Ideas taken from https://services.anu.edu.au/files/development_opportunity/ResearchProposalTips_0.pdf # Title / Topic # Research Problem (Justification) - Why does robust control exist - air conditioning example - but what if the plant is different? What is buddy leaves a window open - We can examine whether or not our controller (the ac unit) can handle the perturbed plant - We can know how open the window is before we have problems - We can guarantee this for this controller design and designed laws - So if we do this can be sure when we build the unit that this is how it will perform? - Well if it's controlled with a microcontroller or other code based solution, no. - The abstraction between the design and the finished controller destroys the guarantee - Things can happen in implementation that make the controller built not true to design - As a result, we need to reverify robustness on built controllers - This exists for structured perturbations. We # Gap In The Literature ## **Slide 1: Robust Control Foundations** **Assertion:** Robust control ensures stability despite system discrepancies. **Evidence:** - Controllers are based on physical models that differ from real systems. - Robust control analyzes resilience to system perturbations. - Evolved from single-input single-output to multi-input multi-output systems. _(Cite Doyle, Green, Brunton)_ --- ## **Slide 2: Structured vs. Unstructured Perturbations** **Assertion:** Robust control addresses structured and unstructured perturbations differently. **Evidence:** - **Structured:** Based on physical tolerances (e.g., spring rates). - **Unstructured:** Accounts for unmodeled dynamics and broader uncertainties. _(Diagram comparing structured and unstructured perturbations)_ _(Cite Doyle, Green)_ --- ## **Slide 3: Disk-Based Unstructured Uncertainty** **Assertion:** Disk-based perturbation quantifies unstructured uncertainties. **Evidence:** - Key equation: $\tilde{P} = (1 + \Delta W_2) P$ - $P$: Nominal plant. - $\Delta$: Perturbation transfer function. - $W_2$: Uncertainty envelope. - Conditions for $W_2$ and $\Delta$: - $\left| \frac{\tilde{P}(j\omega)}{P(j\omega)} - 1 \right| \leq \beta |W_2(j\omega)|$ - $||\Delta||_\infty \leq \beta$. _(Include a visual of how $\Delta$ affects $P$)_ --- ## **Slide 4: Current Limitations in Robust Control** **Assertion:** Current methods lack discrete examples of unstructured perturbations. **Evidence:** - $\Delta$ is undefined for experimental robustness verification. - Structured uncertainties are used experimentally but neglect unmodeled dynamics. _(Cite Farzan, Hamilton)_ --- ## **Slide 5: Diffusion Models as a Solution** **Assertion:** Diffusion models can generate unstructured perturbations. **Evidence:** - Forward process transforms data to Gaussian distribution. - Reverse process generates approximations of target data. - Applications in protein folding, training data generation. _(Diagram of forward/reverse processes in diffusion models)_ _(Cite Sohl-Dickstein, Abramson)_ --- ## **Slide 6: Parallels Between Diffusion Models and This Project** **Assertion:** Diffusion models address sparse perturbation generation in engineering. **Evidence:** - Diffusion models create diverse training data from sparse sets. - Proposed approach: Generate unstructured perturbations from structured sets. _(Illustration of sparse-to-diverse transformation concept)_ # Goals and Outcomes # Research Methodology ## **Slide 1: Research Motivation** **Assertion:** Current methods for generating unstructured perturbations are limited in flexibility and generalizability. - **Evidence:** - Unstructured perturbations lack adaptability to various scenarios. - Proposed approach leverages diffusion generative models for flexible perturbation generation. **Visuals:** - A flowchart contrasting traditional perturbation methods vs. diffusion models. --- ## **Slide 2: Diffusion Model Features** **Assertion:** Frequency response data forms the foundation for feature creation in diffusion models. - **Evidence:** - Features discretize dynamics into a vector of magnitude and phase. - Supports training without imparting unintended structure. **Visuals:** - Diagram from Figure 1 showing the discretization of frequency response. --- ## **Slide 3: Creating Frequency Features** **Assertion:** Discretizing the frequency response enables scalable feature sets. - **Evidence:** - Fine resolution for complex behavior or coarse for computational efficiency. - Features provide physical context across frequency scales. **Visuals:** - Table comparing fine vs. coarse frequency sampling. - Annotated example of magnitude/phase vector with scales labeled. --- ## **Slide 4: Training the Diffusion Model** **Assertion:** Diffusion models learn unstructured perturbations through iterative noise transformation. - **Evidence:** - Forward process adds noise; reverse process removes it. - Training maximizes log-likelihood between input and reconstructed data. **Visuals:** - Flowchart of the diffusion training process. - Key equations (e.g., Eq. \ref{forward_kernel} and \ref{reverse_kernel}) simplified with annotations. --- ## **Slide 5: Generating New Perturbations** **Assertion:** The trained diffusion model generates diverse and flexible perturbations. - **Evidence:** - Outputs are probabilistic, enabling variability. - Perturbation level controlled by adjusting time steps. **Visuals:** - Illustration of forward/reverse process with arrows and annotations. - Graph showing interpolation from partial time steps. --- ## **Slide 6: Ensuring Valid Perturbations** **Assertion:** Generated perturbations must meet robust control requirements. - **Evidence:** - No additional right-hand plane poles. - Supremum gain of Δ below threshold β. **Visuals:** - Diagram of pole-zero constraints. - Workflow for verifying Δ and fitting transfer functions. --- ## **Slide 7: Advantages of Diffusion Models** NOT INCLUDED SO FAR **Assertion:** Diffusion models provide a novel solution for generating unstructured perturbations. - **Evidence:** - Introduce non-deterministic variability into perturbations. - Overcome the limitations of traditional structured approaches. **Visuals:** - Comparative chart: structured vs. unstructured methods. - Examples of perturbed frequency responses generated by the model. # Research Tasks ## **Slide 1: Research Tasks Overview** **Assertion:** This research aims to address verification challenges through structured tasks. - **Evidence:** Four key research tasks support the proposed outcomes: 1. Mission-Beneficiary Fit 2. Find Robust Systems 3. Create Diffusion Model 4. Analyze and Disseminate Results **Visuals:** - A process diagram summarizing the four tasks. --- ## **Slide 2: Mission-Beneficiary Fit** **Assertion:** Understanding beneficiaries ensures relevance and impact of this research. - **Evidence:** - Beneficiary Identification: Research how control engineers might use this work. - Value Proposition: Define and align capabilities with verification needs. **Visuals:** - Chart or table identifying beneficiaries and their verification needs. --- ## **Slide 3: Find Robust Systems** **Assertion:** Identifying relevant plants ensures practical applicability of results. - **Evidence:** - Literature Review: Investigate industrial applications of robust control verification. - Create Example Plants: Reconstruct models of prominent systems for demonstrations. **Visuals:** - Example of a controlled industrial process. - Flowchart of the literature review and modeling process. --- ## **Slide 4: Create Diffusion Model** **Assertion:** A diffusion model is central to generating unstructured perturbations. - **Evidence:** - Identify Model Structure: Choose an architecture (e.g., U-Net). - Train Model: Develop training data and optimize performance. - Generate Perturbations: Apply the model to example plants. **Visuals:** - Diagram of a U-Net-based architecture. - Example of generated unstructured perturbations. --- ## **Slide 5: Analyze and Disseminate Results** **Assertion:** Communicating findings ensures broader adoption and state-of-the-art advancements. - **Evidence:** - Publish results in academic journals. - Demonstrate impact on robustness verification practices. **Visuals:** - Example journal or conference targets. - Overview of the dissemination process. # Metrics of Success ## **Slide 1: Metrics of Success Overview** **Assertion:** Project success will be evaluated through milestone tracking and outcome-based metrics. - **Evidence:** 1. Goals and Outcomes: Milestones tied to the objectives of this research. 2. Unstructured Perturbation Evaluation: Metrics to assess diffusion model output. **Visuals:** - High-level flowchart showing the two categories of success metrics. --- ## **Slide 2: Goals and Outcomes** **Assertion:** The research aims to deliver specific capabilities for creating unstructured perturbations. - **Evidence:** - Approximate unstructured sets through numerous perturbed plants. - Perturb nominal plants using the diffusion model. - Generate frequency-domain responses from training data. **Visuals:** - Table summarizing the three goals and their significance. - Conceptual graphic of a nominal plant with perturbed versions around it. --- ## **Slide 3: Unstructured Perturbation Evaluation** **Assertion:** The diffusion model's success will be judged on distribution and diversity of perturbations. - **Evidence:** - Distribution: Verify uniform coverage of the multiplicative uncertainty disk. - Diversity: Assess non-parametric, dissimilar perturbations among examples. **Visuals:** - Example complex plane with plotted perturbed plants. - Graph comparing similarity metrics across perturbations. --- ## **Slide 4: Statistical Evaluation (Optional Deep Dive)** **Assertion:** Statistical analysis ensures robustness and diversity in generated perturbations. - **Evidence:** - Standard statistical tests applied to the perturbation set. - Covariance vectors calculated for key frequency ranges. **Visuals:** - Example statistical output or covariance plot for one frequency band. - Caption explaining its role in validating uniform coverage. # Risks and Contingencies ## **Slide 1: Risks and Contingencies Overview** **Assertion:** This research has identified key risks and developed contingencies to address them. - **Evidence:** 1. Computational demands of diffusion models. 2. Training data sufficiency. 3. Generalization of interpolation methods to perturbations. **Visuals:** - A risk-contingency matrix outlining the key challenges and corresponding mitigations. --- ## **Slide 2: Risk 1 - Computational Demands** **Assertion:** Diffusion models may require significant computational resources during training and inference. - **Evidence:** - Reverse process inference is computationally intensive due to per-step calculations. - Training complexity scales with model structure and feature count. **Contingencies:** 1. Utilize the University of Pittsburgh’s CRC supercomputing resources. 2. Reduce data features while monitoring model performance. **Visuals:** - Diagram comparing computational cost across time steps. - Icon of computational resources with CRC logo or similar. --- ## **Slide 3: Risk 2 - Insufficient Training Data** **Assertion:** Structured perturbations alone may not condition the model adequately. - **Evidence:** - Structured perturbations simplify training but may lack diversity. **Contingencies:** 1. Augment training with manually or algorithmically generated $\Delta$ examples (e.g., bounded by supermum gain $\beta$). 2. Diversify training data sources to improve robustness. **Visuals:** - Example of structured vs. manual perturbation samples on the complex plane. - Flowchart showing training data augmentation process. --- ## **Slide 4: Risk 3 - Interpolation Limitations** **Assertion:** Interpolation methods may fail to regulate perturbations effectively. - **Evidence:** - Image-based interpolation success may not generalize to this domain. **Contingencies:** 1. Implement $r(\mathcal{P}_t)$-based reverse process steering for controlled perturbations【cite sources】. 2. Explore alternative interpolation techniques tailored to frequency domain applications. **Visuals:** - Conceptual illustration of $r(\mathcal{P}_t)$ steering function in reverse process. - Example showing failure of simple interpolation and correction with $r(\mathcal{P}_t)$. --- ## Slide 5: Risk Mitigation Framework (Optional Summary Slide) **Assertion:** Addressing risks proactively ensures project success. - **Evidence:** - Computational strategies, diversified training, and alternative steering methods safeguard outcomes. **Visuals:** - Funnel graphic showing risks addressed through mitigations leading to project success.