Researchers at the Massachusetts Institute of Technology (MIT) have developed a pair of robotic arms called Supernumerary Robotic Limbs (SRLs) to provide extra hands for numerous tasks people cannot do on their own.

The latest prototypes for the limbs were presented by researchers at the IEEE International Conference on Robotics and Automation (ICRA) on Monday in Hong Kong, according to Discovery News.

One of the models included a pair of limbs springing from the user's shoulders. Another model featured limbs that extended from the waist.

The SRL is designed to help people with tasks in which a person is busy handling other objects. A video shows the limbs being used in a construction context, in which something that needs to be attached to a ceiling must be held with assistance, screwed or hammered into place simultaneously. A more common example would be using the limbs to open a door while the user is holding something with both hands, Discovery News reported.

Two robotic arms are mounted onto the user's shoulders so that the reaction forces on them align with the spine. Both arms have end effectors that are interchangeable and can be customized. Both of the limbs also have five degrees of freedom to move. The entire system weighs close to 4.5 kilograms (10 pounds).

To make sure users don't have to use their own arms to control the robotic ones, the SRL watches what the user does with his/her arms in order to decide what movements to make. The system monitors two inertial measurement units (IMUs), which are worn by the user on the wrists. The SRL includes a third IMU, which is placed at the base of the robot's shoulder mount for tracking the SRL's overall movements and orientation, Discovery News reported.  

The accelerometer and gyro data collected from the IMUs is used to predict the most useful position for the SRL's arms. For example, if a user raises his/her hands above his/her head, the SRLs will raise above his/her head as well, since it believes the user is trying to hold something up.

The research team is currently using the SRL prototype to test a variety of "behavioral modes" so that the limbs can be programmed to do anything users want them to do.