- Fleshed out the original idea to completely remove the long slope at
the end of deceleration issue. This third time should absolutely
eliminate it.
- Changed the acceleration setting to kept as mm/min^2 internally,
since this was creating unneccessary additional computation in the
planner. Human readable value kept at mm/sec^2.
- Updated grbl version 0.7d and settings version to 4. NOTE: Please
check settings after update. These may have changed, but shouldn't.
- Before updating the new features (pause, e-stop, federate override,
etc), the edge branch will soon be merged with the master, barring any
immediate issues that people may have, and the edge branch will be the
testing ground for the new grbl version 0.8.
- Added another way to further ensure the long slope deceleration issue
is eliminated. If the stepper rate change is too great near zero, the
stepper rate is adjusted at half increments to the end of travel,
creating a smooth transition. - If the new STEPPER_IDLE_LOCK_TIME is
set as zero, this delay is not compiled at compile-time. - NOTE: The
next update is likely going to be major, involving a full re-write of
the stepper.c program to integrate a simple way to apply pauses,
jogging, e-stop, and feedrate overrides. The interface should be
flexible enough to be easily modified for use with either hardware
switches or software commands. Coming soon.
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.
- The long standing issue of a long slope at deceleration is likely
fixed. The stepper program was not tracking and timing the end of
acceleration and start of deceleration exactly and now is fixed to
start and stop on time. Also, to ensure a better acceleration curve fit
used by the planner, the stepper program delays the start of the
accelerations by a half trapezoid tick to employ the midpoint rule. -
Settings version 3 migration (not fully tested, but should work) -
Added a MINIMUM_PLANNER_SPEED user-defined parameter to planner to let
a user change this if problems arise for some reason. - Moved all
user-definable #define parameters into config.h with clear comments on
what they do and recommendations of how to change them. - Minor
housekeeping.
- Fixed the planner TODO regarding minimum nominal speeds. Re-arranged
calculations to be both more efficient and guaranteed to be greater
than zero. - Missed a parenthesis location on the rate_delta
calculation. Should fix a nearly in-perceptible issue with incorrect
acceleration ramping in diagonal directions. - Increased maximum dwell
time from 6.5sec to an 18hour max. A crazy amount more, but that's how
the math works out. - Converted the internal feedrate values to mm/min
only, as it was switching between mm/min to mm/sec and back to mm/min.
Also added a feedrate > 0 check in gcode.c. - Identified the long slope
at the end of rapid de/ac-celerations noted by stephanix. Problem with
the numerical integration truncation error between the exact solution
of estimate_acceleration_distance and how grbl actually performs the
acceleration ramps discretely. Increasing the
ACCELERATION_TICKS_PER_SECOND in config.h helps fix this problem.
Investigating further.
- Serial functions contained quite a few modulo operations that would
be executed with high frequency when streaming. AVR processors are very
slow when operating these. In one test on the Arduino forums, it showed
about a 15x slow down compared to a simple if-then statement. -
Clarified some variable names and types and comments.
- Update grbl version and settings version to automatically reset
eeprom. FYI, this will reset your grbl settings. - Saved
3*BLOCK_BUFFER_SIZE doubles in static memory by removing obsolete
variables: speed_x, speed_y, and speed_z. - Increased buffer size
conservatively to 18 from 16. (Probably can do 20). - Removed expensive!
modulo operator from block indexing function. Reduces significant
computational overhead. - Re-organized some sqrt() calls to be more
efficient during time critical planning cases, rather than non-time
critical. - Minor bug fix in planner max junction velocity logic. -
Simplified arc logic and removed need to multiply for CW or CCW
direction.
- Significant improvements in the planner. Removed or reordered
repetitive and expensive calculations by order of importance:
recalculating unchanged blocks, trig functions [sin(), cos(), tan()],
sqrt(), divides, and multiplications. Blocks long enough for nominal
speed to be guaranteed to be reached ignored by planner. Done by
introducing two uint8_t flags per block. Reduced computational overhead
by an order of magnitude. - Arc motion generation completely
re-written and optimized. Now runs with acceleration planner. Removed
all but one trig function (atan2) from initialization. Streamlined
computations. Segment target locations generated by vector
transformation and small angle approximation. Arc path correction
implemented for accumulated error of approximation and single precision
calculation of Arduino. Bug fix in message passing.
No changes in functionality. Path vectors moved from ring buffer to
local planner static variables to save 3*(BUFFER_SIZE - 1) doubles in
memory. Detailed comments. Really need to stop micro-updating. Should be
the last until a planner optimization (ala Jens Geisler) has been
completed.
Reverse planner was over-writing the initial/buffer tail entry speed,
which reset the forward planner and caused it to lose track of its
speed. Should now accelerate into short linear segments much nicer now.
Beta pre-processor script used to clean and streamline g-code for
streaming and converts G02/03 arcs into linear segments. Allows for full
acceleration support if the pre-processed g-code is then streamed to
grill, sans G02/03 arcs. Added a simple example streaming script for
Python users.
- Junction jerk now re-defined as junction_deviation. The distance from
the junction to the edge of a circle tangent to both previous and
current path lines. The circle radii is used to compute the maximum
junction velocity by centripetal acceleration. More robust and
simplified way to compute jerk. - Fixed bugs related to entry and exit
factors. They were computed based on the current nominal speeds but not
when computing exit factors for neighboring blocks. Removed factors and
replaced with entry speeds only. Factors now only computed for stepper
trapezoid rate conversions. - Misc: Added min(), next_block_index,
prev_block_index functions for clarity.
Comments, block delete characters, and blank lines are no longer passed
to the gcode parser and should free up some memory by ignoring these
characters. Gcode parser now expects clean gcode only. There was a bug
if there were block deletes or comments not in the first character (i.e.
spindle on/off for proofing geode without turning it on, or a NXX
followed by a comment). This should fix it by bypassing the problem.
Left a commented line for easily turning on and off block deletes for a
later feature, if desired.
Comments, block delete characters, and blank lines are no longer passed
to the gcode parser and should free up some memory by ignoring these
characters. Gcode parser now expects clean gcode only. There was a bug
if there were block deletes or comments not in the first character (i.e.
spindle on/off for proofing geode without turning it on, or a NXX
followed by a comment). This should fix it by bypassing the problem.
Left a commented line for easily turning on and off block deletes for a
later feature, if desired.
