Biomimetic chameleon soft robot with artificial crypsis and disruptive coloration skin

Development of an artificial camouflage at a complete device level remains a vastly challenging task, especially under the aim of achieving more advanced and natural camouflage characteristics via high-resolution camouflage patterns. Our strategy is to integrate a thermochromic liquid crystal layer with the vertically stacked, patterned silver nanowire heaters in a multilayer structure to overcome the limitations of the conventional lateral pixelated scheme through the superposition of the heater-induced temperature profiles. At the same time, the weaknesses of thermochromic camouflage schemes are resolved in this study by utilizing the temperature-dependent resistance of the silver nanowire network as the process variable of the active control system. Combined with the active control system and sensing units, the complete device chameleon model successfully retrieves the local background color and matches its surface color instantaneously with natural transition characteristics to be a competent option for a next-generation artificial camouflage.

Visual perception and camouflage response to 3-D backgrounds and cast shadows in the European cuttlefish Sepia officinalis

To conceal themselves on the seafloor European cuttlefish Sepia officinalis express a large repertoire of body patterns. Scenes with 3-D relief are especially challenging because neither is it possible to directly recover visual depth from the 2-D retinal image, nor for the cuttlefish to alter its body shape to resemble nearby objects. Here we characterise cuttlefish's camouflage responses to 3-D relief, and to cast shadows, which are complementary depth cues. Animals were recorded in the presence of cylindrical objects of fixed (15mm) diameter, but varying in height, greyscale and strength of cast shadows, and to corresponding 2-D pictorial images. With the cylinders the cuttlefish expressed a ‘3-D’ body pattern, which is distinct from previously described Uniform, Mottle, and Disruptive camouflage patterns. This pattern was insensitive to variation in object height, contrast, and cast shadow, except when shadows were most pronounced, in which case the body patterns resembled those used on the 2-D backgrounds. This suggests that stationary cast shadows are not used as visual depth cues by cuttlefish, and that rather than directly matching the 2-D retinal image, the camouflage response is a two-stage process whereby the animal first classifies the physical environment and then selects an appropriate pattern. Each type of pattern is triggered by specific cues that may compete allowing the animal to select the most suitable camouflage, so the camouflage response is categorical rather than continuously variable. These findings give unique insight into how an invertebrate senses its visual environment to generate the body pattern response.

Variable crab camouflage patterns defeat search image formation

Understanding what maintains the broad spectrum of variation in animal phenotypes and how this influences survival is a key question in biology. Frequency dependent selection – where predators temporarily focus on one morph at the expense of others by forming a “search image” – can help explain this phenomenon. However, past work has never tested real prey colour patterns, and rarely considered the role of different types of camouflage. Using a novel citizen science computer experiment that presented crab “prey” to humans against natural backgrounds in specific sequences, we were able to test a range of key hypotheses concerning the interactions between predator learning, camouflage and morph. As predicted, switching between morphs did hinder detection, and this effect was most pronounced when crabs had “disruptive” markings that were more effective at destroying the body outline. To our knowledge, this is the first evidence for variability in natural colour patterns hindering search image formation in predators, and as such presents a mechanism that facilitates phenotypic diversity in nature.

Adaptive Camouflage for Moving Objects

Targets that are well camouflaged under static conditions are often easily detected as soon as they start moving. We investigated and evaluated ways to design camouflage that dynamically adapts to the background and conceals the target while taking the variation in potential viewing directions into account. In a human observer experiment, recorded imagery was used to simulate moving (either walking or running) and static soldiers, equipped with different types of camouflage patterns and viewed from different directions. Participants were instructed to detect the soldier and to make a rapid response as soon as they have identified the soldier. Mean target detection rate was compared between soldiers in standard (Netherlands) Woodland uniform, in static camouflage (adapted to the local background) and in dynamically adapting camouflage. We investigated the effects of background type and variability on detection performance by varying the soldiers’ environment (such as bushland and urban). In general, detection was easier for dynamic soldiers compared to static soldiers, confirming that motion breaks camouflage. Interestingly, we show that motion onset and not motion itself is an important feature for capturing attention. Furthermore, camouflage performance of the static adaptive pattern was generally much better than for the standard Woodland pattern. Also, camouflage performance was found to be dependent on the background and the local structures around the soldier. Interestingly, our dynamic camouflage design outperformed a method which simply displays the ‘exact’ background on the camouflage suit (as if it was transparent), since it is better capable of taking the variability in viewing directions into account. By combining new adaptive camouflage technologies with dynamic adaptive camouflage designs such as the one presented here, it may become feasible to prevent detection of moving targets in the (near) future.

Camouflage Combat Uniform

The development, testing, and fielding of combat uniforms for soldiers offer acquisition professionals an opportunity to analyze how programs progress through the U.S. defense acquisition system. This case centers on the U.S. Army’s decision to change the camouflage patterns on combat uniforms and equipment for soldiers. The case is broadly applicable to project managers, business managers, engineers, testers, and logisticians involved in project management, while specifically targeting defense acquisition professionals. Emphasis is placed on the development of critical thinking and analysis skills in the areas of stakeholder management, resource management, and decision making in a complex environment. The case is developed in two distinct parts. Part I provides an analysis of the Army’s development of a plan with an increased chance of success in meeting desired objectives. Part II analyzes how the Army decided to change the camouflage pattern on combat uniforms through an informed, knowledge-based process.