Application of repetitive control to noncircular piston turning process

Noncircular pistons are becoming more and more popular in the automotive industry. The challenge of machining this kind of pistons lies in the rigorous demand of the cutting feed mechanism for large force generation, high stiffness, fast response, long stroke and high accuracy. To meet the requirements, a new piezoelectric actuator based fast tool servo mechanism is developed. The reference profile is repeated in nature during the noncircular piston turning process. To utilize this periodic characteristic, two repetitive controllers are designed, which are zero-phase-error-tracking control (ZPETC) and two-parameter robust repetitive control (TPRRC). Experimental results indicate that TPRRC has better tracking accuracy and disturbance rejection ability than ZPETC in the noncircular piston turning process.