cartesian: Do acceleration and lookahead on requested coordinates

Perform all acceleration calculations and lookahead checks in
millimeters using the cartesian coordinate system of the request.  The
conversion to step coordinates is now done at the time of the step
timing creation.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/cartesian.py

@@ -13,48 +13,30 @@ import lookahead, stepper, homing
 StepList = (0, 1, 2, 3)
 
 class Move:
-    def __init__(self, kin, relsteps, speed):
+    def __init__(self, kin, pos, move_d, axes_d, speed, accel):
         self.kin = kin
-        self.relsteps = relsteps
+        self.pos = tuple(pos)
-        self.junction_max = self.junction_start_max = self.junction_delta = 0.
+        self.axes_d = axes_d
-        # Calculate requested distance to travel (in mm)
+        self.move_d = move_d
-        steppers = self.kin.steppers
+        self.junction_max = speed**2
-        absrelsteps = [abs(relsteps[i]) for i in StepList]
+        self.junction_delta = 2.0 * move_d * accel
-        stepper_d = [absrelsteps[i] * steppers[i].step_dist
+        self.junction_start_max = 0.
-                     for i in StepList]
-        self.move_d = math.sqrt(sum([d*d for d in stepper_d[:3]]))
-        if not self.move_d:
-            self.move_d = stepper_d[3]
-            if not self.move_d:
-                return
-        # Limit velocity to max for each stepper
-        velocity_factor = min([steppers[i].max_step_velocity / absrelsteps[i]
-                               for i in StepList if absrelsteps[i]])
-        move_v = min(speed, velocity_factor * self.move_d)
-        self.junction_max = move_v**2
-        # Find max acceleration factor
-        accel_factor = min([steppers[i].max_step_accel / absrelsteps[i]
-                            for i in StepList if absrelsteps[i]])
-        accel = min(self.kin.max_accel, accel_factor * self.move_d)
-        self.junction_delta = 2.0 * self.move_d * accel
     def calc_junction(self, prev_move):
         # Find max start junction velocity using approximated
         # centripetal velocity as described at:
         # https://onehossshay.wordpress.com/2011/09/24/improving_grbl_cornering_algorithm/
-        if not prev_move.move_d or self.relsteps[2] or prev_move.relsteps[2]:
+        if not prev_move.move_d:
             return
-        steppers = self.kin.steppers
+        junction_cos_theta = -((self.axes_d[0] * prev_move.axes_d[0]
-        junction_cos_theta = -sum([
+                                + self.axes_d[1] * prev_move.axes_d[1])
-            self.relsteps[i] * prev_move.relsteps[i] * steppers[i].step_dist**2
+                               / (self.move_d * prev_move.move_d))
-            for i in range(2)]) / (self.move_d * prev_move.move_d)
         if junction_cos_theta > 0.999999:
             return
         junction_cos_theta = max(junction_cos_theta, -0.999999)
         sin_theta_d2 = math.sqrt(0.5*(1.0-junction_cos_theta));
         R = self.kin.junction_deviation * sin_theta_d2 / (1.0 - sin_theta_d2)
-        accel = self.junction_delta / (2.0 * self.move_d)
         self.junction_start_max = min(
-            accel * R, self.junction_max, prev_move.junction_max)
+            R * self.kin.max_xy_accel, self.junction_max, prev_move.junction_max)
     def process(self, junction_start, junction_end):
         # Determine accel, cruise, and decel portions of the move
         junction_cruise = self.junction_max
@@ -84,9 +66,12 @@ class Move:
         # Calculate step times for the move
         next_move_time = self.kin.get_next_move_time()
         for i in StepList:
-            steps = self.relsteps[i]
+            new_step_pos = int(self.pos[i]*self.kin.steppers[i].inv_step_dist
+                               + 0.5)
+            steps = new_step_pos - self.kin.stepper_pos[i]
             if not steps:
                 continue
+            self.kin.stepper_pos[i] = new_step_pos
             sdir = 0
             if steps < 0:
                 sdir = 1
@@ -133,13 +118,15 @@ class CartKinematics:
         steppers = ['stepper_x', 'stepper_y', 'stepper_z', 'stepper_e']
         self.steppers = [stepper.PrinterStepper(printer, config.getsection(n))
                          for n in steppers]
-        self.max_accel = min(s.max_step_accel*s.step_dist
+        self.max_xy_speed = min(s.max_step_velocity*s.step_dist
-                             for s in self.steppers[:2]) # XXX
+                                for s in self.steppers[:2])
-        dummy_move = Move(self, [0]*len(self.steppers), 0.)
+        self.max_xy_accel = min(s.max_step_accel*s.step_dist
-        dummy_move.junction_max = 0.
+                                for s in self.steppers[:2])
         self.junction_deviation = config.getfloat('junction_deviation', 0.02)
+        dummy_move = Move(self, [0.]*4, 0., [0.]*4, 0., 0.)
         self.move_queue = lookahead.MoveQueue(dummy_move)
-        self.pos = [0, 0, 0, 0]
+        self.commanded_pos = [0., 0., 0., 0.]
+        self.stepper_pos = [0, 0, 0, 0]
         # Print time tracking
         self.buffer_time_high = config.getfloat('buffer_time_high', 5.000)
         self.buffer_time_low = config.getfloat('buffer_time_low', 0.150)
@@ -214,24 +201,50 @@ class CartKinematics:
             self.print_time, buffer_time, self.print_time_stall)
     # Movement commands
     def get_position(self):
-        return [self.pos[i] * self.steppers[i].step_dist
+        return list(self.commanded_pos)
-                for i in StepList]
     def set_position(self, newpos):
-        self.pos = [int(newpos[i]*self.steppers[i].inv_step_dist + 0.5)
+        self.move_queue.flush()
-                    for i in StepList]
+        self.commanded_pos[:] = newpos
+        self.stepper_pos = [int(newpos[i]*self.steppers[i].inv_step_dist + 0.5)
+                            for i in StepList]
+    def _move_with_z(self, newpos, axes_d, speed):
+        self.move_queue.flush()
+        # Limit velocity to max for each stepper
+        move_d = math.sqrt(sum([d*d for d in axes_d[:3]]))
+        velocity_factor = min(
+            [self.steppers[i].max_step_velocity
+             * self.steppers[i].step_dist / abs(axes_d[i])
+             for i in StepList if axes_d[i]])
+        speed = min(speed, self.max_xy_speed, velocity_factor * move_d)
+        # Find max acceleration factor
+        accel_factor = min(
+            [self.steppers[i].max_step_accel
+             * self.steppers[i].step_dist / abs(axes_d[i])
+             for i in StepList if axes_d[i]])
+        accel = min(self.max_xy_accel, accel_factor * move_d)
+        move = Move(self, newpos, move_d, axes_d, speed, accel)
+        move.process(0., 0.)
+    def _move_only_e(self, newpos, axes_d, speed):
+        self.move_queue.flush()
+        s = self.steppers[3]
+        speed = min(speed, self.max_xy_speed, s.max_step_velocity * s.step_dist)
+        accel = min(self.max_xy_accel, s.max_step_accel * s.step_dist)
+        move = Move(self, newpos, abs(axes_d[3]), axes_d, speed, accel)
+        move.process(0., 0.)
     def move(self, newpos, speed, sloppy=False):
-        # Round to closest step position
+        axes_d = [newpos[i] - self.commanded_pos[i] for i in StepList]
-        newpos = [int(newpos[i]*self.steppers[i].inv_step_dist + 0.5)
+        self.commanded_pos[:] = newpos
-                  for i in StepList]
+        if axes_d[2]:
-        relsteps = [newpos[i] - self.pos[i] for i in StepList]
+            self._move_with_z(newpos, axes_d, speed)
-        self.pos = newpos
-        if relsteps == [0]*len(newpos):
-            # no move
             return
-        #logging.debug("; dist %s @ %d\n" % (
+        move_d = math.sqrt(axes_d[0]**2 + axes_d[1]**2)
-        #    [newpos[i]*self.steppers[i].step_dist for i in StepList], speed))
+        if not move_d:
-        # Create move and queue it
+            if axes_d[3]:
-        move = Move(self, relsteps, speed)
+                self._move_only_e(newpos, axes_d, speed)
+            return
+        # Common xy move - create move and queue it
+        speed = min(speed, self.max_xy_speed)
+        move = Move(self, newpos, move_d, axes_d, speed, self.max_xy_accel)
         move.calc_junction(self.move_queue.prev_move())
         self.move_queue.add_move(move)
     def home(self, axis):