Pipe Fixing Robot 

A little more information and renders for the pipe crawling robot without the pipe fixing assembly. Primarily built for smaller diameter pipes, this concept has magnetic wheels which allow it to crawl inside metal pipes. The motors and wheels are suspended from the shoulder mounts which allow the wheels to angle and conform to the curved surface of the pipe.

In the image below the locking assembly is visible in more detail. The cam and motor at the center forces the locking frames towards the body panels pushing the pins into the alignment holes. This fixes the wheels in either the vertical or horizontal positions.

The wheels can change positions once the frame is lifted. Rotating wheels in opposite directions forces them towards the center/sides. Then the pins can be pushed down to lock the wheels in place again.

The locking frame helps limit the number of locking pins and actuators to just one. However, this mechanism needs a more work to be robust and reliable.

Below is the robot in the horizontal crawling form. This allows the robot to crawl up the side of the pipe. The robot is in its 'crab' form.

Another render of the same orientation...just because.

To fix leaks and small cracks, the bot would place down magnetic pads over them. Another option would be using filler/resin which would also help protect the crack from growing under mechanical or thermal stresses. To localize the bot, wheel rotations could be used (magnets could ensure almost no slipping)  and combining this with data from an IMU could provide greater accuracy.  Ultrasonic sensors could also be added so that the bot knows it is at the crack. This type of bot design allows for use in a much wider range of pipe sizes with forks and bends. The biggest disadvantage of this design is that  it would only work with ferromagnetic pipes.

For work with plastic/concrete pipes a different design with spring loaded arms around a central body could be used.

Another more radical idea would be to use  a design where the bot floats in the water or is lifted up using wings and is pushed by the force of the water flowing itself or a propulsion system like a water jet. In the former it can control its speed by changing the profile presented to the flow with a sail like feature. The difficulty with this concept would be to stop the robot at the correct spot.