Dynamics and Control of Tethered Multi-Rotor Unmanned Aerial Vehicles with Switchable Powered and Autorotation Modes

本研究项目将通过提高用于监视、通信和传感的系留式无人机的飞行时间和能效，促进动态建模和控制设计的进步，促进国家的繁荣、福利和安全。绳系无人机的使用值得关注，因为它们可以提供一种紧凑、便携、临时和可快速部署的替代直升机或卫星的选择。目前的系统，通过导电系绳供电，可以增加无人机在空中停留的时间，并减轻机载电池的重量。该项目将研究使用合适的叶片几何形状、拍打/摇摆自由度和主动反馈控制，目的是在普遍风速较高时通过切换到自动旋转来提高无人机的能效。因此，新设计将有能力通过在运行时利用风能来减少能源需求。该系统将是便携式的，易于部署，并可主动控制。它将是灵活的，机动的，它在两种飞行模式之间切换的能力将允许在所需的高度和方向进行强健的悬停。该项目将利用中佛罗里达大学的iSTEM计划，让女性和未被充分代表的少数族裔学生参与研究活动，并通过奥兰多科学中心实现社区推广。该项目将促进与能源和电力行业的持续合作研究，并与对系留无人机有商业兴趣的当地行业合作伙伴创建新的合作。该研究将通过在动态建模和控制设计方面进行广泛努力，在系留无人机的操作方面取得根本性进展。两种飞行模式，其独特的驱动和输入设置，以及不同的自转气动特性，使系统的控制有别于传统的多旋翼系统。该系统具有多输入多输出的结构，因果关系交替，干扰源多，参数范围广，需要主动控制才能实现功能。这个系统允许一个均衡的连续体。这项研究将确定在这个平衡空间内可行的和最优子空间，其中(1)动量理论成立并给出准确的空气动力学预测，(2)产生足够的升力，(3)系绳张力被限制在可接受的范围内。系统的稳定化将采取根本的新方向，包括切换控制、不确定性量化和前馈动作。在自转过程中，将采用差动再生制动实现姿态稳定。通过系绳长度驱动和间歇模式切换，将实现稳健的自转。因此，能效和主动姿态/高度控制将成为一体。该结构的几何对称性将有助于使用降阶模型进行控制设计，同时最大限度地减少一般性损失。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This research project will promote the progress of dynamic modeling and control design, and advance the national prosperity, welfare and security by increasing both the time aloft and the energy efficiency of tethered unmanned aerial vehicles (UAVs), which are used for surveillance, communication, and sensing. The use of tethered UAVs deserves attention since they can provide a compact, portable, temporary, and rapidly deployable alternative to helicopters or satellites. The presented system, powered through an electrically conductive tether, can increase the time UAVs can remain in the air and reduce the weight of on-board batteries. The project will study the use of suitable blade geometry, a flapping/teetering degree of freedom, and active feedback control with the goal to enhance energy efficiency of a UAV by switching to autorotation when prevailing wind speeds are high. Accordingly, the new design will have the capability of reducing its energy requirement by harnessing wind energy while in operation. The system will be portable, easily deployable, and actively controlled. It will be agile, maneuverable, and its ability to switch between two flight modes will allow robust hovering at desired altitudes and orientations. The project will leverage University of Central Florida iSTEM program to involve women and underrepresented minority students in research activities and enable community outreach via the Orlando Science Center. The project will foster ongoing collaborative research with the energy and power industry and create new collaboration with local industry partners that have business interest in tethered UAVs.The research will make fundamental advances in operation of tethered UAVs by undertaking extensive efforts in dynamic modeling and control design. The two flight modes, their unique set of actuations and inputs, and the distinct aerodynamic characteristics of autorotation, distinguish the control of the system from conventional multi-rotor systems. The system has a Multi-Input Multi-Output structure, alternating causalities, many disturbance sources, a wide array of parameters, and requires active control for delivering the functionalities. The system admits a continuum of equilibria. This research will determine the feasible and optimal subspaces within this equilibrium space where, (1) the momentum theory holds and gives an accurate prediction of the aerodynamics, (2) sufficient lift is generated, and (3) the tether tension is confined within acceptable limits. Stabilization of the system will take fundamentally new directions, involving switched control, uncertainty quantification, and feed-forward actions. During autorotation, differential regenerative braking will be employed for attitude stabilization. Robust autorotation will be achieved by tether length actuation and intermittent mode switching. Thereby energy efficiency and active attitude/altitude control will become integrally coupled. The geometric symmetry of the structure will facilitate control design using reduced-order models while incurring minimal loss of generality.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.