Compact laser altimeter dedicated to drone ballistic carriers

Over the past few decades, the use of low cost Miniature Unmanned Aerial Vehicles (MUAV), as well as Micromechanical Flying Insects (MFI) in targets aerial surveillance and reconnaissance has experienced almost an exponentially growth not only in conventional military areas, but also in civil, industrial and aerospace applications. Despite obvious inherent advantages, such as a very attractive cost-efficiency ratio and a low risk to the drone operator safety, MUAV/MFI based technologies still present multiple challenges. The major drawback of conventional MUAV/MFI is that a relatively low on-board energy storage capacity and an inherent weakness of the MUAV/MFI propulsion drive systems. It results in a relatively low flight speed and an inability to fly in bad meteorological conditions, such as strong wind and could be critical for many applications, such as the forest fires or nuclear accident zones monitoring. In order to overcome these drawbacks, we propose to deliver MUAV/MFI to the designated target zone using ballistic carriers, such as mortar round or infantry man-portable unguided rocket. Accordingly, our research team intends to develop a prototype of MUAV/MFI ballistic carrier involving standard mortar rounds of 81 mm and 120 mm calibers.
In this paper, we report the results of theoretical and experimental investigations on the MUAV/MFI ballistic carriers being developed by our research team and we address specifically the concept of compact laser altimeter dedicated to the ballistic carriers, as well as the first proof-of-concept experimental investigations, demonstrating its practical feasibility. One of the main challenges facing the implementation of the proposed concept of the mortar launched altimeter is to ensure its reliable operation after extremely high launch shock accelerations. This requirement determines the optical concept and materials selection and optimization, as well as the accuracy of alignment of the optical system. Recent mortar gun tests, performed in the frame of our experimental investigations, demonstrated that the key optical and electronic elements and sub-systems of the developed altimeter prototype can withstand launch accelerations of at least 5000g, as well as typical shock accelerations during parachute deployment phase. In additional, it should be noted that the fuze front surface area available for the placement of rangefinder optical lens assemblies is limited by military standards requirements, as well as by the air intake duct of the air drive turbine used as a power generator, that also poses some challenges for integrating the altimeter into mortar fuze head. The experimental investigations of the first altimeter prototype developed in compliance with these requirements, demonstrated the enabling range finding up to 1000 m, when operating at night time environments.