Development of an adaptive disturbance rejection system for the rapidly deployable stable platform—Part 2: Controller design and closed loop response

Abstract

Currently, both military and civilian operations that require at-sea cargo transfers are severely limited by environmental conditions and loading forces that induce vessel motions. To increase the robustness of at-sea cargo transfer to these environmental conditions and loading forces, efforts have recently been made toward an actively controlled, rapidly deployable stable platform (RDSP). The purpose of the research presented here is to implement an output feedback adaptive controller and adaptive disturbance rejection scheme that will mitigate the effect of environmental conditions and reject disturbances caused by various loading situations. Because of the controller's distinct ability to adapt to various operating conditions, anticipate and reject load disturbances of unknown magnitude, and adjust to stay within input saturation constraints, the framework is a good fit for the RDSP. Three missions are considered using a previously developed 3 degree of freedom simulation of a 1/10th scale RDSP prototype. Results show successful mitigation of load disturbances and a significant reduction in pitch motions using a control command that remains within the given amplitude and rate constraints. In the case of cargo transfer operations, the adaptive control system is able to significantly increase the cargo throughput by rejecting the disturbances before they are able to cause large pitching dynamics.