Patient-driven control of FES-supported standing up: a simulation study

Abstract

To control movements aided by functional electrical stimulation (FES) in paraplegic patients, stimulation of the paralyzed lower limbs might be adjusted in response to voluntary upper body effort. Recently, Donaldson and Yu proposed a theoretical approach, called "control by handle reactions of leg muscle stimulation" (CHRELMS), in which stimulation of the lower limbs depends on upper body effort, i.e., body posture and recorded hand reactions, and is aimed to minimize arm forces during standing up and standing. An alternative strategy is presented in this paper, which accounts for voluntary upper body effort as well, but does not require estimation of hand reactions. The objective of this study is to test both strategies by applying them to a generic two-dimensional (2-D) neuromusculoskeletal model. The model takes into account the major properties of muscle and segmental dynamics during FES-supported standingup movements of a paraplegic patient. In comparison to standing up without FES-support, both closed-loop strategies yield satisfying standing-up movements although no reference information (e.g., a desired trajectory) is required. Arm forces can be significantly reduced. Using the model to optimize the controller, timeconsuming and strenuous trial-and-error experimentation could be avoided. However, final experimental studies are planned to verify the presented strategies.

Research on musculoskeletal model of elbow joint for evaluating the feasibility of FES

“…The pulse width was controlled to modulate the activation of the artificially stimulated muscle, while the pulse amplitude and frequency were pre-fixed. The muscle recruitment dynamic of motor units is expressed by a piecewise-linear function of pulse width shown below [5,10]. …”

“…The pathological tremor usually occurs in the wrist or elbow joint of patients suffering from Parkinson's disease and significantly weakens the daily activities, such as holding meal spoon or inserting the keys. Recently, Functional Electric Stimulation (FES) was intensively studied to restore the function of pathological extremities [2][3][4][5]. The exploration of the origin of tremor is fundamental to improving the treatments.…”

Rehabilitation of the Paralyzed Lower Limbs Using Functional Electrical Stimulation: Robust Closed Loop Control

“…The force-length relation (Riener & Fuhr, 1998) expressed by equation (Eq. 12) as well as the maximal isometric force that could be generated by a muscle were identified using a special experimental platform ( Fig.…”

“…In fact, few studies have treated the human muscle as an entire physiological element in a control scheme. Some authors used linear muscle models; others represent the muscle as a non-linear function of recruitment with dynamics activation, angle and angular velocity dependence (Riener & Fuhr, 1998); . The muscle model used in this study has been recently published (El-Makssoud et al, 2004-a) and it is based on a complex physio-mathematical formulation of the macroscopic Hill and microscopic Huxley concepts reflecting the dynamic phenomenon that occurred during muscle contraction and relaxation.…”

Simulation of Antagonistic Muscle Actions Through the Use of Sliding-Mode Control Techniques

“…Larger models tend to be concerned only with paraplegia or robotics (Davoodi et al, n.d.;Ephanov and Hurmuzlu, 1997;Popovic et al, 1999;Riener and Fuhr, 1998). For this study a model was developed to simulate both normal gait and relatively minor pathological locomotion patterns.…”