Adaptive force regulation of muscle strengthening rehabilitation device with mag

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IEEE Trans Neural Syst Rehabil Eng. 2006 Mar;14(1):55-63.

Adaptive force regulation of muscle strengthening rehabilitation

device with magnetorheological fluids.

Dong S, Lu KQ, Sun JQ, Rudolph K.

Department of Mechanical Engineering, University of Delaware, Newark,

DE 19716, USA.

In rehabilitation from neuromuscular trauma or injury, strengthening

exercises are often prescribed by physical therapists to recover as

much function as possible. Strengthening equipment used in clinical

settings range from low-cost devices, such as sandbag weights or

elastic bands to large and expensive isotonic and isokinetic devices.

The low-cost devices are incapable of measuring strength gains and

apply resistance based on the lowest level of torque that is produced

by a muscle group. Resistance that varies with joint angle can be

achieved with isokinetic devices in which angular velocity is held

constant and variable torque is generated when the patient attempts

to move faster than the device but are ineffective if a patient

cannot generate torque rapidly. In this paper, we report the

development of a versatile rehabilitation device that can be used to

strengthen different muscle groups based on the torque generating

capability of the muscle that changes with joint angle. The device is

low cost, is smaller than other commercially available machines, and

can be programmed to apply resistance that is unique to a particular

patient and that will optimize strengthening. The core of the device,

a damper with smart magnetorheological fluids, provides passive

exercise force. A digital adaptive control is capable of regulating

exercise force precisely following the muscle strengthening profile

prescribed by a physical therapist. The device could be programmed

with artificial intelligence to dynamically adjust the target force

profile to optimize rehabilitation effects. The device provides both

isometric and isokinetic strength training and can be developed into

a small, low-cost device that may be capable of providing optimal

strengthening in the home.