P17310: RIT Observatory Telescope Dome Controls
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Systems Design

Table of Contents

Team Vision for System-Level Design Phase

The plan for the System-Level Design phase was to determine possible system configurations which would allow autonomous control of the dome. A simulation model as well as a schematic of the original system were to also be generated.

A concept for system control was finalized which will utilize a calibrated encoder as well as a 6-Degree-of-Freedom (6DoF) sensor for feedback into a microcontroller. The original dome control circuit was mapped into a schematic and was translated into LabVIEW for future testing.

Functional Decomposition

public/Systems Level Design Documents/Functional Decomp Draft.png

ER Mapping to Functional Decomposition

public/Systems Level Design Documents/ER to Functional Decomp Mapping.PNG

Benchmarking

Encoder

public/Systems Level Design Documents/Encoder_Benchmark.PNG

6-Degree-of-Freedom Sensor

public/Systems Level Design Documents/6DoF_Benchmarking.PNG

Infrared Camera

public/Systems Level Design Documents/InfraredCamera_Benchmark.PNG

Microcontroller

public/Systems Level Design Documents/Microcontroller_Benchmark.PNG

Morphological Chart and Concept Selection

public/Systems Level Design Documents/Morph_Chart.PNG

Selection Criteria

  1. Cost
  2. Time
  3. Power Consumption
  4. Maintenance Requirements
  5. Easy Installation
  6. General Complexity
  7. Safety
  8. Usability

Concept Development

public/Systems Level Design Documents/Pugh Chart.PNG

Active File

Feasibility: Prototyping, Analysis, Simulation

Encoder

8 teeth on gear => 4 degrees of rotation for the dome
10 teeth on gear => 5 degrees of rotation for the dome
12 teeth on gear => 6 degrees of rotation for the dome
8 teeth on gear => 250 pulses per degree of dome rotation
10 teeth on gear => 200 pulses per degree of dome rotation
12 teeth on gear => 166.67 pulses per degree of dome rotation

6-Degree-of-Freedom Sensor

Question

Can a 6DoF sensor (IMU) be used to report telescope position?

Assumptions

Analysis

A six degrees of freedom sensor utilizes an internal accelerometer as well as a gyroscope/magnetometer to track a system in 3 dimensions. Benchmarking was done to compare the acceleration as well as rotational sensitivity requirements of differently configured 6DoF sensors. It was found that a magnetometer would have a high tracking error due to magnetic field disruption caused by the dome. Therefore a 6DoF sensor utilized a gyroscope for rotational tracking was chosen and compared to the spec of the telescope.

public/Systems Level Design Documents/6dof.png

The specs of the 12" f/10 LX200GPS are shown below:

public/Systems Level Design Documents/telescope spec.png

Telescope Slew Rate-Rotational Speed

Min Rotational Speed = .25 arc-min/sec=.004 degrees/sec

Max Rotational Speed = 480 arc-min/sec=8 degrees/sec

The rotational speed was compared to the gyroscope sensitivity to ensure accurate data collection.

public/Systems Level Design Documents/gyroscope spec.PNG

Most 6DoF sensors have variable sensitivity scales which can be set based on the speed of the device being monitored.

Simulation of System

Below is a link to a LabView model of the telescope and manual dome controls.

LabView Dome Model

Systems Architecture

public/Systems Level Design Documents/system architecture.png

Designs and Flowcharts

public/Systems Level Design Documents/Design Flowchart.png

The top level schematic of the control box can be found here:Control Box Schematic

Risk Assessment

public/Systems Level Design Documents/System Design Risks.PNG

For a master list of project risks, click here.

Plans for next phase

Agenda

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

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

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

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

Ahmed Alhurubi'sThree Week Plan: Ahmed's Goals


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