Abstract
A complete methodology for an unmanned coaxial rotor helicopter with unstructured uncertainties was proposed to achieve high-accuracy tracking performance from modelling to robust control. An integrative approach was introduced to systematically construct a whole dynamic model. The key parameters were selected carefully after iteratively being checked by empirical coefficients to decrease the budget and risk of programme. Moreover, a new control scheme is proposed to simultaneously incorporate six inputs to control six states based on the investment of singularity value responses and the general rule of relative gain array. Coprime factor uncertainty model is considered to represent a class of unstructured uncertainties, such as unmolded actuator dynamics and unpredicted interferences between two rotors. Furthermore, the [Formula: see text] loop-shaping control was proposed to apply the control design of the coaxial rotor helicopter to manage complicated uncertainties and multivariable coupling. Finally, simulation results show the effectiveness of the proposed controller design in the step response of the closed loop. The stable closed-loop plant is achieved and the tolerant size of unstructured uncertainty is up to 36.09%. Good step responses and satisfied decoupling were also investigated in detail.
Highlights
Interest in coaxial rotor helicopter has been increasing rapidly in recent years.[1,2,3] The coaxial rotor is a configuration that adopted two coaxially counter-rotating rotors
Coprime factor uncertainty model is considered to represent a class of unstructured uncertainties
Simulation results show the effectiveness of the proposed controller design in the step response of closed loop
Summary
Interest in coaxial rotor helicopter has been increasing rapidly in recent years.[1,2,3] The coaxial rotor is a configuration that adopted two coaxially counter-rotating rotors. It is found that lateral cyclic trim values are larger than longitudinal cyclic pitch values to balance the equilibrium equation in the constructed model Another interesting consequence is that the upper rotor shared 56.4% of the total thrust under torquebalanced condition (Table 5). The thrusts ratio exhibits a good agreement with other unrestricted experimental results.[20] the trim and state values show that the constructed model is an effective representation of the main characteristics of the coaxial rotor in hovering condition. These findings indicate that the constructed dynamic model has an ability to depict the basic axis symmetry characteristic of a coaxial rotor helicopter. The main idea of the method is that it minimizes the infinity norm of the transfer function matrix between exogenous signal and objective signal vectors max stab K‘
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