Force–displacement profiles and photographs showing differing behavior between the series- and parallel-configured three-fingered gripper. (a) Plot of digit forces versus actuator displacement while digits are in contact with an object in a grasping test (parallel configuration). (b) Pictures of an acrylic cutout of the U.S. state of Oklahoma in stages of a grasping test (parallel configuration). A line is drawn along the Oklahoma–Kansas border to better visualize the rotation. (c) Plot of digit forces versus actuator displacement while digits are in contact with an object in a grasping test (series configuration). (d) Pictures of an acrylic cutout of the U.S. state of Oklahoma in stages of a grasping test (series configuration). A line is drawn along the Oklahoma–Kansas border to better visualize the rotation.