From 76bbfb39ae3c46a874ace54b6d645810cc37d7ac Mon Sep 17 00:00:00 2001 From: midopple Date: Sun, 29 Jan 2012 00:18:21 +0100 Subject: New Version Sprinter V2 - Look Vorward Funktion - - Stepper Control with Timer 1 - SOFT PWM for Extruder heating --> Free Timer 1 - G2 / G3 Command for arc real arc - Baudrate 250 kbaud - M30 Command delete file on SD Card - Text moved to flash to free RAM - M203 Command for Temp debugging --- Sprinter/arc_func.cpp | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 143 insertions(+) create mode 100644 Sprinter/arc_func.cpp (limited to 'Sprinter/arc_func.cpp') diff --git a/Sprinter/arc_func.cpp b/Sprinter/arc_func.cpp new file mode 100644 index 0000000..03b6d1f --- /dev/null +++ b/Sprinter/arc_func.cpp @@ -0,0 +1,143 @@ +/* + arc_func.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 . +*/ + +#include +#include + +#include "Configuration.h" +#include "Sprinter.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 + 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 extruder_travel = target[E_AXIS] - position[E_AXIS]; + 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; + float extruder_per_segment = extruder_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[4]; + 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]; + + // Initialize the extruder axis + arc_target[E_AXIS] = position[E_AXIS]; + + for (i = 1; i