• via http://docs.google.com/View?id=ddjmqgw3_43gm6gvggf
• http://www.google.com/#hl=en&source=hp&q=pid+kalman&aq=f&aqi=&oq=&fp=7d15299a959dbb33

Roll Rate

File: In sw/airborne/fw_h_ctl.c we define the roll rate loop:

float cmd = throttle_dep_pgain * ( err + h_ctl_roll_rate_igain * roll_rate_sum_err / H_CTL_ROLL_RATE_SUM_NB_SAMPLES + h_ctl_roll_rate_dgain * d_err);

Note that the roll Pgain is variable with throttle and multiplies through the entire equation affecting the I and D terms as well for ease of tuning.