ROBOTIC VACUUM CLEANER

A robotic vacuum cleaner comprises a main body (12, fig 1), a wheel 28, a drive motor, a gearbox 36, and a distance sensor (26, fig 2). The distance sensor is for sensing a distance between the main body and a surface upon which the wheel is located. The robotic vacuum cleaner includes a suspension system coupling the wheel to the main body. The suspension system includes a first arm 60 and a second arm 62, the first arm coupled to the gearbox at a first pivot point 70 and coupled to the main body at a second pivot point 74, the second arm coupled to the gearbox at a third pivot point 80 and coupled to the main body at a fourth pivot point 82. The first pivot point is spaced from the third pivot point by a first distance A, and the second pivot point is spaced form the fourth pivot point by a second distance B greater than the first distance. The ratio of the second distance to the first distance is in the region of 1.1 to 3.0.