A supporting structure (100) comprises two pairs of legs (2) and four wheels (2w) each arranged at a lower end of a respective one of the legs. Each leg comprises an upper segment (2u) and a lower segment (21), and optionally a retractable leg extension segment (2e) for contacting ground instead of the corresponding wheel. Such supporting structure is adapted for producing a lowering motion while keeping the legs crossed on both lateral sides. Such supporting structure may be adapted for assisting a disabled person in travelling on the ground, and also possibly in climbing stairs.
