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。对于非最小相位系统，由于系统动力学的特殊结构，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有在有足够的干扰预览信息时才能有效。本研究将探讨非最小相位系统在干扰未知情况下的前馈控制。理论发展将适用于一般的非最小相位系统，并可应用于各种应用。需要解决的研究问题是：(i)稳定性，因为由于外回路关闭而造成的多次输出过渡可能造成稳定性的丧失；（ii）性能，例如，在侵略性干扰触发的多次转换下，保持系统输出在期望区域内，以及（iii）计算工作量。将计算量保持在可接受的水平上是很重要的，例如，从一组预先计算的轨迹中近似输出转换的前馈。可交付成果包括设计非最小相位系统控制器的工具、保证稳定性和性能的条件、研究结果的文档和工程学生教育。本研究将影响各种应用（非最小相动力学），例如，(i)精确控制探针-样品力，以避免原子力显微镜高速运行时样品损坏；（ii）存在具有挑战性的先验测量的阵风扰动的风力涡轮机；（三）对风干扰更敏感的小型无人机的飞行控制。研究生和本科生将受益于课堂教学和参与研究。除了通过课堂、研讨会、出版物和会议报告向学生和其他学者传播外，研究结果还将通过每年的开放日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.