From mathematical models and frequency-response analysis to controller design and real-machine validation. Engineering projects, notes and interactive tools for motion control, FRF identification and force control.https://dunleiwang.com/enhttps://dunleiwang.com/notes/why-displacement-lags-force-command/https://dunleiwang.com/notes/why-displacement-lags-force-command/A force command is issued, the DAC output changes — yet detectable displacement appears only ~150 ms later. A structured checklist of physical and signal-chain causes, and how to separate them.Fri, 10 Jul 2026 00:00:00 GMTforce-controlcontact-dynamicsfrictionlatencyhttps://dunleiwang.com/notes/stable-frf-with-welch-averaging/https://dunleiwang.com/notes/stable-frf-with-welch-averaging/Segment length, window, overlap and averaging count decide whether an FRF is smooth and trustworthy or noisy and biased. A practical recipe with the trade-offs made explicit.Sun, 05 Jul 2026 00:00:00 GMTfrfwelchsignal-processingsystem-identificationhttps://dunleiwang.com/projects/bonding-head-z-force-control/https://dunleiwang.com/projects/bonding-head-z-force-control/Modeling and validation of a nonlinear contact-force loop for a bonding head Z-axis: unilateral contact model, friction compensation, and analysis of the delay between force command and displacement response.Wed, 01 Jul 2026 00:00:00 GMTforce-controlmotion-controlcontact-dynamicshttps://dunleiwang.com/notes/anti-resonance-repeatability/https://dunleiwang.com/notes/anti-resonance-repeatability/A 280 Hz anti-resonance that moves between measurements is telling you something about contact stiffness, preload and clearance. A debugging plan for unrepeatable anti-resonances.Sun, 28 Jun 2026 00:00:00 GMTanti-resonancecontact-dynamicsmechanical-dynamicsfrfhttps://dunleiwang.com/notes/gantry-linear-yaw-modes/https://dunleiwang.com/notes/gantry-linear-yaw-modes/Why a dual-drive gantry is naturally described by sum and difference coordinates, what the transformation actually assumes, and how mode separation simplifies both identification and control.Sat, 20 Jun 2026 00:00:00 GMTmimodecouplingmotion-controlsystem-identificationhttps://dunleiwang.com/projects/gantry-mimo-frf-identification/https://dunleiwang.com/projects/gantry-mimo-frf-identification/Two-input two-output frequency-response identification of a gantry stage: linear and yaw excitation, 2×2 FRF matrix, coherence assessment, DAC input correlation and its impact on decoupling.Mon, 15 Jun 2026 00:00:00 GMTsystem-identificationfrf-analysismotion-controlhttps://dunleiwang.com/notes/encoder-resolution-small-motion/https://dunleiwang.com/notes/encoder-resolution-small-motion/When the target position error approaches a few encoder counts, quantization — not tuning — dominates. How resolution propagates into error budget, velocity estimation and achievable bandwidth.Wed, 10 Jun 2026 00:00:00 GMTencoderquantizationmotion-controlsignal-processinghttps://dunleiwang.com/projects/motion-system-sizing-framework/https://dunleiwang.com/projects/motion-system-sizing-framework/A structured sizing methodology for motion axes: from motion requirement through profile kinematics, force/torque, power and thermal margin, encoder quantization, delay budget and resonance target — to predicted motion performance. Implemented as a tested TypeScript module and an interactive calculator.Wed, 20 May 2026 00:00:00 GMTmotion-controlmechanical-dynamicsengineering-software