Notes from my online journal [krishna-bhatt.com]

A collection of notes, random thoughts, and observations (mostly unintelligible). Unfortunately, I cannot post everything publicly due to IP. Cheers! -Krishna

Latest posts

TractX: RecoBundlesX configuration and dependencies

RecobundlesX config pile: lengths / votes / seed / processes / transforms older requirements fighting newer deps, then headers lost in conversion. keep one coherent set of inputs for the next run Recorded configuration: length filtering minL=20 ,...

TractX: FDC filename and header mismatch

PRE.mif vs IN.mif again... right next to 'header transformations ... do not match' check template + correspondence + directions/index files. renaming it won't fix the space it's in pipeline context: step 19 writes fiber-density correspondence to...

TractX: whole-brain tracking and SIFT run

SIFT COMPLETE — 20 million → 2 million keep FOD + mask + both tractograms together. SIFT filtering and SIFT2 weights are different outputs, don't mix filenames files: the command operates in the template directory. Keep FOD.mif ,...

TractX: fixel indexing and bundle membership

fixel index first, voxel coords second — multiple directions can live at the same xyz need one attribute order, stop hardcoding the reshape. tiny fake grid with 2 crossing bundles might be easier to debug than an entire brain representation:...

TractX: filtering and validation questions

pretty tractogram ≠ correct connections, annoying but useful reminder keep validity definition with the score. especially when changing clustering / endpoint voting problem: a streamline's visual plausibility is not enough to establish that it...

Balancerator: Bluetooth message reference

Bluetooth crib: 1=current angle, 2=average, 3=run mechanism missing bits: delimiter? ack? reconnect mid-command? don't let a half-packet turn into a real angle Updated protocol from the app notes: Request Purpose Response / behavior...

Latency and battery: averages versus tails

mean total 1.8844 s, but 21/50 trials over 2 s keep the tail, not just the average. battery trace gets to ~18 min continuous use... need duty-cycle notes next to that The latency sheet separates logic, mechanical and total response time across...

GRU data dictionary and split audit

GRU sheets: 850 train / 150 test, no exact row overlap label 0 includes quick falls AND walking. need collection method + session split before treating that as a clean safe/unsafe dataset The three GRU spreadsheets are actual tabular data, not...

Balancerator: app requirements and timing conflict

app: angle view, dated fall log, notification action 1 sec in requirements vs 3 sec in command table. also ±50° trigger vs model trigger... pick one version before implementing the scheduler transport requirement: the mobile-app document...

Balancerator: angle-estimation reference

gyro prediction + accel correction; check the variance notation before copying the Kalman function Ts = 0.004 from the example, still needs replacing. wondering how much loop-timer jitter alone shifts the estimate inputs: angular velocity from...

Balancerator: gyro-noise quantities

ARW 0.5487, BI 8.62 — first below target, second still above need the stationary recording + exact Allan-curve fit region. 'gyro noise' is way too vague a label Terms: angle random walk describes the integrated effect of rate noise; bias...

Balancerator: inclination-to-servo scaling sketch

scaleMotors / convertDeg — ints eating decimals, static input, degree/radian mess redo from the COM equation. test zero + both signs + acos limits BEFORE motor movement reference functions: scaleMotors(float inclination) and convertDeg(float...

Balancerator: two-servo power fault

second servo added → sweep turned into vibration / continuous rotation?? separate supplies got the test working. need to measure the power behavior instead of leaving the explanation at 'probably draw/reset' symptom: after adding the second...

Balancerator: shoulder-and-waist load distribution

lunch-bag straps + folded towels for padding, surprisingly useful supplies 23.302 N shoulders / 21.150 N waist. keep strap lengths with the numbers assembly: repurpose lunch-bag cross-body straps, loop them through the wheel assembly, and attach...

Balancerator: leg-support trial

waist load down, thigh stress up. same total weight, new annoyance temporary leg assembly came apart too... moving on to shoulder straps recorded distribution: waist 31.923 N; legs 12.529 N. Together these equal the previous 44.452 N total, so...

Balancerator: waist-only load test

waist-only test: 45 min, 44.452 N, awkward arms + waist fatigue weight placement matters a lot more than just total mass. shoulders next? legs first in the notes protocol: wear the initial device while walking for 45 minutes; combine qualitative...

Balancerator: weight-box construction details

extra cardboard made the boxes too small for the plates lol side layers out, tape around instead. save rope spacing + shaft height before changing anything else assembly notes, Days 9–11: use cardboard containers in place of printed parts....

Balancerator: spool-supported counterweights

printer unavailable → use the discarded filament spools rope carries the box, shaft pushes it. possible side issue: crooked spool = periodic wobble = fake body movement to the gyro? fabrication constraint: school printing required supplying...

Balancerator: center-of-mass model

move the weights → shift COM, motor shouldn't hold the whole load 43.3 kg / 73.07 cm / 50 cm shaft... keep the sketch with this or the angles are going to become nonsense again mechanical idea: use two moving pendulum weights to shift...

Beep Boop Bop Testing

Update the settings of your site from the admin panel , you can change the title, description and the social networks from Settings > General ....

Cookie Dispenser: verified firmware hardware map

CookieDispenser.ino pin map here, actual code rather than guessing from the wiring picture btSerial on 5/6 is commented out; active status LED is pin 4. easy thing to miss Recovered the actual CookieDispenser.ino linked in the presentation,...

Cookie Bluetooth protocol and app archive map

send '3' → count header + ba/bb/etc cookie events queue has 10 slots, append doesn't check capacity. if the reply gets lost, can refresh retry without counting the same cookie twice? The presentation links both the .ino and the MIT App Inventor...

Cookie dispenser: test protocol and limits

5 days, repeated fingerprints, count cookies + retries separately keep the failed attempts too. also '10' in the lock table means no access within the limit, not success on try 10 Daily allowance test: enroll one administrator and five child...

Cookie dispenser: blocking access through the chute

fingerprint lock, then someone just tilts the box. right. 3×3 cm blocker through the chute slot — check it doesn't become a cookie jam machine failure mode: authentication at the fingerprint sensor does not prevent someone from accessing the...

Cookie dispenser: four-LED interface

4 LEDs = tiny vocabulary, no serial monitor needed. patterns should make sense without a decoder ring... save for later: blink rhythm vs color, esp if the colors are hard to tell apart problem: the original interaction depends on reading the...

Cookie dispenser: roles, state and daily reset

fingerprint → whose cookie allowance? admin / child paths need to stay separate clock resets when unplugged... accidental unlimited-cookie mode. need a power-cycle test System: Arduino UNO, fingerprint sensor, motor-driven dispensing lever,...