Practical Experience with Multivariable Positivity Controllers

This paper presents a summary of our experience with the application of positivity designed multivariable controllers for the NASA ACES flexible beam experiment at NASA Marshall Space Flight Center. Multivariable controllers were designed using sets of rotational sensors/actuators (rate gyros/torque actuators) and linear sensors/actuators (accelerometers/LMED´s). Our experience with this set of controllers demonstrated the difficulty of designing controllers with significant modal uncertainty and significant phase uncertainty. With the aid of multivariable scaling techniques these designs were able to ultimately achieve a high level of closed loop damping.