Comprehensive System Identification of Ducted Fan UAVs - Cal Poly

Table 3.17 – Actuator Calibration Factors for Input and Output Channels to DegreesSERVOVOLTAGECALIBRATION FACTORIN ChannelOUT Channel(degrees/unit input) (servo deg/POT units)DS8417JR94091DS368HS12MGCS-10BB5 0.000749 0.03916 0.000749 0.03915 0.000963 0.03776 0.000963 0.03805 0.000811 0.0416 0.000811 0.04095 0.000829 0.04166 0.001036 0.04925 0.000836 0.04116 0.000836 0.0411The hardware fed signals from -50,000 to 50,000 to the servos and recordedpotentiometer deflection from roughly 1500 to 4500. The calibration factors in Table 3.17relate these to degrees of command and deflection of the servo. They are a result of thegeometries and readings for each actuator-voltage combination tested.Data was recorded at 50 Hz and there was no filtering of the input and outputchannels. An unidentified glitch was observed in the output signal and showed itself as asignal spike at roughly every 5 samples (0.1 sec). This was evaluated and it wasdetermined to be minor in identifying the dynamics. With that exception, there was verylittle noise in the signals.Frequency sweep actuator commands were used to generate test data from whichfrequency responses of control surface response due to actuator command could beidentified. From these frequency responses, transfer functions of the actuator dynamicswere extracted. The non-linear effects, such as rate and position limits were identified byusing a square-wave command.- 61 -