A simple tool to measure spasticity in spinal cord injury subjects.

This work presents a wearable device and the algorithms for quantitative modelling of joint spasticity and its application in a pilot group of subjects with different levels of spinal cord injury. The device comprises light-weight instrumented handles to measure the interaction force between the subject and the physical therapist performing the tests, EMG sensors and inertial measurement units to measure muscle activity and joint kinematics. Experimental tests included the passive movement of different body segments, where the spasticity was expected, at different velocities. Tonic stretch reflex thresholds and their velocity modulation factor are computed, as a quantitative index of spasticity, by using the kinematics data at the onset of spasm detected through thresholding the EMG data. This technique was applied to two spinal cord injury subjects. The proposed method allowed the analysis of spasticity at muscle and joint levels. The obtained results are in line with the expert diagnosis and qualitative spasticity characterisation on each individual

Control of force impulse in human-machine impact

The clinical study of postural control requires a disturbance to be imposed to the subject under evaluation. Among various kinds of disturbance, a mechanical stimulation, consisting in an impulsive force impressed to a certain point of the body, can be used. This paper describes the study of a device conceived to generate such a disturbance. The device is based on a commercial pneumatic actuator, equipped with appropriate force and motion feedback sensors, and properly controlled. The major item is to take into account the interaction between the device and the human, in order to individuate the optimal control technique to generate the desired force pattern. A mathematical model of the device and the human-machine interaction is presented and a sliding mode control technique is proposed. Finally, the results of simulations are reported and discussed