Systems integration in telerobotics: case study: maintenance of electric power lines

Teleoperation has been proven useful for maintenance of power distribution networks in Japan, the United States, Canada, and in Europe. It is generally thought, however, that automation would greatly improve performance. Telerobotics can indeed compensate for the losses of dexterity and sensory feedback caused by practical manipulation and vision systems. Time delays and communication bandwidth are not an issue, however, and operators are still required for decision making, hence autonomy is not a goal in itself in this application. This paper presents how the operator and practical robotic techniques are used together to form a complete system, and illustrates the capabilities of that system. We show that simple graphical interfaces can guide the operator through a series of operations to mediate the manual and automatic phases of the tasks. To this end, robot and sensor functions are available at various levels of abstraction, allowing interactions ranging from delicate manual control to task supervision, including various levels of cooperation between the human and the machines. The system includes multiple robots, force sensors and tools, video cameras and laser range sensors, as well as a number of hand controllers, the integration of which requires techniques such as impedance control, force feedback, kinematic calibration and image processing. We stress the importance of the validation of theories in complete applications to reveal the real problems, and we point out and discuss some of those practical problems