Integral sliding mode altitude control for a small model helicopter with ground effect compensation

Abstract

Abstract-In this paper, a robust altitude control for small RC helicopters near ground surface is proposed. Stable takeoff, landing and hovering near surface are realized by both ground effect compensation and robust sliding mode control which suppresses the modeling error of dynamics and ground effect. To prevent the steady state error induced by the boundary layer which is indispensable to avoid chattering phenomena, integral sliding mode function is introduced which achieves asymptotic convergence to the desired altitude with continuous control input. We verified the robustness and effectiveness of the proposed control method through experiments of a RC small scale helicopter on hovering control near ground surface and external disturbance attenuation.

Fault tolerant longitudinal aircraft control using non‐linear integral sliding mode

“…Remark 4: Note that equation (43) is the closed loop system associated with the baseline controller in (23), and that the unknown term ∆(x) does not appear. This is because ∆(x) is 'matched' uncertainty [18] and is therefore rejected by the sliding mode controller.…”

“…A number of authors have applied sliding mode techniques to the design of flight control laws: see for example [23], [24], [25], [26]. However many of these papers do not consider the fault tolerant control aspects and focus instead on the robustness properties introduced by the sliding modes.…”

Characterization of the Aerodynamic Ground Effect and Its Influence in Multirotor Control

“…A classical analytical model for the ground effect is provided by [11], using potential flow with a single source to model the rotor airflow and the method of images to account for the ground effect. Other authors have provided empirical expressions for the rotor thrust increment in ground effect for large [16] and small UAV helicopters [17]. The model in [11] has been widely used because it has a simple analytical form and has been experimentally shown to accurately capture the relationship between rotor thrust in ground effect and rotor height over the ground surface.…”

Flow sensing, estimation and control for rotorcraft in ground effect

“…Mahony and Hamel [4] develop a parametric adaptive controller that estimates the helicopter aerodynamics onboard and modulates the motor torque, rather than the collective pitch, during takeoff and landing and takes advantage of the reduced sensitivity of the control input to aerodynamics effects. Nonaka and Sugizaki [5] implement ground-effect compensation and integral sliding mode control to suppress the modeling error of the vehicle dynamics in ground effect. These control techniques often require a system model with empirically fit aerodynamic coefficients that are unique to each vehicle.…”

“…Nonaka and Sugizaki [5] take an empirical approach to measuring the ground effect on rotor thrust as a function of motor voltage. Mahony and Hamel [4] use an approximation of the down-flow velocity ratio based on a piecewise linear approximation of Prouty [8] to estimate rotor-thrust variation IGE.…”