AC_AttitudeControl: fixed limiting of throttle mix values

use constrain instead of reset to keep as much of user requested value
as possible

also raise limit for MIX_MIN to 0.5 after discussion with Leonard

libraries/AC_AttitudeControl/AC_AttitudeControl.h

@@ -39,6 +39,8 @@
 #define AC_ATTITUDE_CONTROL_MIN_DEFAULT                 0.1f    // minimum throttle mix default
 #define AC_ATTITUDE_CONTROL_MAN_DEFAULT                 0.1f    // manual throttle mix default
 #define AC_ATTITUDE_CONTROL_MAX_DEFAULT                 0.5f    // maximum throttle mix default
+#define AC_ATTITUDE_CONTROL_MIN_LIMIT                   0.5f    // min throttle mix upper limit
+#define AC_ATTITUDE_CONTROL_MAN_LIMIT                   4.0f    // man throttle mix upper limit
 #define AC_ATTITUDE_CONTROL_MAX                         5.0f    // maximum throttle mix default
 
 #define AC_ATTITUDE_CONTROL_THR_MIX_DEFAULT             0.5f  // ratio controlling the max throttle output during competing requests of low throttle from the pilot (or autopilot) and higher throttle for attitude control.  Higher favours Attitude over pilot input

libraries/AC_AttitudeControl/AC_AttitudeControl_Multi.cpp

@@ -354,18 +354,18 @@ void AC_AttitudeControl_Multi::rate_controller_run()
 void AC_AttitudeControl_Multi::parameter_sanity_check()
 {
     // sanity check throttle mix parameters
-    if (_thr_mix_man < 0.1f || _thr_mix_man > 4.0f) {
+    if (_thr_mix_man < 0.1f || _thr_mix_man > AC_ATTITUDE_CONTROL_MAN_LIMIT) {
         // parameter description recommends thr-mix-man be no higher than 0.9 but we allow up to 4.0
         // which can be useful for very high powered copters with very low hover throttle
-        _thr_mix_man.set_and_save(AC_ATTITUDE_CONTROL_MAN_DEFAULT);
+        _thr_mix_man.set_and_save(constrain_float(_thr_mix_man, 0.1, AC_ATTITUDE_CONTROL_MAN_LIMIT));
     }
-    if (_thr_mix_min < 0.1f || _thr_mix_min > 0.25f) {
+    if (_thr_mix_min < 0.1f || _thr_mix_min > AC_ATTITUDE_CONTROL_MIN_LIMIT) {
-        _thr_mix_min.set_and_save(AC_ATTITUDE_CONTROL_MIN_DEFAULT);
+        _thr_mix_min.set_and_save(constrain_float(_thr_mix_min, 0.1, AC_ATTITUDE_CONTROL_MIN_LIMIT));
     }
     if (_thr_mix_max < 0.5f || _thr_mix_max > AC_ATTITUDE_CONTROL_MAX) {
         // parameter description recommends thr-mix-max be no higher than 0.9 but we allow up to 5.0
         // which can be useful for very high powered copters with very low hover throttle
-        _thr_mix_max.set_and_save(AC_ATTITUDE_CONTROL_MAX_DEFAULT);
+        _thr_mix_max.set_and_save(constrain_float(_thr_mix_max, 0.5, AC_ATTITUDE_CONTROL_MAX));
     }
     if (_thr_mix_min > _thr_mix_max) {
         _thr_mix_min.set_and_save(AC_ATTITUDE_CONTROL_MIN_DEFAULT);

libraries/AC_AttitudeControl/AC_AttitudeControl_Sub.cpp

@@ -367,18 +367,18 @@ void AC_AttitudeControl_Sub::rate_controller_run()
 void AC_AttitudeControl_Sub::parameter_sanity_check()
 {
     // sanity check throttle mix parameters
-    if (_thr_mix_man < 0.1f || _thr_mix_man > 4.0f) {
+    if (_thr_mix_man < 0.1f || _thr_mix_man > AC_ATTITUDE_CONTROL_MAN_LIMIT) {
         // parameter description recommends thr-mix-man be no higher than 0.9 but we allow up to 4.0
         // which can be useful for very high powered copters with very low hover throttle
-        _thr_mix_man.set_and_save(AC_ATTITUDE_CONTROL_MAN_DEFAULT);
+        _thr_mix_man.set_and_save(constrain_float(_thr_mix_man, 0.1, AC_ATTITUDE_CONTROL_MAN_LIMIT));
     }
-    if (_thr_mix_min < 0.1f || _thr_mix_min > 0.25f) {
+    if (_thr_mix_min < 0.1f || _thr_mix_min > AC_ATTITUDE_CONTROL_MIN_LIMIT) {
-        _thr_mix_min.set_and_save(AC_ATTITUDE_CONTROL_MIN_DEFAULT);
+        _thr_mix_min.set_and_save(constrain_float(_thr_mix_min, 0.1, AC_ATTITUDE_CONTROL_MIN_LIMIT));
     }
     if (_thr_mix_max < 0.5f || _thr_mix_max > AC_ATTITUDE_CONTROL_MAX) {
         // parameter description recommends thr-mix-max be no higher than 0.9 but we allow up to 5.0
         // which can be useful for very high powered copters with very low hover throttle
-        _thr_mix_max.set_and_save(AC_ATTITUDE_CONTROL_MAX_DEFAULT);
+        _thr_mix_max.set_and_save(constrain_float(_thr_mix_max, 0.5, AC_ATTITUDE_CONTROL_MAX));
     }
     if (_thr_mix_min > _thr_mix_max) {
         _thr_mix_min.set_and_save(AC_ATTITUDE_CONTROL_MIN_DEFAULT);