166 lines
7.8 KiB
Python
166 lines
7.8 KiB
Python
# Code for handling the kinematics of linear delta robots
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#
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# Copyright (C) 2016-2018 Kevin O'Connor <kevin@koconnor.net>
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#
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# This file may be distributed under the terms of the GNU GPLv3 license.
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import math, logging
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import stepper, homing, mathutil
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# Slow moves once the ratio of tower to XY movement exceeds SLOW_RATIO
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SLOW_RATIO = 3.
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class DeltaKinematics:
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def __init__(self, toolhead, config):
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# Setup tower rails
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stepper_configs = [config.getsection('stepper_' + a) for a in 'abc']
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rail_a = stepper.PrinterRail(
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stepper_configs[0], need_position_minmax = False)
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a_endstop = rail_a.get_homing_info().position_endstop
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rail_b = stepper.PrinterRail(
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stepper_configs[1], need_position_minmax = False,
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default_position_endstop=a_endstop)
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rail_c = stepper.PrinterRail(
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stepper_configs[2], need_position_minmax = False,
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default_position_endstop=a_endstop)
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self.rails = [rail_a, rail_b, rail_c]
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# Setup stepper max halt velocity
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self.max_velocity, self.max_accel = toolhead.get_max_velocity()
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self.max_z_velocity = config.getfloat(
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'max_z_velocity', self.max_velocity,
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above=0., maxval=self.max_velocity)
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max_halt_velocity = toolhead.get_max_axis_halt() * SLOW_RATIO
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max_halt_accel = self.max_accel * SLOW_RATIO
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for rail in self.rails:
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rail.set_max_jerk(max_halt_velocity, max_halt_accel)
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# Read radius and arm lengths
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self.radius = radius = config.getfloat('delta_radius', above=0.)
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arm_length_a = stepper_configs[0].getfloat('arm_length', above=radius)
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self.arm_lengths = arm_lengths = [
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sconfig.getfloat('arm_length', arm_length_a, above=radius)
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for sconfig in stepper_configs]
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self.arm2 = [arm**2 for arm in arm_lengths]
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self.abs_endstops = [(rail.get_homing_info().position_endstop
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+ math.sqrt(arm2 - radius**2))
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for rail, arm2 in zip(self.rails, self.arm2)]
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# Determine tower locations in cartesian space
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self.angles = [sconfig.getfloat('angle', angle)
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for sconfig, angle in zip(stepper_configs,
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[210., 330., 90.])]
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self.towers = [(math.cos(math.radians(angle)) * radius,
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math.sin(math.radians(angle)) * radius)
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for angle in self.angles]
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for r, a, t in zip(self.rails, self.arm2, self.towers):
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r.setup_itersolve('delta_stepper_alloc', a, t[0], t[1])
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# Setup boundary checks
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self.need_motor_enable = self.need_home = True
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self.limit_xy2 = -1.
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self.home_position = tuple(
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self._actuator_to_cartesian(self.abs_endstops))
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self.max_z = min([rail.get_homing_info().position_endstop
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for rail in self.rails])
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self.min_z = config.getfloat('minimum_z_position', 0, maxval=self.max_z)
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self.limit_z = min([ep - arm
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for ep, arm in zip(self.abs_endstops, arm_lengths)])
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logging.info(
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"Delta max build height %.2fmm (radius tapered above %.2fmm)" % (
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self.max_z, self.limit_z))
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# Find the point where an XY move could result in excessive
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# tower movement
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half_min_step_dist = min([r.get_steppers()[0].get_step_dist()
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for r in self.rails]) * .5
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min_arm_length = min(arm_lengths)
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def ratio_to_dist(ratio):
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return (ratio * math.sqrt(min_arm_length**2 / (ratio**2 + 1.)
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- half_min_step_dist**2)
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+ half_min_step_dist)
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self.slow_xy2 = (ratio_to_dist(SLOW_RATIO) - radius)**2
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self.very_slow_xy2 = (ratio_to_dist(2. * SLOW_RATIO) - radius)**2
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self.max_xy2 = min(radius, min_arm_length - radius,
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ratio_to_dist(4. * SLOW_RATIO) - radius)**2
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logging.info("Delta max build radius %.2fmm (moves slowed past %.2fmm"
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" and %.2fmm)" % (
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math.sqrt(self.max_xy2), math.sqrt(self.slow_xy2),
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math.sqrt(self.very_slow_xy2)))
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self.set_position([0., 0., 0.], ())
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def get_steppers(self, flags=""):
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return [s for rail in self.rails for s in rail.get_steppers()]
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def _actuator_to_cartesian(self, spos):
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sphere_coords = [(t[0], t[1], sp) for t, sp in zip(self.towers, spos)]
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return mathutil.trilateration(sphere_coords, self.arm2)
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def calc_position(self):
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spos = [rail.get_commanded_position() for rail in self.rails]
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return self._actuator_to_cartesian(spos)
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def set_position(self, newpos, homing_axes):
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for rail in self.rails:
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rail.set_position(newpos)
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self.limit_xy2 = -1.
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if tuple(homing_axes) == (0, 1, 2):
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self.need_home = False
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def home(self, homing_state):
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# All axes are homed simultaneously
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homing_state.set_axes([0, 1, 2])
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forcepos = list(self.home_position)
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forcepos[2] = -1.5 * math.sqrt(max(self.arm2)-self.max_xy2)
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homing_state.home_rails(self.rails, forcepos, self.home_position,
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limit_speed=self.max_z_velocity)
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def motor_off(self, print_time):
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self.limit_xy2 = -1.
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for rail in self.rails:
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rail.motor_enable(print_time, 0)
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self.need_motor_enable = self.need_home = True
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def _check_motor_enable(self, print_time):
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for rail in self.rails:
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rail.motor_enable(print_time, 1)
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self.need_motor_enable = False
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def check_move(self, move):
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end_pos = move.end_pos
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end_xy2 = end_pos[0]**2 + end_pos[1]**2
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if end_xy2 <= self.limit_xy2 and not move.axes_d[2]:
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# Normal XY move
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return
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if self.need_home:
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raise homing.EndstopMoveError(end_pos, "Must home first")
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end_z = end_pos[2]
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limit_xy2 = self.max_xy2
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if end_z > self.limit_z:
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limit_xy2 = min(limit_xy2, (self.max_z - end_z)**2)
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if end_xy2 > limit_xy2 or end_z > self.max_z or end_z < self.min_z:
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# Move out of range - verify not a homing move
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if (end_pos[:2] != self.home_position[:2]
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or end_z < self.min_z or end_z > self.home_position[2]):
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raise homing.EndstopMoveError(end_pos)
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if move.axes_d[2]:
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move.limit_speed(self.max_z_velocity, move.accel)
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limit_xy2 = -1.
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# Limit the speed/accel of this move if is is at the extreme
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# end of the build envelope
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extreme_xy2 = max(end_xy2, move.start_pos[0]**2 + move.start_pos[1]**2)
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if extreme_xy2 > self.slow_xy2:
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r = 0.5
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if extreme_xy2 > self.very_slow_xy2:
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r = 0.25
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max_velocity = self.max_velocity
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if move.axes_d[2]:
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max_velocity = self.max_z_velocity
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move.limit_speed(max_velocity * r, self.max_accel * r)
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limit_xy2 = -1.
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self.limit_xy2 = min(limit_xy2, self.slow_xy2)
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def move(self, print_time, move):
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if self.need_motor_enable:
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self._check_motor_enable(print_time)
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for rail in self.rails:
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rail.step_itersolve(move.cmove)
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# Helper function for DELTA_CALIBRATE script
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def get_calibrate_params(self):
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out = { 'radius': self.radius }
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for i, axis in enumerate('abc'):
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rail = self.rails[i]
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out['angle_'+axis] = self.angles[i]
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out['arm_'+axis] = self.arm_lengths[i]
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out['endstop_'+axis] = rail.get_homing_info().position_endstop
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out['stepdist_'+axis] = rail.get_steppers()[0].get_step_dist()
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return out
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def load_kinematics(toolhead, config):
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return DeltaKinematics(toolhead, config)
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