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In this paper we propose a tank-like climbing robot, called Tankbot, using flat (non-patterned) and soft elastomer adhesive treads. This wheeled climbing robot design enables continuous, vibration-free, and strong attachment to wide range of smooth and rough surfaces, relatively fast and smooth motion, and improved capability to traverse obstacles and to carry high payloads. Tankbot is lightweight (60—150 g) and can climb on any slope from 0• to 360• on smooth surfaces. Moreover, climbing vertically up, down, and laterally on relatively rough surfaces, such as a wooden door, a painted wall, and a brick wall, is also possible. A passive or active tail is added to Tankbot to transfer the peeling force to the front wheel and to assist for transitioning to different surface slopes. It is shown that the normal component of the peeling force with respect to the surface is crucial and has to be maximized to maximize the climbing stability. Moreover, it is demonstrated that the tread tension should be in a specific range to maximize the normal peeling force. With the aid of the derived models, different Tankbot prototypes with different body and tread dimensions are manufactured and tested for different tasks. It is shown that a 115 g Tankbot can carry up to 300 g on a regular painted wall. Tankbot can go over obstacles of up to 16 mm in diameter, perform both internal and external vertical wall to ceiling transitions, steer in two dimensions with a minimum turning diameter of 80 cm, and loiter on painted walls for up to 5 min.

In this paper, flat elastomers are proposed as an attachment material for climbing robots on less than a few micrometer-scale rough surfaces due to their energy-efficient, quiet, and residue-free characteristics. The proper elastomer is chosen by the use of the current adhesion, friction, and peeling elastomer-contact-mechanics models. Then, adhesion and friction properties of the chosen dry flat-elastomer thick films (Vytaflex-10) are characterized on acrylic and smooth and rough glass surfaces for variations in preloads, speeds, contact times, and elastomer thicknesses. A climbing robot with four-bar-based legged-body kinematics is designed and fabricated as simple and lightweight as possible to demonstrate the feasibility of the elastomers as attachment materials on relatively smooth surfaces. The robot utilizes a passive alignment system to make the footpads parallel to the surface on light contact, a peeling mechanism to minimize the detachment vibration, and a passive tail to minimize the pitch-back moment. Experimental results showed that the robot can climb stably on vertical, smooth surfaces in any direction and can walk inverted for a limited amount of time.

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