A pair of springs connected to the suction cup's base helps maintain the plug's position, restoring the plug seal in the absence of object forces. If the cup makes contact with an object, a hinge action raises the plug away from the suction tube. The moment the cup's lips are pushed against the object, the passive reaction forces from the cup lips are transferred to the rubber base of the cup, which stretches over the collar and allow the structure to compress. Acting as a pivot for the hinges, the collar causes the hinges to rotate and the edges of the hinges slide along the underside of the flange and raise the plug away from the suction tube opening. As a result, the suction cup self-seals when not in contact with an object and self-opens the cup's lips makes contacts with an object. In 2015, several improvements were made to the design of the self-sealing suction cup to improve its grasping capabilities. The previous design demonstrated the following flaws:   To address these flaws, researchers from ARL decreased the number of components by consolidating the functions of several parts, which reduced the uncompressed height of the suction cup by almost 50% to 0.72 cm. The cup diameter was also reduced to 1.07 cm. A lever system was added to the base of the cup, which pivots the collar to lift the plug. In addition, the tube doubles as a spring, which helps restore the levers and the plug to their closed position. A plastic restraint was added around the cup to aid with handling the hyper-extension, shear, and torsional forces. The self-sealing suction cup has been subjected to a series of tests to determine the quality of its performance. A flexible test rig with four dime-sized suction cups and plastic ribs connected with rubber tubes was created for force-displacement and testing. A force-displacement test that compared the performance between the self-sealing suction cup, an identical suction cup, and a commercially available suction cup found that the internal structures of the self-sealing cup allowed more force to be exerted for the same displacement compared to the other cups. However, under identical conditions, the self-sealing cup achieved a maximum force of 12.5 N while the commercially available cup achieved a maximum force of 12.9 N. A seal quality test measured the pressure generated from each self-sealing suction cup. The results showed that an array of four cups maintained a pressure of 93.8% atmospheric.