Hexapod · Field Manual

GOAL: ALL 6 LEGS ASSEMBLED, MOUNTED, WIRED; ROBOT STANDS ON ITS OWN. · 3 EVENINGS · DAY 6–8

01 · Safety prerequisites

▸470 µF – 1000 µF electrolytic across V+ / GND at each PCA9685

Servo current spikes are vicious. Place close to the board.

▲Tie ESP32 GND to servo-rail GND

Separate grounds cause random PWM glitches. This has confused many people. Tie them at the buck GND.

02 · What you need from Shop

03 · Tasks

T12Print parts + install heat-set inserts· depends T1

Acceptance:All STL parts printed cleanly; M3 brass inserts seated flush at every screw boss; parts grouped by leg.

T13Assemble one leg + verify range· depends T11, T12

Acceptance:Leg holds neutral stance under code; IK lands the foot within 5 mm of the commanded XYZ target.

T14Assemble remaining 5 legs· depends T13

Acceptance:All 6 legs hold a symmetric neutral pose when bus.centerAll() is called.

T15Mount legs, PCA9685s, route wiring· depends T14

Acceptance:Tidy, labelled wiring; nothing crosses a moving joint; visual inspection passes for all 18 servo leads.

T16First standing pose· depends T15

Acceptance:Robot stands on its own under bus.centerAll() with no leg slipping or buckling.

Calibration steps

STEP 1
Mount-angle convention
Leg 0 = right-front, going clockwise viewed from above. Mount angles: 60°, 0°, -60°, -120°, 180°, 120°. If you mount them in a different order, every IK target needs to be rotated.
STEP 2
One leg fully right before moving on
Don't bulk-build all six legs hoping calibration will sort itself later. Build leg 0, verify IK lands the foot within 5 mm, then replicate. Catches print/servo issues early.

Reference docs

Phase 3 — Mechanical build.