A multi-unit mobile robot comprising a plurality of separate carriages or units linked together by linkages. Each unit comprises hinged first and second segments which facilitates pitch relative motion between the segments, and accordingly the units. By controlling actuators to the hinges, one can cause the robot to coil around and compress against the exterior, or compress against the interior, of an object to be traversed. The linkage between mobile units facilitates at least one of lateral pivot or yaw relative motion between units, and optionally roll. Each hinged platform is carried by a pair of Mecanum wheels, which facilitate movement of the unit in any direction.Among other possible uses, the multi-unit mobile robot can be used to service windmill blades and towers, and carrying cargo up and down windmill towers by directing a multi-unit mobile robot to wrap around the and traverse the tower.