Generally, when the flying speed of the agricultural multi-rotor is relatively high, the vibration of the sprayer drone frame will change due to the large change in the output power of the motor and the propeller from that at low speed. The critical speed of the smaller multi-rotor is about 30m/s, and the critical speed of the larger multi-rotor is about 20m/s. Of course, this value is different for multi-rotors and must be analyzed in detail.
Generally, ESCs designed for crop spray drone have no low-voltage protection, no overheating protection, but start-up protection, overload protection and throttle signal loss protection. Overload protection means that when the load suddenly becomes extremely large, the ESC will cut off the power and can only operate normally after the throttle is returned to zero. When it loses step, the ESC will automatically try to restart. Startup protection means that when the engine fails to start normally within two seconds after increasing the throttle, the motor and ESC will shut off the power output, and the throttle stick must be placed at the lowest point again to start. Throttle signal loss protection means that when the ESC detects that the throttle remote control signal has been lost for more than 0.25 seconds, it will immediately turn off the output, so as to avoid greater losses due to the continued high-speed rotation of the propeller.
