Simple acts such as opening a jar or lighting a match depend on the ability to grasp objects with different shapes and to apply well-regulated forces and movements in different directions. When we hold a glass of water, the forces applied by the fingers are directed against the surface of the glass, and our brain coordinates these forces to prevent slippage and maintain the orientation of the glass. The planned studies will combine computational methods derived from control engineering and robotics with techniques and theories from neuroscience to understand how the brain controls grip forces when lifting and manipulating objects and how it estimates an object's mechanical properties. The investigations will consider how grasping an object is affected by uncertainties about the object properties (e.g., it's hardness, slipperiness, texture, etc) and how fundamental manipulation skills may be enhanced by artificially augmenting tactile information. The outcomes of these studies will influence several domains including (1) neuroscience (understanding our ability to control and manipulate objects with our hands); (2) technology (for presenting force information to users of robotic devices such as teleoperation and robot-assisted surgery); and (3) neurorehabilitation (for developing intelligent robotic prostheses and new exercises to promote the recovery of lost manual skills). These studies will establish a collaborative interaction between scientists in the United States and Israel having a range of expertise that includes robotics, control, motor systems neuroscience and neurorehabilitation.
Getting the fingers to cooperate during dexterous manipulation requires the integration of different types of information. The fingers have a rich array of tactile sensors that generate signals related to the interaction with the object. However, for the brain to know the magnitude and direction of these forces, it must also know the orientation of the fingers in space. This information is obtained by other sources that form the basis for the sense of position of the body in space. The control of grasp can also be informed by kinesthetic force sensors in the muscles that in turn are integrated with the sense of the joint's configuration in space. This project takes advantage of a new technology that allows applying controlled stretches to the skin of the fingers. Skin stretch devices mounted on a robotic manipulator will be used to apply a variety of controlled perturbations while subjects are performing manipulation tasks. Perturbations will be applied to increase or decrease the consistency between tactile and kinesthetic feedback, and to investigate how the brain adapts the ability to maintain a stable grasp during both unpredictable and predictable forces. The approach will combine theory and experiments to tackle the integration of multiple information sources in perception and in controlling manipulation and grip forces.
This project is being supported by a partnership between the National Science Foundation and the U.S.-Israel Binational Science Foundation.
