The invention mainly concerns a mobility assistance vehicle (1) designed to negotiate obstacles (33, 35) while keeping the attitude of same horizontal, comprising a mechanical structure (2) supporting at least one seat (3), control means (19), at least four articulated legs (6a, 6b, 6c, 6d) and equipped with motorised wheels, characterised in that: i. each first segment (7a-7d) is mounted on one of the lateral sides (200) of the mechanical structure (2) by a motorised articulation (10a, 10b, 10c, 10d), each opposing lateral side (200) being linked to at least two legs (6a-6d), and in that, ii. the control means (19) are capable of controlling the motorised articulations (9a -9d, 10-10d) of the legs (6a-6d) separately from each other, in particular when said legs (6a-6d) are raised successively in order to negotiate an obstacle (33, 35) in a permanently stable situation.
