Fix and improve PID loops (#14373)

- Windup guarding was missing. The kludge in place of windup guard is removed. D term filter calculations are simplified to require fewer `float` calculations. Sign change for D term output to make debugging output clearer.
- Use "no overshoot" for bed PID tuning.

Marlin/src/module/temperature.cpp

@@ -350,11 +350,13 @@ temp_range_t Temperature::temp_range[HOTENDS] = ARRAY_BY_HOTENDS(sensor_heater_0
     PID_t tune_pid = { 0, 0, 0 };
     float max = 0, min = 10000;
 
+    const bool isbed = (heater < 0);
+    
     #if HAS_PID_FOR_BOTH
-      #define GHV(B,H) (heater < 0 ? (B) : (H))
-      #define SHV(B,H) do{ if (heater < 0) temp_bed.soft_pwm_amount = B; else temp_hotend[heater].soft_pwm_amount = H; }while(0)
-      #define ONHEATINGSTART() (heater < 0 ? printerEventLEDs.onBedHeatingStart() : printerEventLEDs.onHotendHeatingStart())
-      #define ONHEATING(S,C,T) do{ if (heater < 0) printerEventLEDs.onBedHeating(S,C,T); else printerEventLEDs.onHotendHeating(S,C,T); }while(0)
+      #define GHV(B,H) (isbed ? (B) : (H))
+      #define SHV(B,H) do{ if (isbed) temp_bed.soft_pwm_amount = B; else temp_hotend[heater].soft_pwm_amount = H; }while(0)
+      #define ONHEATINGSTART() (isbed ? printerEventLEDs.onBedHeatingStart() : printerEventLEDs.onHotendHeatingStart())
+      #define ONHEATING(S,C,T) (isbed ? printerEventLEDs.onBedHeating(S,C,T) : printerEventLEDs.onHotendHeating(S,C,T))
     #elif ENABLED(PIDTEMPBED)
       #define GHV(B,H) B
       #define SHV(B,H) (temp_bed.soft_pwm_amount = B)
@@ -370,7 +372,7 @@ temp_range_t Temperature::temp_range[HOTENDS] = ARRAY_BY_HOTENDS(sensor_heater_0
     #if WATCH_BED || WATCH_HOTENDS
       #define HAS_TP_BED BOTH(THERMAL_PROTECTION_BED, PIDTEMPBED)
       #if HAS_TP_BED && BOTH(THERMAL_PROTECTION_HOTENDS, PIDTEMP)
-        #define GTV(B,H) (heater < 0 ? (B) : (H))
+        #define GTV(B,H) (isbed ? (B) : (H))
       #elif HAS_TP_BED
         #define GTV(B,H) (B)
       #else
@@ -456,23 +458,25 @@ temp_range_t Temperature::temp_range[HOTENDS] = ARRAY_BY_HOTENDS(sensor_heater_0
 
               SERIAL_ECHOPAIR(MSG_BIAS, bias, MSG_D, d, MSG_T_MIN, min, MSG_T_MAX, max);
               if (cycles > 2) {
-                float Ku = (4.0f * d) / (float(M_PI) * (max - min) * 0.5f),
-                      Tu = ((float)(t_low + t_high) * 0.001f);
-                tune_pid.Kp = 0.6f * Ku;
+                const float Ku = (4.0f * d) / (float(M_PI) * (max - min) * 0.5f),
+                            Tu = float(t_low + t_high) * 0.001f,
+                            pf = isbed ? 0.2f : 0.6f,
+                            df = isbed ? 1.0f / 3.0f : 1.0f / 8.0f;
+                tune_pid.Kp = Ku * pf;
+                tune_pid.Kd = tune_pid.Kp * Tu * df;
                 tune_pid.Ki = 2 * tune_pid.Kp / Tu;
-                tune_pid.Kd = tune_pid.Kp * Tu * 0.125f;
                 SERIAL_ECHOPAIR(MSG_KU, Ku, MSG_TU, Tu);
                 SERIAL_ECHOLNPGM("\n" MSG_CLASSIC_PID);
                 SERIAL_ECHOLNPAIR(MSG_KP, tune_pid.Kp, MSG_KI, tune_pid.Ki, MSG_KD, tune_pid.Kd);
                 /**
-                tune_pid.Kp = 0.33*Ku;
-                tune_pid.Ki = tune_pid.Kp/Tu;
-                tune_pid.Kd = tune_pid.Kp*Tu/3;
+                tune_pid.Kp = 0.33 * Ku;
+                tune_pid.Ki = tune_pid.Kp / Tu;
+                tune_pid.Kd = tune_pid.Kp * Tu / 3;
                 SERIAL_ECHOLNPGM(" Some overshoot");
                 SERIAL_ECHOLNPAIR(" Kp: ", tune_pid.Kp, " Ki: ", tune_pid.Ki, " Kd: ", tune_pid.Kd, " No overshoot");
-                tune_pid.Kp = 0.2*Ku;
-                tune_pid.Ki = 2*tune_pid.Kp/Tu;
-                tune_pid.Kd = tune_pid.Kp*Tu/3;
+                tune_pid.Kp = 0.2 * Ku;
+                tune_pid.Ki = 2 * tune_pid.Kp / Tu;
+                tune_pid.Kd = tune_pid.Kp * Tu / 3;
                 SERIAL_ECHOPAIR(" Kp: ", tune_pid.Kp, " Ki: ", tune_pid.Ki, " Kd: ", tune_pid.Kd);
                 */
               }
@@ -496,7 +500,7 @@ temp_range_t Temperature::temp_range[HOTENDS] = ARRAY_BY_HOTENDS(sensor_heater_0
       // Report heater states every 2 seconds
       if (ELAPSED(ms, next_temp_ms)) {
         #if HAS_TEMP_SENSOR
-          print_heater_states(heater >= 0 ? heater : active_extruder);
+          print_heater_states(isbed ? active_extruder : heater);
           SERIAL_EOL();
         #endif
         next_temp_ms = ms + 2000UL;
@@ -507,9 +511,9 @@ temp_range_t Temperature::temp_range[HOTENDS] = ARRAY_BY_HOTENDS(sensor_heater_0
             #if WATCH_BED && WATCH_HOTENDS
               true
             #elif WATCH_HOTENDS
-              heater >= 0
+              !isbed
             #else
-              heater < 0
+              isbed
             #endif
           ) {
             if (!heated) {                                          // If not yet reached target...
@@ -569,7 +573,7 @@ temp_range_t Temperature::temp_range[HOTENDS] = ARRAY_BY_HOTENDS(sensor_heater_0
         // Use the result? (As with "M303 U1")
         if (set_result) {
           #if HAS_PID_FOR_BOTH
-            if (heater < 0) _SET_BED_PID(); else _SET_EXTRUDER_PID();
+            if (isbed) _SET_BED_PID(); else _SET_EXTRUDER_PID();
           #elif ENABLED(PIDTEMP)
             _SET_EXTRUDER_PID();
           #else
@@ -805,9 +809,7 @@ float Temperature::get_pid_output(const int8_t e) {
       static float temp_iState[HOTENDS] = { 0 },
                    temp_dState[HOTENDS] = { 0 };
       static bool pid_reset[HOTENDS] = { false };
-      float pid_error = temp_hotend[HOTEND_INDEX].target - temp_hotend[HOTEND_INDEX].current;
-      work_pid[HOTEND_INDEX].Kd = PID_K2 * PID_PARAM(Kd, HOTEND_INDEX) * (temp_hotend[HOTEND_INDEX].current - temp_dState[HOTEND_INDEX]) + float(PID_K1) * work_pid[HOTEND_INDEX].Kd;
-      temp_dState[HOTEND_INDEX] = temp_hotend[HOTEND_INDEX].current;
+      const float pid_error = temp_hotend[HOTEND_INDEX].target - temp_hotend[HOTEND_INDEX].current;
 
       if (temp_hotend[HOTEND_INDEX].target == 0
         || pid_error < -(PID_FUNCTIONAL_RANGE)
@@ -825,13 +827,17 @@ float Temperature::get_pid_output(const int8_t e) {
       else {
         if (pid_reset[HOTEND_INDEX]) {
           temp_iState[HOTEND_INDEX] = 0.0;
+          work_pid[HOTEND_INDEX].Kd = 0.0;
           pid_reset[HOTEND_INDEX] = false;
         }
-        temp_iState[HOTEND_INDEX] += pid_error;
+
+        work_pid[HOTEND_INDEX].Kd = work_pid[HOTEND_INDEX].Kd + PID_K2 * (PID_PARAM(Kd, HOTEND_INDEX) * (temp_dState[HOTEND_INDEX] - temp_hotend[HOTEND_INDEX].current) - work_pid[HOTEND_INDEX].Kd);
+        const float max_power_over_i_gain = (float)PID_MAX / PID_PARAM(Ki, HOTEND_INDEX);
+        temp_iState[HOTEND_INDEX] = constrain(temp_iState[HOTEND_INDEX] + pid_error, 0, max_power_over_i_gain);
         work_pid[HOTEND_INDEX].Kp = PID_PARAM(Kp, HOTEND_INDEX) * pid_error;
         work_pid[HOTEND_INDEX].Ki = PID_PARAM(Ki, HOTEND_INDEX) * temp_iState[HOTEND_INDEX];
 
-        pid_output = work_pid[HOTEND_INDEX].Kp + work_pid[HOTEND_INDEX].Ki - work_pid[HOTEND_INDEX].Kd;
+        pid_output = work_pid[HOTEND_INDEX].Kp + work_pid[HOTEND_INDEX].Ki + work_pid[HOTEND_INDEX].Kd;
 
         #if ENABLED(PID_EXTRUSION_SCALING)
           work_pid[HOTEND_INDEX].Kc = 0;
@@ -850,15 +856,9 @@ float Temperature::get_pid_output(const int8_t e) {
           }
         #endif // PID_EXTRUSION_SCALING
 
-        if (pid_output > PID_MAX) {
-          if (pid_error > 0) temp_iState[HOTEND_INDEX] -= pid_error; // conditional un-integration
-          pid_output = PID_MAX;
-        }
-        else if (pid_output < 0) {
-          if (pid_error < 0) temp_iState[HOTEND_INDEX] -= pid_error; // conditional un-integration
-          pid_output = 0;
-        }
+        pid_output = constrain(pid_output, 0, PID_MAX);
       }
+      temp_dState[HOTEND_INDEX] = temp_hotend[HOTEND_INDEX].current;
 
     #else // PID_OPENLOOP
 
@@ -908,23 +908,18 @@ float Temperature::get_pid_output(const int8_t e) {
       static PID_t work_pid = { 0 };
       static float temp_iState = 0, temp_dState = 0;
 
-      float pid_error = temp_bed.target - temp_bed.current;
-      temp_iState += pid_error;
+      const float max_power_over_i_gain = (float)MAX_BED_POWER / temp_bed.pid.Ki,
+                  pid_error = temp_bed.target - temp_bed.current;
+
+      temp_iState = constrain(temp_iState + pid_error, 0, max_power_over_i_gain);
+
       work_pid.Kp = temp_bed.pid.Kp * pid_error;
       work_pid.Ki = temp_bed.pid.Ki * temp_iState;
-      work_pid.Kd = PID_K2 * temp_bed.pid.Kd * (temp_bed.current - temp_dState) + PID_K1 * work_pid.Kd;
+      work_pid.Kd = work_pid.Kd + PID_K2 * (temp_bed.pid.Kd * (temp_dState - temp_bed.current) - work_pid.Kd);
 
       temp_dState = temp_bed.current;
 
-      float pid_output = work_pid.Kp + work_pid.Ki - work_pid.Kd;
-      if (pid_output > MAX_BED_POWER) {
-        if (pid_error > 0) temp_iState -= pid_error; // conditional un-integration
-        pid_output = MAX_BED_POWER;
-      }
-      else if (pid_output < 0) {
-        if (pid_error < 0) temp_iState -= pid_error; // conditional un-integration
-        pid_output = 0;
-      }
+      const float pid_output = constrain(work_pid.Kp + work_pid.Ki + work_pid.Kd, 0, MAX_BED_POWER);
 
     #else // PID_OPENLOOP