Nonlinear Adaptive Control of Hydraulic System With Observing and Compensating Mismatching Uncertainties

Integral Sliding-Mode Observer-Based Disturbance Estimation for Euler–Lagrangian Systems

“…In practice, x 2 is usually obtained by taking the derivative of x 1 and noise is involved. Therefore, the target of this paper is to design an observer for the system (8) to simultaneously estimate the velocityx 2 and the disturbancê d(x 1 , t) only using the position measurement x 1 .…”

“…T HIS paper is concerned with disturbance estimation and fault detection and isolation (FDI) of mechatronic systems using analytical redundancy based methods. Specifically, it focuses on the online estimation of system actuator faults [1]- [3], external disturbances or forces [4], [5], parametric perturbations [6] and unmodeled system dynamics [7], [8] of a class of Euler-Lagrangian systems which usually share similar mathematical formulations [9]. It is well known that the analysis and diagnosis of fault signals or disturbances are critical techniques of FDI technology.…”

“…For example, in human-robot interaction (HRI), it is important to detect and classify collisions and contacts to guarantee safety in collaborative tasks [10], [11], such that robots and humans are allowed to share the same workspace and physical injuries are avoided [12]- [14]. More generally, disturbance estimation is also popularly studied for feed-forward disturbance compensation control [8], [15], robust control [16], [17] or fault-tolerant control [18], [19] strategies for various mechatronic systems.…”

Disturbance observer‐based output feedback control of hydraulic servo system considering mismatched uncertainties and internal pressure dynamics stability

“…The displacement of the piston x p , velocity of the piston x˙p and two pressures P 1 and P 2 are selected as the system states to describe the HVSA system dynamics. To implement the state feedback control law with back-stepping design approach, the universal practice is to take the place of two pressure states P 1 and P 2 with a load pressure state P L such as in most published papers [3,17,31]. As a result, the subsequent stability analysis based on Lyapunov approach is only valid for P L , rather than P 1 and P 2 .…”

“…As a result, the mechanical dynamics uncertainties problem cannot be directly addressed with the standard ESO. Although an improved ESO-based control scheme was developed in [31] to cope with the mechanical dynamics uncertainties, additional pressure sensors were required. In addition, the proposed strategy in [31] is somewhat complex and less convenient to carry out in industry.…”