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Freedom planet torque3/23/2023 ![]() ![]() Indoor quadcopters are usually relatively small in size and cannot utilize GPS for absolute positioning. Due to their compact size, low cost, and agility, these systems are being used in various applications. The small unmanned aerial vehicles (SUAV) have become a reality, thanks to recent microcomputer technology, sensor technology, control systems, and dynamics theory advancements. To control and stabilize the aircraft, these UAVs use an electrical control system and sensors. Quadcopter designs have recently been popular in UAV research. ![]() These flight motions can be achieved by controlling the rotational speeds of the four motors. Yaw is movement in a clockwise or anticlockwise manner while staying level to the ground to change the quadcopter’s direction. Pitch is the movement of the quadcopter by tilting either front or back to allow forward or backward movement. Roll is the movement of the quadcopter by tilting either left or right to allow side movements. Thrust controls the quadcopter’s altitude for ascending and descending and is achieved by increasing or reducing the rotational speed of motors 1, 2, 3, and 4, simultaneously. The quadcopter can be kept in a balanced position without spinning if the generated torque of the motors T1, T2, T3, and T4 is the same. Two opposite rotors rotate in the same direction the altitude and position of the quadcopter can be controlled by varying the rotor’s angular speed. The quadcopter is designed with four rotors in cross-configuration, as shown in Figure 1. ![]() The quadcopter is controlled by adjusting the rotors’ angular speeds, which alters the quadcopter’s torque and thrust characteristics. A quadcopter’s dynamics are highly nonlinear it is an underactuated system with six degrees of freedom and four control inputs which are the rotor velocities. To balance the torque, these rotors are built with two pairs of opposite rotors revolving clockwise and the other rotor pair moving anticlockwise. They are multirotor aircrafts propelled by four rotors. IntroductionĪ quadcopter, also known as a quadrotor, is a rotor-based aerial vehicle. The PD controller produces satisfactory results for system stabilization, but the FBL system combined with the PD controller performs better for trajectory tracking of the quadcopter system. The proposed control algorithms are implemented on the quadcopter model using MATLAB and analyzed in terms of system stabilization and trajectory tracking. The study further investigates the problem of nonlinear quadcopter system’s mathematical modelling and control for stabilization and trajectory tracking using the feedback linearization (FBL) technique combined with the PD controller. The aim of the study was achieved but the downside is that it takes a longer time to achieve this stability so it is not efficient and should only be considered when absolute zero stability is the aim without considering time efficiency. Thus, a new approach where the position variables are mapped to the angle variables which are controllable so as to drive all states to zero stability was proposed in this study. In such an approach, the PD controller that was used for attitude stabilization was able to stabilize the angles to zero states, but the position variables cannot be stabilized because the state variables are not observable. However, there is a problem with the normal approach of the complete derivation of the full state FBL system using NDI as gathered from the literature review. Another nonlinear control technique called full state feedback linearization (FBL) using nonlinear dynamic inversion (NDI) is developed and implemented on the quadcopter system. A PD control algorithm is developed for the nonlinear system for stabilization. The mathematical model of the system dynamics of the quadcopter is derived using Newton and Euler equations with proper references to the appropriate frame or coordinate system. This study presents a nonlinear quadcopter system’s mathematical modeling and control for stabilization and trajectory tracking. A quadcopter is an unmanned aerial vehicle (UAV) that is able to do vertical take-off and landing. This paper presents an adequate mathematical representation of a quadcopter’s system dynamics and effective control techniques. ![]()
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