Motion and vibration controls for clean image captures of robotic system for automated bridge inspection

Abstract

A bridge inspection robot is developed by the Bridge Inspection Robot Development Interface (BRIDI) at Hanyang University in Korea for an aim of checking the safety status of a bridge and gathering accurate data such as crack width and length. This robot looks similar to the conventional bucket crane, but is much smaller in size and light-weight. At the end of the telescoping boom, a robot platform is mounted which allows the operator to scan the underside of bridge deck through the camera. The environmental conditions under real bridges, however, are neither constant nor controllable. The boom is susceptible to vibration which may compromise the performance of the vision system. This paper presents for developed an inspection robot platform consists of rotary joint mechanisms for both pan and tilt motions of machine vision system and prismatic (up/down) joint mechanism for the gravitational direction movement. Using the suggested motion control system, the machine vision system is able to capture the clean crack image and calculate the length and width of the corresponding crack. Also, this paper proposes a control system to mitigate transverse vibration of the boom by installing on actuator at the elbow of the working boom. This control system is studied using a mathematical model analysis and a scaled model test in the laboratory. The results show that the proposed control system can effectively reduce the telescoping boom vibrations.