US 12,482,128 B2
Identifying stability of an object based on surface normal vectors
Zhanping Xu, Sunnyvale, CA (US); Kartheek Chandu, Dublin, CA (US); Glenn D. Sweeney, Sebastopol, CA (US); and Robert Vets, Seattle, WA (US)
Assigned to GM CRUISE HOLDINGS LLC, San Francisco, CA (US)
Filed by GM Cruise Holdings LLC, San Francisco, CA (US)
Filed on Aug. 17, 2022, as Appl. No. 17/890,124.
Prior Publication US 2024/0062405 A1, Feb. 22, 2024
Int. Cl. G06T 7/70 (2017.01); B60W 60/00 (2020.01); G06T 7/20 (2017.01)
CPC G06T 7/70 (2017.01) [G06T 7/20 (2013.01); B60W 60/00 (2020.02); B60W 2420/403 (2013.01); B60W 2520/16 (2013.01); B60W 2520/18 (2013.01); G06T 2207/10028 (2013.01); G06T 2207/30252 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method comprising:
accessing image data tracking a surface as an object moves relative to the surface, wherein the image data is gathered by one or more sensors coupled to the object and is part of a field of view of the one or more sensors aiming at the surface;
identifying a reference normal vector of the surface;
identifying, from the image data, a dynamic normal vector of the surface associated with the object moving over the surface;
defining coordinates axes for the surface in a three dimensional space based on the reference normal vector;
projecting the dynamic normal vector onto the coordinate axes; and
determining one or a combination of the roll, pitch, and azimuth of the object with respect to the surface based on corresponding projections of the dynamic normal vector onto the coordinate axes; and
determining one or a combination of roll, pitch, and azimuth of the object with respect to the surface based on the reference normal vector and the dynamic normal vector;
wherein a pitch angle of the object is determined by ϕP=a tan tan (ny/nx), where ny and nx are two of the corresponding projections of the dynamic normal vector on two of the coordinate axes;
wherein a roll angle of the object is determined by ϕP=a tan tan (nz/nx), where nz and nx are two of the corresponding projections of the dynamic normal vector on two of the coordinate axes;
wherein an azimuth angle of the object is determined by ϕAZ=a tan tan (ny/nz), where ny and nz are two of the corresponding projections of the dynamic normal vector on two of the coordinate axes; and
wherein the object is an autonomous vehicle and the method further comprises determining whether at least a portion of the autonomous vehicle loses contact with the surface based on one or a combination of the roll, the pitch, and the azimuth of the object with respect to the surface.