Abstract: Portable threshold locators (32B, 32C, 32D) are placed in a room (120) at locations to define at least part of a boundary within which an autonomous vehicular appliance is to be confined. Typically, the threshold locator is placed in a doorway (32B) or at the top of a staircase (32D). The vehicle has a detection system which allows the autonomous vehicular appliance to detect the presence of the portable threshold locator. The detection system receives a signal from the threshold locator and the autonomous vehicular appliance uses the received signal to avoid the threshold marked by the locator (32B, 32C, 32D). The autonomous vehicular appliance is preferably a robotic floor cleaning appliance, such as a robotic vacuum cleaner.

Abstract: A robotic floor cleaning device comprises a chassis (10), motor-driven wheels (11) supporting the chassis (10), a motor-driven suction fan (9), a dirty air inlet (2) and a motor-driven rotatable agitator (4) at the dirty air inlet (2) for agitating the surface. A control system navigates the device around a room and distributes power to the motor-driven wheels (11) and to the agitator (4). The control system detects when the agitator (4) has jammed (100, 102) and, in the event of a jam, attempts to clear the jam (104, 106). After successfully clearing the jam the control system turns the agitator (4) off (114, 116, 118) or navigates the cleaning device around the location at which the jam occurred (119). The cleaning device can store the location of the jam for use in preventing further jams when the cleaning device returns to a similar position in the room.

Abstract: An autonomous vehicle, such as a robotic cleaning device, includes wheels which support the vehicle and allow the vehicle to traverse a surface. Downward looking wheel sensors sense the presence of a surface in front of the wheels. Another sensor is provided at or near a leading edge of the vehicle for sensing the presence beneath the leading edge of the vehicle. The vehicle is arranged so that movement of the vehicle is possible if the leading edge sensor senses that there is no surface beneath the leading edge of the vehicle, provided that the wheel sensors indicate that there is a surface adjacent to the wheel. When the leading edge sensor senses that there is no surface beneath the leading edge of the vehicle, the vehicle performs an edge following routine.