Comparison of linear position and velocity control strategies for a direct servodrive

Direct servodrives are common in applications demanding high positioning accuracy, tracking precision and motion dynamics. The optimal control structure is the key factor in obtaining the performance desired. The study considers several linear position and velocity control strategies based on either PID position control or nested loop control with P position and PI velocity controllers. For the comparative analysis the two basic control structures were enhanced with additional filters, observers and predictors. The simulation results proved by experiment show that the proposed enhancement of a nested loop control structure with a Smith predictor increases the performance to that of a system with a PID control structure. The analysis shows that PID position control structure having high performance and low computing resource utilization can be recommended for exact tracking servo applications.