A novel Kriging-median inverse compensator for modeling and compensating asymmetric hysteresis of pneumatic artificial muscle

Abstract

McKibben muscle is a kind of pneumatic artificial muscles (PAMs), and has been widely applied on robotic field as an actuator. Nevertheless, because of friction and elastic deformation, it has a strong asymmetric hysteresis which effects its actuating performance. In this paper, a novel Kriging prediction model (KPM) is proposed for describing PAM hysteresis. For improving predictive accuracy, a median filter is introduced and follows KPM, which is named Kriging-median inverse compensator (KMIC). Combining with PID controller, we present a KMIC-PID controller which consists of an open-loop KMIC and a close-loop PID controller. In order to verify the compensation control performance, some simulations and experiments are done, and the results are compared with traditional PID controller. Moreover, we introduce a Kalman filter during the experimental process, so that the effect of sensor noise can be eliminated. The Kalman filter is based on PID control parameters, so the controller used in experiment are named KMIC-Kalman PID (KPID). The simulation and experiment results show that the proposed controller has a significant compensation effect for PAM hysteresis in the condition of low frequency signal, because the hysteresis belongs to static characteristic. Furthermore, KMIC-KPID controller restricts the effect of sensor noise, which increases robustness of the system.

A novel learning adaptive hysteresis inverse compensator for pneumatic artificial muscles

“…In figure 3, u f (t) is the predictive inflation pressure for the PAM, and l(t) is the actual displacement of the PAM. As described in the literature [19], KMIC always has good hysteresis compensation performance in a particular situation. But, the displacement of a PAM decreases with the increase of the external load under a constant inflation pressure condition.…”

“…Mathematical function based models (such as neural network model and polynomial approximation model) have a simple structure and good fitting performance, but they cannot clearly describe hysteresis characteristics unless the model input variable structure is designed reasonably. In our previous work, we presented a novel mathematical function based model named ordinary Kriging prediction model (OKPM) for describing the hysteresis of PAM [19]. This model not only has a good fitting performance but also describe hysteresis characteristics intuitively.…”

“…According to the hysteresis model, a feedforward hysteresis compensator can be designed by deriving or identifying the inverse of the model. Then we can take the compensator into a feedback loop control system, thus doing compensation control for PAM [16][17][18][19][20].…”

On Structural Identifiability of System with Nonsymmetric Nonlinearities

“…Nonsymmetric nonlinear systems used to control various objects [1][2][3][4][5]. A genetic procedure [1] proposed for the nonsymmetric hysteresis identification.…”

“…Its analogue is used in [1]. In [3,4], models propose considering the influence of the excitation frequency on the hysteresis. A generalized Bouc-Wen model [5] proposed to describe strongly asymmetric hysteresis.…”