Electrical

The Compute Module comprises two connected stacks: the Head Compute Unit in the head and the Robot Processing Unit (RPU) in the torso.

The head stack contains three boards. The Head Board sits at the base, the Raspberry Pi 5 mounts above it on standoffs, and the Media HAT Board mounts on the Pi 5 header. The Media HAT Board provides the buzzer and helps prevent brownouts on the Pi 5.

The Head Compute Unit is the electronics stack, not the entire mechanical head assembly. Its camera, mounts, covers, and neck hardware are identified separately in the build instructions.

The torso stack also contains three boards. The Radxa CM5 mounts on the Radxa Carrier Board, forming the Motion Control Board (MCB). The Power Distribution Board (PDB) then fits above the Carrier Board. Together, the MCB and PDB form the Robot Processing Unit (RPU).

The CM5 handles high-frequency, low-latency workloads, including locomotion, actuator control, and IMU feedback. The Carrier Board provides the interfaces for communication with all 25 actuators. The PDB distributes power to connected hardware.

A 1000 mm Ethernet cable links the Pi 5 to the Carrier Board. A separate 1000 mm XT30-Male to XT30-Female power cable connects the PDB to the Head Board. The Head Compute Unit and RPU work together while remaining in separate locations on the robot.

Keeping media, external networking, and application services on the Pi 5 separates those workloads from the CM5's time-sensitive control loop.

The published system specification identifies five CAN interfaces at 1 Mbps and one at 500 kbps. The actuator network distributes battery power and CAN communication from the body outward through six physical branches.

Each actuator has two electrically equivalent XT30 (2+2) ports. Each port carries BATT+, BATT-, CAN_H, and CAN_L, allowing power and communication to continue from one actuator to the next.

There is no fixed electrical input or output port. Use the port and orientation shown in the applicable assembly step so the cable follows the intended mechanical path.

The six branches enter the body at left hip pitch, right hip pitch, waist yaw, left shoulder pitch, right shoulder pitch, and neck yaw. Within each branch, actuators form a chain from the central body toward the distal joint.

At each branch entry, CAN_H and CAN_L route toward the RPU while BATT+ and BATT- route toward the robot power bus.

For example, each leg follows:

This topology keeps the number of body-entry connections small while allowing each limb to carry power and CAN through the same connector system.

The Raspberry Pi 5 is the currently supported edge computer for camera, audio, networking, and edge services. Other Raspberry Pi models are not validated for Asimov 1.

The current pack design is a 13-series, 4-parallel lithium-ion battery.

The pack includes a protection circuit module for over-charge, over-discharge, and over-current protection.