1. Introduction
High voltage lines need to be inspected regularly, at least once a year. At
present, this work is done by teams on foot, as well as by helicopter missions.
Inspections on foot need a lot of time and in some situations are even impossible
due to difficult terrain such as mountains or steep valleys. The helicopter
missions are somewhat quicker but very costly, tedious and difficult, especially
for the pilot, since he needs to fly at minimum distance to the power lines. The
possibility of strong side winds additionally turns this task into a dangerous
situation [4].
Figure 1. Common mast tip with ground cable departing on both sides.
The main goal of this project is to develop a device that moves along the
wires and traverses the standard mast tip of the Swiss power industry. Figure 1
shows such a mast tip that is widely used in Switzerland and most other
European countries. On each side one can see the ground cable leaving the tip
towards the next mast. These cables do not transmit power and are installed on
top of the other cables to protect from damages caused by lightning. The main
difficulty to deal with was to find a mechanism that can move on the sloping
wire (also around horizontal angles) and ride over all the different obstacles on
top. So far, different research groups have developed several robots that can
cross obstacles on the wires [1-3]. Most of these robots use active structures that
result in designs with a relatively high number of actuators and sensors –
leading to a complex control and resulting in relatively big and expensive
devices of slow speed.
In order to realize a robot that is simpler, faster and more robust, the main
goal within this work is to realize a vehicle structure with a passive articulation
that can just roll over the specified obstacles.