AC_AutoTune: clean up FreqResp library and add comments

libraries/AC_AutoTune/AC_AutoTune.cpp

@@ -1823,9 +1823,9 @@ void AC_AutoTune::dwell_test_run(uint8_t freq_resp_input, float start_frq, float
     // wait for dwell to start before determining gain and phase or just start if sweep
     if ((float)(now - dwell_start_time_ms) > 6.25f * cycle_time_ms || (!is_equal(start_frq,stop_frq) && settle_time == 0)) {
         if (freq_resp_input == 1) {
-            freqresp_rate.determine_gain(filt_target_rate,rotation_rate, dwell_freq);
+            freqresp_rate.update_rate(filt_target_rate,rotation_rate, dwell_freq);
         } else {
-            freqresp_rate.determine_gain(command_out,rotation_rate, dwell_freq);
+            freqresp_rate.update_rate(command_out,rotation_rate, dwell_freq);
         }
         if (freqresp_rate.is_cycle_complete()) {
             if (!is_equal(start_frq,stop_frq)) {
@@ -2024,7 +2024,7 @@ void AC_AutoTune::angle_dwell_test_run(float start_frq, float stop_frq, float &d
 
     // wait for dwell to start before determining gain and phase
     if ((float)(now - dwell_start_time_ms) > 6.25f * cycle_time_ms || (!is_equal(start_frq,stop_frq) && settle_time == 0)) {
-        freqresp_angle.determine_gain_angle(command_out, filt_target_rate, rotation_rate, dwell_freq);
+        freqresp_angle.update_angle(command_out, filt_target_rate, rotation_rate, dwell_freq);
         if (freqresp_angle.is_cycle_complete()) {
             if (!is_equal(start_frq,stop_frq)) {
                 curr_test_freq = freqresp_angle.get_freq();

libraries/AC_AutoTune/AC_AutoTune_FreqResp.cpp

@@ -7,13 +7,7 @@ is set.  This function must be reset using the reset flag prior to the next dwel
 #include <AP_HAL/AP_HAL.h>
 #include "AC_AutoTune_FreqResp.h"
 
-float AC_AutoTune_FreqResp::update()
-{
-    float dummy = 0.0f;
-    return dummy;
-}
-
-// Initialize the Frequency Response methods. Must be called before running dwell or frequency sweep tests
+// Initialize the Frequency Response Object. Must be called before running dwell or frequency sweep tests
 void AC_AutoTune_FreqResp::init(InputType input_type)
 {
     excitation = input_type;
@@ -43,7 +37,7 @@ void AC_AutoTune_FreqResp::init(InputType input_type)
 // and the cycles_complete flag is set. For frequency sweep tests, phase and gain are determined for every cycle and 
 // cycle_complete flag is set to indicate when to pull the phase and gain data.  The flag is reset to enable the next 
 // cycle to be analyzed.
-void AC_AutoTune_FreqResp::determine_gain(float tgt_rate, float meas_rate, float tgt_freq)
+void AC_AutoTune_FreqResp::update_rate(float tgt_rate, float meas_rate, float tgt_freq)
 {
     uint32_t now = AP_HAL::millis();
     uint32_t half_cycle_time_ms = 0;
@@ -209,12 +203,12 @@ void AC_AutoTune_FreqResp::determine_gain(float tgt_rate, float meas_rate, float
     prev_meas = meas_rate;
 }
 
-// determine_gain_angle - this function receives time history data during a dwell and frequency sweep tests for angle_p tuning  
+// update_angle - this function receives time history data during a dwell and frequency sweep tests for angle_p tuning  
 // and determines the gain, phase, and max acceleration of the response to the input. For dwell tests once the designated number  
 // of cycles are complete, the average of the gain, phase, and max acceleration are determined over the last 5 cycles and the 
 // cycles_complete flag is set. For frequency sweep tests, phase and gain are determined for every cycle and cycle_complete flag is set
 // to indicate when to pull the phase and gain data.  The flag is reset to enable the next cycle to be analyzed.
-void AC_AutoTune_FreqResp::determine_gain_angle(float command, float tgt_angle, float meas_angle, float tgt_freq)
+void AC_AutoTune_FreqResp::update_angle(float command, float tgt_angle, float meas_angle, float tgt_freq)
 {
 
     uint32_t now = AP_HAL::millis();

libraries/AC_AutoTune/AC_AutoTune_FreqResp.h

@@ -19,30 +19,28 @@ public:
     tgt_peak_info_buffer = new ObjectBuffer<peak_info>(AUTOTUNE_DWELL_CYCLES);
 }
 
-//    CLASS_NO_COPY(AC_PI);
-
-    // update calculations
-    float update();
-
     enum InputType {
         DWELL = 0,                 
         SWEEP = 1, 
     };
 
+    // Initialize the Frequency Response Object. 
+    // Must be called before running dwell or frequency sweep tests
     void init(InputType input_type);
 
-    // determines the gain and phase for a dwell
-    void determine_gain(float tgt_rate, float meas_rate, float tgt_freq);
+    // determines the gain and phase based on rate response for a dwell or sweep
+    void update_rate(float tgt_rate, float meas_rate, float tgt_freq);
 
-    // determines the gain and phase for a dwell
-    void determine_gain_angle(float command, float tgt_angle, float meas_angle, float tgt_freq);
+    // determines the gain and phase based on angle response for a dwell or sweep
+    void update_angle(float command, float tgt_angle, float meas_angle, float tgt_freq);
 
-    // enable external query if cycle is complete and phase and gain data are available
+    // enable external query if cycle is complete and freq response data are available
     bool is_cycle_complete() { return cycle_complete;}
 
+    // reset cycle_complete flag
     void reset_cycle_complete() { cycle_complete = false; }
 
-    // frequency response accessors
+    // frequency response data accessors
     float get_freq() { return curr_test_freq; }
     float get_gain() { return curr_test_gain; }
     float get_phase() { return curr_test_phase; }
@@ -72,7 +70,7 @@ private:
     sweep_peak_finding_data sweep_meas;
     sweep_peak_finding_data sweep_tgt;
 
-    //store determine gain data in ring buffer
+    //store gain data in ring buffer
     struct peak_info {
         uint16_t curr_count;
         float amplitude;