Precision FBL PID Tuning & Diagnostic Wizard

1. Aircraft Specification & Preset Generator

Configure your rotorcraft specs to dynamically generate custom starting filter frequencies and baseline PID values.

Helicopter Size Class

Mass distribution dictates inertia and mechanical resonant nodes.

Powertrain System

Determines initial filter harshness and noise floor assumptions.

Target Main Rotor Speed (RPM)

RPM

Used to center Dynamic Notch harmonics and RPM filter thresholds.

⚡ Recommended Calculated Starting Profile

Gyro Static LPF1 Cutoff 70 Hz PT1 / Low-pass

Dynamic Notch Range 120 - 360 Hz 3 Notch Generations

Cyclic Base P / D P: 52 | D: 28 Ail / Elev Proportions

Tail Base P / D P: 65 | D: 35 Rudder Axis

2. Filter Setup & Frequency Management

Filters remove mechanical noise before PID calculation. Too much filter = phase latency; too little = hot servos and twitchiness.

Phase Latency Target: < 3.2 ms

Dynamic Notch Filter Setup

Sweeps to eliminate motor and blade harmonic frequency spikes automatically.

3 Generations

Set Count to 3 notches. Configure Min Frequency to match 0.8x of your target headspeed frequency (29 Hz) and Max Frequency to 500 Hz.

dyn_notch_count = 3 | dyn_notch_q = 300 | dyn_notch_min_hz = 29

Gyro Low-Pass Filters (LPF1 & LPF2)

Broadband noise suppression for high-frequency vibration.

PT1 Recommended

Start with Gyro LPF1 PT1 @ 70 Hz. Keep LPF2 disabled or set high (150 Hz) unless Blackbox logs reveal persistent noise above 120 Hz.

RPM Filter Telemetry Harmonic Matrix

Tracks exact ESC motor RPM for surgically pinpoint notches.

Optional / Ideal

If ESC telemetry (RPM) is connected, enable RPM filtering. Set motor pole count accurately to pin notch filters directly to rotor frequencies.

⚠️ Field Temperature Safety Test

Always perform this check before proceeding to PID tuning!

Hover the helicopter for 30 seconds in a steady hover.
Land and immediately feel the cyclic and tail servos.
Cool/Warm: Safe to proceed.
Hot to touch: Lower LPF cutoff or add Matrix Notch. Filtering is insufficient!

Sequenced Walkthrough

Step 1 of 6: Cyclic D-Term Damping

Primary Objective

D-term acts as a shock absorber for stopping cyclic flips and rolls. Raise cyclic D-term until hard stops are crisp without bounce, but before high-frequency chatter or motor heating occurs.

🕹️ Recommended Test Flight Maneuver Rapid Roll & Pitch Snap Stops

LEFT STICK (THROTTLE/YAW)

RIGHT STICK (CYCLIC AIL/ELEV)

Perform aggressive, instantaneous right-aileron pulses and hard releases. Watch the stop behavior closely.

What do you observe in flight?

Tuning Guidance:

Select an observation above to reveal suggested gain adjustment...

3. Flight Behavior Diagnostic Matrix

Select an undesirable flight artifact to instantly receive diagnostic root-cause analysis and exact gain remedies.

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4. Advanced Parameters & Blackbox FFT Log Analysis

Fine-tune specialized parameters and learn how to analyze flight log spectrum graphs for surgical perfection.

🚀 Cyclic & Yaw Boost Tuning Dynamic Acceleration

Boost adds short-burst acceleration on initial stick movement to overcome mechanical rotor inertia without increasing overall static P-gain.

• Low Boost (0-10): Smooth scale, traditional feel.

• High Boost (15-30): Ultra-robotic, instant stick response for 3D flight.

🧘 I-Term Relax Configuration Anti-Windup

Limits Integral accumulation during rapid acrobatic maneuvers to eliminate bounce-back and robotic settling after high-speed flips or rolls.

Mode: GYRO | Cutoff Frequency: 15 Hz (Mid-size/Large) or 25 Hz (Micro)

⚖️ HSI (High Speed Integral) Offset & Limits High Speed Flight

Prevents elevator pitch-up (porpoising) during maximum speed forward flight passes while maintaining acrobatic agility.

📊 Blackbox Log Analysis Checklist

1. Record Log Flight Set Blackbox rate to 1kHz or 2kHz. Perform hover, 3s pitch pumps, full roll/flip stops.

2. Inspect FFT Unfiltered Noise Look at gyroUNFILT FFT graph. Identify:

Motor/Gear peak (high frequency)
Blade pass frequency (RPM x blade count)

3. Verify Filter Spectrum Compare gyroUNFILT vs gyroFILT. Ensure noise peaks above 100Hz are attenuated below -30dB floor.

🧰 PID Delta Calculator & Exporter

Calculate parameter deltas or export your current flight tuning setup into shareable text.

AXISP GAINI GAIND GAIN

Roll (Ail)

Pitch (Elev)

Yaw (Tail)

📝 Field Session Flight Log

Keep quick field notes of changes made per flight test battery.