MARS 7-DOF Manipulator for Mobile Platforms
MARS (Modular Anthropomorphic Robotic System) is a commercially available 7 degree-of-freedom (7-DOF) robotic manipulator specifically designed to be easily integrated into mobile or static robotic systems. This Modular Anthropomorphic Robotic System (MARS) manipulator gains its modularity aspect by integrating the control and power electronics within each arm joint, thus allowing the arm to be quickly mounted to a robotic fixture with only two electrical connections (power and communication). Thus, other than a computer (e.g., a laptop) to communicate with the arm and coordinate joint motion, no additional external control box is necessary, reducing overall system volume requirements.
MARS is derived from NASA's space-qualified Robonaut arm design. In an effort to reduce cost and improve maintainability, several key features have been changed from Robonaut's arm design. The primary differences between the two are that our MARS arm substitutes the high dexterity hand with two additional degrees of freedom (wrist pitch and roll) and provides a mating adapter to accommodate commercial end effectors, such as BarrettHand BH8-262. Additionally, Robonaut's costly force and torque sensors are replaced with control software equivalents that limit motor current and position error associated with excessive loads and obstacle collisions.
In its fully extended position, MARS reaches 114cm, excluding end effector, and has a full-reach payload of 10kg, which is half of its 20kg mass. Consuming as little as 10W with all of the joint brakes engaged and motor amplifiers disabled, the entire arm typically consumes less than 250W during normal movement and loading. All joints except the wrist roll have fail-safe brakes, allowing position to be maintained without consuming power by driving the motor continuously. Communication occurs through a 3-wire RS485 connector, with an additional RS232 interface routed through the arm directly to the end effector. The computer interface allows for arm homing and both joint-space and Cartesian space control. Complete specifications for the MARS manipulator can be found in the MARS specs.pdf document and dimensions can be found in the engineering drawing.