## 3 System Design
### System Architecture
The path planner must also determine path planning based upon contingency management requirements of the system for subsystem failures. The path-planning algorithm is a significant consideration of this paper and current capabilities are discussed later in this paper. 3. Mission Executive:  
The Mission Executive (ME) is the primary decision maker for the vehicle. The functionality of the ME defines whether to perform the current task defined by the path planner or reacts to safety management information. The ME also provides and receives communication updates with other vehicles, operators, and other sources as required. The ME commands the vehicle management system to perform flight maneuvers and other vehicle system functionality. The ME could be considered equivalent to a human operator within a manned vehicle system. 2. Sensor Management  
Sensor Management provides the control for all the mission sensors installed on the vehicle. Mission sensors are defined as any sensor utilized to perform the mission. Sensors that are used to manage the vehicle control and health are handled within vehicle management. There may be some cross utilization of these sensors for both systems. However, the management of those sensors would be handled by their primary user. Portions of sensor management, such as sensor types and control, are well understood in existing systems. However, the sensor data processing will require continued and significant research to provide autonomous sensor data at a decision level that can be trusted. There are three key functions within the sensor management framework. * Mission Sensors: Mission sensors are the sensors specifically installed on the aircraft for data gathering in direct support of mission completion. The mission sensors will be dependent upon the vehicle and mission requirements. These sensors will perform the primary mission duties and could include electro-optical/infrared sensors, radar sensors, radio frequency sensors, or any number of other types. The sensors will have a direct interface to the data-processing module and the control-executive module. These sensors will perform their tasks based upon commands received from the sensor-control executive. * Sensor-Data Processing: The sensor-data processor will analyze received data and make a decision on the information received based upon algorithms defined. The processing could be utilized for any number of tasks including target recognition, geo-location, target motion, and sensor response. The data will also be processed for transmission, as required, and sent to the sensor-control executive for passage to the communication management for dissemination. A significant level of research is ongoing in areas of sensor data fusion, image processing, and recognition that can support decisions and vehicle tasking. * Sensor Control Executive: The sensor-control executive (SCE) is the primary controller of all sensors and sensor taskings. The SCE interfaces with the ME and provides sensor availability, sensor capability, sensor data evaluation (target ID, geo-location, _etc._), and sensor health. The ME provides the SCE with sensor tasking. The SCE will be required to automatically identify what sensors it has installed on board and what their capabilities are. * Safety Management Safety Management provides overall safety monitoring for the vehicle. The types of safety management performed can be dependent upon vehicle type, sensors installed, capabilities required, and vehicle capabilities. The systems defined in this architecture are notional but are critical for UASs. The safety executive can provide high-priority tasking to the mission executive that can result in overriding current activities for safety reasons. Safety management is an area that is understood, but the integration of it with autonomous systems continues to be researched and developed across vehicle types. The core safety management functions defined in this architecture are explained here, but are not exhaustive of possible functions.