2026: OpenSCAD robot and remote, physical joint limits, model in Unity

hardware/openscad/ rebuilds the broken Fusion models as OpenSCAD:
body (top/bottom plate, standoffs, battery bay, switch), legs (coxa
bracket, femur link, tibia, horn adapters, TPU socks, servo cables),
the whole robot, and the remote (shell, lid, Nextion 3.5", JH-D400X-R4
sticks, 18650 UPS board, IMU, Teensy 4.0, USB-C breakout). Every part
was checked by slicing against the original STEP solids; the original's
bugs are fixed and listed in PLANNING.md.

The robot now uses a hexagon leg layout (corner legs 60 deg round from
the mid legs; the corner coxa brackets need turning on their splines).
Physical limits from a collision sweep of the model are in Config.h:
per-leg coxa limits and LEG_CLEARANCE_MM 56 (a leg is 55.2 mm wide at
the joints); the sim API exports them (version 7). sim_smoke passes.

Unity loads the model (export_unity.py -> Resources/OpenScadModel,
OpenScadModel.cs builds a new rig in place of the old scene's robot).
The PCB model's mounting holes now use the exact EasyEDA grid. README
shows renders of both.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-current/robot/Config.h

@@ -9,12 +9,19 @@
 // ---- Leg geometry ----
 // Taken from the Unity model (Hexapod_Simulation_Unity/Assets/Main.unity,
 // 1 Unity unit = 10 mm): hip pivots at x = +-10 / 0, z = +-5 / +-6.5;
-// coxa 5.5, femur 10, tibia 15. BENCH: confirm against the real chassis.
+// coxa 5.5, femur 10, tibia 15. Confirmed exactly against the real
+// chassis's CAD (hardware/openscad, from the Fusion model): coxa axes at
+// these mounts, coxa 55 / femur 100 / tibia 150 mm to the centre of the
+// 10 mm foot ball. The femur and knee axes lie in the coxa pivot plane
+// (Z = 0), 13.5 mm above the bottom plate's top face.
 constexpr int NUM_LEGS = 6;
 // Leg order: 0=front-right, 1=mid-right, 2=rear-right, 3=rear-left, 4=mid-left, 5=front-left
 // Angles measured counterclockwise from the body's +X (forward) axis, viewed from above.
-// This is the direction the coxa points at servo center: straight sideways on this chassis.
-constexpr float LEG_MOUNT_ANGLE_DEG[NUM_LEGS] = { -90, -90, -90,  90,  90,  90 };
+// This is the direction the coxa points at servo center. Hexagon layout (owner's
+// request): mid legs straight sideways, front/rear legs 60 deg further round, so
+// all six are 60 deg apart. BENCH: the corner coxa brackets sit 60 deg round on
+// their servo splines (4 teeth of 24) compared with the old sideways layout.
+constexpr float LEG_MOUNT_ANGLE_DEG[NUM_LEGS] = { -30, -90, -150, 150, 90, 30 };
 constexpr float LEG_MOUNT_X_MM[NUM_LEGS]      = { 100,   0, -100, -100,  0, 100 };
 constexpr float LEG_MOUNT_Y_MM[NUM_LEGS]      = { -50, -65,  -50,   50,  65,  50 };
 
@@ -23,7 +30,19 @@ constexpr float FEMUR_LEN_MM = 100.0f;
 constexpr float TIBIA_LEN_MM = 150.0f;
 
 // ---- Joint limits, degrees ----
-constexpr float COXA_MIN_DEG  = -60,  COXA_MAX_DEG  = 60;
+// Physical limits from the OpenSCAD model (hardware/openscad, collision
+// sweep of the real parts, see PLANNING.md "Physical limits"), and servo
+// travel (+-90 coxa/femur, -180..0 tibia):
+//   coxa  mid legs          -66.5 .. 66.5   coxa bracket shell hits the plate
+//   coxa  0 front-right, 3 rear-left   -95.75 .. 66.75 (servo: -90)
+//   coxa  2 rear-right, 5 front-left   -66.75 .. 95.75 (servo: 90)
+//   femur                  -101 .. 101   femur link hits the coxa bracket (servo: 90)
+//   tibia                  -177 .. 12.75 rod folds into the femur link / shell hits it (servo: 0)
+// The limits below keep ~3 deg from those and the earlier software limits
+// where those are tighter. Per leg, because the corner legs' ranges differ (in
+// the old sideways layout they could only swing ~36 deg towards the mid leg).
+constexpr float COXA_MIN_DEG[NUM_LEGS] = { -60, -60, -60, -60, -60, -60 };
+constexpr float COXA_MAX_DEG[NUM_LEGS] = {  60,  60,  60,  60,  60,  60 };
 constexpr float FEMUR_MIN_DEG = -80,  FEMUR_MAX_DEG = 80;
 constexpr float TIBIA_MIN_DEG = -150, TIBIA_MAX_DEG = -20;
 
@@ -41,8 +60,10 @@ constexpr float STANCE_HEIGHT_RATE_MM_S = 60.0f;
 // ---- Leg collision ----
 // Minimum distance between the center lines of neighbouring legs' segments
 // (coxa, femur, tibia). Gait strides and body poses are scaled down to keep
-// it. BENCH: set to roughly the width of a leg (servo body + bracket).
-constexpr float LEG_CLEARANCE_MM = 30.0f;
+// it. From the OpenSCAD model: at the joints a leg reaches 33.7 mm to its
+// horn side (rear) and 21.5 mm to its bearing side (front), so two
+// neighbours touch at 55.2 mm between center lines.
+constexpr float LEG_CLEARANCE_MM = 56.0f;
 
 // ---- Servos (Teensy 3.6, hardware PWM at SERVO_PWM_HZ) ----
 // One entry per servo: pulse = us_at_0deg + us_per_deg * joint_deg, clamped

2026-current/robot/Kinematics.cpp

@@ -51,7 +51,7 @@ JointAngles Kinematics::solve(int i, const FootTarget& target) {
   out.femur_deg = degrees(femur_rad);
   out.tibia_deg = degrees(tibia_rad);
 
-  if (out.coxa_deg  < COXA_MIN_DEG  || out.coxa_deg  > COXA_MAX_DEG)  out.valid = false;
+  if (out.coxa_deg  < COXA_MIN_DEG[i] || out.coxa_deg  > COXA_MAX_DEG[i]) out.valid = false;
   if (out.femur_deg < FEMUR_MIN_DEG || out.femur_deg > FEMUR_MAX_DEG) out.valid = false;
   if (out.tibia_deg < TIBIA_MIN_DEG || out.tibia_deg > TIBIA_MAX_DEG) out.valid = false;