Stabilization of Inverted Pendulum on a Cart in the Presence of Uncertainties

Author(s):  
Joonho Lee ◽  
Jongeun Choi

This paper presents an output feedback control design to stabilize the inverted pendulum at the upright equilibrium as an extension of our previous work [1]. Compared to our previous work, we add one more time scale between a pendulum angle and angular velocity to reduce a traveled distance of the cart. State feedback control is designed to enable the pendulum to pass through input singularity configurations. Extended High-Gain Observers are used to estimate velocity and acceleration terms while dynamic inversion utilizes the estimates to deal with input coefficient uncertainties and singularity configurations. The proposed control is verified through numerical simulations.

Author(s):  
Grace S. Deaecto ◽  
José C. Geromel

This paper deals with the output feedback H∞ control design problem for continuous-time switched linear systems. More specifically, the main goal is to design a switching rule together with a dynamic full order linear controller to satisfy a prespecified H∞ level defined by the L2 gain from the input to the output signal. Initially, the state feedback version of this problem is solved in order to put in evidence the main difficulties we have to face toward the solution of the output feedback control design problem. The results reported in this paper are based on the so called Lyapunov–Metzler inequalities, which express a sufficient condition for switched linear systems global stability. The solution of the previously mentioned output feedback control design problem through a linear matrix inequality based method is the main contribution of the present paper. An academic example borrowed from literature is used for illustration.


Author(s):  
Joonho Lee ◽  
Jongeun Choi

This paper proposes an output feedback control design for quadrotor Unmanned Aerial Vehicles (UAVs) to deal with unmeasured system states, system uncertainties, and external disturbances. Extended High-Gain Observers (EHGOs) are used to estimate the uncertainties and unmeasured system states. Dynamic inversion utilizes the estimates from EHGOs in the second and third fastest time scales in order to deal with input uncertainties and a form of non-affine control inputs. In plant dynamics, rotational dynamics in the fourth fastest time scale, is forced to be faster than translational dynamics in the slowest time scale to overcome the lack of the number of control inputs in this underactuated mechanical system. Using the singular perturbation method, stability of the closed-loop system is conducted. Throughout numerical simulations, the proposed control algorithm is verified.


Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1325 ◽  
Author(s):  
Yasuo Sasaki ◽  
Daisuke Tsubakino

Complexity of online computation is a drawback of model predictive control (MPC) when applied to the Navier–Stokes equations. To reduce the computational complexity, we propose a method to approximate the MPC with an explicit control law by using regression analysis. In this paper, we extracted two state-feedback control laws and two output-feedback control laws for flow around a cylinder as a benchmark. The state-feedback control laws that feed back different quantities to each other were extracted by ridge regression, and the two output-feedback control laws, whose measurement output is the surface pressure, were extracted by ridge regression and Gaussian process regression. In numerical simulations, the state-feedback control laws were able to suppress vortex shedding almost completely. While the output-feedback control laws could not suppress vortex shedding completely, they moderately improved the drag of the cylinder. Moreover, we confirmed that these control laws have some degree of robustness to the change in the Reynolds number. The computation times of the control input in all the extracted control laws were considerably shorter than that of the MPC.


Author(s):  
Jianqin Wang ◽  
Zaojian Zou ◽  
Tao Wang

The paper studies the path following of a ship sailing in restricted waters based on an output feedback control, which consists of a state feedback control law and an extended updated-gain high-gain observer. According to the separation principle, the state feedback control and the extended updated-gain high-gain observer are designed separately. The state feedback control law is designed based on a robust guaranteed cost control method assuming that system states are measurable. Sufficient conditions are given for the control based on a linear uncertain system. The extended updated-gain high-gain observer, whose gains are updated according to the nonlinear functions of available evaluation errors, is used to reconstruct system states. Then the output feedback control is obtained by replacing states value in the state feedback control law with its estimation yielded by the state observer. Numerical simulations confirm the effectiveness of the proposed control method for the path following of a ship sailing in restricted waters.


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