PHASE 1

Power and wiring

Sense Head. Two rails. E-stop kills actuators. Common ground by design.

                    WALL AC
                       |
              +--------+--------+
              |                 |
         [12V brick]       [USB-C / PD
              |             for Jetson/Pi]
              |                 |
              v                 v
         SERVO_RAIL          LOGIC_RAIL
              |                 |
         [eFuse/fuse]      [Jetson / Pi]
              |                 |
         [E-STOP NC]--+    USB hub / cams
              |       |    IMU · mic · speaker
              v       |
         [servo bus]  |
         pan + tilt   |
                      |
              (LED "ACTUATORS ARMED")

   GND_LOGIC ----+---- GND_SERVO   (star point)

Principles

  1. Logic and actuator rails stay separate.
  2. E-stop cuts servo power or enable. Not software-only.
  3. Star ground near supplies.
  4. Size the 12V supply for servo motion spikes.

Common failures

SymptomCauseFix
Reboots when servos moveBrown-outSeparate rails; bigger servo PSU
Servo jitterBad ground / noiseStar ground; bulk cap on servo rail
E-stop "works" but motion continuesSoftware-only stopRewire the cut path
Camera dropoutsUSB power/cablePowered hub; shorter cable