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| author | Kevin O'Connor <kevin@koconnor.net> | 2017-03-15 23:08:29 -0400 |
|---|---|---|
| committer | Kevin O'Connor <kevin@koconnor.net> | 2017-03-16 13:15:09 -0400 |
| commit | df6d3107f2b9948bc9dc28c4a1dd6a9ea9fda0fe (patch) | |
| tree | 96f7281931872006d1816a4bd7cc58199246f023 /klippy/stepper.py | |
| parent | cbdc54843d428ee66db2692cac4becd61887bf16 (diff) | |
| download | kutter-df6d3107f2b9948bc9dc28c4a1dd6a9ea9fda0fe.tar.gz kutter-df6d3107f2b9948bc9dc28c4a1dd6a9ea9fda0fe.tar.xz kutter-df6d3107f2b9948bc9dc28c4a1dd6a9ea9fda0fe.zip | |
stepper: Fix set_min_stop_interval() calculation
The previous calculation was only valid if the stepper is always
commanded to a position that is an exact multiple of the
step_distance. The safety check was programmed with a value too large
for other commanded positions, which could result in "No next step"
errors. Fix by changing the calculation to use the worst case
scenario.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
Diffstat (limited to 'klippy/stepper.py')
| -rw-r--r-- | klippy/stepper.py | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/klippy/stepper.py b/klippy/stepper.py index 6917afa9..32a17c2b 100644 --- a/klippy/stepper.py +++ b/klippy/stepper.py @@ -50,11 +50,17 @@ class PrinterStepper: self.position_endstop = config.getfloat('position_endstop') self.position_max = config.getfloat('position_max', 0.) self.need_motor_enable = True + def _dist_to_time(self, dist, start_velocity, accel): + # Calculate the time it takes to travel a distance with constant accel + time_offset = start_velocity / accel + return math.sqrt(2. * dist / accel + time_offset**2) - time_offset def set_max_jerk(self, max_halt_velocity, max_accel): - jc = max_halt_velocity / max_accel - inv_max_step_accel = self.step_dist / max_accel - min_stop_interval = (math.sqrt(3.*inv_max_step_accel + jc**2) - - math.sqrt(inv_max_step_accel + jc**2)) + # Calculate the firmware's maximum halt interval time + last_step_time = self._dist_to_time( + self.step_dist, max_halt_velocity, max_accel) + second_last_step_time = self._dist_to_time( + 2. * self.step_dist, max_halt_velocity, max_accel) + min_stop_interval = second_last_step_time - last_step_time self.mcu_stepper.set_min_stop_interval(min_stop_interval) def motor_enable(self, move_time, enable=0): if enable and self.need_motor_enable: |