Fig. 6.

Robot experimental results of the SLIP foot. (A) Robotic SLIP foot diagram. (B) Contact jump (glass), where the foot preload is zero (high-speed video snapshots). (C) Noncontact jumps (sandstone), where the foot preload is zero (high-speed video snapshots). A type-3 slip, where the foot loading is greater than the surface friction but does not leave the surface, is shown. Motion of the red circle represents the approximate motion of the feature in the images. (D) Experimental results per jump (per leg rates are half) for the SLIP foot and each constituent part separated into contact and non-contact-type jumps. Feet include: SLIP, complete foot; SLIP-none, no pad or spines (3D-printed ABS pad base); SLIP-pad, no spines; and SLIP-spine, no pad. (E) Robot foot tracking of noncontact jumps, presenting the jumping-axis velocity, slip-axis velocity, and behaviors of symmetric and asymmetric feet, such as reorientation, contact, planting, bouncing, and mechanism traits such as variable cable friction. (F) Robot experiments, for flat and 45° surface angles, showing no loss of jumping performance. Robot experiments at twice the energy (80% increase in energy density due to an additional 13.2 g), comparing the flat performance to that of type-3 slipping on wood at a 45° surface angle, are shown (superimposed high-speed video snapshots).