To camouflage an object is to hide it, conceal it so that it blends in with the surrounding environment. For the military, it’s a tactical necessity and can make the difference between a platoon’s success or failure, a soldier’s life or death. It’s no wonder that the military takes camouflage very seriously. Especially for vehicles.
Over thirty years ago, the U.S. military established policies and procedures to camouflage military vehicles: all sizes and shapes of trucks and accompanying trailers, vans, tanks, forklifts, weapons systems, watercraft transporters, even fire trucks and water purification units.
The colors of a soldier’s uniform are chosen according to the theatre of deployment, and the same rule applies for a vehicle’s paint. The U. S. Marine Corps Depot Operations are responsible for the three R’s of military vehicles: repair, refurbish, rebuild. Because the depots operate as a large scale garage and not a mass manufacturer, the vehicles are refurbished according to the military’s current needs. For example, a jeep that was in service in a tropical region may get a paint job that is appropriate for desert operations. But the depots are under considerable pressure to reduce costs and increase productivity, and re-painting a vehicle’s camouflage patterns is a manual and therefore labor-intensive, time-consuming task. Matt Collins, Vice-President of Vision Systems International (VSI) (Ann Arbor, MI) describes the painting of camouflage patterns on vehicles as a ‘bottleneck operation’. “The patterns are complex and are outlined in chalk by hand before the paint is applied, also by hand.”.
Complex indeed! The camouflage palette contains several military-approved colors, three of which will be used on a vehicle according to its theatre of deployment. The base color is applied to the vehicle’s entire surface and is accented with two additional colors in the camouflage pattern. Each HMMWV (High Mobility Multipurpose Wheeled Vehicle, pronounced ‘humvee’) has its own camouflage painting pattern (CPP), and can be configured with any number of ‘accessories’, items that are added to the base vehicle and are not removed during the refurbishment process. “Those accessories become objects that we have to identify and locate,” explains Collins. The absence of exact standards for the patterns complicates matters even more. “There just aren’t any standards in electronic formats, such as CAD, so it makes for somewhat fluid, ill-defined pattern specifications. When automating a manual process, the lack of specificity creates a lot of interesting challenges,” notes Collins.
VSI’s goal was to develop a vision system that could control a robot to perform as much of the manual process as possible. That is, VSI wanted the robot to paint the camouflage pattern on the given vehicle. With machine vision technology, a smart camera, and of course a robot, Vision Solutions has brought the project to its final phase: deploying a new depot paint facility.
VisionHub, the Central Nervous System
VisionHub is VSI’s proprietary platform that adds 3D capabilities to 2D imaging systems such as those provided by smart cameras. In VisionHub, the Matrox Iris P-300 smart camera takes on the role of ‘Eye’. VisionHub uses the image data to identify and determine location (coordinate) information of the various vehicle types and accessories and convert it into 3-D space. With the position data calibrated for the robot’s coordinate frame, VSI’s 3D algorithms determine the coordinates of the vehicle and its accessories. Then, the robot gets to work and paints the vehicle with the required patterns, which depend on the vehicle’s size, shape, model type and accessory mix.
The work cell is subjected to structured light illumination (SLI), a method of projecting light patterns on an object to generate a 3D image. VSI’s custom SLI algorithms analyze the way the striped light bars bend around the contours of the vehicle to generate the 3D image data. “We consider our structured light library superior to anything else available on the market,” says Collins. “So being able to load our algorithm was important to us. The Matrix Iris architecture allows us to load our algorithms directly onto the smart camera. Plus, we also get the advantage of parallel processing.”