Sliding mode based laser-beam auto-alignment for laser interferometry-based localisation of multirotor helicopters

This paper presents the development and implementation of laser interferometry-based sensing and measurement for precise localisation of multirotor helicopters. A sliding mode-based control architecture is developed incorporating position measurements from the laser measurement system. The control architecture facilitates the auto-alignment of a laser-beam emanating from the laser measurement system and a retroreflector mounted on the target multirotor helicopter. The dynamics model of the multirotor helicopter is developed in order to define the sliding-mode based control law to effectuate position and motion control. A computational analysis of the computational stability of the control algorithm is performed. Further, an experimental research facility is established with a 4-rotor multirotor helicopter and a laser interferometry-based sensing and measurement system. Experimental analysis offers evidence that the sliding mode-based control architecture is able to maintain incident laser-beam and retroreflector alignment, facilitating continuous, real-time precise position measurements. It is further demonstrated that the sliding mode-based control architecture outperforms a proportional-derivative-based control architecture delivering the same functionality.