Clone Robotics has developed a highly biomimetic robotic hand that not only resembles a hand covered in a transparent skin but also has 27 degrees of freedom—the same as human hands. The transparent skin covers 36 artificial muscles that run down the length of the robotic forearm and into the fingers. The muscles are a new class of hydraulic McKibben muscles, which can expand and contract by injection of fluid into thin mesh tubes by use of external pumps. The company, however, uses a powerful heating element running through the artificial muscle that rapidly heats the fluid inside the tubes. This causes an almost sixfold increase in pressure, which results in expansion of the tubes. In this manner, operators can control the robot hand simply and precisely using an electric current.

The company also has a prototype Clone Hand that uses a water pump to distribute pressure through the various muscles that run through the forearm and hand, each with its own hydraulic valve and pressure sensor. The prototype also includes magnetic sensors to relay information on joint angles. The muscles are twice as strong as human muscles and highly robust, with durability of more than 650,000 cycles, whereas the valves can function for more than 1 million cycles. The first beta Clone Hands will be ready for shipment by late 2022; the company continues to develop the Clone Torso (to which the Clone Hand can also attach). The Clone Torso will have a rigid spine but two full arms and more than 120 muscles through the neck, shoulders, arms, and chest. The company has also designed a hydraulic powering system that can fit inside a human-size torso.

Implications

Technological advances and growing demand from several industries are facilitating the accelerating R&D efforts in the field of humanoid robots, actuators, and manipulators that have humanlike motion. For example, the Clone Hand could see use via teleoperation in hostile or unsafe environments such as nuclear-waste facilities, space, hazardous-chemical plants, and construction. In addition, the robot could also serve as a convenient tool for several everyday tasks in a home; Clone Robotics states that the Clone Hand is low in cost and energy efficient to operate.

Biomimetic robotic hands have numerous benefits over simpler robotic grippers and manipulators. For example, they have the potential to adjust faster to complex environments and to adapt to new challenges without significant training because the world around them is designed for human hands. Operators could potentially train robotic hands such as the one from Clone Robotics using videos of human hands, whereas simpler robotic manipulators may require operators to create complex virtual training systems designed specifically for that manipulator and suited to its motion capabilities.