Outer Loop Requirements for Vertical Lift Unmanned Aerial System Automated Flying Qualities

Abstract

An unmanned aerial system automation qualities framework (previously known as the unmanned aerial system handling qualities framework) has been in development to determine a set of criteria and mission task elements for evaluating the airworthiness of unmanned aerial systems. The framework is being developed to apply across a range of unmanned aircraft from Group 1 to Group 4-5, via scalable predicted (quantitative) automation qualities metrics as well as scalable mission task elements. Prior work has developed scalable mission task elements and predictive attitude response criteria, scaled from MIL-DTL-32742 (which supersedes ADS-33E-PRF). This paper extends the UAS automation qualities framework to provide predictive (quantitative) criteria for velocity and position responses. The paper evaluates Froude scaled velocity disturbance rejection bandwidth and position disturbance rejection bandwidth requirements from MIL-DTL-32742 and describes and evaluates two new metrics, velocity bandwidth and tracking bandwidth, as possible new criteria. These metrics are defined in the paper and were evaluated as predictive quantities for automation handling qualities level using lateral reposition and depart/abort mission task elements. The evaluation was conducted by modifying the control system to achieve parametric variation of the metrics of interest and then assessing the performance with simulation and flight test of mission task elements. Three small unmanned vertical lift aircraft were used in this study; the University of Portland hexacopter, the USNTPS X8-M coaxial quadcopter and Synergy 626 single main rotor helicopter. It was found that the newly defined tracking bandwidth and velocity disturbance rejection bandwidth are key predictive criteria for automation qualities level for automated mission task elements on the test aircraft.