The abilities of robots continue to advance with highly capable products performing a variety of tasks, looking almost humanlike as they speak, and even garnering appearances in movies. Perhaps less attractive but equally or even more useful, creeping or crawling robots bring drones down to earth and, in fact, inside the earth. Unlike the micro air vehicles (MAVs) in Part 2, sewer robots are currently available from several companies, but researchers are still investigating ways to improve them.
Large as well as smaller cities have extensive underground pipes. The older the city is, the more complex and frequent the need to repair hard to access problems. For example, the United Kingdom (UK) has about one million kilometers (621,000 miles) of pipes. Annual maintenance and repairs for these pipes requires about 1.5 million road excavations a year. Besides causing either full or partial road closures, these activities are noisy, dirty, cause a lot of inconvenience, and cost around £5.5 billion ($6.8 billion) a year. It’s easy to see why sewer robots gather a lot of attention.
The interest in sewer robots stems from the number of potential robots that could be required and the major problems that they can solve.
With over 15 years of experience, one manufacturer makes what it calls a multi-functional crawler that uses a variety of job-specific modules for underground pipe inspection, cleaning, cutting, and rehabilitation. While the uses can be quite different, all require a rugged vision system. Equipped with a pan & tilt inspection camera, operations performed by the crawling robots include inspection to find problems and cutting by using air, water or electric means to remove items such as roots, cement, grout, concrete, failed liners, and mineral deposits.
For these scrawling robots , the video camera uses analog high definition (HD) technology with 1080 pixels and 30 feet per second (fps) (recorded). The camera’s pan is infinite and the camera tilt is 230°. With manual focus and lighting provided by intensity adjustable LEDs, the camera’s visibility is maintained through a lens cleaner and operator controls.
In the UK, Pipebots is a large UK government-funded research project working on robots to help maintain the underground pipe system.
Autonomous operation of the crawling pipebots occurs through the use of an array of on-board sensors. When fully developed, the robots will rely on computer vision and a combination of an accelerometer, gyroscope, and magnetic field sensor (that provide an inertial measurement unit (IMU)) to detect where they are and possibly a laser range finder. Ultrasound and infrared distance sensors will help the robots to navigate the pipes. Acoustic and ultrasound sensors will detect cracks in water pipes, blockages in sewer pipes, and measure the overall condition of these pipes. Analysis using sonic waves assesses the extent of the blockage and complements the visual inspection provided by the camera. Pipebots will have different sizes, depending on the pipes they are used in. For example, the smallest ones will have to fit in a cube with a side of 2.5cm (1 inch), while the largest ones could be as wide as 50cm (19.7 inch).