BB.Servo.Robotis (bb_servo_robotis v0.3.0)

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Beam Bots integration for Robotis/Dynamixel servos.

This library provides controller, actuator, and sensor modules for integrating Dynamixel servos with the Beam Bots robotics framework. It uses the robotis hex package for low-level serial communication.

Features

  • Closed-loop position feedback: Unlike PWM servos, Dynamixel servos report their actual position, enabling true closed-loop control.
  • Multiple servos on one bus: All servos share a single serial connection through the controller.
  • Safety integration: Torque is automatically disabled when the robot is disarmed or crashes.

Supported Servos

Currently supports XM430 series servos (W210, W350) via the U2D2 USB adapter. The library uses Protocol 2.0.

Example Usage

defmodule MyRobot do
  use BB

  controller :dynamixel, {BB.Servo.Robotis.Controller,
    port: "/dev/ttyUSB0",
    baud_rate: 1_000_000,
    control_table: Robotis.ControlTable.XM430
  }

  topology do
    link :base do
      joint :shoulder, type: :revolute do
        limit lower: ~u(-90 degree), upper: ~u(90 degree), velocity: ~u(60 degree_per_second)

        actuator :servo, {BB.Servo.Robotis.Actuator,
          servo_id: 1,
          controller: :dynamixel
        }

        sensor :position, {BB.Servo.Robotis.Sensor,
          servo_id: 1,
          controller: :dynamixel,
          poll_interval_ms: 20
        }
      end
    end
  end
end

Modules