P19151: Satellite Tracking System

Gate Reviews

Table of Contents

MSD I: Readiness to move to Build & Test

Status Review

Current state of the project

Mechanical: The physical-mechanical components of the project have all been accounted for and modeled with the exception of the housing for the electrical components at the base of the pole. Standard parts have been added to the design, hole placements finalized, and overall design concept ironed out with our customer and subject matter experts. Weatherproofing of the design has been accounted for. Detailed drawings of the specialty parts have started to be made and will continue to be worked on over winter break to be finished by the start of next semester. These drawings will be used by the machine shop to create the specialty parts that will be needed for our design.

Backup plans have been set in place for our high-risk mechanical areas which include: --Incorrect belt length/rigidity -Backup: Add an idler pulley system to the underside of the upper plastic plate that will add additional force to the timing belt used for the elevation rotation. Add an idler pulley system and additional plastic column to the design (in the lower half of the box) to add additional force for the timing belt used for the azimuth rotation. --Wind deflection/backlash on the gears due to wind forces Backup: Double check motor feedback values with the DOF sensors to account for any small changes in the position of the antenna due to the wind. --Moisture buildup inside the assembly Backup: The holes used to hold the plastic pieces for waterjet cutting during the fabrication of the parts can serve a dual purpose of releasing moisture buildup from inside the assembly. These will have to be covered with a mesh to prevent any bugs/dirt from getting inside the assembly. Moisture buildup is something we will test during our test phase of MSD II. --Backorder of parts Backup: Have started to already order major components with a longer lead time so that they will arrive by the start of MSD II. --Access to assembly is limited by budget Backup: Budget permitting, a rotational pole design has been planned so that the assembly may be more easily removed from the top of the pole. The pole will rotate down on a hinge and allow for the user to easily access the assembly.

All other risk areas have been accounted for and changes have been made to the design.

Electrical: The control system for the motors has been designed on the hardware level. The Arduino microcontroller has successfully communicated with the Degree of Freedom (DOF) sensor over I2C and is able to easily take readings from it. The Arduino has also successfully communicated with a motor driver board, although register settings needed to drive the motor are yet to be determined. Serial communication with the embedded computer has also been achieved. (See Computer/Software) The general firmware for the microcontroller has yet to be developed.

The power system has been mostly designed with the current system being powered over ethernet and using a battery to supply the system for heavier current loads. The battery charges while the system is idle and not drawing much current.

High risk areas relating to the electrical system are as follows: --Winter temperatures may decrease the power output of the battery Backup: Batteries rated for low temperatures will be used. Currently, we are exploring options such as gel batteries or glass mat. These batteries fair better in lower temperatures, although further testing is required. --Unexpected power loss causing loss of known states Backup: While our new power system greatly reduces this risk by having an inherent battery backup, it would still be possible for a power loss to occur, for example if the cable to the battery were to become disconnected. To mitigate this, limit switches will be included to allow the system to come back to a known state.

Computer/Software: The computer and software side of the project is in good shape. The embedded computer is in-hand and exploration of the device has been performed, giving a good sense of the capabilities and limitations, as well as the path that will work the best for development of the project. Python 3 has been selected as the target language, given the tight integration between its libraries and the Raspberry Pi. The Pi will communicate with the motor control Arduino through the USB serial port, which has already been tested on both the Pi and the Arduino side. The Pi will use an SDR to record the satellite transmissions. One candidate device, the RTL-SDR, is already in-hand and testing with the Pi has started using GNURadio as the base package. Additional experimentation is still required, as some issues with incompatible versions were experienced, but there are known-good configurations, using the RTL-SDR on a Raspberry Pi with GNURadio is possible and has been done before. The other candidate SDR unit actually requires less software than the RTL, and so should be even easier to set up, and is also a configuration that has been used by others before. Various packages providing enhanced user interfaces within the Linux terminal were tested to see if they would work for the project. Unfortunately, both of the packages that were evaluated did not give the desired performance over SSH, meaning they could not be used for the project. As a result, the target UI scheme will use text only, but will likely include colored text and non-blocking keyboard input, putting it slightly above a raw text-only interface. Tasks for MSD II include writing the code and some additional system configuration, including configuring the Pi to access the remote repository, and acquiring a static IP address, domain name, and email address.

Schedule Comparison: Mechanical -- Mechanical status is on schedule and where we wanted to be by the end of the semester per the original schedules we had created during the semester. Electrical -- Electrical status is on schedule with what tests are still relevant to our modified design and what we expected to complete by the end of the semester. Computer -- Computer stats is on schedule and where we wanted to be by the end of the semester per the original schedules we had created during the semester.

Overall our schedule did fluctuate throughout the semester with each phase.

Team Member Status: All team members contributed equally in their respective areas during this semester with no problems. All of our peer evaluations were filled out and discussed at the end of each phase and we never had any problems with work ethic, completing things on time, or communication.

Learning Points: We learned the value of staying flexible and accepting criticism. Throughout the MSD I process, the design went through a wide range of changes, from multiple location changes, to multiple complete redesign of the mechanical system. By staying flexible, we were able to undergo these changes as well as critique and insight from our valued guides and subject matter experts to ultimately produce a design we are quite proud of.

MSD II: Project close-out


Status Review

Current state of the project

Deliverables Checklist and Website Status

Lessons learned, etc.

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