364 FORMATION OF THE CONTROL SIGNALS BASED ON APPLICATION OF THE NEURAL NETWORK APPROACHES BIOSCIENCE BIOTECHNOLOGY RESEARCH COMMUNICATIONS
Nikolay V. Dorofeev etal.
THE PROBLEM OF MANAGEMENT OF THE
REHABILITATION SYSTEMS
Currently, the functionality of existing rehabilitation
systems is insuf cient for patients with spine patholo-
gies. This is due, rst of all, to their limited application
in conditions of low mobility of the patient (fractures,
gunshot wounds, etc.) or the lack of a priori informa-
tion on the patient’s permissible movements (during
rehabilitation) without causing additional harm to his
health. However, the process of rehabilitation is acceler-
ated if the correct load on the pathological parts of the
spine is calculated (Yezhov et al., 2013; Tuktamyshev
& Bezmaternykh, 2014; Vengerova & Solovyova, 2008;
Zubareva, 2011, Maksimova, 2012; Kulik, 2017, Sobolev
etal., 2017).
The control signals for the rehabilitation exoskeleton
are formed on the basis of the patient’s desired move-
ments and are limited by the physiological parameters
and state of the patient.
Arbitrary movements of the patient are formed by
the exoskeleton on the basis of the recorded nerve
(electroencephalography), muscle (electromyography).
Involuntary movements of the patient are formed by the
mechanical (strain gage) signals of the exoskeleton at
different stages of motor processes in various (informa-
tive) areas of the patient’s body, (Grecheneva et al.,
2017).
Problems in recording arbitrary movements of the
patient are the error of the measuring path, the quality
of recognition of informative signals and pathology of
the human neuromuscular system.
So, for example, all movements of the musculoskel-
etal system of a human without pathologies begin in
the central nervous system, namely in the motor zone
of the cerebral cortex. The generated electrical signals
of movement (motion impulses) from the brain through
the spinal cord are transmitted to the peripheral nerv-
ous system along those nerve bers (motor neurons) that
must cause the necessary contractions of the muscular
system, (Sobolev etal., 2017).
Motor neurons have feedbacks, which receive infor-
mation from muscle bers, receptors and other sensory
receptors, in order to further coordinate movement and
prevent muscle damage. Since the moment of formation
of an impulse in the cerebral cortex before the move-
ment (contraction or relaxation of the muscles), some
time passes, individual intervals of which are described
in (Sinitskaya & Gribanov, 2014; Zakharova etal., 2012;
Grecheneva etal., 2017).
In general, the movement (especially arbitrary) is the
result of complex neuropsychophysiological processes in
which a plan of motion or reaction to stimuli is formed,
and its constant correction occurs throughout the entire
movement. In addition to the motor zone of the cerebral
cortex, other areas of the brain are involved: the poste-
rior parietal cortex, the limbic system, the cerebellum,
the frontal cortex, etc. (
Sinitskaya & Gribanov, 2014).
When processing and analyzing the signals of motor
neuron activity, attention should be paid to the fact that
useful signals, although cyclic, are not stationary. In
addition, the distribution of the noise component of the
signals is not normal (Zakharova etal., 2012).
Functional changes of any part of the path from the
place of formation of motor signals to the muscle cause
changes in the parameters of motion of the involved
kinematic pairs and the musculoskeletal system as a
whole. Figure 1 shows the averaged electromyograms
obtained (Fig. 2a and 2b) and the dynamics of the devia-
tion angle from the axis of the spine (Fig. 2c and 2d) in
the state of rest of a healthy person (Fig. 2a and 2c) and
a person with a tremor of the back muscles (Fig. 2b and
2d) (Butukhanov, 2009).
Deviations in the electrophysiological signals
involved in the locomotion activity of the musculo-
skeletal system, from normal values for healthy people
manifest themselves in amplitude, phase, shape, and
other characteristics of the signals and depend on the
different concentration of the attention, the accuracy
etc. (Voznesenskaya, 2006; Doronin & Doronina, 2010;
Rakhmilevich et al., 2012; E mov, 2012, Zakharova &
Shemirova, 2016; Shchenyavskaya & Zakharova, 2015;
Zakharova etal., 2016).
The need for high accuracy of recording of the patient
movements is due to possible damage to nerve bers
and the nervous system as a whole. When a nerve tis-
sue is damaged, a number of processes occur succes-
sively, leading to the death of damaged nerve cells and
the subsequent death of intact ones. According to mod-
ern ideas, the main factors leading to the destruction of
nerve cells are a violation of microcirculation, hypoxia
and ischemia. There is a link between the degree of neu-
ronal damage and the change in the level of the constant
potential and the membrane potential of neurons (Su -
anova and Shapkin 2014; Shanitsin etal., 2013).
Damage to the nervous tissues of the spinal cord
changes the frequency and amplitude of the spinal cord
signals and depends on the amount of pressure (com-
pression) and the degree of damage to the nerve ber.
Relying on the works on a dependence of the amplitude
of the electrospinogram on the subdural pressure can be
described in accordance with Table 1.
Thus, damage to the spinal cord causes an increase
in spontaneous electrical activity, and in case of signi -
cant damage, further decrease in spontaneous electrical
activity. In this case, the frequency characteristics of the
activity of the spinal cord correspond to the frequency
characteristics of activity of the cerebral cortex, but with