This article was taken from the December 2014 issue of WIRED magazine. Be the first to read WIRED's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
This agile, four-legged robot is the StarlETH -- one of five designs shortlisted for the Total ARGOS challenge, a €500,000 (£400,000) prize to produce the world's first "Autonomous Robot for inspecting Gas and Oil Sites". Whereas other teams have opted for wheels and tank tracks, StarlETH is the only quadruped - a crucial feature that its designers say gives them the edge. "We can climb obstacles, move sideways and shift the robot's centre of mass," says Mark Höpflinger, one of the postdocs at the ETH Zürich's Autonomous Systems Lab, who built the robot with Marco Hutter, Michael Bloesch, Christian Gehring and C. David Remy.
StarlETH's legs mimic how muscles store, release and transfer energy. With fine control of its movement, it handles rough terrain and responds well to external disturbances -- crouching and shifting its body towards a gust of wind or counteracting a swinging motion. Unlike other quadrupeds, StarlETH uses electric motors instead of bulky hydraulics -- so it's sleek and nimble (40cm tall and 26kg). Although other quadrupeds excel in select areas, StarlETH tries to have it all -- energy efficiency, versatility, speed and robustness. "We plan to work on as many industrial applications as we can," says Höpflinger.
Actuation Series elastic actuators convert electrical energy into movement, in three directions per leg: electric motors spin a gear to drive the legs, with springs at each joint decoupling the motors and gears from the joint.
Autonomy An on-board PC and battery pack allows StarlETH (Springy Tetrapod with Articulated Robotic Legs) to operate for two hours per mission (the aim is eight hours). The robot can be operated by remote control or can navigate programmed routes by following landmarks and avoiding obstacles.
Sensors Reliable detection of ground contact and accurate measurements of orientation and location are crucial. Lightweight optical-force sensors in the feet measure ground contact and the robot's pose is estimated using acceleration and rotation rates.
Navigation Stereo cameras, mounted front and back, and a laser range-finder perceive the robot's environment and create a 3D map of its surroundings. Future designs will include an acoustic camera to precisely locate sounds.
Gaits StarlETH's algorithms distribute ground-contact force and torque at the joints according to terrain. For rough surfaces, the robot adopts a static gait (at least three feet on the ground). On smoother surfaces, dynamic gaits -- such as a two-footed trot -- allow it to move faster.
This article was originally published by WIRED UK
