Human hands can alter the firmness of their grip. A new two-fingered robotic hand shares that trait. The design enables it to absorb energy from impacts during collisions, preventing whatever the robot is holding from breaking and making it safer for people to work with and near the machines.
Instead of having two fingers that are fixed in place, each of the gripper's fingers has a magnetic base that sits between two neodymium magnets that repulse, or push against, the finger. The air gap between the magnets acts like a spring, creating a little give when the hand picks up an object or collides with an external force. The stiffness of the grip can also be adjusted by increasing or decreasing the space between magnets.
In one set of tests, engineers placed a short stick of spaghetti lengthwise between the fingers of the robotic hand. When the gripper crashed into a fixed object, the device detected the external force being applied, causing the magnets to adjust their position and temporarily reducing the stiffness of the grip. This allowed the gripper to absorb some of the energy from the collision, keeping the spaghetti stick intact.
The gripper can be attached to commercially available robot arms that are already in use in many facilities. This could lower the cost of adapting the technology for companies interested in improving the safety and capabilities of existing machines.