Rotor: Vibration Analyzer

About

Rotor turns your iPhone into a working vibration analyser. Hold it against a running motor, pump, fan or gearbox and read the overall velocity in mm/s RMS, graded A to D against ISO 20816, with the machine class cited. Then it tells you what is wrong, and shows you why it thinks so. THE NUMBER IS REAL Acceleration is integrated to velocity in the frequency domain, line by line, with a high-pass cutoff. It is never cumulative-summed in the time domain, which turns sensor bias into a wandering ramp. The graded overall is summed from a rectangular-windowed spectrum so it stays Parseval-exact instead of double-counting window leakage. If that means something to you, you already know why most phone vibration apps are wrong. VERIFY IT YOURSELF Rotor ships with a self-test. It runs a signal whose answer is known analytically through the same chain a real machine goes through, and shows you measured against expected, side by side. IT NAMES THE FAULT Unbalance, misalignment, looseness, blade and vane pass, gear mesh with sidebands, belt defects and electrical faults at twice line frequency. Every verdict quotes the lines it came from and gives you the specific next step. Check the coupling cold and hot. Inspect the impeller for build-up. Cut the power and watch whether the peak vanishes. IT KNOWS YOUR MACHINE Ten presets set the ISO class, the plausible speed range, where to hold the phone and which faults happen on that kind of kit. Enter the poles and supply frequency off the nameplate and Rotor computes running speed including slip. Count the blades or gear teeth, or measure the belt, and it draws those frequencies as labelled cursors. THREE AXES AT ONCE High axial vibration relative to radial is how misalignment is told apart from unbalance, so Rotor captures all three axes and shows which is worst. IT REFUSES TO GUESS If the sensor clipped, Rotor will not grade the capture, because a clipped waveform invents harmonics that look like severe looseness. If the signal is at the noise floor it asks whether the machine is running rather than awarding a confident Zone A to a desk. If a bearing's frequencies sit above what your phone can sample, it says so, because a missing cursor is not a healthy bearing. WATCH IT GET WORSE Log a reading and it keeps the full spectrum. Next month the trend line shows the overall crossing out of green, with the ISO zone bands drawn behind it. Rotor also compares against that machine's own baseline and lists the individual lines that grew, in dB. BEARINGS, THE HARD WAY Envelope demodulation, done properly. Band-pass the bearing's resonance, take the analytic signal by Hilbert transform, transform the envelope, and the defect rate falls out of the noise. Rotor matches it against the computed BPFO, BPFI, BSF and FTF to name which part is failing, computed from the bearing geometry. FIELD BALANCING Single and two plane by the influence coefficient method. Measure, bolt on a trial weight, measure again, and Rotor solves the correction weight and angle on a polar plot. READ THE SPECTRUM Orders axis, so 1x and 2x land on integers and a bearing line visibly does not. Peak table with frequency, order and likely cause. Linear, exponential and peak-hold averaging. Selectable resolution with the capture time shown. Hanning, flat-top and uniform windows. mm/s and microns or in/s and mils, with the ISO boundaries restated in both so the toggle never changes a verdict. PRIVATE BY DESIGN Everything runs on the device. No account, no cloud, no analytics, no network access at all. BE CLEAR ABOUT THE LIMITS The built-in accelerometer is usable to about 100 Hz. That covers unbalance, misalignment, looseness and ISO overall velocity on most slow and medium speed machines. It cannot see most bearing frequencies, and Rotor says so in the interface at the moment it matters rather than letting you believe a flat spectrum means a healthy bearing. That honesty is the reason to trust every other number in the app.