project specification

Pirate

A robot for moving in small diameter pipe which is capable of negotiating curves, diameter changes, sharp bends and T-joints,intended for (semi) autonomous inspection of gas distribution mains. The PIRATE (Pipe Inspection Robot for Autonomous Exploration) is fully actuated and uses identical modules to make it easier to manufacture and maintain. It has a high spreading factor (63 mm - 125 mm outside diameter) allowing it to be used in a large section of the (urban) low pressuregas distribution net. The robot is able to take a vertical climb, broadening the general application range and facilitating entry in the gas distribution network by means of vertically drilled holes. The robot is largely developed by using additive manufacturing.

Specifications

Spreading factor63 - 125 mm
Inclination of the pipe+/- 30
Manufacturing technology3D printing

Overview

The PIRATE (Pipe  Inspection  Robot  for  Autonomous  Exploration) is fully actuated and uses identical modules to make it easier to manufacture and maintain. It has a high spreading factor (63 mm - 125 mm outside diameter) allowing it to be used in a large section of the (urban) low pressuregas distribution net. 

The robot is able to take a vertical climb, broadening the general application range and facilitating entry in the gas distribution network by means of vertically drilled holes. The robot is largely developed by using additive manufacturing.

The robot uses a modular structure consisting of bending modules, drive modules and one rotation module. Two bending modules form a clamping v-shape which generates the necessary traction force on the tires. Two driven wheels are used for propulsion.

Clamping

The robot uses a V-shaped section consisting of two modules to generate traction force on the tires. The tires are in this case neoprene rubber O-rings of 3 mm diameter. The amount of clamping force that can be generated using this V-shapeis dependent on the diameter of the pipe. The clamping module has a gear train to transfer power from the self-locking worm gear via the spring to the joint. 

For vertical climbing, the amount of clamping torque necessary depends on theavailable friction force. The friction force is depending on the materials: smooth PE or PVC for the pipe wall and rubber O-rings as tires. Every wheel has a motor mounted inside, called ’in wheel drive’.  

Modular

Every wheel has an in-wheel mounted drive system, and every joint is able to bend in one plane, every module of the robot has the same make-up, except for the rotation module in the center. The minimal robot configuration consists of two clamping V-shapes with one center rotation point. This configuration can be made using four exactly the same modules and one different rotation module.

Sensors

The robot consists of rotary hall-effect based sensors. These absolute position sensors have a resolution of 12 bit and are interfaced digitally (using  an  SPI  protocol).  

References

Describes the robotic design, the clamping, all wheel drive, the modular concept, position sensing, and implementation of the design and its iterations.

Edwin Dertien, Mohammad Mozaffari Foumashi, Kees Pulles, et al.

Describes the design considerations of the inspection system, the design of the robot, the prototype, and the conclusion.

Edwin Dertien, Mohammad Mozaffari Foumashi, Kees Pulles, et al.

Describes the background of the project, related research, the requirements to develop the robot, its design, research results, and the conclusion.

Edwin Dertien, Stefano Stramigioli. 2011

Wevolver 2022