication

MaxIm DL 6 control and detect the motion of the telescope and that was the result of the last visit to the observatory. Due to previous research that presented in the last phase, which is using Meade LX200GPS driver. http://ascom-standards.org/Downloads/ScopeDrivers.htm

public/Detailed Design Documents/1_driver.png

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After installing the driver and delete the old drive, the telescope has been connected to COM4.

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Mount type is German Equatorial.

Click on view then click on observatory then click on telescope setup then click on options and choose Meade LX200GPS/R and from its setting choose COM4 by clicking on the arrow. And same steps again with choosing Universal Meade Setup and choosing COM4.

public/Detailed Design Documents/4_meade.png

Finally, the telescope is controlling and tracking through the software easily.

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Latch Automation

Design Requirements

Current Design

The current design incorporates a solid Aluminum 6061 multi-angled moment arm. Hook clearance is attained using a hinge system combined with two small electric motors in tandem to pull the hook arm vertically or past vertical past the chain position. Strong, but flexible wire would be wound using these motors to raise and lower the hook arm as necessary. Current base models of this design are shown below:

public/Detailed Design Documents/Design 2 - Extended - Render.PNG

Latch Moment Arm Assembly Realistic Render - Extended Arm


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Latch Moment Arm Assembly Realistic Render - Retracted Arm


FEA Simulations

Analysis Assumptions
Simulation Setup

public/Detailed Design Documents/Latch_Sim_Mesh_Full.PNG

Latch Moment Arm Assembly - FEA Mesh Arrangement

Ambient Temperature
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Latch Moment Arm Assembly - Maximum Clearance (35 N) - Von Mises Stress - Full Model

Displacement Animation


public/Detailed Design Documents/Latch_Sim_35N_Ambient_VMStress_Focused.PNG

Latch Moment Arm Assembly - Maximum Clearance (35 N) - Von Mises Stress - Motor Connection Stress Concentration


public/Detailed Design Documents/Latch_Sim_35N_Ambient_Safety_Factor_Focused.PNG

Latch Moment Arm Assembly - Maximum Clearance (35 N) - Material Safety Factor at Stress Concentration Point


public/Detailed Design Documents/Latch_Sim_35N_Ambient_Shear_YZ_Motor.PNG

Latch Moment Arm Assembly - Maximum Clearance (35 N) - Motor Shear Stress (YZ) Distribution

High Temperature (100 °F)

public/Detailed Design Documents/Latch_Sim_35N_100F_VMStress_Full.PNG

Latch Moment Arm Assembly - Maximum Clearance (35 N) - Von Mises Stress - Full Model


public/Detailed Design Documents/Latch_Sim_35N_100F_VMStress_Focused.PNG

Latch Moment Arm Assembly - Maximum Clearance (35 N) - Von Mises Stress - Motor Connection Stress Concentration


public/Detailed Design Documents/Latch_Sim_35N_100F_Safety_Factor_Focused.PNG

Latch Moment Arm Assembly - Maximum Clearance (35 N) - Material Safety Factor at Stress Concentration Point


public/Detailed Design Documents/Latch_Sim_35N_100F_Shear_YZ_Motor.PNG

Latch Moment Arm Assembly - Maximum Clearance (35 N) - Motor Shear Stress (YZ) Distribution (Shaft Max = ~15 MPa)

Low Temperature (-30 °F)

public/Detailed Design Documents/Latch_Sim_35N_-30F_VMStress_Full.PNG

Latch Moment Arm Assembly - Maximum Clearance (35 N) - Von Mises Stress - Full Model


public/Detailed Design Documents/Latch_Sim_35N_-30F_VMStress_Hinge.PNG

Latch Moment Arm Assembly - Maximum Clearance (35 N) - Von Mises Stress - Hinge Stress Concentration


public/Detailed Design Documents/Latch_Sim_35N_-30F_Safety_Factor_Hinge.PNG

Latch Moment Arm Assembly - Maximum Clearance (35 N) - Material Safety Factor at Stress Concentration Point


public/Detailed Design Documents/Latch_Sim_35N_-30F_Shear_YZ_Motor.PNG

Latch Moment Arm Assembly - Maximum Clearance (35 N) - Motor Shear Stress (YZ) Distribution (Shaft Max = ~45 MPa)

FEA Summary

The following table contains a summary of all important FEA results and correlated values: public/Detailed Design Documents/Latch FEA Summary.PNG

Active File


Component Sourcing Options

public/Detailed Design Documents/Torque Motor 1 - DC.PNG public/Detailed Design Documents/Torque Motor 2 - Gear.PNG public/Detailed Design Documents/Gearbox for Gear Motor.PNG

public/Detailed Design Documents/Mini Motor Example 2.PNG public/Detailed Design Documents/Mini Motor Example 1.PNG

public/Detailed Design Documents/FlexForce Sensor.PNG

Cost Analysis

The following contains a list of approximate costs related to Design 2 shown previously:

Note: All costs exclude any additions due to shipping and handling.


Current State Design Risks

New Risks
Mitigation

Additional Options/Ideas

Outstanding Tasks and Current Conclusions

Bill of Material (BOM)

public/Detailed Design Documents/BOM.PNG

Active File.

Design and Flowcharts

public/Detailed Design Documents/Design Flowchart.jpg

Requirements

Customer Requirements

public/Detailed Design Documents/Customer Requirements Table.PNG

Engineering Requirements

public/Detailed Design Documents/Engineering Requirements Table.PNG

Risk Assessment

public/Detailed Design Documents/Risks.PNG

For a master list of project risks, click here.

Plans for Next Phase

public/Detailed Design Documents/Prelim Gantt.PNG

Ahmed Alhurubi's Three Week Plan: Ahmed's Goals

Joe Brescia's Three Week Plan: Joe's Goals

Raymond Castro's Three Week Plan: Ray's Goals

Wilson Quizhpi's Three Week Plan: Wilson's Goals

Sarah Williams's Three Week Plan: Sarah's Goals


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