In this paper, a vision sensing system was developed in order to measure the gesture of a serial construction robot and the cylinder displacement of each actuator. The system consists of a single CCD video camera and several light sources which were used to acquire the distance information of key points of the construction robot. The three-dimensional coordinates of key points were obtained from a two-dimensional video image by using image processing. The gesture of the construction robot and the cylinder displacement of each hydraulic actuator were calculated via the inverse kinematics method. In addition, the validity of the proposed method was confirmed through an experiment of parameter estimation for the friction characteristics of a hydraulic cylinder.