BigDog — an infantryman’s best friend

Whether it’s loping through the undergrowth, scrambling up snowy banks or skittering across the ice, BigDog is an astonishing and somewhat unsettling sight.

Developed for the US defence research agency DARPA by MIT spin-out Boston Dynamics, the four-legged robot has been designed to carry soldiers’ equipment across terrain too rugged and difficult for existing tracked and wheeled vehicles.

Around 1m tall and 1.1m long, the 109kg quadruped is able to stand, squat, crawl, trot, run (its current top speed is 7mph) and even bound. It has been tested in mud, snow and water, has carried a 154kg load and last summer it set a world record for legged vehicles when it completed a 12.8-mile, eight-hour hike without stopping or refueling.

The power supply is a two-stroke internal combustion engine, the eerie whirring noise of which adds to the robot’s air of menace. The engine drives a hydraulic pump that delivers oil through accumulators and other devices to the hydraulic leg actuators.