Xu Chen Xu Chen
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    • 🤖 UW Robotics From the Kickoff Retreat to the First Lab
    • 🎉 11 New Papers and a Patent in 2026 — ICRA, IROS, CDC, ICPR, IFAC, AIM, and More!
    • Tomizuka Fest 2026: Celebrating Five Decades of Mentorship in Mechanical Systems Control
    • The Precision Engineering and the Mechatronics Mindset
    • 🚀 New Paper Published in Robotics and Computer-Integrated Manufacturing!
    • 🎉 New Best Student Paper Award on System Identification with Non-Uniform Feedback
    • 🎉 Wrapping up the Winter Quarter and the Graduate Linear Systems Class
    • Starting a new journey
  • Teaching
    • Introduction to Programming, Robotics, and Computer-Aided Technology
      • Introduction
      • An Engineering Introduction to The Command Line
      • Introduction to Programming and Python
      • Python Syntax
      • Python Flow Control
      • Python Data Types
      • Python Functions
      • Introduction to Robotics
      • Introduction to 3D Printing
      • Introduction to 3D Scanning
    • 3D Printing - Learn by Building
      • Summary
      • Firmware
      • Delta Robot Kinematics
    • Engineering Analysis
      • Ordinary Differential Equation
      • Linear Algebra
      • Fourier Analysis
      • Partial Differential Equation
      • Vector Algebra
      • Gradient
      • Leibniz Rule
    • Introduction to Control Theory
      • 1. Power of Controls
      • 2. Block Diagram Simplification
      • 3. Modeling
      • 4. Laplace Transform
      • 5. Inverse Laplace Transform
      • 6. First- and Second-Order Systems
      • 7. Second-Order Step Response
      • 8. Dominant Poles
      • 9. Effect of Zeros
      • 10. Routh-Hurwitz Stability
      • 11. PD Control of an Unstable System
      • 12. Steady-State Error
      • 13. Root Locus Technique
      • 14. Departure and Arrival Angles
      • 15. High-Order Poles and Root Locus
      • 16. Pole Locations and Response
      • 17. PD Transient Design
      • 18. Lead and Lag Compensators
      • 19. PID Design with Root Locus & Python
      • 20. Bode Plots: Sinusoidal Response
      • 21. Bode Plots: Phase Lead and Resonance
      • 22. Bode Plots: Dominant Poles and Zeros
      • 23. Nyquist: The Argument Principle
      • 24. The Nyquist Criterion
      • 25. Nyquist Contour Detours
      • 26. Nyquist Stability and Margins
    • Advanced Control Systems I
      • Introduction
      • The Power of Control
      • Terminology
      • Laplace transform
      • Inverse Laplace transform
      • Z transform
      • Inverse Z transform
      • Introduction to the state space
      • From state space to transfer functions
      • State-space discretization
      • Transfer function discretization
      • Stability overview and the method of eigenvalue and pole locations
      • Lyapunov Stability
      • Kalman decomposition
      • State feedback
      • Observers and observer-state feedback
      • Linear Quadratic (LQ) optimal control
    • Introduction To Python For Modern Controls
      • Introduction
      • Setting Up Your Python Environment
      • Frequency Response Analysis of Linear Systems
      • State-Space Representation and Solutions in Python
      • State-Space Realization
      • Stability
      • State Feedback
      • Controllability
      • Continuous-Time Luenberger Observer Design
      • Discrete Time Observer Design
      • Linear Quadratic Optimal Control
    • Advanced Control Systems II
      • Introduction
      • Dynamic programming
      • Discrete-time LQ optimal control
      • Review of probability theory
      • Principle of least squares
      • Kalman filter
      • Linear Quadratic Gaussian problem
      • Principles of feedback design
      • Discretization
      • Loop transfer recovery
      • Frequency-shaped LQ
      • Zero-phase-error tracking control
      • Preview control
      • Internal model principle and repetitive control
      • Disturbance observer
    • Special Topic - Control Parameterization and Loop Shaping
      • Introduction
      • Closed-loop Stability
      • Principles of Feedback Design
      • Linearization
      • Modeling Project Template
      • SISO Youla-Kucera Parameterization
      • Signal Models
      • Pseudo YK Parameterization
      • Model Inversion
      • Project
    • System Identification and Adaptive Control
      • Introduction
      • Discretization and sampling
      • Regressor models
      • Recursive least squares
      • Stability of adaptive systems
      • Parallel adaptation
      • Parameter convergence of adaptation algorithms
      • Internal Model Principle
      • Adaptive pole placement
      • Adaptive disturbance observer
      • Nonlinear system identification
    • Robotics, vision, and mechatronics for manufacturing
      • Introduction
    • Book on Modern Control Engineering with Python
    • _index
    • _index
  • Publications
    • The Good, the Bad, and the Template: Contrastive Anomaly Detection in 3D
    • PyHDD Benchmark: A Python-Based Framework for Magnetic-Head Positioning Control Systems in Hard Disk Drives
    • Robotic Autofocus Algorithm for Visual Inspection in Precision Manufacturing Using Focus Value and Ratio-Based Velocity Control
    • Contrastive Learning on 3D Point Clouds for Robotic Geometric Defect Detection
    • Admittance-Based Surface Alignment for Human-in-the-Loop Robotic Visual Inspection
    • R-SLPR: Region-based Small-to-Large Point-cloud Registration with Contrastive Learning
    • Iterative Youla-Kucera Loop Shaping For Precision Motion Control
    • Robust Signal Recovery of Structured Beyond Nyquist Frequency Signals Using Finite and Infinite Impulse Response Filter Designs
    • Coverage Path Planning for Ultrasonic Non-Destructive Inspection
    • Learning to Detect Slip through Tactile Estimation of the Contact Force Field and its Entropy Properties
    • Agile Surface Inspection Framework for Aerospace Components Using Unsupervised Machine Learning
    • Effect of Intra-Build Design Parameters on the Fracture Toughness Properties of EBM Ti6Al4V
    • A Robotic Surface Inspection Framework and Machine-Learning Based Optimal Segmentation For Aerospace and Precision Manufacturing
    • AIM 2024: Proceedings of 2024 IEEE/ASME International Conference on Advanced Intelligent Mechatronics
    • ISFA 2024: Proceedings of 2024 ISCIE/ASME International Symposium on Flexible Automation
    • Optimal Loop Shaping and Disturbance Rejection Beyond the Nyquist Frequency using a Forward Model Disturbance Observer and Convex Optimization Based Filter Design
    • State-Space System Identification beyond the Nyquist Frequency with Collaborative Non-Uniform Sensing Data
    • A Recursive System Identification with Non-uniform Data under Coprime Collaborative Sensing
    • Collaborative Robotics, Controls, and Machine Learning for Automated Visual Inspection of Complex Parts and Surfaces
    • Control-oriented Modeling and Multirate Feedback Control in Laser Powder Bed Fusion Additive Manufacturing
    • Learning to Detect Slip through Tactile Measures of the Contact Force Field and its Entropy
    • Multi-Track Melt Pool Width Modeling in Powder Bed Fusion Additive Manufacturing
    • Understanding and Controlling the Sensitivity of Event Cameras in Responding to Static Objects
    • Least Squares Solution for System Identification with Non-uniform Data under a Coprime Collaborative Sensing Scheme
    • Preheating Temperature Control and Low-Contrast Imaging Data Analytics for Laser Powder Bed Fusion
    • Microstructure and Microhardness of Electron Beam Melted Ti-6Al-4V Components with Differential Thickness in Initial Deposition Layers
    • Control-oriented Modeling and Learning of Fast 3-Dimensional Laser-material Interaction from 2-Dimensional Images
    • A Robotic Chess Player and the Impacts of Mechanical and Environmental Setting in Data Collection
    • A Mass-transfer Based Approach to Model and Predict VOC Emission From Selective Laser Sintering With Multiple Printing Parameters
    • Learning Of Fast 3-dimensional Laser-material Interaction From 2-dimensional Images
    • Target Tracking Under Delayed and Irregularly-Sampled Visual Feedback for a Robotic Air-Hockey System
    • A Machine Learning-based Portable Inspection Method For Evaluation Of Tool Surface Condition And Release Coating In Composites Manufacturing
    • Closed-loop Feedback For Additive Manufacturing Simulation
    • Adaptive Illuminance Control
    • Method for Segmenting Images
    • A New Kinetic Modelling of Polyamide 12 Degradation in Selective Laser Sintering
    • An Image Segmentation Framework for In-Situ Monitoring in Laser Powder Bed Fusion Additive Manufacturing
    • Control-oriented In-situ Imaging and Data Analytics for Coaxial Monitoring of Powder Bed Fusion Additive Manufacturing
    • Shape-Adaptive Lighting for Complex Geometries in Automated Visual Inspection
    • Target Tracking Under Delayed and Irregularly-Sampled Visual Feedback for a Robotic Air-Hockey System
    • A Control of Surface Quality in Selective Laser Sintering Additive Manufacturing With Reclaimed Polyamide Materials
    • A Combined Theoretical and Experimental Approach to Model Polyamide 12 Degradation in Selective Laser Sintering Additive Manufacturing
    • Control-oriented Mechatronic Design and Data Analytics for Quality-assured Powder Bed Fusion Additive Manufacturing
    • Provision of Controlled and Consistent Light Distribution Over an Uneven Topography to Maximize Efficacy of Machine-Vision based Defect Identification
    • Adaptive Illuminance Control of Uniform and Uneven Topographies
    • System and Method for Defect Detection in Laser Powder Bed Fusion Additive Manufacturing
    • New Hammerstein Modeling and Analysis for Controlling Melt Pool Width in Powder Bed Fusion Additive Manufacturing
    • Control-Oriented Modeling and Repetitive Control of In-Layer and Cross-Layer Thermal Interactions in Selective Laser Sintering
    • Evaluating Poly (Ether Ether Ketone) Powder Recyclability for Selective Laser Sintering Applications
    • Process Control of Surface Quality and Part Microstructure in Selective Laser Sintering Involving Highly Degraded Polyamide 12 Materials
    • Quantitative Influences of Successive Reuse on Thermal Decomposition, Molecular Evolution and Elemental Composition of Polyamide 12 Residues in Selective Laser Sintering
    • Focused Section on Machine Learning, Estimation and Control for Intelligent Robotics
    • A New Kinetic Modelling of Polyamide 12 Degradation in Selective Laser Sintering
    • An In-situ Imaging and Data Analytics for Selective Laser Sintering in Presence of System Degradation
    • Closed-loop Feedback For Additive Manufacturing Simulation
    • Local Loop Shaping for Rejecting Band-Limited Disturbances in Nonminimum-phase Systems with Application to Laser Beam Steering for Additive Manufacturing
    • Closed-loop High-fidelity Simulation Integrating Finite Element Modeling with Feedback Controls in Additive Manufacturing
    • New Hammerstein Modeling and Analysis for Controlling Melt Pool Width in Powder Bed Fusion Additive Manufacturing
    • A Collaborative Sensing and Model-based Realtime Recovery of Fast Temporal Flows from Sparse Measurements
    • Active Interlayer Heating for Sustainable Selective Laser Sintering With Reclaimed Polyamide 12 Powders
    • Closed-loop Simulation Integrating Finite Element Modeling with Feedback Controls in Powder Bed Fusion Additive Manufacturing
    • A Factory-Centric Workforce Development Approach for Aerospace Industry
    • H-infinity-based Selective Inversion of Nonminimum-phase Systems for Feedback Controls
    • A Process Control and Interlayer Heating Approach to Reuse Polyamide 12 Powders and Create Parts With Improved Mechanical Properties in Selective Laser Sintering
    • Introduction to the Focused Section on Machine Learning, Estimation and Control for Intelligent Robotics
    • Multivariable Robust Blade Pitch Control Design to Reject Periodic Loads on Wind Turbines
    • Robotic Target Following with Slow and Delayed Visual Feedback
    • Closed-loop High-fidelity Simulation Integrating Finite Element Modeling with Feedback Controls in Additive Manufacturing
    • A Dynamic Target Tracking Under Slow and Delayed Vision Feedback
    • Control-Oriented Modeling and Repetitive Control of In-Layer and Cross-Layer Thermal Interactions in Selective Laser Sintering
    • Following Fast-Dynamic Targets With Only Slow and Delayed Visual Feedback - a Kalman Filter and Model-Based Prediction Approach
    • Model-based Sparse Information Recovery by Collaborative Sensor Management
    • Wide-band Loop Shaping for Modulation of Energy Transmission in Nonminimum-phase Systems
    • Synthesis and Analysis of Multirate Repetitive Control for Fractional-order Periodic Disturbance Rejection in Powder Bed Fusion
    • A Multirate Repetitive Control for Fractional-Order Servos in Laser-Based Additive Manufacturing
    • A Spectral Analysis and Its Implications of Feedback Regulation beyond Nyquist Frequency
    • Periodic Wind Disturbance Rejection using Robust Individual Pitch Control
    • A Multirate Fractional-Order Repetitive Control for Laser-Aided Additive Manufacturing
    • Discrete-Time Nonlinear Damping Backstepping Control With Observers for Rejection of Low and High Frequency Disturbances
    • Realtime Control-Oriented Modeling and Disturbance Parameterization for Smart and Reliable Powder Bed Fusion Additive Manufacturing
    • Rejecting Fast Narrow-Band Disturbances With Slow Sensor Feedback for Quality Beam Steering in Selective Laser Sintering
    • Control of Dual-stage HDDs with Enhanced Repetitive Disturbance Rejection
    • Adaptive Loop Shaping for Wideband Disturbances Attenuation in Precision Information Storage Systems
    • Disturbance Observer Based Pitch Control of Wind Turbines for Enhanced Speed Regulation
    • A Robust Optimal Design for Strictly Positive Realness in Recursive Parameter Adaptation
    • A Tutorial on Loop-shaping Control Methodologies for Precision Positioning Systems
    • An Inverse-Free Disturbance Observer for Adaptive Narrow-Band Disturbance Rejection With Application to Selective Laser Sintering
    • Data Storage Devices and Methods with Frequency-Shaped Sliding Mode Control
    • Multi-band beyond-Nyquist Disturbance Rejection on a Galvanometer Scanner System
    • Disturbance Observer Based Control Design for Wind Turbine Speed Regulation
    • Spectral Distribution and Implications of Feedback Regulation beyond Nyquist Frequency
    • Enhanced Wide-Spectrum Vibration Suppression Based on Adaptive Loop Shaping
    • Extended State Observer with Phase Compensation to Deal with High-frequency Vibrations in Hard Disk Drives
    • Input-to-output Discontinuity and Transient Improvement in Add-on Control Design
    • Multirate Forward-model Disturbance Observer for Feedback Regulation beyond Nyquist Frequency
    • Interlaced Direct Adaptive Regulation Scheme Applied to a Benchmark Problem
    • Disturbance Observer Based Pitch Control of Wind Turbines for Disturbance Rejection
    • Discrete-time Reduced-Complexity Youla Parameterization for Dual-input Single-output Systems
    • Modified Direct Adaptive Regulation Scheme Applied to a Benchmark Problem
    • An Open-source Selective Laser Sintering Additive Manufacturing System
    • Discrete-time Output Feedback Nonlinear Control for Combined Low- and High-frequency Disturbance Compensation
    • Real-time Kinematic Modeling and Prediction of Human Joint Motion in a Networked Rehabilitation System
    • Data Storage Device Comprising Slew Rate Anti-Windup Compensation for Microactuator
    • Disk Drive Filtering Disturbance Signal and Error Signal for Adaptive Feed-Forward Compensation
    • Adaptive Sliding Mode Spacecraft Attitude Control
    • Adaptive Suppression of High-Frequency Wide-Spectrum Vibrations With Application to Disk Drive Systems
    • Discrete-Time Frequency-Shaped Sliding Mode Control for Audio-Vibration Rejection in Hard Disk Drives
    • Transient Enhancement in Add-On Feedforward Algorithms for High-Performance Mechatronic Systems
    • Selective Iterative Learning Control to Deal With Iteration-Dependent Disturbances
    • A Nonlinear Feedback Control Scheme for Transient Performance Enhancement in Hard Disk Drives
    • Methods for Closed-loop Compensation of Ultra-high Frequency Disturbances in Hard Disk Drives and Hard Disk Drives Utilizing Same
    • Control Design for Cancellation of Unnatural Reaction Torque and Vibrations in Variable-Gear-Ratio Steering System
    • Reduced-Complexity and Robust Youla Parameterization for Discrete-Time Dual-Input-Single-Output Systems
    • Selective Model Inversion and Adaptive Disturbance Observer for Rejection of Time-varying Vibrations on an Active Suspension
    • Control Methodologies for Precision Positioning Systems
    • Neural-Network Based Automatic PID Gain Tuning in the Presence of Time-Varying Disturbances in Hard Disk Drives
    • Add-on Loop Shaping via Youla Parameterization for Precision Motion Control
    • Inverse-Based Local Loop Shaping and IIR-filter Design For Precision Motion Control
    • A Convex Optimization Approach for Solving the Robust Strictly Positive Real (SPR) Problem
    • Decoupled Disturbance Observers for Dual-Input-Single-Output Systems With Application to Vibration Rejection in Dual-Stage Hard Disk Drives
    • An Enhanced Repetitive Control Algorithm using the Structure of Disturbance Observer
    • Reduced-complexity Adaptive Youla Parameterization for Broadband-Vibration Rejection in Dual-stage Hard Disk Drives
    • A Minimum Parameter Adaptive Approach for Rejecting Multiple Narrow-Band Disturbances with Application to Hard Disk Drives
    • Spiral Servo Writing in Hard Disk Drives Using Iterative Learning Based Tracking Control
    • A Structure for All Stabilizing Controllers and Its Applications to Narrow-Band Disturbance Rejection in Hard Disk Drives
    • An Indirect Adaptive Approach to Reject Multiple Narrow-Band Disturbances in Hard Disk Drives
    • Unknown Multiple Narrow-band Disturbance Rejection in Hard Disk Drives--an Adaptive Notch Filter and Perfect Disturbance Observer Approach
    • Optimal Plant Shaping for High Bandwidth Disturbance Rejection in Discrete Disturbance Observers
  • Projects
    • iLSPR A Learning-based Scene Point-cloud Registration method for robotic spatial awareness in intelligent manufacturing
    • PyHDD Benchmark
    • Slip Severity and Control
    • Boeing Advanced Research Collaboration at UW
    • Adaptive Vibration Control Benchmark
    • American Control Conference 2024
    • Illustrating Number Theory and Controls
    • 2023 IEEE/ASME International Conference on Advanced Intelligent Mechatronics
    • 2024 IEEE/ASME International Conference on Advanced Intelligent Mechatronics
    • Collaborative Robots
    • Composite Manufacturing
    • IEEE/ASME Transactions on Mechatronics
    • Intelligent Grasping
    • Journey to controls
    • New Book!
    • Modeling, Estimation and Control Conference
    • American Control Conference 2021
    • ASME DSCD Technical Committee on Vibrations
    • Boeing Advanced Research Center
    • Dynamic Systems and Control Conference 2016 & 2020
    • International Symposium on Flexible Automation 2020, 2022, 2024
    • UW Advanced Composites Center
    • 2020 IEEE/ASME International Conference on Advanced Intelligent Mechatronics
    • 2021 IEEE/ASME International Conference on Advanced Intelligent Mechatronics
    • A vision for robotics
    • Beyond-Bandwidth Control in High-Speed Precision Mechatronics
    • Focused Section on Machine Learning, Estimation and Control for Intelligent Robotics at International Journal of Intelligent Robotics and Applications
    • Jumping in controls
    • Manufacturing Robotics Training Resources in Northwest U.S.
    • Reliable Additive Manufacturing
    • Robotic Inspection of Complex Metallic Parts
    • Sensing and Control under Constrained Information Feedback
    • Sustainable Additive Manufacturing
    • LaTeX for Controls Research
    • Adaptation over Unsteady Dynamics
  • Sample_publications
    • iLSPR A Learning-based Scene Point-cloud Registration method for robotic spatial awareness in intelligent manufacturing
    • Unified Reconstruction of Static and Dynamic Scenes from Events
    • Learned Slip-Detection-Severity Framework using Tactile Deformation Field Feedback for Robotic Manipulation
    • Learning to Detect Slip through Tactile Measures of the Contact Force Field and its Entropy
    • A Recursive System Identification With Non-Uniform Temporal Feedback Under Coprime Collaborative Sensing
    • A Review of Aging, Degradation, and Reusability of PA12 Powders in Selective Laser Sintering Additive Manufacturing
    • Adaptive Lighting for Curved and Nonuniform Objects in Optomechanical Inspection Systems
    • Transmission of Signal Nonsmoothness and Transient Improvement in Add-On Servo Control
    • Multirate Forward-model Disturbance Observer for Feedback Regulation beyond Nyquist Frequency
    • Overview and New Results in Disturbance Observer based Adaptive Vibration Rejection with Application to Advanced Manufacturing
    • Pseudo Youla-Kucera Parameterization with Control of the Waterbed Effect for Local Loop Shaping
    • New Repetitive Control with Improved Steady-State Performance and Accelerated Transient
    • Optimal Decoupled Disturbance Observers for Dual-Input Single-Output Systems
    • Selective Model Inversion and Adaptive Disturbance Observer for Time-Varying Vibration Rejection on an Active-Suspension Benchmark
  • Recognitions
    • Best Paper on Robotics Award, ASME Dynamic Systems and Control Division
    • Best Student Paper on Vibrations Award, ASME Dynamic Systems and Control Division
    • ARM Champion Award
    • Best Paper, ISCIE/ASME International Symposium on Flexible Automation
    • Boeing Visiting Professorship
    • National Academy of Engineering (NAE) 2023 Frontiers of Engineering Alumnus
    • Mechatronic Systems Outstanding Young Researcher Award
    • UW+Amazon Science Hub Faculty Research Award
    • SME Sandra L. Bouckley Outstanding Young Manufacturing Engineer Award
    • Best Student Paper on Robotics, ASME Dynamic Systems and Control Division
    • Best Paper, ISCIE/ASME International Symposium on Flexible Automation
    • NSF CAREER Award
    • Best Paper on Vibrations Award, ASME Dynamic Systems and Control Division
    • Young Investigator Award, ISCIE/ASME International Symposium on Flexible Automation
  • Projects
  • Experience
  • Hugo-Templates
    • Learn JavaScript
  • Blog
    • 📈 New Review Paper on Additive Manufacturing
  • Recent & Upcoming Talks
    • Interactive Number Games for all Ages
  • Teaching

Reliable Additive Manufacturing

Jul 22, 2020 · 1 min read
Go to Project Site

Towards a zero-waste agile manufacturing of quality-assured, short-run products.

Last updated on Jul 22, 2020
Manufacturing Additive Manufacturing 3D Printing
Xu Chen
Authors
Xu Chen
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