About 3 dof robot arm control

Hi, I am designing a 3 DOF robot arm, and i have some questions,

  1. U2D2 POWER HUB can be supplied with a battery? what type of battery?
  2. If i want to use PD control with gravity compensation, apart from adjusting Kp Kd and Goal current, is there another option that Dynamixel offers to compensate for gravity?
  1. The Power Hub Board doesn’t come with any preinstalled battery connections. You can connect any power supply that you would like to use, including a battery through the onboard terminal block input, barrel jack, or two pin power connection.
  2. DYNAMIXEL servos do not feature any built in gravity compensation features.