Electrical Muscle Stimulator with Atypical Waveform
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Electrical Muscle Stimulator with Atypical Waveform P. S. Mart’yanova, * and D. V. Churikova aScientific
and Technological Center of Unique Instrumentation, Russian Academy of Sciences, Moscow, 117342 Russia *e-mail: [email protected] Received January 30, 2020; revised January 30, 2020; accepted February 25, 2020
Abstract—A model of electrical muscle stimulator that generates electrical pulses delivered to the neuromuscular human system is proposed. A specific feature of the proposed device is related to nonstandard pulse trains of output signals. The main working parameters are presented, the working principle is described, and schemes and simulation results are presented for several key components. DOI: 10.1134/S1064226920100046
INTRODUCTION Electrical muscle stimulation employs electric pulses with different waveforms, repetition rates, and amplitudes that affect muscles of the human musculoskeletal system. The main feature of the electrical muscle stimulation lies in the fact that the number of activated muscle fibers is greater than that in normal muscle contraction [1, 2]. This circumstance makes it possible to generate greater muscle forces in comparison with the regime of normal exercises. Starting from the 1950s, the method is efficiently employed in sports, fitness, and medicine. When spontaneous muscle contraction is impossible, artificial activation using electrical muscle stimulation allows motion of an immobile muscle and, hence, faster rehabilitation after traumas of the musculoskeletal system. In most commercially available electrical muscle stimulators (EMSs), rectangular pulse trains are delivered to human muscles (Fig. 1a) [2–4]. However, application of signals with gradually increasing amplitude (Fig. 1b) rather than standard signals makes it possible to recruit a greater number of muscle fibers. Activation of a greater number of muscle fibers allows generation of greater muscle force in the simulated muscle group and, hence, an increase in the force potential of an athlete. In this work, we propose a new device, which is the EMS with atypical waveform.
tex-M0 architecture, supports modern interfaces (I2C, LIN, SPI, and USART), and contains built-in counters and peripheral devices. The microcontroller is supplemented with 12-bit DACs (DAC6311), TLP117 photocoupler for galvanic coupling, highvoltage transistors, encoders, and several additional elements. Figure 2 shows the structural scheme of the proposed device. The working principle is as follows. The microcontroller generates two signals (digital data of the SPI interface and a train of rectangular pulses) that are fed to built-in counter. Then, the two signals pass through the galvanic coupling to the DAC the output analog signal of which represents a piecewise linear function (Fig. 3). In the shaping amplifier, the piecewise linear signal is multiplied by the rectangular-pulse signal.
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DEVELOPMENT OF EMS The analysis of the results of [5–7] has shown that the proposed devi
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