An Extended Hand Movement Model for Haptic-based Remote Operation of Infrastructuremaintenance Robots

When human operator is in the control loop of a robotic system, which operates in unstructured, complex and dynamic environments such as those in construction and steel bridge maintenance, human factors will have significant effect on the operational performance and control of the robot. This paper aims to investigate this effect and develop efficient methods for operational performance improvement. An eXtended Hand Movement (XHM) model for eye-guided hand movement is developed with the aim of providing natural and comfortable interaction between a human operator and a robot. A haptic force-speed-accuracy control method is then designed based on the XHM model and implemented in a steel bridge maintenance robotic system. An experiment is conducted to verify the model and control method. Experimental results demonstrated significant improvement in control accuracy and operational performance in a steel bridge maintenance robotic system. Keyword: Human-Robot Interaction, Haptic Interface, Human Factor, Steel Bridge Maintenance Robot  INTRODUCTION Industrial robots have been widely used to perform welldefined repetitive tasks in carefully constructed simple environments such as manufacturing factories. The future of industrial robots is to operate in complex, unstructured and unknown (or partially known) dynamic environments such as those in construction and steel bridge maintenance, to assist human workers in undertaking hazardous tasks. Autonomous operation of industrial robots in such environments is ideal, but there are a lot of challenges that need to be addressed. Semi-autonomous or manual operation with human interaction is a practical solution because it utilises human intelligence and experience combined with the power and accuracy of an industrial robot. Therefore, haptic-based human-robot interaction provides an enabling methodology. However, there are still many challenging issues which need to be solved. When human operator is in the control loop of a robotic system, human factors will have significant effect on the performance of haptic-based human interactive operation. This paper aims to investigate this effect and an efficient method for operational performance improvement. An eXtended Hand Movement (XHM) model for eye-guided hand movement is investigated in this paper with the aim of providing natural and comfortable interaction between a human operator and a robot, and improving the operational performance. The model is studied for increasing the speed of the robot manipulator while maintaining the control accuracy. This model is then applied into a steel bridge maintenance robotic system [1][21]. Fig. 1 shows the robotic system developed for sandblasting operation in steel bridge maintenance. It consists of a robot arm affixed with sandblasting equipment and placed on a mobile platform. A haptic device with force feedback is used to operate the robot in a complex environment. A virtual spring method [2] is used as the haptic device and robot arm interface for guiding the robot arm to target points. Attractive force (AF) method [3][4] and three dimensional virtual force field (3D-VF) method [5] are also used for target position control and real time collision avoidance. When a human operator is in the control loop of the robot arm by means of the haptic device, for example sandblasting path planning, end-effector (or sandblasting nozzle) motion control and robot collision avoidance, the S34-2