Fig. 2
From: Sum of phase-shifted sinusoids stimulation prolongs paralyzed muscle output
(LEFT) Open-loop SOPS stimulation scheme. Pulse width vectors that produce sinusoidal moments through individual contacts were determined by tracking the desired sinusoid with a PI controller. PW vectors that successfully tracked the sinusoid with low RMS error for each contact were saved and implemented continuously during open-loop SOPS. (RIGHT) Closed-loop SOPS control scheme. Individually tuned PI controllers adjust stimulation to the “most on” MUP at each time point to maintain a constant target moment. Other MUPs continue to receive PW vectors that produce sinusoidal moments on that contact