Marlin/Marlin/src/module/delta.cpp

/**
 * Marlin 3D Printer Firmware
 * Copyright (c) 2020 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/>.
 *
 */

/**
 * delta.cpp
 */

#include "../inc/MarlinConfig.h"

#if ENABLED(DELTA)

#include "delta.h"
#include "motion.h"

// For homing:
#include "planner.h"
#include "endstops.h"
#include "../lcd/ultralcd.h"
#include "../MarlinCore.h"

#if HAS_BED_PROBE
  #include "probe.h"
#endif

#if ENABLED(SENSORLESS_HOMING)
  #include "../feature/tmc_util.h"
  #include "stepper/indirection.h"
#endif

#define DEBUG_OUT ENABLED(DEBUG_LEVELING_FEATURE)
#include "../core/debug_out.h"

// Initialized by settings.load()
float delta_height;
abc_float_t delta_endstop_adj{0};
float delta_radius,
      delta_diagonal_rod,
      delta_segments_per_second;
abc_float_t delta_tower_angle_trim;
xy_float_t delta_tower[ABC];
abc_float_t delta_diagonal_rod_2_tower;
float delta_clip_start_height = Z_MAX_POS;
abc_float_t delta_diagonal_rod_trim;

float delta_safe_distance_from_top();

/**
 * Recalculate factors used for delta kinematics whenever
 * settings have been changed (e.g., by M665).
 */
void recalc_delta_settings() {
  constexpr abc_float_t trt = DELTA_RADIUS_TRIM_TOWER;
  delta_tower[A_AXIS].set(cos(RADIANS(210 + delta_tower_angle_trim.a)) * (delta_radius + trt.a), // front left tower
                          sin(RADIANS(210 + delta_tower_angle_trim.a)) * (delta_radius + trt.a));
  delta_tower[B_AXIS].set(cos(RADIANS(330 + delta_tower_angle_trim.b)) * (delta_radius + trt.b), // front right tower
                          sin(RADIANS(330 + delta_tower_angle_trim.b)) * (delta_radius + trt.b));
  delta_tower[C_AXIS].set(cos(RADIANS( 90 + delta_tower_angle_trim.c)) * (delta_radius + trt.c), // back middle tower
                          sin(RADIANS( 90 + delta_tower_angle_trim.c)) * (delta_radius + trt.c));
  delta_diagonal_rod_2_tower.set(sq(delta_diagonal_rod + delta_diagonal_rod_trim.a),
                                 sq(delta_diagonal_rod + delta_diagonal_rod_trim.b),
                                 sq(delta_diagonal_rod + delta_diagonal_rod_trim.c));
  update_software_endstops(Z_AXIS);
  set_all_unhomed();
}

/**
 * Get a safe radius for calibration
 */

#if EITHER(DELTA_AUTO_CALIBRATION, DELTA_CALIBRATION_MENU)

  #if ENABLED(DELTA_AUTO_CALIBRATION)
    float calibration_radius_factor = 1;
  #endif

  float delta_calibration_radius() {
    return calibration_radius_factor * (
      #if HAS_BED_PROBE
        FLOOR((DELTA_PRINTABLE_RADIUS) - _MAX(HYPOT(probe.offset_xy.x, probe.offset_xy.y), PROBING_MARGIN))
      #else
        DELTA_PRINTABLE_RADIUS
      #endif
    );
  }

#endif

/**
 * Delta Inverse Kinematics
 *
 * Calculate the tower positions for a given machine
 * position, storing the result in the delta[] array.
 *
 * This is an expensive calculation, requiring 3 square
 * roots per segmented linear move, and strains the limits
 * of a Mega2560 with a Graphical Display.
 *
 * Suggested optimizations include:
 *
 * - Disable the home_offset (M206) and/or position_shift (G92)
 *   features to remove up to 12 float additions.
 */

#define DELTA_DEBUG(VAR) do { \
    SERIAL_ECHOLNPAIR_P(PSTR("Cartesian X"), VAR.x, SP_Y_STR, VAR.y, SP_Z_STR, VAR.z); \
    SERIAL_ECHOLNPAIR_P(PSTR("Delta A"), delta.a, SP_B_STR, delta.b, SP_C_STR, delta.c); \
  }while(0)

void inverse_kinematics(const xyz_pos_t &raw) {
  #if HAS_HOTEND_OFFSET
    // Delta hotend offsets must be applied in Cartesian space with no "spoofing"
    xyz_pos_t pos = { raw.x - hotend_offset[active_extruder].x,
                      raw.y - hotend_offset[active_extruder].y,
                      raw.z };
    DELTA_IK(pos);
    //DELTA_DEBUG(pos);
  #else
    DELTA_IK(raw);
    //DELTA_DEBUG(raw);
  #endif
}

/**
 * Calculate the highest Z position where the
 * effector has the full range of XY motion.
 */
float delta_safe_distance_from_top() {
  xyz_pos_t cartesian{0};
  inverse_kinematics(cartesian);
  const float centered_extent = delta.a;
  cartesian.y = DELTA_PRINTABLE_RADIUS;
  inverse_kinematics(cartesian);
  return ABS(centered_extent - delta.a);
}

/**
 * Delta Forward Kinematics
 *
 * See the Wikipedia article "Trilateration"
 * https://en.wikipedia.org/wiki/Trilateration
 *
 * Establish a new coordinate system in the plane of the
 * three carriage points. This system has its origin at
 * tower1, with tower2 on the X axis. Tower3 is in the X-Y
 * plane with a Z component of zero.
 * We will define unit vectors in this coordinate system
 * in our original coordinate system. Then when we calculate
 * the Xnew, Ynew and Znew values, we can translate back into
 * the original system by moving along those unit vectors
 * by the corresponding values.
 *
 * Variable names matched to Marlin, c-version, and avoid the
 * use of any vector library.
 *
 * by Andreas Hardtung 2016-06-07
 * based on a Java function from "Delta Robot Kinematics V3"
 * by Steve Graves
 *
 * The result is stored in the cartes[] array.
 */
void forward_kinematics_DELTA(const float &z1, const float &z2, const float &z3) {
  // Create a vector in old coordinates along x axis of new coordinate
  const float p12[3] = { delta_tower[B_AXIS].x - delta_tower[A_AXIS].x, delta_tower[B_AXIS].y - delta_tower[A_AXIS].y, z2 - z1 },

  // Get the reciprocal of Magnitude of vector.
  d2 = sq(p12[0]) + sq(p12[1]) + sq(p12[2]), inv_d = RSQRT(d2),

  // Create unit vector by multiplying by the inverse of the magnitude.
  ex[3] = { p12[0] * inv_d, p12[1] * inv_d, p12[2] * inv_d },

  // Get the vector from the origin of the new system to the third point.
  p13[3] = { delta_tower[C_AXIS].x - delta_tower[A_AXIS].x, delta_tower[C_AXIS].y - delta_tower[A_AXIS].y, z3 - z1 },

  // Use the dot product to find the component of this vector on the X axis.
  i = ex[0] * p13[0] + ex[1] * p13[1] + ex[2] * p13[2],

  // Create a vector along the x axis that represents the x component of p13.
  iex[3] = { ex[0] * i, ex[1] * i, ex[2] * i };

  // Subtract the X component from the original vector leaving only Y. We use the
  // variable that will be the unit vector after we scale it.
  float ey[3] = { p13[0] - iex[0], p13[1] - iex[1], p13[2] - iex[2] };

  // The magnitude and the inverse of the magnitude of Y component
  const float j2 = sq(ey[0]) + sq(ey[1]) + sq(ey[2]), inv_j = RSQRT(j2);

  // Convert to a unit vector
  ey[0] *= inv_j; ey[1] *= inv_j; ey[2] *= inv_j;

  // The cross product of the unit x and y is the unit z
  // float[] ez = vectorCrossProd(ex, ey);
  const float ez[3] = {
    ex[1] * ey[2] - ex[2] * ey[1],
    ex[2] * ey[0] - ex[0] * ey[2],
    ex[0] * ey[1] - ex[1] * ey[0]
  },

  // We now have the d, i and j values defined in Wikipedia.
  // Plug them into the equations defined in Wikipedia for Xnew, Ynew and Znew
  Xnew = (delta_diagonal_rod_2_tower.a - delta_diagonal_rod_2_tower.b + d2) * inv_d * 0.5,
  Ynew = ((delta_diagonal_rod_2_tower.a - delta_diagonal_rod_2_tower.c + sq(i) + j2) * 0.5 - i * Xnew) * inv_j,
  Znew = SQRT(delta_diagonal_rod_2_tower.a - HYPOT2(Xnew, Ynew));

  // Start from the origin of the old coordinates and add vectors in the
  // old coords that represent the Xnew, Ynew and Znew to find the point
  // in the old system.
  cartes.set(delta_tower[A_AXIS].x + ex[0] * Xnew + ey[0] * Ynew - ez[0] * Znew,
             delta_tower[A_AXIS].y + ex[1] * Xnew + ey[1] * Ynew - ez[1] * Znew,
                                z1 + ex[2] * Xnew + ey[2] * Ynew - ez[2] * Znew);
}

/**
 * A delta can only safely home all axes at the same time
 * This is like quick_home_xy() but for 3 towers.
 */
void home_delta() {
  DEBUG_SECTION(log_home_delta, "home_delta", DEBUGGING(LEVELING));

  // Init the current position of all carriages to 0,0,0
  current_position.reset();
  destination.reset();
  sync_plan_position();

  // Disable stealthChop if used. Enable diag1 pin on driver.
  #if ENABLED(SENSORLESS_HOMING)
  TERN_(X_SENSORLESS, sensorless_t stealth_states_x = start_sensorless_homing_per_axis(X_AXIS));
  TERN_(Y_SENSORLESS, sensorless_t stealth_states_y = start_sensorless_homing_per_axis(Y_AXIS));
  TERN_(Z_SENSORLESS, sensorless_t stealth_states_z = start_sensorless_homing_per_axis(Z_AXIS));
  #endif

  // Move all carriages together linearly until an endstop is hit.
  current_position.z = (delta_height + 10 - TERN0(HAS_BED_PROBE, probe.offset.z));
  line_to_current_position(homing_feedrate(Z_AXIS));
  planner.synchronize();

  // Re-enable stealthChop if used. Disable diag1 pin on driver.
  #if ENABLED(SENSORLESS_HOMING)
  TERN_(X_SENSORLESS, end_sensorless_homing_per_axis(X_AXIS, stealth_states_x));
  TERN_(Y_SENSORLESS, end_sensorless_homing_per_axis(Y_AXIS, stealth_states_y));
  TERN_(Z_SENSORLESS, end_sensorless_homing_per_axis(Z_AXIS, stealth_states_z));
  #endif

  endstops.validate_homing_move();

  // At least one carriage has reached the top.
  // Now re-home each carriage separately.
  homeaxis(A_AXIS);
  homeaxis(B_AXIS);
  homeaxis(C_AXIS);

  // Set all carriages to their home positions
  // Do this here all at once for Delta, because
  // XYZ isn't ABC. Applying this per-tower would
  // give the impression that they are the same.
  LOOP_XYZ(i) set_axis_is_at_home((AxisEnum)i);

  sync_plan_position();

  #if DISABLED(DELTA_HOME_TO_SAFE_ZONE) && defined(HOMING_BACKOFF_POST_MM)
    constexpr xyz_float_t endstop_backoff = HOMING_BACKOFF_POST_MM;
    if (endstop_backoff.z) {
      current_position.z -= ABS(endstop_backoff.z) * Z_HOME_DIR;
      line_to_current_position(homing_feedrate(Z_AXIS));
    }
  #endif
}

#endif // DELTA