Machine Design

Small Servocontrollers to Support “Friendlier” Industrial Robots

Barrett Technology,

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A stand-alone miniature servomotor controller that works inside a special robotic arm from Barrett Technology Inc., Cambridge, Mass., could boost robotics by making industrial robots more human-centric. Called the “Puck,” the diminutive device resembles a small hockey puck. It weighs 43 gm and measures 35 mm in diameter and 17 mm in height.

In this small package, the Puck carries a controller with an encoder. The device mounts on each drive motor of the company’s Whole-Arm Manipulator (WAM) robotic arm. Unlike traditional robotic arms, WAM provides so-called “backdrivability,” so forces exerted anywhere on the arm control its drive motors via velocity, position, and torque sensors. Should an end effector strike an unintended object, for example, a drive motor might halt the arm’s swing. The result is an industrial robot that is safer for close contact with humans.

The solid, heat-dissipating Puck also makes for a friendlier robot because it eliminates the need for external controllers and cabling. This slashes the total power an arm needs to about 40 or 50 W, amounts that won’t harm humans.

Barrett won a $500,000 grant from the National Science Foundation to engineer the device for brushless servocontroller applications. The company has since been keeping a low profile while it works on the design and cutting the device’s cost. The robotics industry publication, Robotics Business Review, calls the Puck transformational technology that will significantly increase the number and range of robotics applications.

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