Problem-driven notes, not a diary. Four fixed formats: Problem, Method, Debugging and Implementation. Each note states the problem, likely causes, how to measure, and what to test next.
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.
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.
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.
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.
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.