Nonlinear extrusion

Marlin/Configuration_adv.h

@@ -2275,6 +2275,14 @@
   //#define EXPERIMENTAL_I2S_LA   // Allow I2S_STEPPER_STREAM to be used with LA. Performance degrades as the LA step rate reaches ~20kHz.
 #endif
 
+/**
+ * Nonlinear Extrusion Control
+ *
+ * Control extrusion rate based on instantaneous extruder velocity. Can be used to correct for
+ * underextrusion at high extruder speeds that are otherwise well-behaved (i.e., not skipping).
+ */
+//#define NONLINEAR_EXTRUSION
+
 // @section leveling
 
 /**

Marlin/src/core/language.h

@@ -301,6 +301,7 @@
 #define STR_CHAMBER_PID                     "Chamber PID"
 #define STR_STEPS_PER_UNIT                  "Steps per unit"
 #define STR_LINEAR_ADVANCE                  "Linear Advance"
+#define STR_NONLINEAR_EXTRUSION             "Nonlinear Extrusion"
 #define STR_CONTROLLER_FAN                  "Controller Fan"
 #define STR_STEPPER_MOTOR_CURRENTS          "Stepper motor currents"
 #define STR_RETRACT_S_F_Z                   "Retract (S<length> F<feedrate> Z<lift>)"

Marlin/src/gcode/feature/nonlinear/M592.cpp

@@ -0,0 +1,51 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2023 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "../../../inc/MarlinConfig.h"
+
+#if ENABLED(NONLINEAR_EXTRUSION)
+
+#include "../../gcode.h"
+#include "../../../module/stepper.h"
+
+void GcodeSuite::M592_report(const bool forReplay/*=true*/) {
+  report_heading(forReplay, F(STR_NONLINEAR_EXTRUSION));
+  SERIAL_ECHOLNPGM("  M593 A", stepper.ne.A, " B", stepper.ne.B, " C", stepper.ne.C);
+}
+
+/**
+ * M592: Get or set nonlinear extrusion parameters
+ *  A<factor>   Linear coefficient (default 0.0)
+ *  B<factor>   Quadratic coefficient (default 0.0)
+ *  C<factor>   Constant coefficient (default 1.0)
+ *
+ * Adjusts the amount of extrusion based on the instantaneous velocity of extrusion, as a multiplier.
+ * The amount of extrusion is multiplied by max(C, C + A*v + B*v^2) where v is extruder velocity in mm/s.
+ * Only adjusts forward extrusions, since those are the ones affected by backpressure.
+ */
+void GcodeSuite::M592() {
+  if (parser.seenval('A')) stepper.ne.A = parser.value_float();
+  if (parser.seenval('B')) stepper.ne.B = parser.value_float();
+  if (parser.seenval('C')) stepper.ne.C = parser.value_float();
+}
+
+#endif // NONLINEAR_EXTRUSION

Marlin/src/gcode/gcode.cpp

@@ -935,6 +935,10 @@ void GcodeSuite::process_parsed_command(const bool no_ok/*=false*/) {
         case 575: M575(); break;                                  // M575: Set serial baudrate
       #endif
 
+      #if ENABLED(NONLINEAR_EXTRUSION)
+        case 592: M592(); break;                                  // M592: Nonlinear Extrusion control
+      #endif
+
       #if HAS_ZV_SHAPING
         case 593: M593(); break;                                  // M593: Input Shaping control
       #endif

Marlin/src/gcode/gcode.h

@@ -259,6 +259,7 @@
  * M554 - Get or set IP gateway. (Requires enabled Ethernet port)
  * M569 - Enable stealthChop on an axis. (Requires at least one _DRIVER_TYPE to be TMC2130/2160/2208/2209/5130/5160)
  * M575 - Change the serial baud rate. (Requires BAUD_RATE_GCODE)
+ * M592 - Get or set nonlinear extrusion parameters. (Requires NONLINEAR_EXTRUSION)
  * M593 - Get or set input shaping parameters. (Requires INPUT_SHAPING_[XY])
  * M600 - Pause for filament change: "M600 X<pos> Y<pos> Z<raise> E<first_retract> L<later_retract>". (Requires ADVANCED_PAUSE_FEATURE)
  * M603 - Configure filament change: "M603 T<tool> U<unload_length> L<load_length>". (Requires ADVANCED_PAUSE_FEATURE)
@@ -1106,6 +1107,11 @@ class GcodeSuite {
     static void M575();
   #endif
 
+  #if ENABLED(NONLINEAR_EXTRUSION)
+    static void M592();
+    static void M592_report(const bool forReplay=true);
+  #endif
+
   #if HAS_ZV_SHAPING
     static void M593();
     static void M593_report(const bool forReplay=true);

Marlin/src/inc/SanityCheck.h

@@ -858,6 +858,19 @@ static_assert(COUNT(arm) == LOGICAL_AXES, "AXIS_RELATIVE_MODES must contain " _L
   #endif
 #endif
 
+/**
+ * Nonlinear Extrusion requirements
+ */
+#if ENABLED(NONLINEAR_EXTRUSION)
+  #if DISABLED(ADAPTIVE_STEP_SMOOTHING)
+    #error "ADAPTIVE_STEP_SMOOTHING is required for NONLINEAR_EXTRUSION."
+  #elif HAS_MULTI_EXTRUDER
+    #error "NONLINEAR_EXTRUSION doesn't currently support multi-extruder setups."
+  #elif DISABLED(CPU_32_BIT)
+    #error "NONLINEAR_EXTRUSION requires a 32-bit CPU."
+  #endif
+#endif
+
 /**
  * Special tool-changing options
  */

Marlin/src/module/planner.cpp

@@ -2005,7 +2005,7 @@ bool Planner::_populate_block(
   #if HAS_EXTRUDERS
     dm.e = (dist.e > 0);
     const float esteps_float = dist.e * e_factor[extruder];
-    const uint32_t esteps = ABS(esteps_float) + 0.5f;
+    const uint32_t esteps = ABS(esteps_float);
   #else
     constexpr uint32_t esteps = 0;
   #endif

Marlin/src/module/settings.cpp

@@ -36,7 +36,7 @@
  */
 
 // Change EEPROM version if the structure changes
-#define EEPROM_VERSION "V88"
+#define EEPROM_VERSION "V89"
 #define EEPROM_OFFSET 100
 
 // Check the integrity of data offsets.
@@ -634,6 +634,13 @@ typedef struct SettingsDataStruct {
     hotend_idle_settings_t hotend_idle_config;          // M86 S T E B
   #endif
 
+  //
+  // Nonlinear Extrusion
+  //
+  #if ENABLED(NONLINEAR_EXTRUSION)
+    ne_coeff_t stepper_ne;                              // M592 A B C
+  #endif
+
 } SettingsData;
 
 //static_assert(sizeof(SettingsData) <= MARLIN_EEPROM_SIZE, "EEPROM too small to contain SettingsData!");
@@ -1729,6 +1736,13 @@ void MarlinSettings::postprocess() {
       EEPROM_WRITE(hotend_idle.cfg);
     #endif
 
+    //
+    // Nonlinear Extrusion
+    //
+    #if ENABLED(NONLINEAR_EXTRUSION)
+      EEPROM_WRITE(stepper.ne);
+    #endif
+
     //
     // Report final CRC and Data Size
     //
@@ -2803,6 +2817,13 @@ void MarlinSettings::postprocess() {
         EEPROM_READ(hotend_idle.cfg);
       #endif
 
+      //
+      // Nonlinear Extrusion
+      //
+      #if ENABLED(NONLINEAR_EXTRUSION)
+        EEPROM_READ(stepper.ne);
+      #endif
+
       //
       // Validate Final Size and CRC
       //
@@ -3396,15 +3417,13 @@ void MarlinSettings::reset() {
   //
   // Heated Bed PID
   //
-
   #if ENABLED(PIDTEMPBED)
     thermalManager.temp_bed.pid.set(DEFAULT_bedKp, DEFAULT_bedKi, DEFAULT_bedKd);
   #endif
 
   //
   // Heated Chamber PID
   //
-
   #if ENABLED(PIDTEMPCHAMBER)
     thermalManager.temp_chamber.pid.set(DEFAULT_chamberKp, DEFAULT_chamberKi, DEFAULT_chamberKd);
   #endif
@@ -3456,7 +3475,6 @@ void MarlinSettings::reset() {
   //
   // Volumetric & Filament Size
   //
-
   #if DISABLED(NO_VOLUMETRICS)
     parser.volumetric_enabled = ENABLED(VOLUMETRIC_DEFAULT_ON);
     for (uint8_t q = 0; q < COUNT(planner.filament_size); ++q)
@@ -3598,6 +3616,11 @@ void MarlinSettings::reset() {
   //
   TERN_(FT_MOTION, fxdTiCtrl.set_defaults());
 
+  //
+  // Nonlinear Extrusion
+  //
+  TERN_(NONLINEAR_EXTRUSION, stepper.ne.reset());
+
   //
   // Input Shaping
   //
@@ -3867,6 +3890,11 @@ void MarlinSettings::reset() {
     //
     TERN_(FT_MOTION, gcode.M493_report(forReplay));
 
+    //
+    // Nonlinear Extrusion
+    //
+    TERN_(NONLINEAR_EXTRUSION, gcode.M592_report(forReplay));
+
     //
     // Input Shaping
     //

Marlin/src/module/stepper.cpp

@@ -245,6 +245,13 @@ uint32_t Stepper::advance_divisor = 0,
   bool        Stepper::la_active = false;
 #endif
 
+#if ENABLED(NONLINEAR_EXTRUSION)
+  ne_coeff_t Stepper::ne;
+  ne_fix_t Stepper::ne_fix;
+  int32_t Stepper::ne_edividend;
+  uint32_t Stepper::ne_scale;
+#endif
+
 #if HAS_ZV_SHAPING
   shaping_time_t      ShapingQueue::now = 0;
   #if ANY(MCU_LPC1768, MCU_LPC1769) && DISABLED(NO_LPC_ETHERNET_BUFFER)
@@ -2191,6 +2198,16 @@ hal_timer_t Stepper::calc_timer_interval(uint32_t step_rate) {
   #endif // !CPU_32_BIT
 }
 
+#if ENABLED(NONLINEAR_EXTRUSION)
+  void Stepper::calc_nonlinear_e(uint32_t step_rate) {
+    const uint32_t velocity = ne_scale * step_rate; // Scale step_rate first so all intermediate values stay in range of 8.24 fixed point math
+    int32_t vd = (((int64_t)ne_fix.A * velocity) >> 24) + (((((int64_t)ne_fix.B * velocity) >> 24) * velocity) >> 24);
+    NOLESS(vd, 0);
+
+    advance_dividend.e = (uint64_t(ne_fix.C + vd) * ne_edividend) >> 24;
+  }
+#endif
+
 // Get the timer interval and the number of loops to perform per tick
 hal_timer_t Stepper::calc_multistep_timer_interval(uint32_t step_rate) {
 
@@ -2318,6 +2335,10 @@ hal_timer_t Stepper::block_phase_isr() {
         interval = calc_multistep_timer_interval(acc_step_rate << oversampling_factor);
         acceleration_time += interval;
 
+        #if ENABLED(NONLINEAR_EXTRUSION)
+          calc_nonlinear_e(acc_step_rate << oversampling_factor);
+        #endif
+
         #if ENABLED(LIN_ADVANCE)
           if (la_active) {
             const uint32_t la_step_rate = la_advance_steps < current_block->max_adv_steps ? current_block->la_advance_rate : 0;
@@ -2388,6 +2409,10 @@ hal_timer_t Stepper::block_phase_isr() {
         interval = calc_multistep_timer_interval(step_rate << oversampling_factor);
         deceleration_time += interval;
 
+        #if ENABLED(NONLINEAR_EXTRUSION)
+          calc_nonlinear_e(step_rate << oversampling_factor);
+        #endif
+
         #if ENABLED(LIN_ADVANCE)
           if (la_active) {
             const uint32_t la_step_rate = la_advance_steps > current_block->final_adv_steps ? current_block->la_advance_rate : 0;
@@ -2436,6 +2461,10 @@ hal_timer_t Stepper::block_phase_isr() {
           // step_rate to timer interval and loops for the nominal speed
           ticks_nominal = calc_multistep_timer_interval(current_block->nominal_rate << oversampling_factor);
 
+          #if ENABLED(NONLINEAR_EXTRUSION)
+            calc_nonlinear_e(current_block->nominal_rate << oversampling_factor);
+          #endif
+
           #if ENABLED(LIN_ADVANCE)
             if (la_active)
               la_interval = calc_timer_interval(current_block->nominal_rate >> current_block->la_scaling);
@@ -2636,10 +2665,13 @@ hal_timer_t Stepper::block_phase_isr() {
       acceleration_time = deceleration_time = 0;
 
       #if ENABLED(ADAPTIVE_STEP_SMOOTHING)
-        oversampling_factor = 0;                            // Assume no axis smoothing (via oversampling)
+        // Nonlinear Extrusion needs at least 2x oversampling to permit increase of E step rate
+        // Otherwise assume no axis smoothing (via oversampling)
+        oversampling_factor = TERN(NONLINEAR_EXTRUSION, 1, 0);
+
         // Decide if axis smoothing is possible
-        uint32_t max_rate = current_block->nominal_rate;    // Get the step event rate
         if (TERN1(DWIN_LCD_PROUI, hmiData.adaptiveStepSmoothing)) {
+          uint32_t max_rate = current_block->nominal_rate;  // Get the step event rate
           while (max_rate < MIN_STEP_ISR_FREQUENCY) {       // As long as more ISRs are possible...
             max_rate <<= 1;                                 // Try to double the rate
             if (max_rate < MIN_STEP_ISR_FREQUENCY)          // Don't exceed the estimated ISR limit
@@ -2755,10 +2787,29 @@ hal_timer_t Stepper::block_phase_isr() {
         acc_step_rate = current_block->initial_rate;
       #endif
 
+      #if ENABLED(NONLINEAR_EXTRUSION)
+        ne_edividend = advance_dividend.e;
+        const float scale = (float(ne_edividend) / advance_divisor) * planner.mm_per_step[E_AXIS_N(current_block->extruder)];
+        ne_scale = (1L << 24) * scale;
+        if (current_block->direction_bits.e) {
+          ne_fix.A = (1L << 24) * ne.A;
+          ne_fix.B = (1L << 24) * ne.B;
+          ne_fix.C = (1L << 24) * ne.C;
+        }
+        else {
+          ne_fix.A = ne_fix.B = 0;
+          ne_fix.C = (1L << 24);
+        }
+      #endif
+
       // Calculate the initial timer interval
       interval = calc_multistep_timer_interval(current_block->initial_rate << oversampling_factor);
       acceleration_time += interval;
 
+      #if ENABLED(NONLINEAR_EXTRUSION)
+        calc_nonlinear_e(current_block->initial_rate << oversampling_factor);
+      #endif
+
       #if ENABLED(LIN_ADVANCE)
         if (la_active) {
           const uint32_t la_step_rate = la_advance_steps < current_block->max_adv_steps ? current_block->la_advance_rate : 0;

Marlin/src/module/stepper.h

@@ -284,6 +284,11 @@ constexpr ena_mask_t enable_overlap[] = {
 
 #endif // HAS_ZV_SHAPING
 
+#if ENABLED(NONLINEAR_EXTRUSION)
+  typedef struct { float A, B, C; void reset() { A = B = 0.0f; C = 1.0f; } } ne_coeff_t;
+  typedef struct { int32_t A, B, C; } ne_fix_t;
+#endif
+
 //
 // Stepper class definition
 //
@@ -326,6 +331,10 @@ class Stepper {
       static bool frozen;                 // Set this flag to instantly freeze motion
     #endif
 
+    #if ENABLED(NONLINEAR_EXTRUSION)
+      static ne_coeff_t ne;
+    #endif
+
   private:
 
     static block_t* current_block;        // A pointer to the block currently being traced
@@ -416,6 +425,12 @@ class Stepper {
       static bool        la_active;        // Whether linear advance is used on the present segment.
     #endif
 
+    #if ENABLED(NONLINEAR_EXTRUSION)
+      static int32_t ne_edividend;
+      static uint32_t ne_scale;
+      static ne_fix_t ne_fix;
+    #endif
+
     #if ENABLED(BABYSTEPPING)
       static constexpr hal_timer_t BABYSTEP_NEVER = HAL_TIMER_TYPE_MAX;
       static hal_timer_t nextBabystepISR;
@@ -660,6 +675,10 @@ class Stepper {
     // Calculate timing interval and steps-per-ISR for the given step rate
     static hal_timer_t calc_multistep_timer_interval(uint32_t step_rate);
 
+    #if ENABLED(NONLINEAR_EXTRUSION)
+      static void calc_nonlinear_e(uint32_t step_rate);
+    #endif
+
     #if ENABLED(S_CURVE_ACCELERATION)
       static void _calc_bezier_curve_coeffs(const int32_t v0, const int32_t v1, const uint32_t av);
       static int32_t _eval_bezier_curve(const uint32_t curr_step);

buildroot/tests/STM32F103RC_btt

@@ -12,7 +12,7 @@ set -e
 restore_configs
 opt_set MOTHERBOARD BOARD_BTT_SKR_MINI_E3_V1_0 SERIAL_PORT 1 SERIAL_PORT_2 -1 \
         X_DRIVER_TYPE TMC2209 Y_DRIVER_TYPE TMC2209 Z_DRIVER_TYPE TMC2209 E0_DRIVER_TYPE TMC2209
-opt_enable CR10_STOCKDISPLAY PINS_DEBUGGING Z_IDLE_HEIGHT FT_MOTION FT_MOTION_MENU
+opt_enable CR10_STOCKDISPLAY PINS_DEBUGGING Z_IDLE_HEIGHT FT_MOTION FT_MOTION_MENU ADAPTIVE_STEP_SMOOTHING NONLINEAR_EXTRUSION
 exec_test $1 $2 "BigTreeTech SKR Mini E3 1.0 - TMC2209 HW Serial, FT_MOTION" "$3"
 
 # clean up