In reference to the patent: US7926598
What a patent covers is described by its claims. You should first read the independent claims (claims that don't refer to other claims). Here is the first claim of the cited patent.
A method for operating a mobile robotic vehicle to surmount a series of stair risers, comprising:
driving a support surface to propel the vehicle to place the support surface in contact with the riser of a first stair below an uppermost edge of the first stair riser;
further driving the support surface to cause the forward end of the vehicle to ascend the riser of the first stair, the support surface generating sufficient traction against the riser to climb the riser as the support surface is driven;
pivoting a first pivoting trailing arm to raise a rearward end of the vehicle while the forward end of the vehicle is supported by the first stair; driving the support surface to advance the forward end of the robot over the uppermost edge of the first stair riser;
pivoting the arm to further raise the rearward end of the vehicle such that the forward end of the vehicle tips downward beyond the uppermost edge of the riser of the first stair;
and repeating the driving and pivoting to surmount a second stair of the series of stair risers.
You can see this covers not an entire robot, but the method of enabling the robot to climb stairs using specific design features.