Many vehicles having level compensation for traversing uneven terrain are known. With regards to vehicles for ascending stair cases different solutions are proposed. For instance, CA 2,227,955 discloses a motorized armchair having two serially connected wheel pairs. A seat may pivot around an axis to maintain a level position in one direction. The large number of serially connected wheels may provide for an increased grip when ascending a stair case, however at the cost of a bulky solution, e.g. when ascending a narrow passage in a stair case.
An issue with prior art vehicles is high weight, in order to provide stability of the vehicle, in particular with a payload of large weight. This limits the practical use of such vehicles, e.g. when wanting to travel in an elevator which has limited surface and load capacity available. Lighter vehicles also need less propelling energy, which is a desired advantage.
U.S. Pat. No. 7,631,380 discloses a spine board having an opposing set of wheel assemblies comprising three wheels for manually maneuvering in stairs.
SU 1833182 discloses a wheel chair for manually surmounting stairs having front driving wheels on a balance arm being pivotable with respect to the wheel chair frame. The front driving wheels are off-set to each other.
U.S. Pat. No. 3,893,533 discloses a recreational motor vehicle for use in rough terrain. The front wheels are offset longitudinally to provide a more stable stance for the vehicle and greater driving traction.
A further issue with prior art is the lack of level compensation that keeps the ride smooth, even when driving in stairs. When ascending or descending the stair each step produce a corresponding zic-zac or rocking motion in the vertical and horizontal directions at the seating position of the vehicle. The lack of level compensation in such terrains also result in an inefficient power transfer and thereby use of energy, as traction is repeatedly lost.
Furthermore, another issue with prior art is the lack of adjustability to different terrains. The user of a personal vehicle may encounter different obstacles, e.g. stairs having varying step dimensions, on a daily basis when moving around in the home environment or a public environment. If the vehicle would be optimized to traverse a staircase at home, it may not be suitable for other obstacles. The need for adjustability of the vehicle is thus important in order to safely and comfortably traversing such varying obstacles. Otherwise several vehicles would be needed, each especially adapted to a particular terrain, due to lack of adjustability, and the user would have to switch vehicles regularly, which may not be possible for a user without help. The degree of freedom and independence could accordingly be improved for the vehicle user.
Hence an improved vehicle and/or method providing a safe and comfortable ride across obstacles having different dimensions would be advantageous and in particular allow for a flexible solution to travel across such varying obstacles.