FIGURE 7.

P and PI frequency control, fixed 1.5 mA amplitude and 60 μs pulse duration. (A) P frequency controller. At each controller call, the stimulation frequency is calculated as the current measured error value scaled by the controller gain, K_p. The controller stimulation frequency is bounded between 0 – 250 Hz, thus, negative error values correspond to turning DBS off. (B) PI frequency controller. At each controller call, the stimulation frequency is calculated as the summation of an integral term, i.e., the integration of the measured errors at previous controller calls, and the current measured error value, scaled by the integral time constant, T_i, and the proportional gain, K_p, respectively.