Masonry Magazine October 1997 Page. 29
Robotic Wall Climber
For The Tough Job
by Bill Siuru
Everyday sandblasters, wall and window washers, painters and others work in harms way on the sides of buildings, tanks, smokestacks and bridges. The dangers not only include the possibility of falling but also exposure to hazardous materials like toxic fumes, dust, lead, and other things that can put the human worker's health at risk. Besides the danger and health hazard, doing these jobs with human workers is very labor intensive and often requires expensive scaffolding or cranes plus cumbersome protective respiratory gear and safety equipment.
The answer could be the WallWalkerTM originally developed jointly by Pentek Inc, in Corapolis, PA and Department of Energy (DOE). The WallWalker uses two gear motors attached at the top of the wall or other vertical surface. The process module which can be a hydroblaster, abrasive blaster, automated welder, inspection sensor, paint sprayer, window washing device, etc. is attached by a single once-through cable.
A computer program is used to precisely determine the lengths of the two cable sections using simple triangulation. The lengths of the cable are precisely known to within 0.01 inch (0.25 mm). The program adjusts the module's grid coordinates so it moves across the wall surface precisely and reliably according to the programmed instructions. The shape of the device's path and its velocity is controlled so the working head can move across the surface at speeds of up to 60 feet-per-minute. The WallWalker can be programmed so it can handle walls of virtually unlimited height and width as well as conform to wall surface irregularities. The system can handle working loads of 500 pounds.
Pentek's WallWalker™ performing painting operations for New Jersey's Public Service Electric & Gas. The wall system can perform 100% dustless surface preparation, paint application, and inspection tasks. Photo courtesy of Pentek, Inc.
Originally, the WallWalker was developed for decontaminating large vertical surfaces without exposing workers to hazardous radioactive dust and debris. The automated wall locomotion system was successfully demonstrated at the DOE's Energy Technology Engineering Center (ETEC) in Canoga Park, CA., in August 1996. In the demonstration, the WallWalker robotically performed decontamination and surface removal on an 18' x 12' x 25' deep concrete waste storage vault at the site. Using a special surface scarification module, the WallWalker decontaminated the waste storage vault in 14-inch wides passes with a 1/8" removal depth. The hazardous dust and debris was contained by a vacuum seal between the robot and the wall surface. The hazardous material was immediately conveyed by hose directly into Pentak's VAC-PAC(R), a self-cleaning and drumming HEPA vacuum and waste collection system. A fully integral radiation measuring
Wall Walker™ systems can eliminate scaffolding and remove workers from dangerous positions and/or working environments, while functioning reliable in the most hostel environments. Photo courtesy of Pentek, Inc.
device simultaneously performed pre- and post-decontamination surveys to ensure the cleanup complied with regulatory mandates.
While demonstrated in a radioactive decontamination role, the module can be configured to perform 100% dustless surface preparation using hydroblasting, CO2, baking soda, chemicals, lasers, flashlamps, abrasive blasting, mechanical scarification, and other cleaning techniques. The module can be used to simultaneously prepare the surface, resurface it and then inspect to reduce time and cut costs.
Since the process controls are completely automated and computer controlled, abrasives and coating materials can be applied with amazing precision. It can be operated around-the-clock in most inclement weather with a minimum of workers and supervisory personnel. The WallWalker can also be used to transport materials reducing the number of cranes and lifts needed.
MASONRY-SEPTEMBER/OCTOBER, 1997 29