Snails have amazing adhesive locomotion abilities which help them climb up walls and even across ceilings. They generate this versatile and stable movement by muscular exploiting travelling waves and friction modulation. Inspired by these characteristics, snail-like robots have recently become the focus of growing research. In this paper, we present a novel friction-driven three-foot snail-like robot which employs a simple mechanism to capture and replicate snail-like motion. This robot is driven by two servo motors, which makes it easy and low-cost to fabricate. The robot operates by breaking frictional symmetry in the cyclic motion of the three feet, in much the same way as the three-sphere Golestanian swimmer. The symmetry of its structure and properties of friction give the robot distinctive movements. We present a mathematical model of the robot's locomotion, focusing on its kinetic harmonicperistaltic movement. We designed and fabricated the robot, then undertook simulations and experiments, which closely match the analytic solutions. This robot provides a new approach to realising simpler, lower cost, and potentially more efficient, biomimetic mobile robots.

Suction adhesion is widely used by natural organisms for gripping irregular objects (e.g., rocks), but their artificial counterparts show less adaptation in the same situation. In addition, they can require complex sensing and control systems to function. In this paper, we present a contacttriggered suction cup with the ability to adapt to objects with complex and irregular shapes. The gripper has two states to adhere and release the object and the transformation from release to adhesion is passively triggered by the contact force, making it an autonomous gripper and removing the need for complex driven system. Once the suction cup experiences a contact force above a set threshold, it will automatically capture the contacting object. Only the resetting transformation from adhesion to release is actuated by a vacuum pump. The maximal suction force up to 15.1 N is generated on the non-flat surface with the suction cup diameter of 30 mm. The performance of this gripper is demonstrated on a 7 DoF robot arm which successfully picked up a variety of irregular objects. We believe that this contact-triggered gripper provides a new solution for low cost, energy-effective and adaptive soft gripping.

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