Dynamics and control of small aerial vehicles in contact with environment and of space webs for debris removal.

点击翻译按钮获取中文摘要

This proposal addresses fundamental problems in dynamics and control in the context of two applications: autonomous operation of small unmanned aerial vehicles (UAVs) and space debris removal. The research will ultimately benefit the development community and companies building and marketing UAVs. It will also serve to advance technologies for active space debris removal, which is necessary for a continued and sustainable utilization of near-earth orbits for satellite operation and space science. The funding of this grant will lead to training of five highly qualified personnel through their graduate studies and direct participation in the proposed research topics. Small unmanned aerial vehicles have become a research focus of many robotics groups around the world as applications of these systems have been rapidly expanding into civilian domains. UAVs present numerous challenges in the traditional areas of mobile robotics, in particular, systems design, control law development, state estimation, localization and mapping, path planning, obstacle avoidance and coordinated operation of multiple UAVs. In the present proposal, we depart from these conventional topics and investigate, for the first time, the problems of dynamics and control of small rotary vehicles, such as quadrotors, under the conditions of impact with the environment. We are motivated by the fact that operation of UAVs carries with it a significant risk of collision with surrounding objects, particularly indoors and in unknown, unstructured environments. Therefore, to make small UAV systems safer, to expand their autonomy and ultimately achieve their acceptance in the society at large, our goal for this grant is to investigate dynamics modeling and response of an aerial vehicle under impact conditions, and to develop control methodologies to enable a rotary UAV to recover from a collision with its environment. Our second targeted application stems from the applicant’s leading-edge research in the area of space robotics, and specifically, problems associated with autonomous capture of malfunctioning satellites and space debris. The case for on-orbit servicing and space debris remediation is unequivocal at this point and there is little debate on the role and necessity for these missions. Our research to date has lead to innovative solutions to problems of motion planning and control for capture of unknown tumbling targets using a robotic arm mounted on the servicing (“chaser”) satellite. We plan to expand our efforts towards identifying a feasible solution for active removal of large space debris, by investigating the employment of tethered space webs for capture, subsequent stabilization and de-orbiting of the debris. The space webs (also called tethered nets) concept has been investigated by only a few researchers to date. To our knowledge, there are no comprehensive modeling tools which can be used for a sufficiently accurate, yet computationally practical simulation of the complete debris removal scenario. This would require analysis and modeling of all phases of the mission, starting from tether-net deployment, through impact and ensuing contact between the net and the target, and ending with transporting the debris to a graveyard or lower orbit. Among the aforementioned phases, the impact between the net and the target and subsequent enclosure and stabilization of the target represent the most challenging and least researched problems in dynamics modeling and control of debris capture with a space web. This will be the main area of our investigation on space debris removal in the context of the present grant. Both topics to be considered build on the applicant's prior research and expertise in contact mechanics and dynamics modelling.