Boundary Regulation: Output-Recovery Guidance for Nonminimum Phase Systems

该奖项的研究目标是研究消除非最小相位系统外部干扰的控制方法。非最小相位系统由于其特殊的动力学结构，使得反馈控制器的性能受到限制。最近开发的非因果前馈技术只能是有效的干扰时，足够的预览信息。本研究将探讨非最小相位系统在干扰未知时之前馈控制。理论的发展将是一般的非最小相位系统，并可以应用于不同的应用。要解决的研究问题是：（i）稳定性，因为稳定性的损失可能会出现多个输出过渡由于外环闭合;（ii）性能，例如，保持系统输出在所需的区域内的多个过渡下触发的侵略性干扰，和（iii）计算工作。 重要的是将计算工作量保持在可接受的水平，例如，从一组预先计算的轨迹近似用于输出转变的前馈。这些工具包括为非最小相位系统设计控制器的工具，保证稳定性和性能的条件，研究结果的文档，以及工程学生教育。这项研究将影响各种应用（具有非最小相位动力学），例如，（i）探针-样品力的精确控制，以避免在原子力显微镜的高速操作期间样品损坏;（ii）在存在阵风干扰的情况下的风力涡轮机，所述阵风干扰对先验测量具有挑战性;以及（iii）小型无人驾驶飞行器（UAV）的飞行控制，这些飞行器对风扰动更敏感。研究生和本科工程专业的学生将受益于课堂教学和参与研究。除了通过课程、研讨会、出版物和会议报告向学生和其他学者传播外，研究结果还将通过年度开放日的展览向高中生和社区展示。

The research objective of this award is to investigate control methods for cancelling external disturbances for nonminimum-phase systems. Performance of feedback controller is limited for nonminimum-phase systems due to the special structure of the system dynamics. Recent developed non-causal feedforward techniques can only be effective when sufficient preview information of the disturbance is available. This research will investigate feedforward-based control for nonminimum phase systems when the disturbance is not known in advance. The theoretical developments will be for general nonminimum phase systems, and can be applied in diverse applications. The research issues to be addressed are: (i) Stability, since loss of stability can arise with multiple output transitions due to an outer-loop closure; (ii) Performance, e.g. maintaining system output within the desired region under multiple transitions triggered by aggressive disturbances, and (iii) Computation effort. It is important to keep the computational effort at an acceptable level, e.g., approximating the feedforward for output transitions from a set of pre-computed trajectories. Deliverables include tools to design controllers for nonminimum phase systems, conditions for guaranteed stability and performance, documentation of research results, and engineering student education. This research will impact a variety of applications (with nonminimum phase dynamics), such as, (i) precision control of probe-sample forces to avoid sample damage during high-speed operation of Atomic Force Microscopes; (ii) wind turbines in the presence of wind-gust disturbances that are challenging to measure a-priori; and (iii) flight control of small unmanned aerial vehicles (UAVs), which are more sensitive to wind disturbances. Graduate and undergraduate engineering students will benefit through classroom instruction and involvement in the research. In addition to dissemination to students and other academics through classes, seminars, publications, and conference presentations, the results will be presented to high-school students and the community through exhibits in annual open houses.