Biologically inspired robots – it’s only natural
Imagine a robot that is able to negotiate its own way through any landscape, over any terrain. You may have conjured a mental image of the Terminator, or perhaps those lumbering colossal walkers in the Empire Strikes Back. Long revered in sci-fi classics, autonomously mobile robots pose a real design challenge for engineers.
If you were to design such a robot, what kind of locomotion would it have? How would it know what obstacles lay ahead, and how to deal with them? What would it do if it began to tip over? If you are considering how you would address these problems, it might occur to you that suitable models for your robot already exist.
The U.S. military posed this challenge to the mechatronics development company, Boston Dynamics. In contrast to their deadly screen image, all-terrain robots are intended to substitute for people to do heavy or dangerous work. For instance, they can scout hostile territory for mines or bombs. In civilian life, they can be sent into a burning building to rescue an injured or unconscious victim.
Engineers at Boston Dynamics sought solutions to the problems of designing autonomously mobile robots from nature. After all, structures that propel animals across variable terrain have been around for hundreds of millions of years. They’re called, “legs”. Networks of sensory and nerve cells enable animals to detect changes in their environment, orientate their body, and manoeuvre around obstacles. By extracting their design principles from nature, the engineers developed a range of robots that imitate the locomotive behaviour of animals.
One instructive example is the 73-kg mechanical dog nicknamed, “Spot” (Szondy 2015). Spot is capable of ambling through a wooded forest, up and down hills, over grass or on rubble. It’s equally adept at trotting over flat ground and climbing up and down stairs. Spot is equipped with a stereoscopic vision system to perceive the size, shape, and relative position of objects in the environment. Spot also has sensors that detect the position of its joints, the forces acting on them, and for ground contact. An on-board computer processes all the sensory input through algorithms that direct the positions of the robot’s legs as it moves.
The most evocative of Spot’s abilities is to recover its footing after being knocked over (click here to watch). It’s hard not to react with dismay at watching Spot being kicked by a technician, stumble, then regain its foothold. It’s as though witnessing an act of cruelty to a living animal. How does Spot achieve this lifelike feat? It is equipped with a gyroscope, a kind of rapidly spinning wheel that resists tilting. In addition to stabilizing the robot, the gyroscope provides a reference that aids in the robot’s ability to keep balance.
The principle of designing materials, structures, or systems modelled on biological entities and processes is referred to as biomimicry. In practice, engineers develop prototypes to test particular design solutions. They will keep and refine the ideas that work and discard the ones that don’t. Of course, nature has been doing this for hundreds of millions of years. The features of the best adapted organisms are passed on over countless generations. Organisms with the features that don’t work so well are weeded out of the population. At first blush, nothing would seem as far removed from living things as mechanical and electrical engineering. Boston Dynamics have demonstrated, however, how these fields can draw inspiration from nature.
Boston Dynamics YouTube (2015), Introducing Spot, 28th November 2015; https://www.youtube.com/watch?v=M8YjvHYbZ9w.
David Szondy (11th February, 2015), Boston Dynamics introduces smaller, more kickable robot, Gizmag, http://www.gizmag.com/boston-dynamics-spot/36005/.