Elephants, goldfishes and SOUL: a dissertation on forgetfulness and control systems

Abstract: Adaptive Optics control systems accumulate differential measurements during closed loop operations to estimate turbulence and drive the deformable mirror. But have you ever wondered if your control system should be like an elephant, and never forget, or should it have a weak memory like a goldfish? Are measurement errors always zero mean or does static effects impact performance? Are commands high spatial frequencies good or are you wasting all the inter-actuator stroke for nothing? This work will try to answer these questions showing you results obtained during SOUL commissioning and analysing the impact of the values of the control system poles on Adaptive Optics. So be prepared to focus on forgetfulness and discover the advantages of being a goldfish in a digital world made of elephants.