Dual-Armed Robot Making In-Roads

Robots moved a step closer to human dexterity here this week, as engineers demonstrated a small industrial robot with two arms, two hands and opposable thumbs.

Known as the SDA5D, the robot surprised passerby at the Automate 2011 Show by lifting spherical objects, such as a baseball bat, bottle and football from a nearby table. Engineers said that the dual-armed robot, introduced last year, is starting to make in-roads in industrial applications ranging from automated assembly and distribution to logistics and palletizing.

"People are finding their own opportunities to use dual-armed robots," noted Erik Nieves, technology director for the Motoman Robotics Division of Yaskawa America Inc. "They have an intuitive sense of what these robots can do because they can identify with the idea of having two arms."

Nieves said that the SDA5D's "bigger brother," introduced three years ago and known as the SDA10D, is beginning to be employed in automotive assembly plants and for de-gating operations in plastics manufacturing. It's also being used by the National Aeronautics and Space Administration (NASA) for space simulation operations.

Motoman engineers believe that the concept of a two-armed robot is important for factory automation and assembly. Industrial robots, which are celebrating their fiftieth year in existence in 2011, have long used single-arm designs. Problem is, single-arm robots can't do some simple operations, such as lifting and manipulating non-rigid objects and grabbing odd-shaped boxes.

"Robots are already prevalent in any operation that you can do with one hand," Nieves said. "But if you're going to grow your area of application into assembly, you need to endow the robot with the same kind of dexterity that a human operator has."       

Nieves said that Motoman succeeded in bringing dual-armed operation to robots because its engineers found a way to eliminate the traditional motor shaft from the servo mechanisms that move robotic arms. By doing so, they endowed the new robot arm with seven axes of movement, which in turn enabled the two arms to work without interfering with one another.

"Instead of having traditional servo motor construction, we got rid of the motor shaft," Nieves said. "That opened it up for the flexibility that's needed for seven-axis construction."

Motoman then supplemented that flexibility by incorporating an adaptive gripper from Robotiq on the ends of the SDA5D's arms. The gripper is considered a significant addition to the dual-armed concept because it adds two fingers and an opposable thumb to each robotic arm. Each gripper employs one motor in each finger and in the opposable thumb, and incorporates a fourth motor that helps position the fingers and thumb in relation to one another. By having fingers and a thumb, the robot is able to lift long baskets of parts and odd-shaped components. (See a video of the robot and grippers in action.)

Nieves said he expects that robot's dexterity and human-like qualities to make in-roads in a broad new array of industrial applications. "People have these wonderfully agile end effectors, called hands, on the ends of each arm," he said. "But even so, there are a lot of tasks that require two arms to do."