In this paper, the terminal sliding mode tracking control is proposed for the uncertain single-input and single-output (SISO) nonlinear system with unknown external disturbance. For the unmeasured disturbance of nonlinear systems, terminal sliding mode disturbance observer is presented. The developed disturbance observer can guarantee the disturbance approximation error to converge to zero in t...

In this paper we exploit the connection between disturbance observer and L1 adaptive control theories. We consider L1 adaptive output–feedback control framework, for which the L1 reference controller is equivalent to the disturbance observer. Using this fact, we investigate several properties of the disturbance observer architecture, leading to various filter design methods towards verification...

Disturbance Observer based robot control algorithms provide good performance while giving a straightforward method of gain selection. Unfortunately, the stability of these algorithms has not been shown rigorously for nonlinear systems such as robots. This paper demonstrates that a disturbance observer based algorithm can be made equivalent to the well known passivity based approaches of Sadegh ...

This work studies the problem of design of discrete-time nonlinear observers in the presence of exogenous disturbances. In particular, the present work proposes a systematic design method for discrete-time nonlinear state and disturbance observers in modular form, consisting of an observer for the disturbance-free part of the system, along with a disturbance observer and a stateestimate correct...

In this paper, the properties of a high gain observer-based disturbance estimation are analysed, and a time delay calculation approach is proposed for improving the identification of model parameter variation. The focus of this paper is the time delay between the actual disturbance and its estimate in a high gain disturbance estimation observer. It is proved, in this paper, the delay depends on...

In the resonance ratio control, which we proposed for vibration suppression and disturbance rejection in torsional system, the estimation speed of the disturbance observer should have been much faster than the resonance frequency of the controlled system. However, too fast disturbance observer sometimes causes implementation problem. In this paper, we give the optimal speed of the disturbance o...

In this paper, a force estimation method is proposed for force control without force sensor. For this, a disturbance observer is applied to each joint of an n degrees of freedom manipulator to obtain a simple equivalent robot dynamics(SERD) being represented as an n independent double integrator system. To estimate the output of disturbance observer due to internal torque, the disturbance obser...

Robust autopilot design for bank-to-turn (BTT) missiles under disturbances and uncertainties is investigated in this paper using the disturbance observer concept. It is well known that the BTT missile dynamics undergo a substantial changes during its flight. In this disturbance observer based control setting, the influences caused by parameter variations are merged into disturbance terms and re...

This paper investigates the tracking control of a wheeled mobile robot in the unknown environment. A disturbance observer is developed with utilization the integral filter. The proposed control scheme employs the disturbance observer control approach to design an auxiliary wheel velocity controller to make the tracking errors, which includes the velocity tracking error, the angular velocity tra...