The Bipedal "Cassie" Robot Walks Like a Human

It's only slightly less terrifying than an AT-ST.

YouTube/ Agility Robotics

Forget drone package delivery. The robotic courier of the future may arrive by land. This week, Agility Robotics, a spinoff of Oregon State University’s robotics program announced its new bipedal robot that may one day deliver your packages. “Cassie,” as the company calls it, sports motors in its hips and ankles, enabling a level of stability that surpasses the team’s previous designs.

A two-legged robot is nothing new. One that actually works? That’s new. Walking on two legs is an improbable victory of human evolution. Theoretically, it seems like it shouldn’t serve us very well. But bipedalism enables humans to cover varied terrain and recover quickly from slips or trips. It’s no wonder that roboticists have long tried to mimic humans. The simple fact remains, though: Humanoid robots usually suck. Cassie seems to change that.

The team’s previous robot, ATRIAS, is also a biped. It boasts impressive dynamic stability, but also exceptional bulk. Cassie builds on the team’s accomplishments with ATRIAS, whose movement resembles a pogo stick. Cassie features scaled down components and additional motors, which enable smoother motions and improved stability. For instance, whereas ATRIAS appears to jog in place when it’s not moving forward, Cassie can stand still without falling over.

The team made this possible by building motors into Cassie’s hip joints and ankles, an improvement that also allows the robot to constantly adjust its posture in order to navigate uneven terrain and correct for missteps. Through extensive research on the assets and shortcomings of ATRIAS, the team found that it wasted lots of energy because its motors worked against each other. By learning from their mistakes, the researchers ended up with what looks like a much simpler design.

In fact, it’s quite complex, but since the researchers custom designed so many of the components, they were able to keep Cassie’s bulk to a minimum. Since it’s so lightweight, Cassie could carry additional computer equipment in the future, including hardware that would enable the robot to perceive its environment. This feature will be crucial in the event that Cassie is used for either of the missions the team envisions: search-and-rescue operations or package delivery.

Cassie’s design resembles the bottom half of an ostrich, which is no accident. Though the team did not model the design on living creatures, the researchers have used ATRIAS to study how birds run, so the same principles are at play in this new design.

Cassie is just one of a growing number of bipedal robots, but so far it seems like one of the most nimble. And while the company hopes to use it to deliver packages in the future, that’s not yet a reality.

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