IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 15, Issue 4 Ser. I (Jul. – Aug. 2020), PP 08-14 www.iosrjournals.org DOI: 10.9790/1676-1504010814 www.iosrjournals.org 8 | Page Design A PID Regulator For Stabilizing Quadrotor Hoa T. T. Nguyen 1 , Dung Thien Tran 2 1 Electronics Engineering Department, Thai Nguyen University of Technology, Viet Nam 2 Instrument and Control Engineering Department, Thai Nguyen University of Technology, Viet Nam. Abstract: Stabilizing Quadrotor is the main point needed to be solved before making this track along the desired trajectory. This paper presents an explicit procedure to design a Proportional – Integral – Derivative (PID) regulator for stabilizing Quadrotor. For more details, the mathematical model of Quadrotor is described under an engineering point of view, based on which a suitable PID controller (P, PI, PD, or PID) is designed and programmed on STM32 microcontroller. Besides, a good control feedback system needs a clean feedback signal, so the effects of sensor noises are reduced by applying the complement filter. The performances of the control system and how sensor noises are well eliminated are going to be demonstrated by not only simulation but also experimental results --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 30-06-2020 Date of Acceptance: 16-07-2020 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction For people with mobility and physical impairments, certain activities or interaction with the world mostly depend on relatives or doctors. This would prove burdensome to the national socio-economic development. Quadrotor, a typical unmanned aerial vehicle, has many applications in daily life such as in search and rescue, surveillance, and other applications. It attracts considerable attention from researchers, engineers. The quad-copter [1], [2], [3], [4] consists of 4 propellers arranged on “x” or “+” -shapes. The symmetry of the quad- copter body gives the simplicity to the controller design as it can be controlled through varying the speed of the propellers [2]. The rotational speeds of four rotors are independent, so it’s possible to control the pitch, roll, and yaw attitude of the vehicle. Stabilizing quad-copter is the first mission before we can think about tracking along desired trajectories, and there are so many control strategies for balancing quad-copter in the air in which PID control algorithm [5] is the most popular due to its convenience. PID means Proportional – Integral – Derivative, and it functions to force the output of the plant to follow the expectation. Based on the engineering point of view, there are three Euler’s angles, Roll, Pitch, Yaw, should be taken into account in order to stabilize the quad -copter hanging on the sky. This paper presents how to understand the working principle of quad-copter physically, and then constructs the control scheme utilizing digital PID controllers for controlling each angle. In order to set up the experimental model, this paper mainly discusses the process to implement a real model of quad-copter such as noise effect elimination of the sensor, and digital PD controller on the microcontroller. The paper is organized such that a physically mathematical model of quad-copter is shown in section 2. Then control feedback system design is given in section 3. Section 4 demonstrates the experimental setup and results. Finally, some discussions and conclusions will be included in section 5.. II. Mathematical Modeling Of Quadrotor Quadrotor dynamics Figure 1 shows quadrotor frame system with a vehicle frame (x,y,z). The forces and moments on quadrotor are calculated by equation from (1) to (3). 2 i f i F k    ; 2 i m i M k    (1)   1 2 x M F F l    ;   2 4 y M F F l    (2) w m g   (3) In which F stand for forces and M index stand for moments. x M and y M are denoted for moments along the x-axis and y-axis respectively. l is the length from the rotor to the center of the quadrotor frame, w is a gravitational force caused by weight. .