# State of the Art Review about Bio-Inspired Design and Applications: An Aerospace Perspective
## 4 Applications of Bio-Inspiration in the Aerospace Industry
### Sensors
A neural network based  
Figure 23: Optic sensors based on Elementary Motion Detection (**a**) Compound eye of a fly (**b**) A bio mimicked synthetic compound eye [80]. Figure 24: VODKA sensor mounted onto an MAV [81]. on LGMD was designed, modelled, and experimentally analysed, with results indicating reliability in terms of collision avoidance. A sensor to detect appropriate landing sites, considering the movements of landmasses on a planetary structure, was developed by NASA [87]. The optical sensor worked on the compound vision principle and could be used for remotely measuring the displacements. Implementing a 2D optic flow sensor based on the compound vision of flying insects in an autonomous MAV indicated that the sensor could track objects successfully at a maximum frame rate of 120 fps [88]. Multiple sensors were efficiently assembled within the synthetic compound eye and also had low power consumption. Birds' ability to use atmospheric conditions to benefit their flight was exploited in a design based on harvesting energy under different wind conditions [89]. The experimental analysis revealed that harvesting energy using various pressure sensors and other components enabled the aircraft to maintain altitude. Another implementation of pressure and strain sensors using a trained artificial neural network helped detect unsteady flow and stall [90]. (c) Structures  
The influence of biomimetics in the aerospace industry has led to the development and implementation of several bionic structures in advanced, high-end applications. There have been significant developments of bionic systems, other than the standard honeycomb and Kagome structures. Apart from applying a dragonfly-inspired wing in MAVs, dragonflies also possess a very optimized body structure and could ensure lightweight aerospace body parts. Their self-cleansing wings provide constant dirt removal that helps maintain stability [91]. The segmented body of a honeybee was used to influence an aircraft's nose cone [92]. A segmented nose structure helped the vehicle with enhanced manoeuvability due to improved bending properties and the aircraft's axial scalability. The structure of the skin of an aerospace vehicle is of great prominence as a thermal protection layer. A bio-inspired quadrilateral shape structure (BIQS) was tested on a similar setup for its ability to reduce the vibrations due to impact with debris post-capture [93]. Figure 25 depicts the complete structure, including the BIQS, for an in-orbit capture. It was found that the BIS provided a better vibrational damping performance in comparison with a spring-mass damper. A lightweight, thermal resistant corrugated core sandwich structure inspired from a peacock mantis shrimp was preferred over a honeycomb structure owing to its lower weight, lower heating rate, and minimum deflection at high heating [94]. The heat flow (via transpiration) from the combustion chamber for a hypersonic vehicle was biologically mimicked. A parallelogram-style non-smooth structure was used which improved the cooling rate, like the skin of a tapeworm [31]. A rover to tackle the harsh conditions offered by Mars, which can lead to increased travel time, was theoretically designed at NASA [95]. The design idea involved a giant spherical robot equipped with several separate wind-driven micro flying rovers that would be detached from the spherical bot, just like the seeds of a dandel  
Figure 25: An in-orbit capture, with the BIQS system to suppress post-capture vibrations [93]. A wheel design inspired by an African ostrich's feet was developed based on its ability to travel on the sand, owing to its unique toe structure [96]. The wheel design could be an effective means of traveling on Mars, with its capability of reducing soil resistance. Considering the debris present in space at the moment, the ISS and other satellites could be in danger of being struck at any moment.