The information used to create the functional decomposition was gained through research papers provided by team sponsor, Dr. Bowman and independent research into Psyche’s environment. In addition, the team held a meeting with Dr. Bowman to ask questions regarding the needs and scope of the project. Her responses were interpreted into a list of engineering needs which the team used to create a list of functions necessary to meet those needs. Using these functions, the team defined four subsystems: Structure, Communication, Control, and Output.
Functions are discrete actions that may correlate with multiple systems. The system, its subsystems, and their functions were organized into a hierarchy chart and a cross-reference table to better visualize the relationships between the lower-level functions of the system and the subsystems that they would fall under. In a few cases, the previously defined functions were branched into even more specific functions. In the hierarchy chart, each function falls under the one function or subsystem it is most related to, providing a clear visualization of functions as “branches” of higher-level functions. However, many functions have relationships to multiple subsystems. The cross-reference table defines functions related to the four subsystems with many correlated to two or more subsystems.
The Functional Cross Reference Table is another method to visualize the functional decomposition of the A.M. system. Similar to the hierarchy chart, the main system is comprised of four sub-systems which are comprised of functions. Functions that correspond to multiple subsystems have multiple X’s in their row. Corresponding to multiple subsystems could be implicative for more important functions.
The additive manufacturing system needs to integrate its four main systems to perform its desired functions. Each system has its own specific functions that perform jointly to make an across-the-board function possible. Moreover, to compensate for the internal forces within the device, the controls system and structure system need to work together. Controls will measure and read internal forces, so it can notify and alert structure if an imbalance is present. Structure can then assess and correct this force imbalance. The communications, controls, and output systems will be needed to relay instructions to output. First, communications will take instructions from an outside source. Controls will relay these instructions to the output system, so they can be integrated into the printing software.
In the table above, functions were ranked on a scale of 1 to 10. A ranking of 10 shows a function with the most potential for smart integration, and a ranking of 1 shows the least potential. The system producing the desired output is ranked 10 because it requires effort from every other system to be possible. Moreover, there needs to be structure to consolidate the build, communications to receive the build, controls to regulate the build, and output to execute the build. In contrast, functions like minimizing vibrations and shielding from vibrations most likely operate within their own system of structure.
The Functional Cross Reference Table demonstrates an emphasis on control systems. These control systems can only act appropriately with efficient communication systems. The entire system relies on a solid structure to produce an output. As shown in Table 4, the output is the most important function. Receiving inputs and communication from the user is also integral to the project objectives. Each function is a building block that allows for progress towards the main purpose of the system. The following subsystems each have a priority rank of 1-10 assigned based on how vital each subsystem is to the success of the system, with priority rank 10 being the most important and priority rank 1 being of least importance. The output subsystem produces the desired print. Its basic function is to convert input material and instructions into a physical output. Multiple additive manufacturing methods will be considered to ensure successful printing in the harsh environment of Psyche while, simultaneously, satisfying our customer’s needs. The output subsystem essentially determines the success of the entire system. If all other subsystems function correctly, but the output does not, then the whole system fails. Additionally, all subsystems act to support the output. For these reasons, the output subsystem ranked as a priority rank of 10. The communication subsystem is integral in achieving specific customer needs. The Psyche mission is unmanned and will receive instructions over long distances. Having the ability to effectively receive directions and transferring the inputs into outputs is a building block that the system relies on. The system would become static without an efficient method of communication. The long distance between Earth and Psyche establishes challenges that a successful system must overcome. Communication hardware must also be durable to survive Psyche’s conditions. The output subsystem relies on information that will be received and relayed by this subsystem. Due to customer need specifying that the project need only rely on existing methods of long distance communication, this component must only have a method of interfacing with the control system, receiving a priority rank of 4. The control subsystem acts as the interface between the communication subsystem and the output subsystem, relaying instructions received into action done by the output subsystem. In addition, the control subsystem is responsible for compensating for the environment of Psyche to ensure that the output system can operate as intended. The primary environmental factor of concern is the fluctuating temperature due to Psyche’s short days. The control system compensates for the fluctuating temperature by sensing the temperature within the system and then employing some method of temperature control to keep the system within manageable operating conditions. This subsystem has received a priority rank of 8 due to it being very important to the performance of the output subsystem and the system as a whole. The structure system addresses functions such as producing desired outputs, regulating temperature, compensating for internal forces, minimizing vibrations, shielding the system from radiation, and protecting the system from particulates. Producing the desired output is the most important function of the design. This can better be achieved by maintaining accuracy and precision. Vibrations can misalign calibration tools or make an unstable production area. Radiation can damage electronics, which could cause irreparable damage to the whole design’s function. Space dust and particulates can clog any unprotected moving parts, disturb or dirty the print bed causing uneven or unsatisfactory outputs, or cause shorts in electronic circuitry. These potential problems must be addressed by this system because minor issues can affect major goals. This subsystem is a priority rank 7 because it contributes to the long-term maintenance of the output system’s operation. The control, output, and structure subsystems all have a priority ranking of 7 and above marking them as the components that will receive a larger portion of the team’s time and resources due to their importance to the success of the project. The communication system while still important has a lower priority ranking and will still receive adequate attention and time, but it will not be prioritized over the other subsystems.
In the additive manufacturing system, the out system must be able to output tangible parts from the input material and instructions. The utility of the system will be dependent on the ability to produce viable prints consistently. The structures of the system must protect the process from harsh space environments to allow the controls of the system to manufacture output. The communications system will need to be able to transfer intelligible data. The controls system must work as the glue between the other three systems. The controls must process the instructions from communications, environmental data from structures, and feedback from the output system. The outcome of all these systems will be a viable output with an effective tolerance. A measure of mission success will be how well each individual system performs and how well they interact with one another.
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