Real Time Discrete Control Algorithm for Gimbal System Design in Mini Unmanned Aerial Vehicles

Abstract

Nowadays, gimbal systems have been a very critical role to obtain some important information related to live images photos and target detection in unmanned aerial vehicles. The most basic performance criterion of gimbal systems depends on its stabilization in which the desired reference tracking must be accomplished by designing complex controller structure. For this purpose, a discrete controller design is presented to provide reduced cost, high-performance, 3-axis gimbal systems in real-time operation. Firstly, the mathematical model of the system was obtained and 3D – computer aided design was made in order to calculate the system parameters like inertia, damping factor, etc. After that forward and inverse kinematic equations for the gimbal system were obtained in order to calculate the reference degree in each axis. The discrete controller was derived from energy-based computed torque proportional controller which was based on the Lyapunov Stability Theorem in discrete notation. The reference tracking results at 10 milliseconds sampling time are as follows; 0 overshoot for 3 axes with lack of steady-state errors, and the time constants are 0.1575, 0.1610, and 0.27 second which are acceptable for roll, pitch, and yaw axes, respectively. In addition, the discrete-time performance of the proposed controller was compared with a PID controller designed in continuous time, and it was shown that the continuous-time design did not work efficiently as well as discrete time one.