First arcs version. (Arcs not working ok)
This commit is contained in:
Erik van der Zalm
parent
2e8e8878e5
commit
0b82465168
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@ -3,6 +3,9 @@
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//#define DEBUG_STEPS
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#define MM_PER_ARC_SEGMENT 1
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#define N_ARC_CORRECTION 25
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// BASIC SETTINGS: select your board type, thermistor type, axis scaling, and endstop configuration
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//// The following define selects which electronics board you have. Please choose the one that matches your setup
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@ -35,6 +35,7 @@
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#include "planner.h"
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#include "stepper.h"
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#include "temperature.h"
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#include "motion_control.h"
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#ifdef SIMPLE_LCD
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#include "Simplelcd.h"
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@ -113,6 +114,7 @@ float destination[NUM_AXIS] = {
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0.0, 0.0, 0.0, 0.0};
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float current_position[NUM_AXIS] = {
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0.0, 0.0, 0.0, 0.0};
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float offset[3] = {0.0, 0.0, 0.0};
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bool home_all_axis = true;
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float feedrate = 1500.0, next_feedrate, saved_feedrate;
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long gcode_N, gcode_LastN;
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@ -441,6 +443,8 @@ inline void get_command()
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switch((int)((strtod(&cmdbuffer[bufindw][strchr_pointer - cmdbuffer[bufindw] + 1], NULL)))){
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case 0:
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case 1:
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case 2:
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case 3:
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#ifdef SDSUPPORT
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if(savetosd)
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break;
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@ -543,6 +547,16 @@ inline void process_commands()
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//ClearToSend();
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return;
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//break;
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case 2: // G2 - CW ARC
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get_arc_coordinates();
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prepare_arc_move(true);
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previous_millis_cmd = millis();
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return;
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case 3: // G3 - CCW ARC
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get_arc_coordinates();
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prepare_arc_move(false);
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previous_millis_cmd = millis();
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return;
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case 4: // G4 dwell
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codenum = 0;
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if(code_seen('P')) codenum = code_value(); // milliseconds to wait
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@ -1139,6 +1153,13 @@ inline void get_coordinates()
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}
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}
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inline void get_arc_coordinates()
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{
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get_coordinates();
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if(code_seen("I")) offset[0] = code_value();
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if(code_seen("J")) offset[1] = code_value();
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}
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void prepare_move()
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{
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plan_buffer_line(destination[X_AXIS], destination[Y_AXIS], destination[Z_AXIS], destination[E_AXIS], feedrate*feedmultiply/60.0/100.0);
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@ -1147,7 +1168,122 @@ void prepare_move()
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}
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}
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void prepare_arc_move(char isclockwise) {
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#if 0
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if (radius_mode) {
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/*
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We need to calculate the center of the circle that has the designated radius and passes
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through both the current position and the target position. This method calculates the following
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set of equations where [x,y] is the vector from current to target position, d == magnitude of
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that vector, h == hypotenuse of the triangle formed by the radius of the circle, the distance to
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the center of the travel vector. A vector perpendicular to the travel vector [-y,x] is scaled to the
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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
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[i,j] at [x/2-y/d*h, y/2+x/d*h] which will be the center of our arc.
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d^2 == x^2 + y^2
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h^2 == r^2 - (d/2)^2
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i == x/2 - y/d*h
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j == y/2 + x/d*h
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O <- [i,j]
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- |
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r - |
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- |
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- | h
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- |
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[0,0] -> C -----------------+--------------- T <- [x,y]
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| <------ d/2 ---->|
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C - Current position
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T - Target position
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O - center of circle that pass through both C and T
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d - distance from C to T
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r - designated radius
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h - distance from center of CT to O
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Expanding the equations:
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d -> sqrt(x^2 + y^2)
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h -> sqrt(4 * r^2 - x^2 - y^2)/2
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i -> (x - (y * sqrt(4 * r^2 - x^2 - y^2)) / sqrt(x^2 + y^2)) / 2
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j -> (y + (x * sqrt(4 * r^2 - x^2 - y^2)) / sqrt(x^2 + y^2)) / 2
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Which can be written:
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i -> (x - (y * sqrt(4 * r^2 - x^2 - y^2))/sqrt(x^2 + y^2))/2
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j -> (y + (x * sqrt(4 * r^2 - x^2 - y^2))/sqrt(x^2 + y^2))/2
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Which we for size and speed reasons optimize to:
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h_x2_div_d = sqrt(4 * r^2 - x^2 - y^2)/sqrt(x^2 + y^2)
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i = (x - (y * h_x2_div_d))/2
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j = (y + (x * h_x2_div_d))/2
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*/
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// Calculate the change in position along each selected axis
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double x = target[gc.plane_axis_0]-gc.position[gc.plane_axis_0];
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double y = target[gc.plane_axis_1]-gc.position[gc.plane_axis_1];
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clear_vector(offset);
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double h_x2_div_d = -sqrt(4 * r*r - x*x - y*y)/hypot(x,y); // == -(h * 2 / d)
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// If r is smaller than d, the arc is now traversing the complex plane beyond the reach of any
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// real CNC, and thus - for practical reasons - we will terminate promptly:
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if(isnan(h_x2_div_d)) { FAIL(STATUS_FLOATING_POINT_ERROR); return(gc.status_code); }
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// Invert the sign of h_x2_div_d if the circle is counter clockwise (see sketch below)
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if (gc.motion_mode == MOTION_MODE_CCW_ARC) { h_x2_div_d = -h_x2_div_d; }
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/* The counter clockwise circle lies to the left of the target direction. When offset is positive,
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the left hand circle will be generated - when it is negative the right hand circle is generated.
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T <-- Target position
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^
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Clockwise circles with this center | Clockwise circles with this center will have
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will have > 180 deg of angular travel | < 180 deg of angular travel, which is a good thing!
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\ | /
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center of arc when h_x2_div_d is positive -> x <----- | -----> x <- center of arc when h_x2_div_d is negative
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C <-- Current position */
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// Negative R is g-code-alese for "I want a circle with more than 180 degrees of travel" (go figure!),
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// even though it is advised against ever generating such circles in a single line of g-code. By
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// inverting the sign of h_x2_div_d the center of the circles is placed on the opposite side of the line of
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// travel and thus we get the unadvisably long arcs as prescribed.
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if (r < 0) {
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h_x2_div_d = -h_x2_div_d;
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r = -r; // Finished with r. Set to positive for mc_arc
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}
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// Complete the operation by calculating the actual center of the arc
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offset[gc.plane_axis_0] = 0.5*(x-(y*h_x2_div_d));
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offset[gc.plane_axis_1] = 0.5*(y+(x*h_x2_div_d));
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} else { // Offset mode specific computations
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#endif
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float r = hypot(offset[X_AXIS], offset[Y_AXIS]); // Compute arc radius for mc_arc
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// }
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// Set clockwise/counter-clockwise sign for mc_arc computations
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// uint8_t isclockwise = false;
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// if (gc.motion_mode == MOTION_MODE_CW_ARC) { isclockwise = true; }
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// Trace the arc
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mc_arc(current_position, destination, offset, X_AXIS, Y_AXIS, Z_AXIS, feedrate*feedmultiply/60.0/100.0, r, isclockwise);
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// }
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// As far as the parser is concerned, the position is now == target. In reality the
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// motion control system might still be processing the action and the real tool position
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// in any intermediate location.
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for(int ii=0; ii < NUM_AXIS; ii++) {
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current_position[ii] = destination[ii];
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}
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}
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#ifdef USE_WATCHDOG
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@ -1219,7 +1355,7 @@ inline void kill()
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disable_e();
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if(PS_ON_PIN > -1) pinMode(PS_ON_PIN,INPUT);
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Serial.println("!! Printer halted. kill() called!!");
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Serial.println("!! Printer halted. kill() called !!");
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while(1); // Wait for reset
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}
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@ -1233,3 +1369,4 @@ void manage_inactivity(byte debug) {
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}
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check_axes_activity();
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}
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133
Marlin/motion_control.cpp
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133
Marlin/motion_control.cpp
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@ -0,0 +1,133 @@
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/*
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motion_control.c - high level interface for issuing motion commands
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Part of Grbl
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Copyright (c) 2009-2011 Simen Svale Skogsrud
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Copyright (c) 2011 Sungeun K. Jeon
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Grbl is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Grbl is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Grbl. If not, see <http://www.gnu.org/licenses/>.
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*/
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//#include "motion_control.h"
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#include "Configuration.h"
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#include "Marlin.h"
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//#include <util/delay.h>
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//#include <math.h>
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//#include <stdlib.h>
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#include "stepper.h"
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#include "planner.h"
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// The arc is approximated by generating a huge number of tiny, linear segments. The length of each
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// segment is configured in settings.mm_per_arc_segment.
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void mc_arc(float *position, float *target, float *offset, uint8_t axis_0, uint8_t axis_1,
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uint8_t axis_linear, float feed_rate, float radius, uint8_t isclockwise)
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{
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// int acceleration_manager_was_enabled = plan_is_acceleration_manager_enabled();
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// plan_set_acceleration_manager_enabled(false); // disable acceleration management for the duration of the arc
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Serial.println("mc_arc");
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float center_axis0 = position[axis_0] + offset[axis_0];
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float center_axis1 = position[axis_1] + offset[axis_1];
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float linear_travel = target[axis_linear] - position[axis_linear];
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float r_axis0 = -offset[axis_0]; // Radius vector from center to current location
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float r_axis1 = -offset[axis_1];
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float rt_axis0 = target[axis_0] - center_axis0;
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float rt_axis1 = target[axis_1] - center_axis1;
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// CCW angle between position and target from circle center. Only one atan2() trig computation required.
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float angular_travel = atan2(r_axis0*rt_axis1-r_axis1*rt_axis0, r_axis0*rt_axis0+r_axis1*rt_axis1);
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if (angular_travel < 0) { angular_travel += 2*M_PI; }
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if (isclockwise) { angular_travel -= 2*M_PI; }
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float millimeters_of_travel = hypot(angular_travel*radius, fabs(linear_travel));
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if (millimeters_of_travel == 0.0) { return; }
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uint16_t segments = floor(millimeters_of_travel/MM_PER_ARC_SEGMENT);
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/*
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// Multiply inverse feed_rate to compensate for the fact that this movement is approximated
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// by a number of discrete segments. The inverse feed_rate should be correct for the sum of
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// all segments.
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if (invert_feed_rate) { feed_rate *= segments; }
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*/
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float theta_per_segment = angular_travel/segments;
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float linear_per_segment = linear_travel/segments;
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/* Vector rotation by transformation matrix: r is the original vector, r_T is the rotated vector,
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and phi is the angle of rotation. Based on the solution approach by Jens Geisler.
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r_T = [cos(phi) -sin(phi);
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sin(phi) cos(phi] * r ;
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For arc generation, the center of the circle is the axis of rotation and the radius vector is
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defined from the circle center to the initial position. Each line segment is formed by successive
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vector rotations. This requires only two cos() and sin() computations to form the rotation
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matrix for the duration of the entire arc. Error may accumulate from numerical round-off, since
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all double numbers are single precision on the Arduino. (True double precision will not have
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round off issues for CNC applications.) Single precision error can accumulate to be greater than
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tool precision in some cases. Therefore, arc path correction is implemented.
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Small angle approximation may be used to reduce computation overhead further. This approximation
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holds for everything, but very small circles and large mm_per_arc_segment values. In other words,
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theta_per_segment would need to be greater than 0.1 rad and N_ARC_CORRECTION would need to be large
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to cause an appreciable drift error. N_ARC_CORRECTION~=25 is more than small enough to correct for
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numerical drift error. N_ARC_CORRECTION may be on the order a hundred(s) before error becomes an
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issue for CNC machines with the single precision Arduino calculations.
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This approximation also allows mc_arc to immediately insert a line segment into the planner
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without the initial overhead of computing cos() or sin(). By the time the arc needs to be applied
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a correction, the planner should have caught up to the lag caused by the initial mc_arc overhead.
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This is important when there are successive arc motions.
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*/
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// Vector rotation matrix values
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float cos_T = 1-0.5*theta_per_segment*theta_per_segment; // Small angle approximation
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float sin_T = theta_per_segment;
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float arc_target[3];
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float sin_Ti;
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float cos_Ti;
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float r_axisi;
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uint16_t i;
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int8_t count = 0;
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// Initialize the linear axis
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arc_target[axis_linear] = position[axis_linear];
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for (i = 1; i<segments; i++) { // Increment (segments-1)
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if (count < N_ARC_CORRECTION) {
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// Apply vector rotation matrix
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r_axisi = r_axis0*sin_T + r_axis1*cos_T;
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r_axis0 = r_axis0*cos_T - r_axis1*sin_T;
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r_axis1 = r_axisi;
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count++;
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} else {
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// Arc correction to radius vector. Computed only every N_ARC_CORRECTION increments.
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// Compute exact location by applying transformation matrix from initial radius vector(=-offset).
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cos_Ti = cos(i*theta_per_segment);
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sin_Ti = sin(i*theta_per_segment);
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r_axis0 = -offset[axis_0]*cos_Ti + offset[axis_1]*sin_Ti;
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r_axis1 = -offset[axis_0]*sin_Ti - offset[axis_1]*cos_Ti;
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count = 0;
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}
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// Update arc_target location
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arc_target[axis_0] = center_axis0 + r_axis0;
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arc_target[axis_1] = center_axis1 + r_axis1;
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arc_target[axis_linear] += linear_per_segment;
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plan_buffer_line(arc_target[X_AXIS], arc_target[Y_AXIS], arc_target[Z_AXIS], target[E_AXIS], feed_rate);
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}
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// Ensure last segment arrives at target location.
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plan_buffer_line(target[X_AXIS], target[Y_AXIS], target[Z_AXIS], target[E_AXIS], feed_rate);
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// plan_set_acceleration_manager_enabled(acceleration_manager_was_enabled);
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}
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32
Marlin/motion_control.h
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32
Marlin/motion_control.h
Normal file
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@ -0,0 +1,32 @@
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/*
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motion_control.h - high level interface for issuing motion commands
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Part of Grbl
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Copyright (c) 2009-2011 Simen Svale Skogsrud
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Copyright (c) 2011 Sungeun K. Jeon
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|
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Grbl is free software: you can redistribute it and/or modify
|
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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.
|
||||
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You should have received a copy of the GNU General Public License
|
||||
along with Grbl. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef motion_control_h
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#define motion_control_h
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// Execute an arc in offset mode format. position == current xyz, target == target xyz,
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// offset == offset from current xyz, axis_XXX defines circle plane in tool space, axis_linear is
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// the direction of helical travel, radius == circle radius, isclockwise boolean. Used
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// for vector transformation direction.
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void mc_arc(float *position, float *target, float *offset, unsigned char axis_0, unsigned char axis_1,
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unsigned char axis_linear, float feed_rate, float radius, unsigned char isclockwise);
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#endif
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