Nonlinear Disturbance Observer Based Robust Tracking Control of Pneumatic Muscle

Abstract

Presently pneumatic muscles (PMs) are used in various applications due to their simple construction, lightweight, and high force-to-weight ratio. However, pneumatic muscles are facing various problems due to their nonlinear characteristics and various uncertainties in real applications. To cope with the uncertainties and strong nonlinearity of a PM model, a nonlinear disturbance observer (NDO) is designed to estimate the lumped disturbance. Based on the disturbance observer, the tracking control of PM is studied. Stability analysis based on Lyapunov method with respect to our proposed control law is discussed. The simulation results show the validity, effectiveness, and enhancing robustness of the proposed methods.∞ performance have been developed to help humans [9, 10].

A Nonlinear Exact Disturbance Observer Inspired by Sliding Mode Techniques

“…The upper bounds in (13) need not be known. They are updated by the adaptive algorithms defined in (4)- (5). The parameters and should be chosen as large constants so that a fast adjustment of̂( ) can be obtained.…”

“…The motivation is suggested by the fact that if the disturbances can be estimated, then control of the uncertain dynamic systems with disturbances may become easier. For example, the controller with disturbance cancellation functions can be easily constructed by using the estimated disturbances [1][2][3][4][5][6]. The disturbance observer approaches in the literature have been developed either in the transfer function domain or in the state space domain.…”

Finite-Time Composite Position Control for a Disturbed Pneumatic Servo System

“…Pneumatic servo systems play an important role and are widely used in modern industry (see pneumatic muscle systems [1,2], pneumatic brake systems [3], pneumatic manipulators [4,5], ball-plate pneumatic systems [6], etc. ), since they have lots of advantages, such as energy saving, high powerto-weight ratio, low cost, simple structure and operation, and ease of maintenance [7,8].…”

“…Recently, in order to attenuate the undesirable influence caused by system parameter uncertainties and external disturbances, lots of robust control approaches have been developed and widely applied in practical systems, such as sliding mode control [9,10,12], adaptive control [13,14], disturbance observer based control [1,2,15,16], and active disturbance rejective control [11]. Even though the aforementioned methods can attenuate the parameter uncertainties and external disturbances.…”

Compound Control Strategy for MDF Continuous Hot Pressing Electrohydraulic Servo System with Uncertainties and Input Saturation

“…Some scholars view the model uncertainties, external disturbances, and saturation nonlinearities as a composite disturbance term and adopt a NDO to estimate and compensate it appropriately. References [20][21][22][23][24] suggested that NDO-based controllers have advantages on the robustness and compensation of saturation without many design parameters.…”