The U.S. Patent and Trademark Office has issued RE2 Robotics a patent for the invention of a fluid rotary joint that is capable of precise positioning while being driven by both fluids and gasses, including water, hydraulic fluid, and air.

According to RE2 Robotics, the patent, “Fluid Rotary Joint and Method of Using the Same,” further adds to its mobile manipulation intellectual property and underwater robotics expertise.

“The issuance of this patent further solidifies RE2’s position as a world-class intelligent mobile manipulation provider,” says Jorgen Pedersen, president and CEO.

“It also reinforces the brilliance and dedication of our engineers and scientists, who are encouraged to design creative solutions to solve our customers’ most challenging manipulation problems.”

Developed during the design of an inflatable underwater manipulator for explosive ordnance disposal (EOD) applications, the invention can be used in robotic arms to provide precise rotational positioning for dexterous manipulation.

The invention combines a strain wave gear and fluidic actuators in a compact, precise rotary joint. Instead of using expensive toothed interfaces for the flex spline, the strain wave gear uses materials with tunable load transmission characteristics. The fluidic actuators generate the waves that drive the flex spline, and the tunable nature of the flex spline materials enables different modes of behavior, which allows the joint output to be driven in a clockwise or counter-clockwise direction, to freely rotate, or to act as a torque-limiting device by having limited contact with the circular spline.

“By locating this type of actuator at the end of a robotic manipulator, arm mass, inertia, and electromagnetic signature are reduced,” explains Dr. Andrew Mor, principal research scientist and part of the team that invented the joint.

“The actuation of the joint is remote, so we are able to reduce mass at the joint level. In addition, since the joint is inherently torque-limited, it can be tuned and utilized in locations where safety could be an issue, such as with underwater oil and gas inspections or when naval divers are inspecting and neutralizing water-borne explosive devices.”