2011-11-06 12:39:00 +01:00
|
|
|
/*
|
|
|
|
motion_control.c - high level interface for issuing motion commands
|
|
|
|
Part of Grbl
|
|
|
|
|
|
|
|
Copyright (c) 2009-2011 Simen Svale Skogsrud
|
|
|
|
Copyright (c) 2011 Sungeun K. Jeon
|
|
|
|
|
|
|
|
Grbl 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.
|
|
|
|
|
|
|
|
Grbl 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 Grbl. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
*/
|
|
|
|
|
|
|
|
//#include "motion_control.h"
|
|
|
|
#include "Configuration.h"
|
|
|
|
#include "Marlin.h"
|
|
|
|
//#include <util/delay.h>
|
|
|
|
//#include <math.h>
|
|
|
|
//#include <stdlib.h>
|
|
|
|
#include "stepper.h"
|
|
|
|
#include "planner.h"
|
|
|
|
|
|
|
|
// The arc is approximated by generating a huge number of tiny, linear segments. The length of each
|
|
|
|
// segment is configured in settings.mm_per_arc_segment.
|
|
|
|
void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8_t axis_1,
|
|
|
|
uint8_t axis_linear, float feed_rate, float radius, uint8_t isclockwise)
|
|
|
|
{
|
|
|
|
// int acceleration_manager_was_enabled = plan_is_acceleration_manager_enabled();
|
|
|
|
// plan_set_acceleration_manager_enabled(false); // disable acceleration management for the duration of the arc
|
2011-11-06 17:33:09 +01:00
|
|
|
SERIAL_ECHOLN("mc_arc.");
|
2011-11-06 12:39:00 +01:00
|
|
|
float center_axis0 = position[axis_0] + offset[axis_0];
|
|
|
|
float center_axis1 = position[axis_1] + offset[axis_1];
|
|
|
|
float linear_travel = target[axis_linear] - position[axis_linear];
|
|
|
|
float r_axis0 = -offset[axis_0]; // Radius vector from center to current location
|
|
|
|
float r_axis1 = -offset[axis_1];
|
|
|
|
float rt_axis0 = target[axis_0] - center_axis0;
|
|
|
|
float rt_axis1 = target[axis_1] - center_axis1;
|
|
|
|
|
|
|
|
// CCW angle between position and target from circle center. Only one atan2() trig computation required.
|
|
|
|
float angular_travel = atan2(r_axis0*rt_axis1-r_axis1*rt_axis0, r_axis0*rt_axis0+r_axis1*rt_axis1);
|
|
|
|
if (angular_travel < 0) { angular_travel += 2*M_PI; }
|
|
|
|
if (isclockwise) { angular_travel -= 2*M_PI; }
|
|
|
|
|
|
|
|
float millimeters_of_travel = hypot(angular_travel*radius, fabs(linear_travel));
|
|
|
|
if (millimeters_of_travel == 0.0) { return; }
|
|
|
|
uint16_t segments = floor(millimeters_of_travel/MM_PER_ARC_SEGMENT);
|
|
|
|
/*
|
|
|
|
// Multiply inverse feed_rate to compensate for the fact that this movement is approximated
|
|
|
|
// by a number of discrete segments. The inverse feed_rate should be correct for the sum of
|
|
|
|
// all segments.
|
|
|
|
if (invert_feed_rate) { feed_rate *= segments; }
|
|
|
|
*/
|
|
|
|
float theta_per_segment = angular_travel/segments;
|
|
|
|
float linear_per_segment = linear_travel/segments;
|
|
|
|
|
|
|
|
/* Vector rotation by transformation matrix: r is the original vector, r_T is the rotated vector,
|
|
|
|
and phi is the angle of rotation. Based on the solution approach by Jens Geisler.
|
|
|
|
r_T = [cos(phi) -sin(phi);
|
|
|
|
sin(phi) cos(phi] * r ;
|
|
|
|
|
|
|
|
For arc generation, the center of the circle is the axis of rotation and the radius vector is
|
|
|
|
defined from the circle center to the initial position. Each line segment is formed by successive
|
|
|
|
vector rotations. This requires only two cos() and sin() computations to form the rotation
|
|
|
|
matrix for the duration of the entire arc. Error may accumulate from numerical round-off, since
|
|
|
|
all double numbers are single precision on the Arduino. (True double precision will not have
|
|
|
|
round off issues for CNC applications.) Single precision error can accumulate to be greater than
|
|
|
|
tool precision in some cases. Therefore, arc path correction is implemented.
|
|
|
|
|
|
|
|
Small angle approximation may be used to reduce computation overhead further. This approximation
|
|
|
|
holds for everything, but very small circles and large mm_per_arc_segment values. In other words,
|
|
|
|
theta_per_segment would need to be greater than 0.1 rad and N_ARC_CORRECTION would need to be large
|
|
|
|
to cause an appreciable drift error. N_ARC_CORRECTION~=25 is more than small enough to correct for
|
|
|
|
numerical drift error. N_ARC_CORRECTION may be on the order a hundred(s) before error becomes an
|
|
|
|
issue for CNC machines with the single precision Arduino calculations.
|
|
|
|
|
|
|
|
This approximation also allows mc_arc to immediately insert a line segment into the planner
|
|
|
|
without the initial overhead of computing cos() or sin(). By the time the arc needs to be applied
|
|
|
|
a correction, the planner should have caught up to the lag caused by the initial mc_arc overhead.
|
|
|
|
This is important when there are successive arc motions.
|
|
|
|
*/
|
|
|
|
// Vector rotation matrix values
|
|
|
|
float cos_T = 1-0.5*theta_per_segment*theta_per_segment; // Small angle approximation
|
|
|
|
float sin_T = theta_per_segment;
|
|
|
|
|
|
|
|
float arc_target[3];
|
|
|
|
float sin_Ti;
|
|
|
|
float cos_Ti;
|
|
|
|
float r_axisi;
|
|
|
|
uint16_t i;
|
|
|
|
int8_t count = 0;
|
|
|
|
|
|
|
|
// Initialize the linear axis
|
|
|
|
arc_target[axis_linear] = position[axis_linear];
|
|
|
|
|
|
|
|
for (i = 1; i<segments; i++) { // Increment (segments-1)
|
|
|
|
|
|
|
|
if (count < N_ARC_CORRECTION) {
|
|
|
|
// Apply vector rotation matrix
|
|
|
|
r_axisi = r_axis0*sin_T + r_axis1*cos_T;
|
|
|
|
r_axis0 = r_axis0*cos_T - r_axis1*sin_T;
|
|
|
|
r_axis1 = r_axisi;
|
|
|
|
count++;
|
|
|
|
} else {
|
|
|
|
// Arc correction to radius vector. Computed only every N_ARC_CORRECTION increments.
|
|
|
|
// Compute exact location by applying transformation matrix from initial radius vector(=-offset).
|
|
|
|
cos_Ti = cos(i*theta_per_segment);
|
|
|
|
sin_Ti = sin(i*theta_per_segment);
|
|
|
|
r_axis0 = -offset[axis_0]*cos_Ti + offset[axis_1]*sin_Ti;
|
|
|
|
r_axis1 = -offset[axis_0]*sin_Ti - offset[axis_1]*cos_Ti;
|
|
|
|
count = 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
// Update arc_target location
|
|
|
|
arc_target[axis_0] = center_axis0 + r_axis0;
|
|
|
|
arc_target[axis_1] = center_axis1 + r_axis1;
|
|
|
|
arc_target[axis_linear] += linear_per_segment;
|
|
|
|
plan_buffer_line(arc_target[X_AXIS], arc_target[Y_AXIS], arc_target[Z_AXIS], target[E_AXIS], feed_rate);
|
|
|
|
|
|
|
|
}
|
|
|
|
// Ensure last segment arrives at target location.
|
|
|
|
plan_buffer_line(target[X_AXIS], target[Y_AXIS], target[Z_AXIS], target[E_AXIS], feed_rate);
|
|
|
|
|
|
|
|
// plan_set_acceleration_manager_enabled(acceleration_manager_was_enabled);
|
|
|
|
}
|
|
|
|
|