The mobile construction robot system of VTT consists of a track based vehicle, an industrial robot, support legs and process tooling. The main purpose of the control of the vehicle is the navigation and estimation of the position of the vehicle on construction site with an accuracy of ±50mm.The system takes also care of the support legs and communications between the vehicle and the industrial robot and contains necessary user interface. The navigation and positioning is based on internal measurements so far. The automatic movements of the vehicle starts with a user defined position in working area. The desired path is sent to the vehicle as movement commands. The position control with internal sensors stabilizes movements. If amount of manual re-calibration is to be decreased, then external position measurement systems should be integrated to the system interfaces and capacity is reserved for them.