14-06-2012, 05:11 PM
design and validation of mobile robot for power line inspection and maintenance
DESIGN AND VALIDATION OF MOBILE ROBOT FOR POWERLINE INSPECTION AND MAINTANNCE.docx (Size: 1.21 MB / Downloads: 38)
INTRODUCTION
Power line inspection and maintenance activities have lagged behind in the use of robotic technologies even though power line maintenance work must be carried out routinely in hostile environments and hard-to-reach locations. Working on energized lines is now a necessity for most maintenance jobs. Transmission grid owners are looking towards innovation as transmission systems are under pressure from increasing loads and stringent reliability requirements . Although some tasks have been successfully automated and more research teams have been active in mobile robotics in recent years , most research results published in the past are based on concepts or prototype technologies that
never made it onto transmission networks. Following an extensive review of technologies applied to transmission line inspection and maintenance , the authors undertook the development of Line-Scout Technology as part of a Hydro-Québec research program that aims at providing robotic technologies to perform inspection and maintenance on its transmission lines . From the very beginning, the key objective was to design a robust, reliable and field oriented mobile platform that would be applicable to real inspection and maintenance tasks, aligned with power line maintenance teams’ considerations.
SYSTEM REQUIREMENTS
A complete review of transmission line components and circuit configurations was conducted in order to identify the wide variety of obstacles that must be cleared by the robot. Among these, warning spheres (0.76-m diameter, Fig. 1A) and corona rings (Fig. 1B) were chosen as the longest obstacle to cross. Other
examples of critical components identified are double insulator string configurations and vibration dampers potentially damaged by excessive vibration (Fig. 1C, 1D)
DESIGN OF THE TECHNOLOGY
Mechanical Concept:
Using one conductor as a support, rolling with wheels for locomotion not only allows moving quickly and efficiently along the power line, but also makes it possible to roll over some obstacles (compression splices, vibration dampers). To clear other types of obstacles, the approach chosen uses the sequence schematized in Fig. 2. LineScout is built around three independent frames (Fig. 2): the wheel frame (dark frame), which includes two motorized rubber wheels called “traction wheels”, the arm frame (light frame), with two arms and two grippers, and the center frame (white circle), which links together the first two frames (called “extremity frames”) and allows them to slide and pivot. As an obstacle is reached, the arm frame is deployed so that the two arms and grippers can temporarily support the robot while the wheel frame is transferred on the other side of the obstacle. To do so, the wheels themselves are flipped down under the obstacle.
Geometrical Optimization:
One of the main advantages of this concept in comparison to other existing prototype is that it is neither limited to a specific size of obstacle nor to a specific distance between adjacent obstacles, making it versatile and adaptable to various sequence of obstacles. In fact, six different clearing sequences were identified as strategies for crossing consecutive obstacles, depending on their sizes and the distance between them. Three of these variants are presented in Fig. 5. Also on this figure, LoMAX is defined as the maximum length of a crossable obstacle, and DoMIN is defined as the minimum distance between two consecutive obstacles.