One small four-legged step for robotics

Along with Avik De, his business partner and colleague at the University of Pennsylvania in Philadelphia, Kenneally worked to develop more reliable four-legged robots in order to advance research in android mobility. In fact, Ghost Minitaur is the first ever “direct drive” quadrupedal machine.

As Kenneally explains, most electric motors require a gearbox, from robots to cars. While this specific piece helps move the legs, which require much more torque — or rotational force — than conventional electric motors can create, it comes at a cost. Gearboxes are expensive, mechanically fragile and reduce the leg’s maximal speed.

What Kenneally and his team have achieved with the Ghost Minitaur is to remove the need for any gearbox at all — hence direct drive.

“We were able to develop a different way of choosing motors and a bunch of other design insights and we were able to get rid of the gearbox altogether,” he says. “Our robot is the first legged robot that doesn’t need a gearbox — the legs are directly connected to the motor.”

One major advantage, as he says, is that “because there is such a direct mechanical connection to the terrain, the legs are very responsive and can easily feel the forces they exert on the ground.”

In other words, the Ghost Minitaur can feel if it’s made contact with something, or is slipping, and can sense the world around it.