am working with a Tarot 650 quadcopter using Pixhawk 6x, 16×5.5 inch propellers, 350 KV motors, 6S 16000 mAh LiPo, and a front-mounted payload (~800 g). The payload is required for the application (gripper / robotic arm), and the center of gravity has been mechanically adjusted to be near neutral.
Observed Issues
Aggressive Pitch Response with Front Payload
When commanding forward motion, the drone initially pitches forward as expected.
Due to the front payload inertia, the nose drops faster than desired.
The controller then overcorrects, causing the nose to pitch back up aggressively.
This results in a nose-down → nose up oscillatory behavior, especially noticeable during small pitch commands.
Movements feel over aggressive rather than smooth, despite CG being reasonably balanced.
Yaw Stress and Diagonal Motor Heating
During hover (even without forward motion), cross-diagonal motors heat up more than the others.
CG is verified to be acceptable, so heating does not appear to be caused by front rear imbalance.
Yaw corrections appear to be working continuously, suggesting yaw loop over-activity or torque imbalance.
Current yaw gains were initially high (ATC_RAT_YAW_P and ATC_RAT_YAW_I both ~0.22).
AutoTune Behavior
AutoTune was attempted after Stabilize → AltHold at ~18 m altitude and also on a PID rig.
On free flight, AutoTune aborted mid air and the vehicle descended abruptly (no damage).
Log analysis shows autotune_failed, with no battery voltage sag.
On the PID rig, AutoTune consistently fails after ~1 minute with “AutoTune failed, return to manual mode.”
This suggests AutoTune is unable to converge for this heavy, high-inertia configuration.
Low-Altitude and Initial Motion Behavior
At takeoff and low altitude, the drone tends to move in random directions.
In Stabilize mode, it does not hold position (expected), but initial corrections feel exaggerated.
Transmitter trims are centered; accelerometer calibration has been performed.
How to tackle this