Digital stability of the Furuta pendulum based on angle detection

The digital balancing of the Furuta pendulum is studied when the time delay related to the digital control and the dynamics of the actuator have essential effects on stability. Such cases occur when the sampling rate of the digital control is low, that is, the control cycles are slow due to complex signal processing strategies and/or the implementation of cheap low-capacity microprocessors. A corresponding difficulty is that no direct velocity measurement is available. Critical sampling times are identified and stability charts are constructed and validated by experiments including the possible existence of quasi-periodic self-excited oscillations.