Motion: enhancing signals and concealing cues

ABSTRACT Animal colour patterns remain a lively focus of evolutionary and behavioural ecology, despite the considerable conceptual and technical developments over the last four decades. Nevertheless, our current understanding of the function and efficacy of animal colour patterns remains largely shaped by a focus on stationary animals, typically in a static background. Yet, this rarely reflects the natural world: most animals are mobile in their search for food and mates, and their surrounding environment is usually dynamic. Thus, visual signalling involves not only animal colour patterns, but also the patterns of animal motion and behaviour, often in the context of a potentially dynamic background. While motion can reveal information about the signaller by attracting attention or revealing signaller attributes, motion can also be a means of concealing cues, by reducing the likelihood of detection (motion camouflage, motion masquerade and flicker-fusion effect) or the likelihood of capture following detection (motion dazzle and confusion effect). The interaction between the colour patterns of the animal and its local environment is further affected by the behaviour of the individual. Our review details how motion is intricately linked to signalling and suggests some avenues for future research. This Review has an associated Future Leader to Watch interview with the first author.

Virtual Motion Camouflage Based Visual Servo Control of a Leaf Picking Mechanism

For a lately constructed disease detection field robot, the segregation of unhealthy leaves from strawberry plants is a major task. In field operations, the picking mechanism is actuated via three previously derived inverse kinematic algorithms and their performances are compared. Due to the high risk of rapid and unexpected deviation from the target position under field circumstances, some compensation is considered necessary. For this purpose, an image-based visual servoing method via the camera-in-hand configuration is activated when the end-effector is nearby to the target leaf subsequent to performing the inverse kinematics algorithms. In this study, a bio-inspired trajectory optimization method is proposed for visual servoing and the method is constructed based on a prey-predator relationship observed in nature (“motion camouflage”). In this biological phenomenon, the predator constructs its path in a certain subspace while catching the prey. The proposed algorithm is tested both in simulations and in hardware experiments.

Adaptive terminal guidance law with impact-angle constraint

ABSTRACTThis paper proposes an adaptive guidance law for attacking a ground target based on motion camouflage strategy. The coefficients of normal and bi-normal feedback guidance law are given according to the relative motion relationship under Frenet frame. Utilizing the coefficients, the motion camouflage proportional guidance law is derived. In order to improve the initial overload characteristic of the missile, an adaptive feedback coefficient is introduced. Then, the adaptive guidance law is applied to a longitudinal plane interception problem with impact-angle constraint. Finally, the validity of this guidance law for air-to-ground missiles is proved by simulations.