Acceleration Feedback Control for Atmospheric Reduced Gravity Flights

The simulation of reduced gravity environments plays a significant role in advancing scientific research and the on going pursuit of space exploration. While various platforms for microgravity experiments exist, the demand for an accessible, cost-efficient, and flexible solution remains. Aircraft stands out as a promising platform, offering a more economical and readily available option for reduced-gravity research compared to other platforms. This study aims to develop control laws for an autopilot system, enabling precise and reliable aircraft control for a range of reduced gravity levels. The control architecture comprises two specialized controllers, each dedicated to managing acceleration along the tangential and normal axes of the body frame, using the aircraft’s engine thrust and elevator. Building upon prior work, the tangential acceleration controller has three integral actions to enable it to reject the unmeasured drag force efficiently. On the other hand, the accelerometer is positioned in the cockpit to effectively avoid the non-minimum phase behavior of the transfer function from elevator deflection to the normal acceleration of the CG of the airplane. Detailed MATLAB simulation results indicate that the proposed control law allows the system to achieve and maintain any reduced gravity level, including zero gravity, with duration and quality that significantly exceeds the expected benchmarks.