“…Implementation of low-pass filters and band-reject filters, an approach often adopted in the engineering practice to cope with structural resonances, is not effective for high-performance robots since low-pass filters introduce amplitude distortion and destabilizing phase lag, which deteriorates control performance, and bandreject filters are not suitable for applications where the resonance conditions shift during operation, change due to regular wear and tear, or vary because of production inconsistency. Brooks Automation has developed two innovative control concepts to The observer-corrector control strategy (Hosek et al, 2000(Hosek et al, , 2001Hosek, 2001a) has been developed for applications where undesirable resonance conditions appear at frequencies above the minimum bandwidth necessary for required operation of the robot. In this approach, the system subject to control is viewed in terms of its dominant dynamics, which is essential to achieve required functionality, and the resonance properties associated with higher-order dynamic effects, which are imposed on the dominant dynamics and considered to be unnecessary and undesirable for proper operation.…”