Making robots flexible

Any mention of robots typically evokes images of big computer-controlled machines, like those in an industrial assembly line. Despite what movie franchises may want us to believe, Iron Man suits and  transforming cars still belong in the realm of fantasy.

As applications of robotics continue to diversify, flexibility has emerged as one of the most desirable characteristics in a robot. Recent research in the lab of Ramsharan Rangarajan in the Department of Mechanical Engineering, IISc, examines how to incorporate this literally: by building a flexible, bendy robot. Using nonlinear mechanics and optimisation-based algorithms, they have developed a flexible, tendon-actuated arm that functions as a dextrous robot. The “Elastica Robot” ‒ named after the mechanical theory attributed to Euler ‒ not only embraces flexibility but relies on it as for functioning.

“The basic idea is quite intuitive,” says Rangarajan. “You tug on a pair of cables attached to a flexible arm to control how the tip moves. It takes some skill, quite a lot actually, to master such control by hand.” This is precisely where a detailed understanding of structural mechanics helps. “When attempting to control the robot by hand, you are trying to solve differential equations in your head. We let numerical algorithms and optimization theory do this instead,” says Rangarajan. In essence, the work transforms what is perhaps the most basic mechanical element, namely an elastic beam, into a programmable shape-morphing robot.

The researchers believe that such a flexible, remotely-actuated and energy-efficient robot can have diverse applications. The fact that its functioning is independent of the length scale or the material means that it can, in principle, be miniaturised to design medical devices or enlarged for deployment in space-related applications.

An elastica robot: Tip-control in tendon-actuated elastic arms P Handral, R Rangarajan – Extreme Mechanics Letters, 2020

Dr Ramsharan Rangarajan
Assistant Professor
Department of Mechanical Engineering
IISc Bangalore