Team Vision for System-Level Design PhaseDuring the systems design phase we planned to develop three possible system level concepts that would satisfy our engineering requirements from our project definition. In addition to the development of these concepts, we planned to preform preliminary analysis to justify feasibility of concept components. This analysis was also to provide the ability to make a justified decision as to what concept was the best and therefore should be developed further.
Through the completion of MSD 1 weekly assignments we were able to identify 3 varied concepts that could theoretically meet the engineering requirements. Feasibility and Pugh chart analysis was completed, from which concept 3 was selected as the best candidate for further development. Key components of Concept 3 include system redundancy, waterproof AC gear-motors, track type clutch and a wifi enabled micro-controller.
- Current State: Statue successfully rotates, but occasionally has to stop for repairs, and has long periods of downtime due to the statue not being high on maintenance's priority list.
- Desired State: Statue successfully rotates with absolutely no downtime.
- Project Goal: Design a redundant drive system and corresponding control system such that the statue rotates as continuously as possible.
Morphological Chart and Concept Selection
Feasibility: Prototyping, Analysis, Simulation
Grid Electricity Power
Cost of electricity is a found value for the Rochester area.
Solar Panel Power
The purpose of the clutch is to allow the two gears to be able to engage and disengage so maintenance can work on the system without stopping the rotation of the statue. In order to do this, various options were considered. These options consist of directly interfacing the gears, using a friction engaged clutch, and using a belt or chain. Since the current system has a chain, which has caused issues for maintenance, other options need to be considered as the intent behind this project is to reduce maintenance and downtime. The friction engaged clutch engages easily, can engage at high speeds and has a long life, but would require more force to engage. Because of this, the friction clutch is being considered in option 1, and will involve engaging the clutch immediately after the interface with the motors. Opposite of this, by directly interfacing the gears much less force is required to engage the gears, but must be engaged at slower speeds. by directly interfacing the gears another component does not need to be purchased, and provides a low maintenance scenario. Directly interfacing the gears is being considered in option 3, which involves engaging the gears after going through a gearbox to slow the rotation.
The purpose of adding sensors to our design is for the system to be able to detect inadequate operation or drive train component failure. The most feasible options are magnetic, rotational, motion, and distance sensors. A number of affordable options for each category exist, however their intended uses and functionalities allow us to rank them in terms of ease of use for our purposes. Magnetic sensors are the most favored because some such sensors exist for the sole purpose of counting gear teeth as they rotate and detecting magnetic field generation, or lack thereof. Rotational sensors rank second, as their sole purpose is to measure rotation of a body. Motion sensors would operate in a fashion similar to that of magnetic sensors, looking for any motion that exists within the chamber. Distance sensors would be less ideal, as it would require an added feature to the system, such as a fin, that the would be looked for as said feature passes the sensor in a rotation. In the case that the sensor measures nothing - meaning that the system has stopped - the microcontroller would alert maintenance of the failure.
Our reasearch has shown that there are microcontrollers that have Wireless access. The Arduino's do not have the capability to use WPA2 Enterprise systems, but by either using another system (like a Raspberry Pi) it would be able to connect to the internet. The final choice will be made depending on the compatibility of the sensors chosen, but the two current best options are the TI Launchpad CC3200 and the Raspberry Pi 3 B.
Using wifi to contact the maintenance department is the best option since there is already wifi in the infinity quad, and would allow the system to directly send an alert to maintenance. Bluetooth is another viable option, but the range would be very short and would require another device to send the alert. A radio system could also work, but it would be more complex to implement due to the fact that the system is underground, and the signal would need to be sent to something to alert maintenance. While a cord sounds like an easy solution, creating a path for it would be expensive and could possibly allow water to get into the chamber.
Plans for next phase
-Determine worm gear interface/characteristics
-Investigate components form scaled down prototype
-Determine slipping rate of torque limiter
-Develop track design
-Develop code for microcontroller to use (maybe be completed in later design phase)
-Create overall system schematic/CAD models
-Identify exact tachometers to be used
-Investigate possible presence of axial bearing in statue shaft