Development of an Inchworm-inspired soft robot with active friction control of wheels using Double-Network gel brakes

A soft inchworm robot with active friction control of wheels using soft Double-Network (DN) gel was developed and studied. The rotation of the robot’s wheel was controlled using brakes fabricated from DN gel. DN gel is a unique material that exhibits a frictional difference in surface upon voltage application. The directional crawling of the inchworm robot was possible through appropriate activation of DN gel brakes exploiting the property of surface friction. The brakes are in constant contact with the wheel’s axle and impress high and low friction upon voltage application to control the rotation. The control of rolling friction of the wheels results in improved locomotion capabilities and higher speeds compared to inchworm robots that employ sliding friction and body peristalsis. A mathematical model was developed to evaluate the theoretical displacement of the inchworm robot. The system is characterized by low power consumption, tough but soft brake material with good elasticity, low cost, and easy to fabricate with inherent compliance. The DN gel can be fabricated from special 3D printers which makes the whole robot completely 3D printable.