Fig. 2.
a Control platform scheme, where GUI is the graphical user interface, DAC is the digital to analog converter of the NI-6229 board, Ps and Ls are the power and logic switches, Cm is the torque imposed to the motor by the control, Em is the encoder signal acquired by the control and RTAI is the real-time operating system. b Control system scheme, where ωsp(t) is the angular velocity set point defined by the user, ωm(t) is the instantaneous cone angular velocity measured by the motor encoder, Cm is the torque imposed to the motor by the control, n is the signal noise, FF is the feed-forward module, PI is the proportional-integral controller and CPD is the cone-and-plate device