Controller Area Network (CAN)

A two-wire field bus linking multiple motors and sensors together, the standard way robot joints talk to their controller.

CAN is a serial communication bus Bosch designed for cars in the 1980s: a single pair of differential wires links multiple nodes together, giving strong noise immunity and simple wiring, with priority arbitration and error detection built into every frame. Classic CAN tops out at 1 Mbit/s with up to 8 data bytes per frame; CAN FD (CAN with Flexible Data-Rate) is the later upgrade, with a faster data phase and up to 64 bytes per frame. In robots, large numbers of joint motors, dexterous hands, and battery management systems all communicate over CAN or CAN FD, with a host computer sending and receiving commands through a USB-CAN adapter or Linux's SocketCAN. Its bandwidth is limited, so systems with many joints or high control frequencies are often split across multiple bus lines, or switched to EtherCAT instead.

ExampleJoint motors like Damiao's and Xiaomi's CyberGear receive MIT-mode position, velocity, stiffness, damping, and feedforward-torque commands over CAN.

Also called

CAN FD (CAN with Flexible Data-Rate), CAN Bus

Related

EtherCAT (Ethernet for Control Automation Technology) · RS-485 · SocketCAN · CANopen / CiA 402 Drive Profile · Servo Drive (Motor Driver) · MIT Mode

Sources

Wikipedia: CAN bus
Wikipedia: CAN FD