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Fixed some arc bugs

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This commit is contained in:
Erik van der Zalm 2011-11-06 19:37:12 +01:00
parent 76b3f805c0
commit 5cf349a24a
2 changed files with 12 additions and 114 deletions
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113
Marlin/Marlin.pde
View File

@ -1139,8 +1139,8 @@ inline void get_coordinates()
inline void get_arc_coordinates() inline void get_arc_coordinates()
{ {
get_coordinates(); get_coordinates();
if(code_seen("I")) offset[0] = code_value(); if(code_seen('I')) offset[0] = code_value();
if(code_seen("J")) offset[1] = code_value(); if(code_seen('J')) offset[1] = code_value();
} }
void prepare_move() void prepare_move()
@ -1152,119 +1152,16 @@ void prepare_move()
} }
void prepare_arc_move(char isclockwise) { void prepare_arc_move(char isclockwise) {
#if 0 float r = hypot(offset[X_AXIS], offset[Y_AXIS]); // Compute arc radius for mc_arc
if (radius_mode) {
/*
We need to calculate the center of the circle that has the designated radius and passes
through both the current position and the target position. This method calculates the following
set of equations where [x,y] is the vector from current to target position, d == magnitude of
that vector, h == hypotenuse of the triangle formed by the radius of the circle, the distance to
the center of the travel vector. A vector perpendicular to the travel vector [-y,x] is scaled to the
length of h [-y/d*h, x/d*h] and added to the center of the travel vector [x/2,y/2] to form the new point
[i,j] at [x/2-y/d*h, y/2+x/d*h] which will be the center of our arc.
d^2 == x^2 + y^2
h^2 == r^2 - (d/2)^2
i == x/2 - y/d*h
j == y/2 + x/d*h
O <- [i,j]
- |
r - |
- |
- | h
- |
[0,0] -> C -----------------+--------------- T <- [x,y]
| <------ d/2 ---->|
C - Current position
T - Target position
O - center of circle that pass through both C and T
d - distance from C to T
r - designated radius
h - distance from center of CT to O
Expanding the equations:
d -> sqrt(x^2 + y^2)
h -> sqrt(4 * r^2 - x^2 - y^2)/2
i -> (x - (y * sqrt(4 * r^2 - x^2 - y^2)) / sqrt(x^2 + y^2)) / 2
j -> (y + (x * sqrt(4 * r^2 - x^2 - y^2)) / sqrt(x^2 + y^2)) / 2
Which can be written:
i -> (x - (y * sqrt(4 * r^2 - x^2 - y^2))/sqrt(x^2 + y^2))/2
j -> (y + (x * sqrt(4 * r^2 - x^2 - y^2))/sqrt(x^2 + y^2))/2
Which we for size and speed reasons optimize to:
h_x2_div_d = sqrt(4 * r^2 - x^2 - y^2)/sqrt(x^2 + y^2)
i = (x - (y * h_x2_div_d))/2
j = (y + (x * h_x2_div_d))/2
*/
// Calculate the change in position along each selected axis
double x = target[gc.plane_axis_0]-gc.position[gc.plane_axis_0];
double y = target[gc.plane_axis_1]-gc.position[gc.plane_axis_1];
clear_vector(offset);
double h_x2_div_d = -sqrt(4 * r*r - x*x - y*y)/hypot(x,y); // == -(h * 2 / d)
// If r is smaller than d, the arc is now traversing the complex plane beyond the reach of any
// real CNC, and thus - for practical reasons - we will terminate promptly:
if(isnan(h_x2_div_d)) { FAIL(STATUS_FLOATING_POINT_ERROR); return(gc.status_code); }
// Invert the sign of h_x2_div_d if the circle is counter clockwise (see sketch below)
if (gc.motion_mode == MOTION_MODE_CCW_ARC) { h_x2_div_d = -h_x2_div_d; }
/* The counter clockwise circle lies to the left of the target direction. When offset is positive,
the left hand circle will be generated - when it is negative the right hand circle is generated.
T <-- Target position
^
Clockwise circles with this center | Clockwise circles with this center will have
will have > 180 deg of angular travel | < 180 deg of angular travel, which is a good thing!
\ | /
center of arc when h_x2_div_d is positive -> x <----- | -----> x <- center of arc when h_x2_div_d is negative
|
|
C <-- Current position */
// Negative R is g-code-alese for "I want a circle with more than 180 degrees of travel" (go figure!),
// even though it is advised against ever generating such circles in a single line of g-code. By
// inverting the sign of h_x2_div_d the center of the circles is placed on the opposite side of the line of
// travel and thus we get the unadvisably long arcs as prescribed.
if (r < 0) {
h_x2_div_d = -h_x2_div_d;
r = -r; // Finished with r. Set to positive for mc_arc
}
// Complete the operation by calculating the actual center of the arc
offset[gc.plane_axis_0] = 0.5*(x-(y*h_x2_div_d));
offset[gc.plane_axis_1] = 0.5*(y+(x*h_x2_div_d));
} else { // Offset mode specific computations
#endif
float r = hypot(offset[X_AXIS], offset[Y_AXIS]); // Compute arc radius for mc_arc
// }
// Set clockwise/counter-clockwise sign for mc_arc computations
// uint8_t isclockwise = false;
// if (gc.motion_mode == MOTION_MODE_CW_ARC) { isclockwise = true; }
// Trace the arc // Trace the arc
mc_arc(current_position, destination, offset, X_AXIS, Y_AXIS, Z_AXIS, feedrate*feedmultiply/60.0/100.0, r, isclockwise); mc_arc(current_position, destination, offset, X_AXIS, Y_AXIS, Z_AXIS, feedrate*feedmultiply/60.0/100.0, r, isclockwise);
// }
// As far as the parser is concerned, the position is now == target. In reality the // As far as the parser is concerned, the position is now == target. In reality the
// motion control system might still be processing the action and the real tool position // motion control system might still be processing the action and the real tool position
// in any intermediate location. // in any intermediate location.
for(int ii=0; ii < NUM_AXIS; ii++) { for(int i=0; i < NUM_AXIS; i++) {
current_position[ii] = destination[ii]; current_position[i] = destination[i];
} }
} }

13
Marlin/motion_control.cpp
View File

@ -19,12 +19,8 @@
along with Grbl. If not, see <http://www.gnu.org/licenses/>. along with Grbl. If not, see <http://www.gnu.org/licenses/>.
*/ */
//#include "motion_control.h"
#include "Configuration.h" #include "Configuration.h"
#include "Marlin.h" #include "Marlin.h"
//#include <util/delay.h>
//#include <math.h>
//#include <stdlib.h>
#include "stepper.h" #include "stepper.h"
#include "planner.h" #include "planner.h"
@ -35,10 +31,10 @@ void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8
{ {
// int acceleration_manager_was_enabled = plan_is_acceleration_manager_enabled(); // 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 // plan_set_acceleration_manager_enabled(false); // disable acceleration management for the duration of the arc
SERIAL_ECHOLN("mc_arc.");
float center_axis0 = position[axis_0] + offset[axis_0]; float center_axis0 = position[axis_0] + offset[axis_0];
float center_axis1 = position[axis_1] + offset[axis_1]; float center_axis1 = position[axis_1] + offset[axis_1];
float linear_travel = target[axis_linear] - position[axis_linear]; float linear_travel = target[axis_linear] - position[axis_linear];
float extruder_travel = target[E_AXIS] - position[E_AXIS];
float r_axis0 = -offset[axis_0]; // Radius vector from center to current location float r_axis0 = -offset[axis_0]; // Radius vector from center to current location
float r_axis1 = -offset[axis_1]; float r_axis1 = -offset[axis_1];
float rt_axis0 = target[axis_0] - center_axis0; float rt_axis0 = target[axis_0] - center_axis0;
@ -60,6 +56,7 @@ void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8
*/ */
float theta_per_segment = angular_travel/segments; float theta_per_segment = angular_travel/segments;
float linear_per_segment = linear_travel/segments; float linear_per_segment = linear_travel/segments;
float extruder_per_segment = extruder_travel/segments;
/* Vector rotation by transformation matrix: r is the original vector, r_T is the rotated vector, /* 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. and phi is the angle of rotation. Based on the solution approach by Jens Geisler.
@ -90,7 +87,7 @@ void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8
float cos_T = 1-0.5*theta_per_segment*theta_per_segment; // Small angle approximation float cos_T = 1-0.5*theta_per_segment*theta_per_segment; // Small angle approximation
float sin_T = theta_per_segment; float sin_T = theta_per_segment;
float arc_target[3]; float arc_target[4];
float sin_Ti; float sin_Ti;
float cos_Ti; float cos_Ti;
float r_axisi; float r_axisi;
@ -100,6 +97,9 @@ void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8
// Initialize the linear axis // Initialize the linear axis
arc_target[axis_linear] = position[axis_linear]; arc_target[axis_linear] = position[axis_linear];
// Initialize the extruder axis
arc_target[E_AXIS] = position[E_AXIS];
for (i = 1; i<segments; i++) { // Increment (segments-1) for (i = 1; i<segments; i++) { // Increment (segments-1)
if (count < N_ARC_CORRECTION) { if (count < N_ARC_CORRECTION) {
@ -122,6 +122,7 @@ void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8
arc_target[axis_0] = center_axis0 + r_axis0; arc_target[axis_0] = center_axis0 + r_axis0;
arc_target[axis_1] = center_axis1 + r_axis1; arc_target[axis_1] = center_axis1 + r_axis1;
arc_target[axis_linear] += linear_per_segment; arc_target[axis_linear] += linear_per_segment;
arc_target[E_AXIS] += extruder_per_segment;
plan_buffer_line(arc_target[X_AXIS], arc_target[Y_AXIS], arc_target[Z_AXIS], target[E_AXIS], feed_rate); plan_buffer_line(arc_target[X_AXIS], arc_target[Y_AXIS], arc_target[Z_AXIS], target[E_AXIS], feed_rate);
} }