Patent ID: 9567021
Date: 2017-02-14
CPC Classifications: A61G,B62D

Claim:
1. A method of climbing a stair, the method comprising: driving an articulated vehicle along a drive-direction on each stair, the vehicle comprising: driving, while the rigid lower chassis remains rigid and parallel to the ground and the top of the rigid lower chassis remains parallel to the upper chassis, the articulated vehicle to approach a stair with the forward portion of the articulated vehicle; pivoting, while the rigid lower chassis remains rigid, the front legs about the transverse axis from a vertical position next to the lower chassis downward and forward until they touch the top of the step; pivoting, while the rigid lower chassis remains rigid, the back legs about the transverse axis from a vertical position next to the lower chassis downward and forward until they are parallel to the ground; pivoting, while the rigid lower chassis remains rigid and the top of the lower chassis remains parallel to the bottom of the upper chassis, the middle body neck portion forward from the rigid lower chassis, moving the upper chassis forward of the rigid lower chassis; pivoting, while the rigid lower chassis remains rigid, the front and back legs about the transverse axis downward and forward and the middle body neck portion backward until the rigid lower body is above the stair and the front legs are parallel to the stair; driving, while the rigid lower chassis remains rigid and parallel to the top of the stair, the articulated vehicle forward until the front legs are entirely on the stair; pivoting, while the rigid lower chassis remains rigid, the back legs about the transverse axis forward until they are in a vertical position; driving, while the rigid lower chassis remains rigid and parallel to the top of the stair, the articulated vehicle forward until the back legs are entirely on the stair; and pivoting, while the rigid lower body remains rigid, the front legs backwards and upwards until they are in the vertical position.