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。由于系统动力学的特殊结构，对于非最小相位系统，反馈控制器的性能受到限制。最近发展的非因果前馈技术只有在有足够的扰动预览信息时才能有效。本研究将研究非最小相位系统在扰动未知情况下的前馈控制问题。理论的发展将针对一般的非最小相位系统，并可应用于不同的应用。要解决的研究问题是：(I)稳定性，因为由于外环闭合而导致多个输出转变可能导致稳定性的损失；(Ii)性能，例如在由激进扰动触发的多个转变下将系统输出保持在期望区域内；以及(Iii)计算工作量。重要的是将计算工作量保持在可接受的水平，例如，从一组预计算轨迹近似输出转换的前馈。交付内容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专业学生的教育。这项研究将影响各种应用(具有非最小相位动力学)，如：(I)精确控制探针-样本力，以避免原子力显微镜高速运行时样品受到损坏；(Ii)风力涡轮机在存在阵风扰动的情况下难以先验测量；以及(Iii)小型无人机(UAV)的飞行控制，因为无人机对风扰动更敏感。工程专业的研究生和本科生将从课堂教学和参与研究中受益。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，结果还将通过每年开放参观的展品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.