Robotic arm

connector

Rotating Electrical Connector

• http://www.swivelelectricalconnector.com/rotating_electrical_connectors/swivel_electrical_connector_best.php
• http://aksr.co.kr/tech/images/faq04.jpg

Mechanic

• "swivel" http://www.bestmarineimports.com/Connectors.html

products

• http://www.army-technology.com/contractor_images/i_robot/i_robot3.jpg
• http://larryo.org/work/robotics/robotics_hardware.html