MPC Based Attitude Control of Quadcopter
No Thumbnail Available
Date
2021-09
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Quadcopter is a type of UAV having two pairs of counter rotating rotors. Its movement is
controlled by adjusting the relative speed or relative trust and torque of each rotor which are
spun by electric motors. However, quadcopter is nonlinear, underactuated MIMO system
and also its inputs and outputs are constrained, which provide a suitable platform for control
algorithm development and investigation of both stabilization and trajectory tracking
control.
Because quadcopter is severely under-actuated and coupled system, a cascade control approach
is proposed and applied for trajectory tracking control. Three di erent MPC methods,
namely Linear MPC, Feedback linearization based MPC and Nonlinear MPC are designed
for attitude control. Moreover, the control of x, y, and z position is also addressed,
by utilizing a conventional PID controller, to test the performance of the attitude controllers
during trajectory tracking control.
The nonlinear mathematical model of a quadcopter's dynamics, solved from Newton's and
Euler's laws, is investigated by realizing the designed controllers using MATLAB/Simulink.
The introduced attitude controllers are compared based on three performance evaluation
factors, tracking accuracy, control e ort e ciency and output disturbance rejection capacity.
The performance of the proposed control schemes are veri ed by comparative simulation
results and Root Mean Square Error (RMSE) tracking accuracy performance measure. The
simulation results shows Linear MPC o er poor performance even if it is simple to design and
o er fast response compared with the other. Feedback linearization based MPC ensure the
utilization of linear MPC for nonlinear plant, in this case for nonlinear quadcopter model. In
addition, Feedback linearization based MPC and Linear MPC strategies couldn't withstand
output disturbances. Moreover, Feedback linearization based MPC strategy is incapable to
deal with input constraints. Conversely, nonlinear MPC o ers a good performance with
constraints and output uncertainty. Even if it is computationally intensive.
Description
Keywords
MPC, Quadcopter, Control