Certification Challenges for Autonomous Flight Control System Mr. David B. Homan AFRL Air Vehicles Directorate (937)

VACC Technical Paper Nr. VAO Cleared for Public Release on 11 Aug 04. AFRL-WS To be effective assets in the force structure and mission plans, UAS’s must … Be Safe & Reliable Be Responsive & Effective Be Interoperable Not Adversely Effect Operations Capability Cooperative Airspace Operations Background

VACC Technical Paper Nr. VAO Cleared for Public Release on 11 Aug 04. AFRL-WS Background: Flight Safety and Manned/Unmanned Functional Migration Flight Critical Mission Critical Manned Aircraft Unmanned Aircraft Flight Mgmt Vehicle Mgmt Mission Mgmt Vehicle Mgmt On-board Off-board On-board Off-board Pilot is Integrator and Contingency Manager; FMS is mostly advisory. Flight Mgmt FMS and VMS provide Integration and Contingency Mgmt; Operator manages at high-level. Situational awareness Situational awareness? For UAVs, “Pilot Function” becomes huge design and V&V issue

VACC Technical Paper Nr. VAO Cleared for Public Release on 11 Aug 04. AFRL-WS Background: V&V Requirements Flight Critical Mission Critical System Focus is Performance/Security Performance Metric: Throughput and Bandwidth [event driven] Assurance Metric: Probability of Mission Success [Simplex or Back- up] Confidence Rqmt: Performance and security are validated. Consequence of Failure: Potential mission failure System Focus is Performance/Assurance Performance Metric: Sampling Rate and Latency [time triggered] Assurance Metric: Probability of Loss of Control and N x Fail Op/Fail Safe [Triplex or Quad] Confidence Rqmt: Performance and Assurance must be validated; [Failure Modes and Effects Testing] Consequence of Failure: Loss of Aircraft, potential loss of life Rule of Thumb: When you mix mission with flight criticality, the testing is held to most stringent requirement. Consequence of Failure: Loss of Aircraft, potential loss of life Developmental Timeline: Flight Critical ready by First Flight! Any changes requires Total Re-test! Flight Critical V&V isn’t just a software issue, it’s a system issue!! Failure Modes and Effects Testing

VACC Technical Paper Nr. VAO Cleared for Public Release on 11 Aug 04. AFRL-WS New Capabilities Challenge V&V Mixed Criticality Architecture: Non-obtrusive co-existence of mixed criticality Adaptive/Learning/Multi-Modal Functions: Indeterminate or untraceable functionality Mixed Initiative/Authority Mgmt: Human/autonomy or autonomy/autonomy interactions Multi-Entity Systems: Functions that encompass multiple platforms. Sensor Fusion/Integration: Highly confident sensor-derived information These new systems/capabilities Need to be affordably provable New Capabilities (and increasing complexity) are presenting new challenges to the V&V problem.

VACC Technical Paper Nr. VAO Cleared for Public Release on 11 Aug 04. AFRL-WS Mixed Criticality Challenge How can we separate the mission and flight critical functionality as to guarantee safety? SOA: Middleware that provides time/space partitioning (ARINC 653). Issue: Both Criticalities use common HW resources (i.e. processors, backplanes, busses etc); how do we determine PLOC and fault tolerance? Understand failure mechanisms for partitioning Non-critical function must not take out shared resources…Or the probability of its occurrence is predictable… Need guarantee on fault tolerance A A A B B C backplanes Serial bus Processors X X X Answer may reside in a SW/HW architecture specifically designed for mixed operation

VACC Technical Paper Nr. VAO Cleared for Public Release on 11 Aug 04. AFRL-WS Adaptive/Learning/Multimodal Challenge How can we trust functionality that we may not be able to fully test? SOA: We must try to test the complete functional envelope (till $$ runs out…)! Issue: Some new Control capabilities are untraceable and/or non-deterministic Adaptive systems Huge test space Perfect Input data Learning systems Environmental stimuli Lost memory Multi-modal systems Mode transition stability Mode synchronization Recovery mode Answer may reside in bounding the function in run- time to known safe behavior.

VACC Technical Paper Nr. VAO Cleared for Public Release on 11 Aug 04. AFRL-WS Mixed Initiative Challenge How can man and autonomy safely interact? SOA: Human operator always get authority! Issue: Human operator may not have all the information or be able to comprehend situation in real-time: Situational Awareness versus Response Time Assessment of UAV mode/state/health Assessment of surrounding environment “Consequence of mishap” is a factor Complete system health is a factor Workload is a factor AF Poster Child: Auto-Aerial Refueling (AAR) Answer may reside in a authority management specification that would allow the correct party to have decision authority.

VACC Technical Paper Nr. VAO Cleared for Public Release on 11 Aug 04. AFRL-WS Multi-Entity Challenge How can trust systems with multiple players to safely perform cooperative functions? SOA: Keep humans away and hope for the best… Issue: Entities participating in the coordinated function may not be part of individual V&V testing: Linked Interface Control Documents? Entities with different manufacturers? System Configuration Management? Mission-specific programming? Answer may reside in a specification for contingency management, based on system degradation

VACC Technical Paper Nr. VAO Cleared for Public Release on 11 Aug 04. AFRL-WS High Confidence Sensing Challenge How can we trust visual/radar systems for flight critical functions? SOA: Brute force and analytic redundancy Issue: Mission-style sensors don’t have acceptable real-time methods for FDIR… Sensors will likely be multi-function! Redundant HW may not be answer, redundant information? Built-in-test may not provide good real-time coverage. Reliable signal processing/sensor fusion software Answer may reside in sensor designs that compensate for sensor degradation and plan for contingencies