One CPC code can give away the whole robot. Boston Dynamics' grant US11073842B1 ("Perception and fitting for a stair tracker," issued July 27, 2021; inventors Eric Cary Whitman, Gene Brown Merewether) carries B62D 57/02 — propulsion by legs. That single classification says this is not a wheeled rover or a manipulator; it's perception built for a walking machine, where the stakes of misreading a step are a fall.
The mechanism is stair detection and model-fitting: the robot perceives a staircase, fits a geometric model (tread depth, riser height, edges) to it, and tracks that model as it moves. G06K 9/00664 (3D scene recognition) and 9/4604 (edge detection) describe the perception; G05D 1/10 (attitude/altitude control) ties it to the body's balance. For a legged robot, knowing exactly where each edge is isn't convenience — it's the difference between climbing and tumbling.
For the actuation-and-manipulation beat, legged-locomotion perception is a distinct and under-fenced corner of robotics IP. Most perception patents assume a wheeled or static platform; a claim explicitly tied to legged propulsion fences a capability that humanoid and quadruped builders all need and few have cleanly protected. The specificity (stairs) is what makes it defensible — a narrow, hard, real problem.
From a portfolio angle, this fits Boston Dynamics' deliberate shift toward perception-driven, electrically-actuated legged systems. Read alongside its other filings, the stair-tracker grant is a building block in a locomotion-perception portfolio that any competitor building dynamic legged robots will eventually bump into. The B-kind designation (B1) marks it as a granted patent with no pre-grant publication — a clean, examined asset.
Caveats. Stair detection exists in the mobile-robotics and AR literature; the inventive step is the fitting-and-tracking method tied to legged control, so claim 1 is specific about the model and the tracking. And perception classifications point at the task, not the exact algorithm. Read the independent claim for how the stair model is fit and updated.
For the file: a legged-locomotion perception grant fencing a narrow, high-stakes capability. Pull US11073842B1 on PatentBear, read claim 1 for the stair-fitting step, and treat B62D 57/02 as the marker for the whole legged-robotics IP lane.