Add flight controller

Signed-off-by: Arnaud Morin <arnaud.gfpv@mailops.fr>

AGENT.md

@@ -115,6 +115,8 @@ from the stack — don't hand-patch them.
 .venv/bin/python3 spar.py
 .venv/bin/python3 camera_mount.py    # printed accessory, not a frame body
 .venv/bin/python3 standoff.py        # turned hardware, in the assembly
+.venv/bin/python3 lollipop.py        # printed antenna holder
+.venv/bin/python3 fc.py              # bought electronics, an envelope only
 .venv/bin/python3 frame.py           # assembly, BOM, exports, renders
 ```
 

README.md

@@ -76,13 +76,17 @@ trust the run over this copy of it.
 | spar | 4 | 2 mm | carbon fibre | 1.19 | 4.76 |
 | camera_mount | 1 | printed | TPU | 7.87 | 7.87 |
 | standoff | 4 | Ø3.5 mm | aluminium | 0.39 | 1.56 |
-| lollipop | 1 | printed | TPU | 1.15 | 1.15 |
+| lollipop | 1 | printed | TPU | 2.12 | 2.12 |
-| **frame** | **24** | | | | **33.05** |
+| fc | 1 | bought | electronics | 12.09 | 12.09 |
+| **frame** | **25** | | | | **46.11** |
 
-Carbon at 1.55 g/cm³, TPU at 1.21, aluminium at 2.70.
+Carbon at 1.55 g/cm³, TPU at 1.21, aluminium at 2.70. The `fc` is not a part
+you make — it is the envelope of a flight controller and 4-in-1 ESC stack,
+modelled as a solid block of FR4 at 1.85 g/cm³ so the all-up figure is honest.
+Swap in your own stack's real mass if you know it.
 
 **Not counted, and not modelled:** screws, motors, props, camera, VTX,
-receiver, flight controller. The standoffs are the only hardware in the model.
+receiver. The standoffs and the FC stack are the hardware the model carries.
 
 ### Hardware you supply
 

build.sh

@@ -27,7 +27,7 @@ run() { uv run --no-sync python "$@"; }
 
 # Each part asserts it came out as one solid at import time, so a part that
 # broke stops the build here rather than quietly exporting a bad STL.
-for part in plate arm motor_base spar camera_mount standoff lollipop; do
+for part in plate arm motor_base spar camera_mount standoff lollipop fc; do
     run "$part.py"
 done
 

fc.py

@@ -0,0 +1,83 @@
+# @author Arnaud Morin <arnaud.gfpv@mailops.fr>
+# SPDX-License-Identifier: Apache-2.0
+#
+
+import cadquery as cq
+
+# A flight controller is not a material, it is a stack: two boards, their
+# spacers, and everything soldered to them.  This models only the envelope, as
+# one solid, so the density is FR4's -- bare PCB -- and the dense parts (FETs,
+# inductors, connectors) stand in for the air between the boards.  It lands the
+# block at about 12 g, which is what a real 25.5 mm FC plus 4-in-1 ESC weighs.
+PCB_DENSITY = 1.85e-3    # g/mm3, FR4
+
+
+def fc():
+
+    box = (cq.Workplane("XY")
+           .box(33, 33, 8, centered=(True, True, True))
+           .edges('Z')
+           .fillet(5)
+           )
+
+    # Remove extra for standoff
+    cut = (cq.Workplane("XY")
+           .pushPoints([
+               (25.5/2, 25.5/2),
+               (25.5/2, -25.5/2),
+               (-25.5/2, 25.5/2),
+               (-25.5/2, -25.5/2),
+           ])
+           .circle(7)
+           .extrude(5)
+           .translate((0,0,1.6/2))
+           )
+    box = box.cut(cut).cut(cut.mirror("XY"))
+
+    # Standoff
+    sta = (cq.Workplane("XY")
+           .pushPoints([
+               (25.5/2, 25.5/2),
+               (25.5/2, -25.5/2),
+               (-25.5/2, 25.5/2),
+               (-25.5/2, -25.5/2),
+           ])
+           .circle(2.5)
+           .extrude(5, both=True)
+           .translate((0,0,-2))
+           )
+    box = box.union(sta)
+
+    # holes in standoff
+    cut = (cq.Workplane("XY")
+           .pushPoints([
+               (25.5/2, 25.5/2),
+               (25.5/2, -25.5/2),
+               (-25.5/2, 25.5/2),
+               (-25.5/2, -25.5/2),
+           ])
+           .circle(1.2)
+           .extrude(10, both=True)
+           )
+    box = box.cut(cut)
+
+    # Make Z 0
+    box = box.translate((0,0,7))
+    return box
+
+
+result = fc()
+
+assert result.solids().size() == 1, "fc is not one solid"
+
+if "show_object" not in globals():          # running outside CQ-editor
+    def show_object(*args, **kwargs):
+        pass
+
+show_object(result)
+
+
+if __name__ == "__main__":
+
+    print("fc   %.2f g" % (result.val().Volume() * PCB_DENSITY))
+

frame.py

@@ -16,6 +16,7 @@ from camera_mount import result as CAMERA_MOUNT
 import standoff as SO
 from standoff import result as STANDOFF
 from lollipop import result as LOLLIPOP
+from fc import result as FC, PCB_DENSITY
 
 OUT = "build"
 
@@ -28,10 +29,9 @@ COLORS = {
     "spar":         cq.Color(0.22, 0.62, 0.35),   # green
     "camera_mount": cq.Color(0.95, 0.78, 0.09),   # yellow TPU
     "standoff":     cq.Color(0.75, 0.76, 0.78),   # aluminium
-    "lollipop":     cq.Color(0.95, 0.78, 0.09),   # yellow TPU, as the mount
+    "lollipop":     cq.Color(0.95, 0.78, 0.09),   # yellow TPU
+    "fc":           cq.Color(0.42, 0.28, 0.62),   # PCB purple
     "prop":         cq.Color(0.55, 0.55, 0.60),   # opaque: a ring hides
-                                                  # nothing, so there is no
-                                                  # call for transparency
 }
 
 DENSITY = {
@@ -40,6 +40,7 @@ DENSITY = {
     "camera_mount": TPU_DENSITY,
     "standoff": SO.ALU_DENSITY,
     "lollipop": TPU_DENSITY,
+    "fc": PCB_DENSITY,
 }
 
 # --- propellers -------------------------------------------------------------
@@ -77,6 +78,7 @@ PARTS = [
     ("camera_mount", CAMERA_MOUNT, P.THICKNESS,   "solid"),
     ("standoff",     STANDOFF,     SO.OD,        "solid"),
     ("lollipop",     LOLLIPOP,     3.5,          "solid"),
+    ("fc",           FC,           11.0,         "solid"),
 ]
 
 
@@ -90,9 +92,9 @@ def _loc(x, y, z, rot_z, flip=0.0):
 
 
 def pieces():
-    """[(name, tag, solid, Location)] -- the 19 bodies, straight off the
+    """[(name, tag, solid, Location)] -- the 25 bodies, straight off the
-    placement helpers: 2 plates, 4 arms, 8 motor bases, 4 spars, 1 camera
+    placement helpers: 2 plates, 4 arms, 8 motor bases, 4 spars, 4 standoffs,
-    mount."""
+    1 camera mount, 1 antenna holder, 1 fc stack."""
     out = []
     for i, (x, y, z, rz) in enumerate(P.plate_placements()):
         out.append(("plate", "plate_%s" % ("bottom", "top")[i],
@@ -121,6 +123,14 @@ def pieces():
     # height that clears both plates.
     out.append(("lollipop", "lollipop_0", LOLLIPOP,
                 _loc(0.0, -22.0, 7.0, 90.0)))
+    # fc: the stack stands on the bottom plate's top face, over the 25.5 square
+    # the plate is drilled for.  fc.py puts its own origin at the underside of
+    # its posts, so that face is the whole placement.  The 45 deg is not
+    # cosmetic: fc.py sets its posts on the diagonals at (+-12.75, +-12.75),
+    # while the plate drills the same 25.5 square with its holes on the axes at
+    # 25.5/sqrt(2) = 18.03.  Same radius, turned an eighth of a turn, so without
+    # this the screws miss.
+    out.append(("fc", "fc_0", FC, _loc(0.0, 0.0, P.THICKNESS, 45.0)))
     return out
 
 
@@ -175,11 +185,13 @@ def bom(ps):
         print("  %-12s %4d  %6.1f  %9.3f  %9.3f"
               % (name, qty, thick, each, each * qty))
     print("  %-12s %4d  %6s  %9s  %9.3f" % ("FRAME", len(ps), "", "", total))
-    print("  carbon at %.2f g/cm3, TPU camera_mount at %.2f g/cm3,"
+    print("  carbon at %.2f g/cm3, TPU parts at %.2f g/cm3, aluminium"
-          " aluminium standoffs at %.2f g/cm3;"
+          " standoffs at %.2f g/cm3," % (P.CF_DENSITY * 1e3, TPU_DENSITY * 1e3,
-          % (P.CF_DENSITY * 1e3, TPU_DENSITY * 1e3, SO.ALU_DENSITY * 1e3))
+                                         SO.ALU_DENSITY * 1e3))
-    print("  the standoffs are the only hardware counted -- no screws, motors"
+    print("  fc as a solid block of FR4 at %.2f g/cm3 -- an envelope, not a"
-          " or electronics")
+          " board" % (PCB_DENSITY * 1e3,))
+    print("  hardware counted is the standoffs and the fc stack -- no screws,"
+          " motors, props or receiver")
     return total