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# Code for handling the kinematics of cartesian robots
#
# Copyright (C) 2016 Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import logging
import stepper, homing
StepList = (0, 1, 2)
class CartKinematics:
def __init__(self, printer, config):
steppers = ['stepper_x', 'stepper_y', 'stepper_z']
self.steppers = [stepper.PrinterStepper(printer, config.getsection(n))
for n in steppers]
self.limits = [(1.0, -1.0)] * 3
self.stepper_pos = [0, 0, 0]
def build_config(self):
for stepper in self.steppers[:2]:
stepper.set_max_jerk(0.005 * stepper.max_accel) # XXX
for stepper in self.steppers:
stepper.build_config()
def set_position(self, newpos):
self.stepper_pos = [int(newpos[i]*self.steppers[i].inv_step_dist + 0.5)
for i in StepList]
def get_max_speed(self):
max_xy_speed = min(s.max_velocity for s in self.steppers[:2])
max_xy_accel = min(s.max_accel for s in self.steppers[:2])
return max_xy_speed, max_xy_accel
def get_homed_position(self):
return [s.position_endstop + s.get_homed_offset()*s.step_dist
for s in self.steppers]
def home(self, toolhead, axes):
# Each axis is homed independently and in order
homing_state = homing.Homing(toolhead, axes)
for axis in axes:
s = self.steppers[axis]
self.limits[axis] = (s.position_min, s.position_max)
# Determine moves
if s.homing_positive_dir:
pos = s.position_endstop - 1.5*(
s.position_endstop - s.position_min)
rpos = s.position_endstop - s.homing_retract_dist
r2pos = rpos - s.homing_retract_dist
else:
pos = s.position_endstop + 1.5*(
s.position_max - s.position_endstop)
rpos = s.position_endstop + s.homing_retract_dist
r2pos = rpos + s.homing_retract_dist
# Initial homing
homepos = [None, None, None, None]
homepos[axis] = s.position_endstop
coord = [None, None, None, None]
coord[axis] = pos
homing_state.plan_home(list(coord), homepos, [s], s.homing_speed)
# Retract
coord[axis] = rpos
homing_state.plan_move(list(coord), s.homing_speed)
# Home again
coord[axis] = r2pos
homing_state.plan_home(list(coord), homepos, [s], s.homing_speed/2.0)
return homing_state
def motor_off(self, move_time):
self.limits = [(1.0, -1.0)] * 3
for stepper in self.steppers:
stepper.motor_enable(move_time, 0)
def query_endstops(self, move_time):
return homing.QueryEndstops(["x", "y", "z"], self.steppers)
def check_endstops(self, move):
end_pos = move.end_pos
for i in StepList:
if (move.axes_d[i]
and (end_pos[i] < self.limits[i][0]
or end_pos[i] > self.limits[i][1])):
if self.limits[i][0] > self.limits[i][1]:
raise homing.EndstopError(end_pos, "Must home axis first")
raise homing.EndstopError(end_pos)
def check_move(self, move):
limits = self.limits
xpos, ypos = move.end_pos[:2]
if (xpos < limits[0][0] or xpos > limits[0][1]
or ypos < limits[1][0] or ypos > limits[1][1]):
self.check_endstops(move)
if not move.axes_d[2]:
# Normal XY move - use defaults
return
# Move with Z - update velocity and accel for slower Z axis
self.check_endstops(move)
axes_d = move.axes_d
move_d = move.move_d
velocity_factor = min([self.steppers[i].max_velocity / abs(axes_d[i])
for i in StepList if axes_d[i]])
accel_factor = min([self.steppers[i].max_accel / abs(axes_d[i])
for i in StepList if axes_d[i]])
move.limit_speed(velocity_factor * move_d, accel_factor * move_d)
def move(self, move_time, move):
inv_accel = 1. / move.accel
inv_cruise_v = 1. / move.cruise_v
for i in StepList:
inv_step_dist = self.steppers[i].inv_step_dist
new_step_pos = int(move.end_pos[i]*inv_step_dist + 0.5)
step_pos = self.stepper_pos[i]
if new_step_pos == step_pos:
continue
self.stepper_pos[i] = new_step_pos
steps = move.axes_d[i] * inv_step_dist
step_offset = step_pos - move.start_pos[i] * inv_step_dist + 0.5
sdir = 0
if steps < 0:
sdir = 1
steps = -steps
step_offset = 1. - step_offset
mcu_time, so = self.steppers[i].prep_move(move_time, sdir)
move_step_d = move.move_d / steps
# Acceleration steps
#t = sqrt(2*pos/accel + (start_v/accel)**2) - start_v/accel
accel_time_offset = move.start_v * inv_accel
accel_sqrt_offset = accel_time_offset**2
accel_multiplier = 2.0 * move_step_d * inv_accel
accel_steps = move.accel_r * steps
step_offset = so.step_sqrt(
mcu_time - accel_time_offset, accel_steps, step_offset
, accel_sqrt_offset, accel_multiplier)
mcu_time += move.accel_t
# Cruising steps
#t = pos/cruise_v
cruise_multiplier = move_step_d * inv_cruise_v
cruise_steps = move.cruise_r * steps
step_offset = so.step_factor(
mcu_time, cruise_steps, step_offset, cruise_multiplier)
mcu_time += move.cruise_t
# Deceleration steps
#t = cruise_v/accel - sqrt((cruise_v/accel)**2 - 2*pos/accel)
decel_time_offset = move.cruise_v * inv_accel
decel_sqrt_offset = decel_time_offset**2
decel_steps = move.decel_r * steps
so.step_sqrt(
mcu_time + decel_time_offset, decel_steps, step_offset
, decel_sqrt_offset, -accel_multiplier)
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