Inspection of tunnels or canals that are underground and in places of difficult access (e.g. mountains) can be very difficult and dangerous for humans. In the future, these operations have the potential to be performed by autonomous unmanned vehicles that can access much harsher locations and conditions. However, there is a current limitation that is preventing the deployment of this technology for the monitoring of complex and expansive networks of tunnels: standard position reference technologies struggle to perform where GPS or wifi are not available, and/or environmental conditions are challenging.

Therefore, this solution can be embedded in state-of-the-art unmanned vehicles and allow to determine their exact position during inspections of tunnel networks.

The solution is based on the principle of "ANTS TRAIL."

As per the sketch there will be some small sensors which will be carried out by the inspection vehicle. These small sensors will work on radio signals. When the vehicle enters the tunnel it will work to drop each sensor one by one after travelling a certain distance ( 100 to 500 meters). These sensors or small robots will send the signal outside the tunnel after communicating with each other and in this way we can find out exact location of vehicle in the tunnels. These sensors will be lightweight and easily embedded with any vehicle with robotics. The salient feature is that the vehicle can collect back these small sensors on the way back. The design of these sensors will be depend on the surface of tunnels.