Electrical stimulation tracking control for paraplegic patients using T–S fuzzy models

Abstract

This paper presents the design and simulation results considering the use of functional electrical stimulation to control the leg position of paraplegic patients. The plant is described by a nonlinear system using Takagi-Sugeno fuzzy models and a closed-loop control is presented. A transfer function represents the mathematical model related to the muscle torque and the electrical stimulation pulse width. Considering that, during the operation, the leg position is between 0 • and 60 • , then two fuzzy regulators were designed, assuming that the state vector is available or using an observer when only the output is available. This design was based on the Lyapunov stability theory and Linear Matrix Inequalities (LMIs). The simulation results show that the proposed procedures are efficient and offer good results for this control problem. Finally, new conditions regarding the design of the output tracking control, using a suitable nonlinear transformation for the description of the plant in an adequate form, is presented.

Discrete Takagi-Sugeno Fuzzy Models Applied to Control the Knee Joint Movement of Paraplegic Patients

“…FIGURE 2. Graphics of the exact functionf 21 (x 1 ) and its approximation using an 11 th -order Taylor series, as done in [17].…”

“…Recently, few articles have been published in this area, such as [16] and [17]. In [18] and subsequent articles [19]- [22], and [23] published by our research group, some theories are employed to control knee joint movement using neuromuscular electrical stimulation.…”

“…In the present study, to improve the control techniques of previous works with T-S fuzzy models [17], [25], an embedded fuzzy logic was implemented in a digital signal processor (DSP), with closed loop.…”

“…Models [4] through [17] work with nonlinear state space modeling. Although our model does not consider all the effects considered in [16], the T-S fuzzy models utilized in the design follows the recommendations of [3] to reduce the fatigue effect by the variation of pulse width and the stimulus application time instructions with their appropriate reapplication intervals.…”

Adaptive Sliding Mode Control of Functional Electrical Stimulation (FES) for Tracking Knee Joint Movement

“…A large number of FES control techniques have been applied to the lower limb [4], but few of them are capable of providing high accuracy with patients. Human body muscle is non-linear, volatile and the environment is complex [5], which makes it difficult to control FES to achieve the desired FES performance. When designing FES control system, it is the very important to improve the control precision accurately.…”