# Attitude Angle

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### Chang-yin Sun – One of the best experts on this subject based on the ideXlab platform.

• ##### A decoupling control for quadrotor UAV using dynamic surface control and sliding mode disturbance observer
Nonlinear Dynamics, 2019
Co-Authors: Xiaobo Lin, Yao Yu, Chang-yin Sun

Abstract:

This paper proposes a decoupling tracking controller for quadrotors using dynamic surface control (DSC) and second-order sliding mode disturbance observer (SMDO). The DSC used in this paper is improved with the sliding mode differentiators that replace the original low-pass filter, and the SMDO is utilized to restrain the influence of system uncertainties and external disturbances. In addition, instead of the roll Attitude Angle ( $$\varphi$$ φ ) and pitch Attitude Angle ( $$\theta$$ θ ), applying $$\sin {\varphi }$$ sin φ and $$\sin {\theta }$$ sin θ as control variables simplifies the analysis of stability. Moreover, a fuzzy logic-based method is utilized to compensate the influence of battery voltage changing during the procedure of thrust generation. The asymptotic tracking property of the closed-loop system is proven via the Lyapunov-based stability theory. Finally, the real-time experiment results, which contain a hovering case and rectangular path tracking case, are given to validate the practicability of the proposed method.

### Xiaobo Lin – One of the best experts on this subject based on the ideXlab platform.

• ##### A decoupling control for quadrotor UAV using dynamic surface control and sliding mode disturbance observer
Nonlinear Dynamics, 2019
Co-Authors: Xiaobo Lin, Yao Yu, Chang-yin Sun

Abstract:

This paper proposes a decoupling tracking controller for quadrotors using dynamic surface control (DSC) and second-order sliding mode disturbance observer (SMDO). The DSC used in this paper is improved with the sliding mode differentiators that replace the original low-pass filter, and the SMDO is utilized to restrain the influence of system uncertainties and external disturbances. In addition, instead of the roll Attitude Angle ( $$\varphi$$ φ ) and pitch Attitude Angle ( $$\theta$$ θ ), applying $$\sin {\varphi }$$ sin φ and $$\sin {\theta }$$ sin θ as control variables simplifies the analysis of stability. Moreover, a fuzzy logic-based method is utilized to compensate the influence of battery voltage changing during the procedure of thrust generation. The asymptotic tracking property of the closed-loop system is proven via the Lyapunov-based stability theory. Finally, the real-time experiment results, which contain a hovering case and rectangular path tracking case, are given to validate the practicability of the proposed method.

### Ashish K Darpe – One of the best experts on this subject based on the ideXlab platform.

• ##### investigations on characteristics of micro meso scale gas foil journal bearings for 100 200 w class micro power systems using first order slip velocity boundary conditions and the effective viscosity model
Microsystem Technologies-micro-and Nanosystems-information Storage and Processing Systems, 2013
Co-Authors: Skylab P Bhore, Ashish K Darpe

Abstract:

In this paper, a modified compressible Reynolds equation for micro/meso scale gas foil journal bearings considering first order slip and effective viscosity under rarefied flow conditions is presented. The influence of rarefaction effect on the load carrying capacity, Attitude Angle, speed and frequency dependent stiffness and damping coefficients, modal impedance, natural frequencies and unbalance response is studied. From numerical analysis, it has been found that there is significant change in all the static and dynamic characteristics predicted by the no-slip model and model with effective viscosity. There is also a considerable difference between the values predicted by a model with effective viscosity and a model without effective viscosity. For a given eccentricity ratio, the influence of effective viscosity on load carrying capacity and Attitude Angle is more significant for the typical operating speed range of micro/meso scale gas turbines. The influence of effective viscosity decreases with increase in compliance of bearing structure. Similarly, the influence of effective viscosity on frequency dependent stiffness and damping coefficients increases with excitation frequency ratio. Significant change in natural frequency, modal impedance and unbalance response for model with no slip and slip with effective viscosity is observed. The influence of effective viscosity is found to be significant with increase in Knudsen number.

• ##### Investigations on characteristics of micro/meso scale gas foil journal bearings for 100–200 W class micro power systems using first order slip velocity boundary conditions and the effective viscosity model
Microsystem Technologies, 2013
Co-Authors: Skylab P Bhore, Ashish K Darpe

Abstract:

In this paper, a modified compressible Reynolds equation for micro/meso scale gas foil journal bearings considering first order slip and effective viscosity under rarefied flow conditions is presented. The influence of rarefaction effect on the load carrying capacity, Attitude Angle, speed and frequency dependent stiffness and damping coefficients, modal impedance, natural frequencies and unbalance response is studied. From numerical analysis, it has been found that there is significant change in all the static and dynamic characteristics predicted by the no-slip model and model with effective viscosity. There is also a considerable difference between the values predicted by a model with effective viscosity and a model without effective viscosity. For a given eccentricity ratio, the influence of effective viscosity on load carrying capacity and Attitude Angle is more significant for the typical operating speed range of micro/meso scale gas turbines. The influence of effective viscosity decreases with increase in compliance of bearing structure. Similarly, the influence of effective viscosity on frequency dependent stiffness and damping coefficients increases with excitation frequency ratio. Significant change in natural frequency, modal impedance and unbalance response for model with no slip and slip with effective viscosity is observed. The influence of effective viscosity is found to be significant with increase in Knudsen number.