Sliding mode based roll control law design for a research UAV and its flight validation

The choice of sliding surface for robust roll control: Better suppression of high angle of attack/sideslip perturbations

“…Alternatively, the uncertainty may be applied directly to the parameters of equation 6instead of equation 3which yield more realistic random systems. The result of applying 30% uncertainty to the K parameters of equation (6) has been shown in Figure 1(c) and (d) which looks more appropriate for the uncertainty evaluations.…”

“…The dynamic equation of the new variable is composed by employing p_ from equation (6) and _ b from equation (1). Considering the uncertainty in equation (6) and cross-coupling among variables, the dynamic of z is given by…”

“…Success of the design depends on the precise definition of the type of operation so that the neglected dynamic and cross-couplings among variables to be adequately small. Apart from that, a lot of more sophisticated approaches such as: fuzzy logic (FL), 2 intelligently tuned m-PID, 3 robust, 4 intelligently tuned fractional order PID, 5 sliding mode, 6 H1, fractional order PID, 7 dynamic inversion, a combination of model inversion with an online adaptive neural network, a nonlinear adaptive design based on backstepping, neural networks and RBFNN-based adaptive design 8 have also been studied. The main goal in all of the newly developed methods is flight envelope extension and manoeuvrability improvement.…”

“…Sliding mode control (SMC) has been commonly used in aerospace, 6 process control, power control and robotics to administer dynamic and disturbance perturbations. However, SMC results in a high switching gain particularly when the system uncertainty band is large.…”