 Piper Bot Inspection Robot
Submitted to Parallax by Juan Pablo Angulo
This project was developed as a request from a construction company in charge of installing 20 km of piping for a water treatment plant in Saltillo, Mexico. The company had to make sure the ducts were in place and properly installed after placing them 3 to 7 meters underground. Duct diameters ran from 18” to 64” and material was a black polymer. Sometimes after burying the ducts with certain rush, pressure from the material would collapse a duct, but it was hard to notice since it was already 5 metes underground. Inspection wells were placed in the pipes, however the distance between them exceeded 250 feet. Its hard to tell if a duct is not properly installed when looking at it in pitch dark. Construction time was a merely 4 weeks and it was sold and delivered just in time for testing the installed ducts."Brinestein"  Piper-bot was constructed using laser cut materials, and was powered by 4 fixed geared motors with high traction wheels. It carried an EVI-D30 High Quality Sony PTZ camera on board with a 2.4 GHz High Power Video transmitter. Two high intensity MAGlite white LEDs provided enough light to clearly see details inside the ducts. An SRF05 ultrasonic sensor attached to the front of Piper-bot provided diameter measurements of the ducts, while an Memsic Accelerometer provided information regarding roll and pitch angles. Battery information was also sampled using an ADC0831 and a resistor ladder. An odometer was developed in order to register approximate distance to dig from the inspection well in case there was need for a duct fix. Motor control was delegated to a Motor Mind C controller from solutions cubed, while camera PTZ commands were send via infrared through an specific application PIC (instead of using the VISCA port). All the collected data was superimposed on the video signal using a BOB-II video card prior to transmitting. Commands arrived to Piper-bot via 900MHz Full Duplex Aerocomm modems.
A BS2-IC was in charge of everything on the robot, it received ASCII commands through modem, and performed the associated tasks, from the turning on the video camera and sending it pan-tilt-zoom commands or view presets, to reading the ultrasonic sensor and calculating diameter in centimeters, calculating roll and pitch angles, monitoring the battery charge, formatting and sending all data to BOB-II video card and sending commands to the MMC to move the robot inside the pipe.
Redundant check of command-base communication was important (since we didn’t want to crawl to retrieve a lost Piper-bot in the middle of a 18” diam. 250 feet pipe), in case signal from the command base was lost, Piper-bot would begin a routine in which it would wait a few seconds to see if signal reappeared, otherwise it would start navigating autonomously through the pipe until it would reach the end. In a low battery condition a warning is displayed on the video signal so the operator takes precautions, in case of extreme low battery condition Piper-would take command and turn the camera and both lights off in order to stop battery depletion and use the remaining energy to reach the end of the duct in an autonomous navigation pattern.
On the command-base side, another BASIC Stamp II reads data from a Parallax Mini keyboard, it then proceeds to send this data through the Aerocomm modem and wait for confirmation or acknowledgment from Piper-bot. If no acknowledgement is received the command is sent a few more times until its dropped. When no new commands are entered, command base’s BASIC Stamp II sends a beacon command, so Piper-bot knows the command base is still within range; if nothing is received for a while, Piper-bot begins its autonomous navigation routine. A Video Receiver sits at the command base, with an LCD screen that displays real-time video and superimposed information. An optional Video Recorder can be connected to make videos of the inspections. Batteries for both Piper-bot and Command base are Ni-MH 6 cell type.
Piper Bot Video (youtube):
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