Improvements in microfabricaton techniques and an increased understanding of insect locomotion has led to the development of impressive centimeter-sized legged robots. The cockroach-like robots seen in the videos below typically have rigid bodies and a set number of legs.

Following an alternative approach, Hoffman et al. developed a myriapod inspired robot with a flexible backbone and modular number of legs. The added flexibility and potentially large leg-count is expected to increase speed, robustness and stability while helping the robot adapt to difficult terrain or climb.

Because controlling many-legged robots with a flexible backbone is challenging, a dynamic model of the system was designed to predict the behavior of the myriapod and optimize its body parameters.

The resulting six-legged version of the robot seen below weighs 750 mg and is 3.5 by 3.5 cm. The fabrication of such a small robot is done using a Smart Composite Microstructures process that involves sandwiching a flexible material between two layers of rigid material such as carbon fiber. Flexures are created by making precise incisions in the carbon fiber, thereby revealing the flexible material which is then free to bend. Flexures can be solidified at any angle using glue or can be left flexible. What started out as a 2D structure is therefore folded into a 3D mechanical structure. Actuation is added by layering piezoelectric material, carbon fiber and glass fiber.

Results show the robot walking forward at a pace of 1 body length in 10 seconds, with a step size between 0.75 and 1 mm. The step size is dependent on the gait and is expected to vary with different body undulations.

The following video shows the latest version of the robot with 20 legs and insect-like body undulations.

Sabine Hauert is President of Robohub and Assistant Professor at the Bristol Robotics Laboratory.. read more

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