## 3 System Design
### System Architecture  
In the early 2000s, [PERSON], _et al._[15] defined a control architecture for decision making within an autonomous UAS framework. This architecture described a high-level framework for designing autonomous intelligent control systems for UASs. The architecture defined four layers of control: redundancy management, trajectory generation, path planning, and decision making. This general philosophy is still present in many of the design work prevalent today in UAS mission and path planning design. However, this architecture only considers the general control and path planning of a vehicle. To address the high-level requirements previously defined in Section 3.1, a system architecture needs to be developed that can provide the framework for system design and functionality for more than just the mission control of the vehicle. Additionally, a significant portion of the existing research in UAS path planning considers the vehicle a point mass and many of the approaches consider only constant altitude and airspeed. There is minimal consideration of actual vehicle dynamics in the existing research. In order to address the actual vehicle dynamics and utilize those dynamics to improve mission performance utilizing existing methods, an architecture that integrates vehicle dynamics and systems is needed. Figure 1 provides the high-level architecture defined for our proposed autonomous system. The definition proposes five primary functions: Mission Management, Vehicle Management, Sensors Management, Communications Management, and Safety Management. These five areas provide the sufficient top-level framework for any system, regardless of mission and vehicle type. The advantage of this system is that it provides a modular functionality architecture that can be adjusted for specific vehicles but can be common across numerous vehicle types. The autonomous algorithms will reside within the mission management functionality and will be dependent upon common interfaces and architecture. Mission Management:  
The mission management function is the key to the success of the system architecture. A significant portion of the efforts in this area would be consistent with the work of [PERSON], _et al._[15] as discussed earlier. The mission management will provide the primary high-level decision making for the mission performance of the vehicle. The mission management area is the focus of significant research in unmanned and autonomous control. There are three primary functions within the Mission Manager:  
1. Mission Planning:  
The mission planning function provides the mission requirement details for the decision-making process of the mission executive. A mission-planning dataset could include definitions of tasks, priorities, and threats. The mission-planning dataset could be uploaded prior to a mission, during a mission, or self created depending on the autonomous capabilities designed within the system. The mission-tasking information would provide the required tasks the system is desired to perform. A mission-priority schema would provide the executive a decision framework to determine which task is of greater priority. For example, tracking a moving target could be defined as a higher priority than general reconnaissance data collection. Threat definition would provide the system considerations for areas to avoid due to known threats as well as considerations for how to handle newly discovered threats. These considerations could include keep-out zones, self protection actions with sensors, or other actions depending upon system capabilities. 2. Path Planner:  
The path planner is the key algorithm for defining where and how the vehicle should move. The path planner utilizes the considerations defined in the mission planning along with information provided (via the mission executive) on system states. The path planning algorithms could be dynamic or changed for any given mission based upon the needs, priority, and other considerations.