Cassie - A dynamic bipedal robot
Agility Robotics, a spin-off of Oregon State University, is officially announcing a shiny new bipedal robot named Cassie. Cassie is a dynamic walker, meaning that it walks much more like humans do than most of the carefully plodding bipedal robots we’re used to seeing. This makes it better at handling the kind of diverse and complex terrain that we walk over all the time without even thinking, a talent that’s going to be mandatory for robots that want to tackle the different environments and situations that they’ll need to master to be actually useful around people.
In addition to search-and-rescue and disaster relief, Agility Robotics has one particular environment and situation in mind: They want Cassie to be scampering up your steps to deliver packages to your front door.
Cassie is a dynamic bipedal robot developed by Agility Robotics, which says it could be used for research,disaster relief, and, long term, delivery of packages.
Agility Robotics may be a new company, but it’s made up of the folks behind the ATRIAS robots, including MARLO at the University of Michigan, in Ann Arbor. Cassie is the next-generation robot that’s intended to take everything that was learned from the ATRIAS project and build it into a platform that’s both more capable and more practical, as Agility Robotics’ co-founder (and OSU professor) Jonathan Hurst tells us:
There were many, many unknowns in the design of ATRIAS. ATRIAS was the first machine to demonstrate human-like gait dynamics and implement spring-mass walking [reproducing the ground reaction forces and center-of-mass motion of human walking], but it was not a practical machine for any use other than science demonstration.
We learned a few key things with ATRIAS: First, the legs on ATRIAS are configured as a 4-bar linkage, in part to create minimum inertia for the spring-mass model embodiment. However, the configuration results in one motor acting as a brake on the other, with a lot of power cycling internally between motors rather than doing work on the world. After some analysis, we developed the specific leg configuration of Cassie. This allows the motors to be smaller, and the robot to be far more efficient than even ATRIAS was.
This is apparently a required test for legged robots
In addition to increased efficiency, Cassie has all kinds of other practical improvements over ATRIAS. It has a 3-degrees-of-freedom hip like humans do, allowing the robot to move its legs forward and backward, side to side, and also rotate them at the same time. This makes Cassie steerable in a way that ATRIAS wasn’t. It also has powered ankles, which it uses to stand in place without having to constantly move its feet the way ATRIAS does, and it has enough battery power to run some beefy on-board computers, meaning that integrated perception is now an option.