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feat: UWB anchor mount bracket (Issue #564)

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sl-mechanical 2026-03-14 11:51:40 -04:00
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chassis/uwb_anchor_mount.scad
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// ============================================================
// uwb_anchor_mount.scad — Stem-Mounted UWB Anchor Rev A
// Agent: sl-mechanical 2026-03-01
// Closes issues #57, #62
// uwb_anchor_mount.scad — Wall/Ceiling UWB Anchor Mount Bracket
// Issue: #564 Agent: sl-mechanical Date: 2026-03-14
// (supersedes Rev A stem-collar mount — see git history)
// ============================================================
// Clamp-on bracket for 2× MaUWB ESP32-S3 anchor modules on
// SaltyBot 25 mm OD vertical stem.
// Anchors spaced ANCHOR_SPACING = 250 mm apart.
//
// Features:
// • Split D-collar with M4 clamping bolts + M4 set screw
// • Anti-rotation flat tab that keys against a small pin
// OR printed key tab that registers on the stem flat (if stem
// has a ground flat) — see ANTI_ROT_MODE parameter
// • Module bracket: faces outward, tilted 10° from vertical
// so antenna clears stem and faces horizon
// • USB cable channel (power from Orin via USB-A) on collar
// • Tool-free capture: M4 thumbscrews (slot-head, hand-tighten)
// • UWB antenna area: NO material within 10 mm of PCB top face
// Parametric wall or ceiling mount bracket for ESP32 UWB Pro anchor.
// Designed for fixed-infrastructure deployment: anchors screw into
// wall or ceiling drywall/timber with standard M4 or #6 wood screws,
// at a user-defined tilt angle so the UWB antenna faces the desired
// coverage zone.
//
// Components per mount:
// 2× collar_half print in PLA/PETG, flat-face-down
// 1× module_bracket print in PLA/PETG, flat-face-down
// Architecture:
// Wall base -> flat backplate with 2x screw holes (wall or ceiling)
// Tilt knuckle -> single-axis articulating joint; 15deg detent steps
// locked with M3 nyloc bolt; range 0-90deg
// Anchor cradle-> U-cradle holding ESP32 UWB Pro PCB on M2.5 standoffs
// USB-C channel-> routed groove on tilt arm + exit slot in cradle back wall
// Label slot -> rear window slot for printed anchor-ID card strip
//
// Part catalogue:
// Part 1 -- wall_base() Backplate + 2-ear pivot block + detent arc
// Part 2 -- tilt_arm() Pivoting arm with knuckle + cradle stub
// Part 3 -- anchor_cradle() PCB cradle, standoffs, USB-C slot, label window
// Part 4 -- cable_clip() Snap-on USB-C cable guide for tilt arm
// Part 5 -- assembly_preview()
//
// Hardware BOM:
// 2x M4 x 30mm wood screws (or #6 drywall screws) wall fasteners
// 1x M3 x 20mm SHCS + M3 nyloc nut tilt pivot bolt
// 4x M2.5 x 8mm SHCS PCB-to-cradle
// 4x M2.5 hex nuts captured in standoffs
// 1x USB-C cable anchor power
//
// ESP32 UWB Pro interface (verify with calipers):
// PCB size : UWB_L x UWB_W x UWB_H (55 x 28 x 10 mm default)
// Mounting holes : M2.5, 4x corners on UWB_HOLE_X x UWB_HOLE_Y pattern
// USB-C port : centred on short edge, UWB_USBC_W x UWB_USBC_H
// Antenna area : top face rear half -- 10mm keep-out of bracket material
//
// Tilt angles (15deg detent steps, set TILT_DEG before export):
// 0deg -> horizontal face-up (ceiling, antenna faces down)
// 30deg -> 30deg downward tilt (wall near ceiling) [default]
// 45deg -> diagonal (wall mid-height)
// 90deg -> vertical face-out (wall, antenna faces forward)
//
// RENDER options:
// "assembly" single mount assembled (default)
// "collar_front" front collar half for slicing (×2 per mount × 2 mounts = 4)
// "collar_rear" rear collar half
// "bracket" module bracket (×2 mounts)
// "pair" both mounts on 350 mm stem section
// "assembly" full assembly at TILT_DEG (default)
// "wall_base_stl" Part 1
// "tilt_arm_stl" Part 2
// "anchor_cradle_stl" Part 3
// "cable_clip_stl" Part 4
//
// Export commands:
// openscad uwb_anchor_mount.scad -D 'RENDER="wall_base_stl"' -o uwb_wall_base.stl
// openscad uwb_anchor_mount.scad -D 'RENDER="tilt_arm_stl"' -o uwb_tilt_arm.stl
// openscad uwb_anchor_mount.scad -D 'RENDER="anchor_cradle_stl"' -o uwb_anchor_cradle.stl
// openscad uwb_anchor_mount.scad -D 'RENDER="cable_clip_stl"' -o uwb_cable_clip.stl
// ============================================================
$fn = 64;
e = 0.01;
// -- Tilt angle (override per anchor, 0-90deg, 15deg steps) ------------------
TILT_DEG = 30;
// -- ESP32 UWB Pro PCB dimensions (verify with calipers) ---------------------
UWB_L = 55.0;
UWB_W = 28.0;
UWB_H = 10.0;
UWB_HOLE_X = 47.5;
UWB_HOLE_Y = 21.0;
UWB_USBC_W = 9.5;
UWB_USBC_H = 4.0;
UWB_ANTENNA_L = 20.0;
// -- Wall base geometry -------------------------------------------------------
BASE_W = 60.0;
BASE_H = 50.0;
BASE_T = 5.0;
BASE_SCREW_D = 4.5;
BASE_SCREW_HD = 8.5;
BASE_SCREW_HH = 3.5;
BASE_SCREW_SPC = 35.0;
KNUCKLE_T = BASE_T + 4.0;
// -- Tilt arm geometry --------------------------------------------------------
ARM_W = 12.0;
ARM_T = 5.0;
ARM_L = 35.0;
PIVOT_D = 3.3;
PIVOT_NUT_AF = 5.5;
PIVOT_NUT_H = 2.4;
DETENT_D = 3.2;
DETENT_R = 8.0;
// -- Anchor cradle geometry ---------------------------------------------------
CRADLE_WALL_T = 3.5;
CRADLE_BACK_T = 4.0;
CRADLE_FLOOR_T = 3.0;
CRADLE_LIP_H = 4.0;
CRADLE_LIP_T = 2.5;
STANDOFF_H = 3.0;
STANDOFF_OD = 5.5;
LABEL_W = UWB_L - 4.0;
LABEL_H = UWB_W * 0.55;
LABEL_T = 1.2;
// -- USB-C routing ------------------------------------------------------------
USBC_CHAN_W = 11.0;
USBC_CHAN_H = 7.0;
// -- Cable clip ---------------------------------------------------------------
CLIP_CABLE_D = 4.5;
CLIP_T = 2.0;
CLIP_BODY_W = 16.0;
CLIP_BODY_H = 10.0;
// -- Fasteners ----------------------------------------------------------------
M2P5_D = 2.7;
M3_D = 3.3;
M3_NUT_AF = 5.5;
M3_NUT_H = 2.4;
// ============================================================
// RENDER DISPATCH
// ============================================================
RENDER = "assembly";
// ── ⚠ Verify with calipers ───────────────────────────────────
MAWB_L = 50.0; // PCB length
MAWB_W = 25.0; // PCB width
MAWB_H = 10.0; // PCB + components
MAWB_HOLE_X = 43.0; // M2 mounting hole X span
MAWB_HOLE_Y = 20.0; // M2 mounting hole Y span
M2_D = 2.2; // M2 clearance
if (RENDER == "assembly") assembly_preview();
else if (RENDER == "wall_base_stl") wall_base();
else if (RENDER == "tilt_arm_stl") tilt_arm();
else if (RENDER == "anchor_cradle_stl") anchor_cradle();
else if (RENDER == "cable_clip_stl") cable_clip();
// ── Stem ─────────────────────────────────────────────────────
STEM_OD = 25.0;
STEM_BORE = 25.4; // +0.4 clearance
WALL = 2.0; // wall thickness (used in thumbscrew recess)
// ============================================================
// ASSEMBLY PREVIEW
// ============================================================
module assembly_preview() {
%color("Wheat", 0.22)
translate([-BASE_W/2, -10, -BASE_H/2])
cube([BASE_W, 10, BASE_H + 40]);
color("OliveDrab", 0.85) wall_base();
color("SteelBlue", 0.85)
translate([0, KNUCKLE_T, 0]) rotate([TILT_DEG,0,0]) tilt_arm();
color("DarkSlateGray", 0.85)
translate([0, KNUCKLE_T, 0]) rotate([TILT_DEG,0,0])
translate([0, ARM_T, ARM_L]) anchor_cradle();
%color("ForestGreen", 0.38)
translate([0, KNUCKLE_T, 0]) rotate([TILT_DEG,0,0])
translate([-UWB_L/2, ARM_T+CRADLE_BACK_T,
ARM_L+CRADLE_FLOOR_T+STANDOFF_H])
cube([UWB_L, UWB_W, UWB_H]);
color("DimGray", 0.70)
translate([ARM_W/2, KNUCKLE_T, 0]) rotate([TILT_DEG,0,0])
translate([0, ARM_T+e, ARM_L/2]) rotate([0,-90,90]) cable_clip();
}
// ── Collar ───────────────────────────────────────────────────
COL_OD = 52.0;
COL_H = 30.0; // taller than sensor-head collar for rigidity
COL_BOLT_X = 19.0; // M4 bolt CL from stem axis
COL_BOLT_D = 4.5; // M4 clearance
THUMB_HEAD_D= 8.0; // M4 thumbscrew head OD (slot for access)
COL_NUT_W = 7.0; // M4 hex nut A/F
COL_NUT_H = 3.4;
// Anti-rotation flat tab: a 3 mm wall tab that protrudes radially
// and bears against the bracket arm, preventing axial rotation
// without needing a stem flat.
ANTI_ROT_T = 3.0; // tab thickness (radial)
ANTI_ROT_W = 8.0; // tab width (tangential)
ANTI_ROT_Z = 4.0; // distance from collar base
// USB cable channel: groove on collar outer surface, runs Z direction
// Cable routes from anchor module down to base
USB_CHAN_W = 9.0; // channel width (fits USB-A cable Ø6 mm)
USB_CHAN_D = 5.0; // channel depth
// ── Module bracket ───────────────────────────────────────────
ARM_L = 20.0; // arm length from collar OD to bracket face
ARM_W = MAWB_W + 6.0; // bracket width (Y, includes side walls)
ARM_H = 6.0; // arm thickness (Z)
BRKT_TILT = 10.0; // tilt outward from vertical (antenna faces horizon)
BRKT_BACK_T = 3.0; // bracket back wall (module sits against this)
BRKT_SIDE_T = 2.0; // bracket side walls
M2_STNDFF = 3.0; // M2 standoff height
M2_STNDFF_OD= 4.5;
// USB port access notch in bracket side wall (8×5 mm)
USB_NOTCH_W = 10.0;
USB_NOTCH_H = 7.0;
// ── Spacing ───────────────────────────────────────────────────
ANCHOR_SPACING = 250.0; // centre-to-centre Z separation
$fn = 64;
e = 0.01;
// ─────────────────────────────────────────────────────────────
// collar_half(side)
// split at Y=0 plane. Bracket arm on front (+Y) half.
// Print flat-face-down.
// ─────────────────────────────────────────────────────────────
module collar_half(side = "front") {
y_front = (side == "front");
// ============================================================
// PART 1 -- WALL BASE
// ============================================================
// Flat backplate, 2x countersunk M4/#6 wood screws on 35mm centres.
// Two pivot ears straddle the tilt arm; M3 pivot bolt through both.
// Detent arc on +X ear inner face: 7 notches at 15deg steps (0-90deg).
// Shallow rear recess for installation-zone label strip.
// Same part for wall mount and ceiling mount.
//
// Print: backplate flat on bed, PETG, 5 perims, 40% gyroid.
module wall_base() {
ear_h = ARM_W + 3.0;
ear_t = 6.0;
ear_sep = ARM_W + 1.0;
difference() {
union() {
// D-shaped body
intersection() {
cylinder(d=COL_OD, h=COL_H);
translate([-COL_OD/2, y_front ? 0 : -COL_OD/2, 0])
cube([COL_OD, COL_OD/2, COL_H]);
}
// Anti-rotation tab (front half only, at +X side)
if (y_front) {
translate([COL_OD/2, -ANTI_ROT_W/2, ANTI_ROT_Z])
cube([ANTI_ROT_T, ANTI_ROT_W,
COL_H - ANTI_ROT_Z - 4]);
}
// Bracket arm attachment boss (front half only, top centre)
if (y_front) {
translate([-ARM_W/2, COL_OD/2, COL_H * 0.3])
cube([ARM_W, ARM_L, COL_H * 0.4]);
}
translate([-BASE_W/2, -BASE_T, -BASE_H/2])
cube([BASE_W, BASE_T, BASE_H]);
for (ex = [-(ear_sep/2 + ear_t), ear_sep/2])
translate([ex, -BASE_T+e, -ear_h/2])
cube([ear_t, KNUCKLE_T+e, ear_h]);
for (ex = [-(ear_sep/2 + ear_t), ear_sep/2])
hull() {
translate([ex, -BASE_T, -ear_h/4])
cube([ear_t, BASE_T-1, ear_h/2]);
translate([ex + (ex<0 ? ear_t*0.5 : 0), -BASE_T, -ear_h/6])
cube([ear_t*0.5, 1, ear_h/3]);
}
}
// ── Stem bore ─────────────────────────────────────────
translate([0,0,-e])
cylinder(d=STEM_BORE, h=COL_H + 2*e);
// ── M4 clamping bolt holes (Y direction) ──────────────
for (bx=[-COL_BOLT_X, COL_BOLT_X]) {
translate([bx, y_front ? COL_OD/2 : 0, COL_H/2])
rotate([90,0,0])
cylinder(d=COL_BOLT_D, h=COL_OD/2 + e);
// Thumbscrew head recess on outer face (front only — access side)
if (y_front) {
translate([bx, COL_OD/2 - WALL, COL_H/2])
rotate([90,0,0])
cylinder(d=THUMB_HEAD_D, h=8 + e);
}
}
// ── M4 hex nut pockets (rear half) ────────────────────
if (!y_front) {
for (bx=[-COL_BOLT_X, COL_BOLT_X]) {
translate([bx, -(COL_OD/4 + e), COL_H/2])
rotate([90,0,0])
cylinder(d=COL_NUT_W/cos(30), h=COL_NUT_H + e,
$fn=6);
}
}
// ── Set screw (height lock, front half) ───────────────
if (y_front) {
translate([0, COL_OD/2, COL_H * 0.8])
rotate([90,0,0])
cylinder(d=COL_BOLT_D,
h=COL_OD/2 - STEM_BORE/2 + e);
}
// ── USB cable routing channel (rear half, −X side) ────
if (!y_front) {
translate([-COL_OD/2, -USB_CHAN_W/2, -e])
cube([USB_CHAN_D, USB_CHAN_W, COL_H + 2*e]);
}
// ── M4 hole through arm boss (Z direction, for bracket bolt) ─
if (y_front) {
for (dx=[-ARM_W/4, ARM_W/4])
translate([dx, COL_OD/2 + ARM_L/2, COL_H * 0.35])
cylinder(d=COL_BOLT_D, h=COL_H * 0.35 + e);
for (sz = [-BASE_SCREW_SPC/2, BASE_SCREW_SPC/2]) {
translate([0, -BASE_T-e, sz]) rotate([-90,0,0])
cylinder(d=BASE_SCREW_D, h=BASE_T+2*e);
translate([0, -BASE_T-e, sz]) rotate([-90,0,0])
cylinder(d1=BASE_SCREW_HD, d2=BASE_SCREW_D, h=BASE_SCREW_HH+e);
}
translate([-(ear_sep/2+ear_t+e), KNUCKLE_T*0.55, 0])
rotate([0,90,0]) cylinder(d=PIVOT_D, h=ear_sep+2*ear_t+2*e);
translate([ear_sep/2+ear_t-PIVOT_NUT_H-0.4, KNUCKLE_T*0.55, 0])
rotate([0,90,0])
cylinder(d=PIVOT_NUT_AF/cos(30), h=PIVOT_NUT_H+0.5, $fn=6);
for (da = [0 : 15 : 90])
translate([ear_sep/2-e,
KNUCKLE_T*0.55 + DETENT_R*sin(da),
DETENT_R*cos(da)])
rotate([0,90,0]) cylinder(d=DETENT_D, h=ear_t*0.45+e);
translate([0, -BASE_T-e, 0]) rotate([-90,0,0])
cube([BASE_W-12, BASE_H-16, 1.6], center=true);
translate([0, -BASE_T+1.5, 0])
cube([BASE_W-14, BASE_T-3, BASE_H-20], center=true);
}
}
// ─────────────────────────────────────────────────────────────
// module_bracket()
// Bolts to collar arm boss. Holds MaUWB PCB facing outward.
// Tilted BRKT_TILT° from vertical — antenna clears stem.
// Print flat-face-down (back wall on bed).
// ─────────────────────────────────────────────────────────────
module module_bracket() {
bk = BRKT_BACK_T;
sd = BRKT_SIDE_T;
// ============================================================
// PART 2 -- TILT ARM
// ============================================================
// Pivoting arm linking wall_base ears to anchor_cradle.
// Knuckle (Z=0): M3 pivot bore + spring-plunger detent pocket (3mm).
// Cradle end (Z=ARM_L): 2x M3 bolt attachment stub.
// USB-C cable channel groove on outer +Y face, full arm length.
//
// Print: knuckle face flat on bed, PETG, 5 perims, 40% gyroid.
module tilt_arm() {
total_h = ARM_L + 10;
difference() {
union() {
translate([-ARM_W/2, 0, 0]) cube([ARM_W, ARM_T, total_h]);
translate([0, ARM_T/2, 0]) rotate([90,0,0])
cylinder(d=ARM_W, h=ARM_T, center=true);
translate([-ARM_W/2, 0, ARM_L])
cube([ARM_W, ARM_T+CRADLE_BACK_T, ARM_T]);
}
translate([-ARM_W/2-e, ARM_T/2, 0]) rotate([0,90,0])
cylinder(d=PIVOT_D, h=ARM_W+2*e);
translate([0, ARM_T+e, 0]) rotate([90,0,0])
cylinder(d=3.2, h=4+e);
translate([-USBC_CHAN_W/2, ARM_T-e, ARM_T+4])
cube([USBC_CHAN_W, USBC_CHAN_H, ARM_L-ARM_T-8]);
for (bx = [-ARM_W/4, ARM_W/4])
translate([bx, ARM_T/2, ARM_L+ARM_T/2]) rotate([90,0,0])
cylinder(d=M3_D, h=ARM_T+CRADLE_BACK_T+2*e);
for (bx = [-ARM_W/4, ARM_W/4])
translate([bx, ARM_T/2, ARM_L+ARM_T/2]) rotate([-90,0,0])
cylinder(d=M3_NUT_AF/cos(30), h=M3_NUT_H+0.5, $fn=6);
translate([0, ARM_T/2, ARM_L/2])
cube([ARM_W-4, ARM_T-2, ARM_L-18], center=true);
}
}
// ============================================================
// PART 3 -- ANCHOR CRADLE
// ============================================================
// Open-front U-cradle for ESP32 UWB Pro PCB.
// 4x M2.5 standoffs on UWB_HOLE_X x UWB_HOLE_Y pattern.
// Back wall: USB-C exit slot + routing groove, label card slot,
// antenna keep-out cutout (material removed above antenna area).
// Front retaining lip prevents PCB sliding out.
// Two attachment tabs bolt to tilt_arm cradle stub via M3.
//
// Label card slot: insert paper/laminate strip to ID this anchor
// (e.g. "UWB-A3 NE-CORNER"), accessible from open cradle end.
//
// Print: back wall flat on bed, PETG, 5 perims, 40% gyroid.
module anchor_cradle() {
outer_l = UWB_L + 2*CRADLE_WALL_T;
outer_w = UWB_W + CRADLE_FLOOR_T;
pcb_z = CRADLE_FLOOR_T + STANDOFF_H;
total_z = pcb_z + UWB_H + 2;
difference() {
union() {
// ── Back wall (mounts to collar arm boss) ─────────
cube([ARM_W, bk, MAWB_H + M2_STNDFF + 6]);
// ── Side walls ────────────────────────────────────
for (sx=[0, ARM_W - sd])
translate([sx, bk, 0])
cube([sd, MAWB_L + 2, MAWB_H + M2_STNDFF + 6]);
// ── M2 standoff posts (PCB mounts to these) ───────
for (hx=[0, MAWB_HOLE_X], hy=[0, MAWB_HOLE_Y])
translate([(ARM_W - MAWB_HOLE_X)/2 + hx,
bk + (MAWB_L - MAWB_HOLE_Y)/2 + hy,
0])
cylinder(d=M2_STNDFF_OD, h=M2_STNDFF);
translate([-outer_l/2, 0, 0]) cube([outer_l, outer_w, total_z]);
translate([-outer_l/2, outer_w-CRADLE_LIP_T, 0])
cube([outer_l, CRADLE_LIP_T, CRADLE_LIP_H]);
for (tx = [-ARM_W/4, ARM_W/4])
translate([tx-4, -CRADLE_BACK_T, 0])
cube([8, CRADLE_BACK_T+1, total_z]);
}
translate([-UWB_L/2, 0, pcb_z]) cube([UWB_L, UWB_W+1, UWB_H+4]);
translate([0, -CRADLE_BACK_T-e, pcb_z+UWB_H/2-UWB_USBC_H/2])
cube([UWB_USBC_W+2, CRADLE_BACK_T+2*e, UWB_USBC_H+2],
center=[true,false,false]);
translate([0, -CRADLE_BACK_T-e, -e])
cube([USBC_CHAN_W, USBC_CHAN_H, pcb_z+UWB_H/2+USBC_CHAN_H],
center=[true,false,false]);
translate([0, -CRADLE_BACK_T-e, pcb_z+UWB_H/2])
cube([LABEL_W, LABEL_T+0.3, LABEL_H], center=[true,false,false]);
translate([0, -e, pcb_z+UWB_H-UWB_ANTENNA_L])
cube([UWB_L-4, CRADLE_BACK_T+2*e, UWB_ANTENNA_L+4],
center=[true,false,false]);
for (tx = [-ARM_W/4, ARM_W/4])
translate([tx, ARM_T/2-CRADLE_BACK_T, total_z/2])
rotate([-90,0,0])
cylinder(d=M3_D, h=ARM_T+CRADLE_BACK_T+2*e);
for (side_x = [-outer_l/2-e, outer_l/2-CRADLE_WALL_T-e])
translate([side_x, 2, pcb_z+2])
cube([CRADLE_WALL_T+2*e, UWB_W-4, UWB_H-4]);
}
for (hx = [-UWB_HOLE_X/2, UWB_HOLE_X/2])
for (hy = [(outer_w-UWB_W)/2 + (UWB_W-UWB_HOLE_Y)/2,
(outer_w-UWB_W)/2 + (UWB_W-UWB_HOLE_Y)/2 + UWB_HOLE_Y])
difference() {
translate([hx, hy, CRADLE_FLOOR_T-e])
cylinder(d=STANDOFF_OD, h=STANDOFF_H+e);
translate([hx, hy, CRADLE_FLOOR_T-2*e])
cylinder(d=M2P5_D, h=STANDOFF_H+4);
}
}
// ── M2 bores through standoffs ────────────────────────
for (hx=[0, MAWB_HOLE_X], hy=[0, MAWB_HOLE_Y])
translate([(ARM_W - MAWB_HOLE_X)/2 + hx,
bk + (MAWB_L - MAWB_HOLE_Y)/2 + hy,
-e])
cylinder(d=M2_D, h=M2_STNDFF + e);
// ── Antenna clearance cutout in back wall ─────────────
// Open slot near top of back wall so antenna is unobstructed
translate([sd, -e, M2_STNDFF + 2])
cube([ARM_W - 2*sd, bk + 2*e, MAWB_H]);
// ── USB port access notch on one side wall ────────────
translate([-e, bk + 2, M2_STNDFF - 1])
cube([sd + 2*e, USB_NOTCH_W, USB_NOTCH_H]);
// ── Mounting holes to collar arm boss (×2) ────────────
for (dx=[-ARM_W/4, ARM_W/4])
translate([ARM_W/2 + dx, bk + ARM_L/2, -e])
cylinder(d=COL_BOLT_D, h=6 + e);
// ============================================================
// PART 4 -- CABLE CLIP
// ============================================================
// Snap-on C-clip retaining USB-C cable along tilt arm outer face.
// Presses onto ARM_T-wide arm with flexible PETG snap tongues.
// Print x2-3 per anchor, spaced 25mm along arm.
//
// Print: clip-opening face down, PETG, 3 perims, 20% infill.
module cable_clip() {
ch_r = CLIP_CABLE_D/2 + CLIP_T;
snap_t = 1.6;
difference() {
union() {
translate([-CLIP_BODY_W/2, 0, 0])
cube([CLIP_BODY_W, CLIP_T, CLIP_BODY_H]);
translate([0, CLIP_T+ch_r, CLIP_BODY_H/2]) rotate([0,90,0])
difference() {
cylinder(r=ch_r, h=CLIP_BODY_W, center=true);
cylinder(r=CLIP_CABLE_D/2, h=CLIP_BODY_W+2*e, center=true);
translate([0, ch_r+e, 0])
cube([CLIP_CABLE_D*0.85, ch_r*2+2*e, CLIP_BODY_W+2*e],
center=true);
}
for (tx = [-CLIP_BODY_W/2+1.5, CLIP_BODY_W/2-1.5-snap_t])
translate([tx, -ARM_T-1, 0])
cube([snap_t, ARM_T+1+CLIP_T, CLIP_BODY_H]);
for (tx = [-CLIP_BODY_W/2+1.5, CLIP_BODY_W/2-1.5-snap_t])
translate([tx+snap_t/2, -ARM_T-1, CLIP_BODY_H/2])
rotate([0,90,0]) cylinder(d=2, h=snap_t, center=true);
}
translate([0, -ARM_T-1-e, CLIP_BODY_H/2])
cube([CLIP_BODY_W-6, ARM_T+2, CLIP_BODY_H-4], center=true);
}
}
// ─────────────────────────────────────────────────────────────
// single_anchor_assembly()
// ─────────────────────────────────────────────────────────────
module single_anchor_assembly(show_phantom=false) {
// Collar
color("SteelBlue", 0.9) collar_half("front");
color("CornflowerBlue", 0.9) mirror([0,1,0]) collar_half("rear");
// Bracket tilted BRKT_TILT° outward from top of arm boss
color("LightSteelBlue", 0.85)
translate([0, COL_OD/2 + ARM_L, COL_H * 0.3])
rotate([BRKT_TILT, 0, 0])
translate([-ARM_W/2, 0, 0])
module_bracket();
// Phantom UWB PCB
if (show_phantom)
color("ForestGreen", 0.4)
translate([-MAWB_L/2,
COL_OD/2 + ARM_L + BRKT_BACK_T,
COL_H * 0.3 + M2_STNDFF])
cube([MAWB_L, MAWB_W, MAWB_H]);
}
// ─────────────────────────────────────────────────────────────
// Render selector
// ─────────────────────────────────────────────────────────────
if (RENDER == "assembly") {
single_anchor_assembly(show_phantom=true);
} else if (RENDER == "collar_front") {
collar_half("front");
} else if (RENDER == "collar_rear") {
collar_half("rear");
} else if (RENDER == "bracket") {
module_bracket();
} else if (RENDER == "pair") {
// Both anchors at 250 mm spacing on a stem stub
color("Silver", 0.2)
translate([0, 0, -50])
cylinder(d=STEM_OD, h=ANCHOR_SPACING + COL_H + 100);
// Lower anchor (Z = 0)
single_anchor_assembly(show_phantom=true);
// Upper anchor (Z = ANCHOR_SPACING)
translate([0, 0, ANCHOR_SPACING])
single_anchor_assembly(show_phantom=true);
}

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"""
Unit tests for saltybot_uwb_position.uwb_position_node (Issue #546).
No ROS2 or hardware required — tests the covariance math only.
"""
import math
import sys
import os
# Make the package importable without a ROS2 install
sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))
# ── Covariance helper (extracted from node for unit testing) ──────────────────
def polar_to_cartesian_cov(bearing_rad, range_m, sigma_r, sigma_theta):
"""Compute 2×2 Cartesian covariance from polar uncertainty."""
cos_b = math.cos(bearing_rad)
sin_b = math.sin(bearing_rad)
j00 = cos_b; j01 = -range_m * sin_b
j10 = sin_b; j11 = range_m * cos_b
sr2 = sigma_r * sigma_r
st2 = sigma_theta * sigma_theta
cov_xx = j00 * j00 * sr2 + j01 * j01 * st2
cov_xy = j00 * j10 * sr2 + j01 * j11 * st2
cov_yy = j10 * j10 * sr2 + j11 * j11 * st2
return cov_xx, cov_xy, cov_yy
# ── Tests ─────────────────────────────────────────────────────────────────────
class TestPolarToCartesianCovariance:
def test_forward_bearing_zero(self):
"""At bearing=0 (directly ahead) covariance aligns with axes."""
cov_xx, cov_xy, cov_yy = polar_to_cartesian_cov(
bearing_rad=0.0, range_m=5.0, sigma_r=0.10, sigma_theta=0.087
)
assert cov_xx > 0
assert cov_yy > 0
# At bearing=0: cov_xx = σ_r², cov_yy = (r·σ_θ)², cov_xy ≈ 0
assert abs(cov_xx - 0.10 ** 2) < 1e-9
assert abs(cov_xy) < 1e-9
expected_yy = (5.0 * 0.087) ** 2
assert abs(cov_yy - expected_yy) < 1e-6
def test_sideways_bearing(self):
"""At bearing=90° covariance axes swap."""
sigma_r = 0.10
sigma_theta = 0.10
r = 3.0
cov_xx, cov_xy, cov_yy = polar_to_cartesian_cov(
bearing_rad=math.pi / 2, range_m=r,
sigma_r=sigma_r, sigma_theta=sigma_theta
)
# At bearing=90°: cov_xx = (r·σ_θ)², cov_yy = σ_r²
assert abs(cov_xx - (r * sigma_theta) ** 2) < 1e-9
assert abs(cov_yy - sigma_r ** 2) < 1e-9
def test_covariance_positive_definite(self):
"""Matrix must be positive semi-definite (det ≥ 0, diag > 0)."""
for bearing in [0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0]:
for r in [1.0, 5.0, 10.0]:
cov_xx, cov_xy, cov_yy = polar_to_cartesian_cov(
bearing, r, sigma_r=0.10, sigma_theta=0.087
)
assert cov_xx > 0
assert cov_yy > 0
det = cov_xx * cov_yy - cov_xy ** 2
assert det >= -1e-12, f"Non-PSD at bearing={bearing}, r={r}: det={det}"
def test_inflation_single_anchor(self):
"""Covariance doubles (variance ×4) when only one anchor active."""
sigma_r = 0.10
sigma_theta = 0.087
bearing = 0.5
r = 4.0
cov_xx_full, _, _ = polar_to_cartesian_cov(bearing, r, sigma_r, sigma_theta)
cov_xx_half, _, _ = polar_to_cartesian_cov(
bearing, r,
sigma_r * math.sqrt(4.0),
sigma_theta * math.sqrt(4.0),
)
assert abs(cov_xx_half / cov_xx_full - 4.0) < 1e-9
if __name__ == "__main__":
import pytest
pytest.main([__file__, "-v"])