Falcon-III is a robotic personal vehicle that has been designed for uneven terrain usage. It has a two-degree-of-freedom suspension mechanism that allows the passenger's seat orientation (pitch and roll) to be controlled by actively adjusting the height of its wheels. This paper discusses the motion control of such a vehicle on rough terrain. In particular, we show that a feedback control law that measures the vehicle seat attitude and acts to correct it, aiming at maintaining the horizontal seat posture during the traversing of uneven terrain, is by itself insufficient to provide satisfactory performance on certain types of terrain. Therefore, we propose a predictive motion control strategy, in addition to the feedback control law, that dynamically controls the vehicle suspension in order to facilitate the negotiation of obstacles - the motion executed is somewhat similar to that performed by a cyclist when overcoming a step-like obstacle. When tall step-like obstacles have to be negotiated, it may be necessary to dynamically lift one of the wheels from the ground, in which case a gait pattern emerges.

With the appearance of many personal vehicles developed for urban environments, it seems pertinent to address the development of off-road personal vehicles as well. This paper discusses this exact topic, and proposes a three-wheeled configuration which stabilizes the horizontal posture of the vehicle's driver in rough terrain. The merits of such a machine are examined; in addition, a mechanism here called sliding-rod-end is introduced, and the reasons for its use instead of regular rod ends are explained. A full-scale prototype of the machine was built and is briefly presented.