An actuator that uses a PCA9685 controller to drive a servo.

This actuator derives its configuration from the joint constraints defined in the robot:

• Position limits from joint.limits.lower and joint.limits.upper
• Velocity limit from joint.limits.velocity
• PWM range maps linearly to the joint's position range

When a position command is received, the actuator:

1. Clamps the position to joint limits
2. Converts to PWM pulse width
3. Sends PWM command to the PCA9685 controller
4. Publishes a BB.Message.Actuator.BeginMotion for sensors to consume

Example DSL Usage

controller :pca9685, {BB.Servo.PCA9685.Controller, bus: "i2c-1", address: 0x40}

joint :shoulder, type: :revolute do
  limit lower: ~u(-45 degree), upper: ~u(45 degree), velocity: ~u(60 degree_per_second)

  actuator :servo, {BB.Servo.PCA9685.Actuator, channel: 0, controller: :pca9685}
  sensor :feedback, {BB.Sensor.OpenLoopPositionEstimator, actuator: :servo}
end