Soft Robotic Fingertips

Three potential problems exist in multifingered robotic hands. First, the impact forces that result during each instant of grasping a rigid object can affect the functioning of the fingertip sensors. Second, a hand with hard fingers cannot securely grasp objects that have uneven surfaces due to the poor conformability of the fingers. Third, repetitive strains are induced into the fingers throughout a manipulation task. If they are not dissipated, the manipulation becomes jerky, the func tioning of the fingertip sensors is affected, and the life of the finger's skeletal structure may become short. In this work, six fingertips constructed from plastic, rub ber, sponge, fine powder, paste, and gel are experimentally compared for their ability to overcome the above problems. Results show that the sponge fingertip is the most suitable and the plastic fingertip the least suitable for our application. For practical reasons, however, gel is preferred over sponge. In view of these results, it is recommended that future robotic hands employ soft fingers, or at least fingers with soft tips, constructed out of carefully chosen materials.