From 59a84c4925c441e994583da46d9e9782331bf61d Mon Sep 17 00:00:00 2001 From: Sonny Jeon Date: Thu, 29 Sep 2011 16:25:48 -0600 Subject: [PATCH] Added complete stop delay at the end of all motion. Moved grbl preprocessor script into a new repository. Added a very short (25 ms) user-definable delay before the steppers are disabled at the motors are disabled and grbl goes idle. This ensures any residual inertia at the end of the last motion does not cause the axes to drift and grbl to lose its position when manually entering g-code or when performing a tool change and starting the next operation. --- config.h | 12 +- script/grbl_preprocess.py | 227 -------------------------------------- stepper.c | 3 + 3 files changed, 13 insertions(+), 229 deletions(-) delete mode 100755 script/grbl_preprocess.py diff --git a/config.h b/config.h index 89d9aea..7ba20ec 100644 --- a/config.h +++ b/config.h @@ -56,8 +56,16 @@ #define SPINDLE_DIRECTION_PORT PORTB #define SPINDLE_DIRECTION_BIT 5 -// The temporal resolution of the acceleration management subsystem. Higher number -// give smoother acceleration but may impact performance +// This parameter sets the delay time before disabling the steppers after the final block of movement. +// A short delay ensures the steppers come to a complete stop and the residual inertial force in the +// CNC axes don't cause the axes to drift off position. This is particularly important when manually +// entering g-code into grbl, i.e. locating part zero or simple manual machining. If the axes drift, +// grbl has no way to know this has happened, since stepper motors are open-loop control. Depending +// on the machine, this parameter may need to be larger or smaller than the default time. +#define STEPPER_IDLE_LOCK_TIME 25 // (milliseconds) + +// The temporal resolution of the acceleration management subsystem. Higher number give smoother +// acceleration but may impact performance. // NOTE: Increasing this parameter will help any resolution related issues, especially with machines // requiring very high accelerations and/or very fast feedrates. In general, this will reduce the // error between how the planner plans the motions and how the stepper program actually performs them. diff --git a/script/grbl_preprocess.py b/script/grbl_preprocess.py deleted file mode 100755 index bbb08c8..0000000 --- a/script/grbl_preprocess.py +++ /dev/null @@ -1,227 +0,0 @@ -#!/usr/bin/env python -"""\ -G-code preprocessor for grbl (BETA!) -- Converts G02/03 arcs to G01 linear interpolations -- Removes comments, block delete characters, and line numbers -- Removes spaces and capitalizes commands -- Minor input error checking -- OPTIONAL: Remove unsupported grbl G and M commands - -TODO: -- Number precision truncation -- Arc conversion option -- More robust error checking -- Improve interface to command line options -- Improve g-code parsing to NIST standards -- Fix problem with inverse feed rates -- Positioning updates may not be correct on grbl. Need to check. - -Based on GRBL 0.7b source code by Simen Svale Skogsrud - -By: Sungeun (Sonny) Jeon -Version: 20100825 -""" -import re -from math import * -from copy import * - -# -= SETTINGS =- -filein = 'test.gcode' # Input file name -fileout = 'grbl.gcode' # Output file name -ndigits_in = 4 # inch significant digits after '.' -ndigits_mm = 2 # mm significant digits after '.' -mm_per_arc_segment = 0.1 # mm per arc segment -inch2mm = 25.4 # inch to mm conversion scalar -verbose = False # Verbose flag to show all progress -remove_unsupported = True # Removal flag for all unsupported statements - -# Initialize parser state -gc = { 'current_xyz' : [0,0,0], - 'feed_rate' : 0, # F0 - 'motion_mode' : 'SEEK', # G00 - 'plane_axis' : [0,1,2], # G17 - 'inches_mode' : False, # G21 - 'inverse_feedrate_mode' : False, # G94 - 'absolute_mode' : True} # G90 - -def unit_conv(val) : # Converts value to mm - if gc['inches_mode'] : val *= inch2mm - return(val) - -def fout_conv(val) : # Returns converted value as rounded string for output file. - if gc['inches_mode'] : return( str(round(val/inch2mm,ndigits_in)) ) - else : return( str(round(val,ndigits_mm)) ) - -# Open g-code file -fin = open(filein,'r'); -fout = open(fileout,'w'); - -# Iterate through g-code file -l_count = 0 -for line in fin: - l_count += 1 # Iterate line counter - - # Strip comments/spaces/tabs/new line and capitalize. Comment MSG not supported. - block = re.sub('\s|\(.*?\)','',line).upper() - block = re.sub('\\\\','',block) # Strip \ block delete character - block = re.sub('%','',block) # Strip % program start/stop character - - if len(block) == 0 : # Ignore empty blocks - - print "Skipping: " + line.strip() - - else : # Process valid g-code clean block. Assumes no block delete characters or comments - - g_cmd = re.findall(r'[^0-9\.\-]+',block) # Extract block command characters - g_num = re.findall(r'[0-9\.\-]+',block) # Extract block numbers - - # G-code block error checks - # if len(g_cmd) != len(g_num) : print block; raise Exception('Invalid block. Unbalanced word and values.') - if 'N' in g_cmd : - if g_cmd[0]!='N': raise Exception('Line number must be first command in line.') - if g_cmd.count('N') > 1: raise Exception('More than one line number in block.') - g_cmd = g_cmd[1:] # Remove line number word - g_num = g_num[1:] - # Block item repeat checks? (0<=n'M'<5, G/M modal groups) - - # Initialize block state - blk = { 'next_action' : 'DEFAULT', - 'absolute_override' : False, - 'target_xyz' : deepcopy(gc['current_xyz']), - 'offset_ijk' : [0,0,0], - 'radius_mode' : False, - 'unsupported': [] } - - # Pass 1 - for cmd,num in zip(g_cmd,g_num) : - fnum = float(num) - inum = int(fnum) - if cmd is 'G' : - if inum is 0 : gc['motion_mode'] = 'SEEK' - elif inum is 1 : gc['motion_mode'] = 'LINEAR' - elif inum is 2 : gc['motion_mode'] = 'CW_ARC' - elif inum is 3 : gc['motion_mode'] = 'CCW_ARC' - elif inum is 4 : blk['next_action'] = 'DWELL' - elif inum is 17 : gc['plane_axis'] = [0,1,2] # Select XY Plane - elif inum is 18 : gc['plane_axis'] = [0,2,1] # Select XZ Plane - elif inum is 19 : gc['plane_axis'] = [1,2,0] # Select YZ Plane - elif inum is 20 : gc['inches_mode'] = True - elif inum is 21 : gc['inches_mode'] = False - elif inum in [28,30] : blk['next_action'] = 'GO_HOME' - elif inum is 53 : blk['absolute_override'] = True - elif inum is 80 : gc['motion_mode'] = 'MOTION_CANCEL' - elif inum is 90 : gc['absolute_mode'] = True - elif inum is 91 : gc['absolute_mode'] = False - elif inum is 92 : blk['next_action'] = 'SET_OFFSET' - elif inum is 93 : gc['inverse_feedrate_mode'] = True - elif inum is 94 : gc['inverse_feedrate_mode'] = False - else : - print 'Unsupported command ' + cmd + num + ' on line ' + str(l_count) - if remove_unsupported : blk['unsupported'].append(zip(g_cmd,g_num).index((cmd,num))) - elif cmd is 'M' : - if inum in [0,1] : pass # Program Pause - elif inum in [2,30,60] : pass # Program Completed - elif inum is 3 : pass # Spindle Direction 1 - elif inum is 4 : pass # Spindle Direction -1 - elif inum is 5 : pass # Spindle Direction 0 - else : - print 'Unsupported command ' + cmd + num + ' on line ' + str(l_count) - if remove_unsupported : blk['unsupported'].append(zip(g_cmd,g_num).index((cmd,num))) - elif cmd is 'T' : pass # Tool Number - - # Pass 2 - for cmd,num in zip(g_cmd,g_num) : - fnum = float(num) - if cmd is 'F' : gc['feed_rate'] = unit_conv(fnum) # Feed Rate - elif cmd in ['I','J','K'] : blk['offset_ijk'][ord(cmd)-ord('I')] = unit_conv(fnum) # Arc Center Offset - elif cmd is 'P' : p = fnum # Misc value parameter - elif cmd is 'R' : r = unit_conv(fnum); blk['radius_mode'] = True # Arc Radius Mode - elif cmd is 'S' : pass # Spindle Speed - elif cmd in ['X','Y','Z'] : # Target Coordinates - if (gc['absolute_mode'] | blk['absolute_override']) : - blk['target_xyz'][ord(cmd)-ord('X')] = unit_conv(fnum) - else : - blk['target_xyz'][ord(cmd)-ord('X')] += unit_conv(fnum) - - # Execute actions - if blk['next_action'] is 'GO_HOME' : - gc['current_xyz'] = deepcopy(blk['target_xyz']) # Update position - elif blk['next_action'] is 'SET_OFFSET' : - pass - elif blk['next_action'] is 'DWELL' : - if p < 0 : raise Exception('Dwell time negative.') - else : # 'DEFAULT' - if gc['motion_mode'] is 'SEEK' : - gc['current_xyz'] = deepcopy(blk['target_xyz']) # Update position - elif gc['motion_mode'] is 'LINEAR' : - gc['current_xyz'] = deepcopy(blk['target_xyz']) # Update position - elif gc['motion_mode'] in ['CW_ARC','CCW_ARC'] : - axis = gc['plane_axis'] - - # Convert radius mode to ijk mode - if blk['radius_mode'] : - x = blk['target_xyz'][axis[0]]-gc['current_xyz'][axis[0]] - y = blk['target_xyz'][axis[1]]-gc['current_xyz'][axis[1]] - if not (x==0 and y==0) : raise Exception('Same target and current XYZ not allowed in arc radius mode.') - h_x2_div_d = -sqrt(4 * r*r - x*x - y*y)/hypot(x,y) - if isnan(h_x2_div_d) : raise Exception('Floating point error in arc conversion') - if gc['motion_mode'] is 'CCW_ARC' : h_x2_div_d = -h_x2_div_d - if r < 0 : h_x2_div_d = -h_x2_div_d - blk['offset_ijk'][axis[0]] = (x-(y*h_x2_div_d))/2; - blk['offset_ijk'][axis[1]] = (y+(x*h_x2_div_d))/2; - - # Compute arc center, radius, theta, and depth parameters - theta_start = atan2(-blk['offset_ijk'][axis[0]], -blk['offset_ijk'][axis[1]]) - theta_end = atan2(blk['target_xyz'][axis[0]] - blk['offset_ijk'][axis[0]] - gc['current_xyz'][axis[0]], \ - blk['target_xyz'][axis[1]] - blk['offset_ijk'][axis[1]] - gc['current_xyz'][axis[1]]) - if theta_end < theta_start : theta_end += 2*pi - radius = hypot(blk['offset_ijk'][axis[0]], blk['offset_ijk'][axis[1]]) - depth = blk['target_xyz'][axis[2]]-gc['current_xyz'][axis[2]] - center_x = gc['current_xyz'][axis[0]]-sin(theta_start)*radius - center_y = gc['current_xyz'][axis[1]]-cos(theta_start)*radius - - # Compute arc incremental linear segment parameters - angular_travel = theta_end-theta_start - if gc['motion_mode'] is 'CCW_ARC' : angular_travel = angular_travel-2*pi - millimeters_of_travel = hypot(angular_travel*radius, fabs(depth)) - if millimeters_of_travel is 0 : raise Exception('G02/03 arc travel is zero') - segments = int(round(millimeters_of_travel/mm_per_arc_segment)) - if segments is 0 : raise Exception('G02/03 zero length arc segment') -# ??? # if gc['inverse_feedrate_mode'] : gc['feed_rate'] *= segments - theta_per_segment = angular_travel/segments - depth_per_segment = depth/segments - - # Generate arc linear segments - if verbose: print 'Converting: '+ block + ' : ' + str(l_count) - fout.write('G01F'+fout_conv(gc['feed_rate'])) - if not gc['absolute_mode'] : fout.write('G90') - arc_target = [0,0,0] - for i in range(1,segments+1) : - if i < segments : - arc_target[axis[0]] = center_x + radius * sin(theta_start + i*theta_per_segment) - arc_target[axis[1]] = center_y + radius * cos(theta_start + i*theta_per_segment) - arc_target[axis[2]] = gc['current_xyz'][axis[2]] + i*depth_per_segment - else : - arc_target = deepcopy(blk['target_xyz']) # Last segment at target_xyz - # Write only changed variables. - if arc_target[0] != gc['current_xyz'][0] : fout.write('X'+fout_conv(arc_target[0])) - if arc_target[1] != gc['current_xyz'][1] : fout.write('Y'+fout_conv(arc_target[1])) - if arc_target[2] != gc['current_xyz'][2] : fout.write('Z'+fout_conv(arc_target[2])) - fout.write('\n') - gc['current_xyz'] = deepcopy(arc_target) # Update position - if not gc['absolute_mode'] : fout.write('G91\n') - - # Rebuild original gcode block sans line numbers, extra characters, and unsupported commands - if gc['motion_mode'] not in ['CW_ARC','CCW_ARC'] : - if remove_unsupported and len(blk['unsupported']) : - for i in blk['unsupported'][::-1] : del g_cmd[i]; del g_num[i] - out_block = "".join([i+j for (i,j) in zip(g_cmd,g_num)]) - if len(out_block) : - if verbose : print "Writing: " + out_block + ' : ' + str(l_count) - fout.write(out_block + '\n') - -print 'Done!' - -# Close files -fin.close() -fout.close() \ No newline at end of file diff --git a/stepper.c b/stepper.c index 9786387..fdd73f9 100644 --- a/stepper.c +++ b/stepper.c @@ -84,6 +84,9 @@ void st_wake_up() { } static void st_go_idle() { + // Force stepper dwell to lock axes for a defined amount of time to ensure the axes come to a complete + // stop and not drift from residual inertial forces at the end of the last movement. + _delay_ms(STEPPER_IDLE_LOCK_TIME); // Disable steppers by setting stepper disable STEPPERS_DISABLE_PORT |= (1<