Integral‐type‐observer‐based control with measurement uncertainty and application to two‐wheeled inverted pendulum

Abstract

To overcome the deficiencies of traditional disturbance observers in the presence of measurement uncertainty, an integral-type observer-based control using measured signals is proposed. The integral-type observer is in terms of an explicit integral-algebra form of measured signals. As a combination of the integral-type observer and high-gain controller, the observer-based control is a proportional-integral-derivative control with special combination of parameters for feedback linearization, simple in structure and easy in implementation.Without the observer, the high-gain controller alone may not have good control performance, but the proposed observer-based control works very well in stabilizing the system even when the observer performance is not good enough, due to the use of the high-gain control. The main results are applied to the control of a two-wheeled inverted pendulum. K E Y W O R D Sfeedback linearization, high-gain control, integral-type observer, measurement uncertainty, two-wheeled inverted pendulum INTRODUCTIONDisturbance and uncertainty exist commonly in practical control applications and they usually have adverse effects on performance and stability of the control systems. Regarded as a "patch" to improve the robustness and disturbance attenuation abilities, 1 the disturbance-observer-based techniques combining with other control approaches can deal with the disturbance and uncertainty very well. For example, a nonlinear DO (disturbance observer) was proposed in Reference 2 to estimate the difficultly measured friction in the controller of a nonlinear robotic manipulator. In Reference 3, a finite-time DO was used to estimate the mismatched disturbances for a general dynamic system, and the system is stabilized when the DO is combined with a nonsingular terminal sliding mode control. While in Reference 4, a nonlinear DO together with dynamic surface control was used successfully to keep the desired position and heading of ship under input saturation. Nonlinear DO is one of popular methods for disturbance/uncertainty estimation and attenuation with many applications in different fields, such as robot, 2,5,6 aviation, 7-9 navigation, 4 and so on. Some attentions were focused on the general models with nonlinear DO, such as systems with mismatched uncertainty, 10 and uncertain nonlinear systems. 11 Except nonlinear DO, there exists many other approaches to suppress disturbance and uncertainty effect, such as extended state observer, 12 high-order sliding mode observer, 13,14 and so on. More DO-based techniques and their detailed introduction can be found in a review paper. 15

LuGre model–based robust adaptive control for a pump-controlled hydraulic actuator experiencing friction

“…Therefore, better control performance can be expected with the simpler control structure. (2) Unlike observer-based control and the robust control schemes (Chen et al, 2023;Deng and Yao, 2021;Liang and Wang, 2021), the proposed RAC-based control method can effectively suppress the LuGre model-based nonlinear friction and various bounded unknown disturbances without the assumption about their time derivatives. Therefore, the proposed scheme is more promising in practice.…”

“…Aside from adaptive control, by integrating various observers, for example, disturbance observer (DOB) (Chen et al, 2000) and extended state observer (ESO) (Han, 2009), observer-based control algorithms have been extensively used to handle sophisticated nonlinear friction and disturbances in industrial applications (Chen et al, 2023; Khodamipour et al, 2021; Liang and Wang, 2021). The observers provide an online estimation of the friction and disturbances for the controller to perform feedforward compensation.…”